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Pennington Kathleen A, Oestreich Arin K, Kylie H, Fogliatti Candace M, Celeste L, Lydon John P, Schulz Laura C. Conditional knockout of leptin receptor in the female reproductive tract reduces fertility due to parturition defects in mice. Biol Reprod 2022; 107:546-556. [PMID: 35349646 DOI: 10.1093/biolre/ioac062] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/23/2022] [Accepted: 03/18/2022] [Indexed: 11/13/2022] Open
Abstract
Leptin is required for fertility, including initiation of estrous cycles. It is therefore challenging to assess the role of leptin signaling during pregnancy. While neuron-specific transgene approaches suggest that leptin signaling in the central nervous system is most important, experiments with pharmacologic inhibition of leptin in the uterus or global replacement of leptin during pregnancy suggest leptin signaling in the reproductive tract may be required. Here, conditional leptin receptor knockout (Lepr cKO) with a progesterone receptor-driven Cre recombinase was used to examine the importance of leptin signaling in pregnancy. Lepr cKO mice have almost no leptin receptor in uterus or cervix, and slightly reduced leptin receptor levels in corpus luteum. Estrous cycles and progesterone concentrations were not affected by Lepr cKO. Numbers of viable embryos did not differ between primiparous control and Lepr cKO dams on days 6.5 and 17.5 of pregnancy, despite a slight reduction in the ratio of embryos to corpora lutea, showing that uterine leptin receptor signaling is not required for embryo implantation. Placentas of Lepr cKO dams had normal weight and structure. However, over four parities, Lepr cKO mice produced 22% fewer live pups than controls, and took more time from pairing to delivery by their fourth parity. Abnormal birth outcomes of either dystocia or dead pups occurred in 33% of Lepr cKO deliveries but zero control deliveries, and the average time to deliver each pup after crouching was significantly increased. Thus, leptin receptor signaling in the reproductive tract is required for normal labor and delivery. Summary sentence. Mice lacking leptin receptor in the reproductive tract produce fewer live pups and have more adverse labor outcomes than controls, but normal numbers of embryos near term, showing that leptin receptor signaling is required for normal parturition.
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Affiliation(s)
- A Pennington Kathleen
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, MO United States.,Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX United States
| | - K Oestreich Arin
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, MO United States
| | - Hohensee Kylie
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, MO United States
| | - M Fogliatti Candace
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, MO United States
| | - Lightner Celeste
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, MO United States
| | - P Lydon John
- Department of Molecular and Cell Biology, Baylor College of Medicine, Houston, TX United States
| | - C Schulz Laura
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri, Columbia, MO United States
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2
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Allensworth-James M, Banik J, Odle A, Hardy L, Lagasse A, Moreira ARS, Bird J, Thomas CL, Avaritt N, Kharas MG, Lengner CJ, Byrum SD, MacNicol MC, Childs GV, MacNicol AM. Control of the Anterior Pituitary Cell Lineage Regulator POU1F1 by the Stem Cell Determinant Musashi. Endocrinology 2021; 162:6054984. [PMID: 33373440 PMCID: PMC7814296 DOI: 10.1210/endocr/bqaa245] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Indexed: 12/14/2022]
Abstract
The adipokine leptin regulates energy homeostasis through ubiquitously expressed leptin receptors. Leptin has a number of major signaling targets in the brain, including cells of the anterior pituitary (AP). We have previously reported that mice lacking leptin receptors in AP somatotropes display growth hormone (GH) deficiency, metabolic dysfunction, and adult-onset obesity. Among other targets, leptin signaling promotes increased levels of the pituitary transcription factor POU1F1, which in turn regulates the specification of somatotrope, lactotrope, and thyrotrope cell lineages within the AP. Leptin's mechanism of action on somatotropes is sex dependent, with females demonstrating posttranscriptional control of Pou1f1 messenger RNA (mRNA) translation. Here, we report that the stem cell marker and mRNA translational control protein, Musashi1, exerts repression of the Pou1f1 mRNA. In female somatotropes, Msi1 mRNA and protein levels are increased in the mouse model that lacks leptin signaling (Gh-CRE Lepr-null), coincident with lack of POU1f1 protein, despite normal levels of Pou1f1 mRNA. Single-cell RNA sequencing of pituitary cells from control female animals indicates that both Msi1 and Pou1f1 mRNAs are expressed in Gh-expressing somatotropes, and immunocytochemistry confirms that Musashi1 protein is present in the somatotrope cell population. We demonstrate that Musashi interacts directly with the Pou1f1 mRNA 3' untranslated region and exerts translational repression of a Pou1f1 mRNA translation reporter in a leptin-sensitive manner. Musashi immunoprecipitation from whole pituitary reveals coassociated Pou1f1 mRNA. These findings suggest a mechanism in which leptin stimulation is required to reverse Musashi-mediated Pou1f1 mRNA translational control to coordinate AP somatotrope function with metabolic status.
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Affiliation(s)
- Melody Allensworth-James
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Jewel Banik
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Angela Odle
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Linda Hardy
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Alex Lagasse
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Ana Rita Silva Moreira
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Jordan Bird
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | | | - Nathan Avaritt
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | | | | | - Stephanie D Byrum
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Arkansas Children’s Research Institute, Little Rock, Arkansas, USA
| | - Melanie C MacNicol
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Gwen V Childs
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Angus M MacNicol
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
- Correspondence: Angus M. MacNicol, PhD, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, 4301 W Markham St, Little Rock, AR 72205, USA.
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3
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Allensworth-James ML, Odle AK, Lim J, LaGasse AN, Miles TK, Hardy LL, Haney AC, MacNicol MC, MacNicol AM, Childs GV. Metabolic signalling to somatotrophs: Transcriptional and post-transcriptional mediators. J Neuroendocrinol 2020; 32:e12883. [PMID: 32657474 PMCID: PMC8086172 DOI: 10.1111/jne.12883] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/17/2020] [Accepted: 06/10/2020] [Indexed: 12/19/2022]
Abstract
In normal individuals, pituitary somatotrophs optimise body composition by responding to metabolic signals from leptin. To identify mechanisms behind the regulation of somatotrophs by leptin, we used Cre-LoxP technology to delete leptin receptors (LEPR) selectively in somatotrophs and developed populations purified by fluorescence-activated cell sorting (FACS) that contained 99% somatotrophs. FACS-purified, Lepr-null somatotrophs showed reduced levels of growth hormone (GH), growth hormone-releasing hormone receptor (GHRHR), and Pou1f1 proteins and Gh (females) and Ghrhr (both sexes) mRNAs. Pure somatotrophs also expressed thyroid-stimulating hormone (TSH) and prolactin (PRL), both of which were reduced in pure somatotrophs lacking LEPR. This introduced five gene products that were targets of leptin. In the present study, we tested the hypothesis that leptin is both a transcriptional and a post-transcriptional regulator of these gene products. Our tests showed that Pou1f1 and/or the Janus kinase/signal transducer and activator of transcription 3 transcriptional regulatory pathways are implicated in the leptin regulation of Gh or Ghrhr mRNAs. We then focused on potential actions by candidate microRNAs (miRNAs) with consensus binding sites on the 3' UTR of Gh or Ghrhr mRNAs. Somatotroph Lepr-null deletion mutants expressed elevated levels of miRNAs including miR1197-3p (in females), miR103-3p and miR590-3p (both sexes), which bind Gh mRNA, or miRNA-325-3p (elevated in both sexes), which binds Ghrhr mRNA. This elevation indicates repression of translation in the absence of LEPR. In addition, after detecting binding sites for Musashi on Tshb and Prl 3' UTR, we determined that Musashi1 repressed translation of both mRNAs in in vitro fluc assays and that Prl mRNA was enriched in Musashi immunoprecipitation assays. Finally, we tested ghrelin actions to determine whether its nitric oxide-mediated signalling pathways would restore somatotroph functions in deletion mutants. Ghrelin did not restore either GHRH binding or GH secretion in vitro. These studies show an unexpectedly broad role for leptin with respect to maintaining somatotroph functions, including the regulation of PRL and TSH in subsets of somatotrophs that may be progenitor cells.
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Affiliation(s)
- Melody L Allensworth-James
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Angela K Odle
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Juchan Lim
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Alex N LaGasse
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Tiffany K Miles
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Linda L Hardy
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Anessa C Haney
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Melanie C MacNicol
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Angus M MacNicol
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Gwen V Childs
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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4
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Chi L, Li X, Liu Q, Liu Y. Photoperiod may regulate growth via leptin receptor A1 in the hypothalamus and saccus vasculosus of Atlantic salmon ( Salmo salar). Anim Cells Syst (Seoul) 2019; 23:200-208. [PMID: 31231584 PMCID: PMC6566995 DOI: 10.1080/19768354.2019.1595138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/14/2019] [Accepted: 02/17/2019] [Indexed: 10/27/2022] Open
Abstract
Photoperiod is believed to regulate growth in fish, although the mechanism involved is still unclear. In this paper, we report a relationship between leptin-receptor A1 (AsLRa1), melatonin-receptor (AsMR) and photoperiod in Atlantic salmon. Atlantic salmon (mean weight 1071.70 ± 155.54 g) were reared under six photoperiod regimes, four constant light regimes 24L:0D, 18L:6D, 12L:12D and 8L:16D, hours of light (L) and dark (D) and two varying light regimes, LL-SL = 24L:0D-8L:16D, and SL-LL = 8L:16D-24L:0D over a period of seven months. The results showed that AsLRa1 transcripts were mainly existed in the hypothalamus and saccus vasculosus (SV), AsMR was mainly expressed in the hypothalamus. Long photoperiod inhibited the expression of AsLRa1 and AsMR transcripts in the Atlantic salmon brain. The expression pattern of AsLRa1 was similar to the expression pattern of AsMR in the hypothalamus. Food intake was higher in fish with lower AsLRa1 transcript levels. This demonstrated that photoperiod influenced somatic growth by changing expression of AsLRa1 in the hypothalamus and SV to affect appetite. In addition, we found that the SV appears to act as a seasonal sensor regulating reproduction in a similar way to the hypothalamus.
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Affiliation(s)
- Liang Chi
- Qingdao Agricultural University, Qingdao, People's Republic of China
| | - Xian Li
- Institute of Oceanology Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Qinghua Liu
- Institute of Oceanology Chinese Academy of Sciences, Qingdao, People's Republic of China
| | - Ying Liu
- Institute of Oceanology Chinese Academy of Sciences, Qingdao, People's Republic of China
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5
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Gilloteaux J, Subramanian K, Solomon N, Nicaise C. The leptin receptor mutation of the obese Zucker rat causes sciatic nerve demyelination with a centripetal pattern defect. Ultrastruct Pathol 2018; 42:377-408. [PMID: 30339059 DOI: 10.1080/01913123.2018.1522405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Young male Zucker rats with a leptin receptor mutation are obese, have a non-insulin-dependent diabetes mellitus (NIDDM), and other endocrinopathies. Tibial branches of the sciatic nerve reveal a progressive demyelination that progresses out of the Schwann cells (SCs) where electron-contrast deposits are accumulated while the minor lines or intermembranous SC contacts display exaggerated spacings. Cajal bands contain diversely contrasted vesicles adjacent to the abaxonal myelin layer with blemishes; they appear dispatched centripetally out of many narrow electron densities, regularly spaced around the myelin annulus. These anomalies widen and yield into sectors across the stacked myelin layers. Throughout the worse degradations, the adaxonal membrane remains along the axonal neuroplasm. This peripheral neuropathy with irresponsive leptin cannot modulate hypothalamic-pituitary-adrenal axis and SC neurosteroids, thus exacerbates NIDDM condition. Additionally, the ultrastructure of the progressive myelin alterations may have unraveled a peculiar, centripetal mode of trafficking maintenance of the peripheral nervous system myelin, while some adhesive glycoproteins remain between myelin layers, somewhat hindering the axon mutilation. Heading title: Peripheral neuropathy and myelin.
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Affiliation(s)
- Jacques Gilloteaux
- a Department of Anatomical Sciences , St George's University School of Medicine, K.B. Taylor Global Scholar's Program at Northumbria University , Newcastle upon Tyne , UK.,b Unité de Recherche en Physiologie Moléculaire (URPhyM), Laboratoire de Neurodégénérescence et Régénération, Département de Médecine , Université de Namur , Namur , Belgium
| | - Kritika Subramanian
- a Department of Anatomical Sciences , St George's University School of Medicine, K.B. Taylor Global Scholar's Program at Northumbria University , Newcastle upon Tyne , UK.,c Department of Clinical and Epidemiological Virology , Rega Institute of Medical Research, Katholiele Universiteit Leuven , Leuven , Belgium
| | - Nadia Solomon
- a Department of Anatomical Sciences , St George's University School of Medicine, K.B. Taylor Global Scholar's Program at Northumbria University , Newcastle upon Tyne , UK
| | - Charles Nicaise
- b Unité de Recherche en Physiologie Moléculaire (URPhyM), Laboratoire de Neurodégénérescence et Régénération, Département de Médecine , Université de Namur , Namur , Belgium
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6
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Yan A, Chen Y, Chen S, Li S, Zhang Y, Jia J, Yu H, Liu L, Liu F, Hu C, Tang D, Chen T. Leptin Stimulates Prolactin mRNA Expression in the Goldfish Pituitary through a Combination of the PI3K/Akt/mTOR, MKK 3/6/p 38MAPK and MEK 1/2/ERK 1/2 Signalling Pathways. Int J Mol Sci 2017; 18:ijms18122781. [PMID: 29261147 PMCID: PMC5751379 DOI: 10.3390/ijms18122781] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/09/2017] [Accepted: 12/17/2017] [Indexed: 12/17/2022] Open
Abstract
Leptin actions at the pituitary level have been extensively investigated in mammalian species, but remain insufficiently characterized in lower vertebrates, especially in teleost fish. Prolactin (PRL) is a pituitary hormone of central importance to osmoregulation in fish. Using goldfish as a model, we examined the global and brain-pituitary distribution of a leptin receptor (lepR) and examined the relationship between expression of lepR and major pituitary hormones in different pituitary regions. The effects of recombinant goldfish leptin-AI and leptin-AII on PRL mRNA expression in the pituitary were further analysed, and the mechanisms underlying signal transduction for leptin-induced PRL expression were determined by pharmacological approaches. Our results showed that goldfish lepR is abundantly expressed in the brain-pituitary regions, with highly overlapping PRL transcripts within the pituitary. Recombinant goldfish leptin-AI and leptin-AII proteins could stimulate PRL mRNA expression in dose- and time-dependent manners in the goldfish pituitary, by both intraperitoneal injection and primary cell incubation approaches. Moreover, the PI3K/Akt/mTOR, MKK3/6/p38MAPK, and MEK1/2/ERK1/2—but not JAK2/STAT 1, 3 and 5 cascades—were involved in leptin-induced PRL mRNA expression in the goldfish pituitary.
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Affiliation(s)
- Aifen Yan
- Foshan University, Foshan 528000, China.
| | | | - Shuang Chen
- The Beijing Genomics Institute (BGI), Shenzhen 518083, China.
| | - Shuisheng Li
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals, and the Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Yong Zhang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals, and the Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Jirong Jia
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals, and the Guangdong Province Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Hui Yu
- Foshan University, Foshan 528000, China.
| | - Lian Liu
- Foshan University, Foshan 528000, China.
| | - Fang Liu
- Foshan University, Foshan 528000, China.
| | - Chaoqun Hu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
| | | | - Ting Chen
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
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7
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Leeners B, Geary N, Tobler PN, Asarian L. Ovarian hormones and obesity. Hum Reprod Update 2017; 23:300-321. [PMID: 28333235 DOI: 10.1093/humupd/dmw045] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 11/23/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Obesity is caused by an imbalance between energy intake, i.e. eating and energy expenditure (EE). Severe obesity is more prevalent in women than men worldwide, and obesity pathophysiology and the resultant obesity-related disease risks differ in women and men. The underlying mechanisms are largely unknown. Pre-clinical and clinical research indicate that ovarian hormones may play a major role. OBJECTIVE AND RATIONALE We systematically reviewed the clinical and pre-clinical literature on the effects of ovarian hormones on the physiology of adipose tissue (AT) and the regulation of AT mass by energy intake and EE. SEARCH METHODS Articles in English indexed in PubMed through January 2016 were searched using keywords related to: (i) reproductive hormones, (ii) weight regulation and (iii) central nervous system. We sought to identify emerging research foci with clinical translational potential rather than to provide a comprehensive review. OUTCOMES We find that estrogens play a leading role in the causes and consequences of female obesity. With respect to adiposity, estrogens synergize with AT genes to increase gluteofemoral subcutaneous AT mass and decrease central AT mass in reproductive-age women, which leads to protective cardiometabolic effects. Loss of estrogens after menopause, independent of aging, increases total AT mass and decreases lean body mass, so that there is little net effect on body weight. Menopause also partially reverses women's protective AT distribution. These effects can be counteracted by estrogen treatment. With respect to eating, increasing estrogen levels progressively decrease eating during the follicular and peri-ovulatory phases of the menstrual cycle. Progestin levels are associated with eating during the luteal phase, but there does not appear to be a causal relationship. Progestins may increase binge eating and eating stimulated by negative emotional states during the luteal phase. Pre-clinical research indicates that one mechanism for the pre-ovulatory decrease in eating is a central action of estrogens to increase the satiating potency of the gastrointestinal hormone cholecystokinin. Another mechanism involves a decrease in the preference for sweet foods during the follicular phase. Genetic defects in brain α-melanocycte-stimulating hormone-melanocortin receptor (melanocortin 4 receptor, MC4R) signaling lead to a syndrome of overeating and obesity that is particularly pronounced in women and in female animals. The syndrome appears around puberty in mice with genetic deletions of MC4R, suggesting a role of ovarian hormones. Emerging functional brain-imaging data indicates that fluctuations in ovarian hormones affect eating by influencing striatal dopaminergic processing of flavor hedonics and lateral prefrontal cortex processing of cognitive inhibitory controls of eating. There is a dearth of research on the neuroendocrine control of eating after menopause. There is also comparatively little research on the effects of ovarian hormones on EE, although changes in ovarian hormone levels during the menstrual cycle do affect resting EE. WIDER IMPLICATIONS The markedly greater obesity burden in women makes understanding the diverse effects of ovarian hormones on eating, EE and body adiposity urgent research challenges. A variety of research modalities can be used to investigate these effects in women, and most of the mechanisms reviewed are accessible in animal models. Therefore, human and translational research on the roles of ovarian hormones in women's obesity and its causes should be intensified to gain further mechanistic insights that may ultimately be translated into novel anti-obesity therapies and thereby improve women's health.
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Affiliation(s)
- Brigitte Leeners
- Division of Reproductive Endocrinology, University Hospital Zurich, Frauenklinikstr. 10, CH 8091 Zurich, Switzerland.,Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland
| | - Nori Geary
- Department of Psychiatry, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Philippe N Tobler
- Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland.,Laboratory for Social and Neural Systems Research, Department of Economics, University of Zurich, 8006 Zurich, Switzerland
| | - Lori Asarian
- Center for Integrative Human Physiology (ZIHP), University of Zurich, 8057 Zurich, Switzerland.,Institute of Veterinary Physiology, University of Zurich, 8057 Zurich, Switzerland
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Tuersunjiang N, Odhiambo JF, Shasa DR, Smith AM, Nathanielsz PW, Ford SP. Maternal obesity programs reduced leptin signaling in the pituitary and altered GH/IGF1 axis function leading to increased adiposity in adult sheep offspring. PLoS One 2017; 12:e0181795. [PMID: 28771488 PMCID: PMC5542597 DOI: 10.1371/journal.pone.0181795] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 07/09/2017] [Indexed: 11/29/2022] Open
Abstract
Studies in rodents highlight a role for leptin in stimulation of pituitary growth hormone (GH) secretion, with an impact on body composition regulation. We have reported that maternal obesity (MO) during ovine pregnancy results in hyperphagia, glucose-insulin dysregulation, increased adiposity, hypercortisolemia and hyperleptinemia in mature offspring subjected to a bout of ad libitum feeding. We hypothesized that MO reduces leptin signaling in the pituitary and down regulates the GH/IGF1 axis and increases circulating cortisol leading to increased adiposity in their adult offspring. Male lambs born to MO (n = 6) or control (CON, n = 6) ewes were fed only to requirements until placed on a 12 week ad libitum feeding trial at maturity. The pituitary, hypothalamic arcuate nucleus, and liver were collected at necropsy and mRNA and protein expression determined. Plasma cortisol concentrations were increased (P<0.05) in MO vs. CON offspring at the end of the feeding trial. Further, serum concentrations of IGF1 decreased (P<0.01) and GH tended to decrease (P<0.08) in MO vs. CON offspring. Pituitary mRNA and leptin receptor protein expression were decreased in MO vs. CON offspring in association with decreased GH mRNA expression, and decreased IGF1 mRNA and protein expression in liver. Liver 11β-hydroxysteroid dehydrogenase 1 (11βHSD1) expression was increased (P<0.01) and its cofactor hexose-6-phosphate dehydrogenase tended to increase (P<0.06) in MO vs. CON offspring. 11βHSD2 expression remained unchanged. These data indicate that MO induced an increase in liver conversion of cortisone to cortisol in adult offspring and support a role for leptin signaling in the pituitary in mediating offspring adiposity.
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Affiliation(s)
- Nuermaimaiti Tuersunjiang
- Center for the Study of Fetal Programming, Department of Animal Science, University of Wyoming, Laramie, Wyoming, United States of America
| | - John F. Odhiambo
- Center for the Study of Fetal Programming, Department of Animal Science, University of Wyoming, Laramie, Wyoming, United States of America
| | - Desiree R. Shasa
- Center for the Study of Fetal Programming, Department of Animal Science, University of Wyoming, Laramie, Wyoming, United States of America
| | - Ashley M. Smith
- Center for the Study of Fetal Programming, Department of Animal Science, University of Wyoming, Laramie, Wyoming, United States of America
| | - Peter W. Nathanielsz
- Center for the Study of Fetal Programming, Department of Animal Science, University of Wyoming, Laramie, Wyoming, United States of America
| | - Stephen P. Ford
- Center for the Study of Fetal Programming, Department of Animal Science, University of Wyoming, Laramie, Wyoming, United States of America
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9
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Bello AR, Puertas‐Avendaño RA, González‐Gómez MJ, González‐Gómez M, Laborda J, Damas C, Ruiz‐Hidalgo M, Diaz C. Delta-like protein 1 in the pituitary-adipose axis in the adult male mouse. J Neuroendocrinol 2017; 29:e12507. [PMID: 28718206 PMCID: PMC6084355 DOI: 10.1111/jne.12507] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 06/21/2017] [Accepted: 07/12/2017] [Indexed: 12/18/2022]
Abstract
With the aim of studying delta-like protein 1 (DLK1) with respect to the relationship between adipocyte leptin and adenohypophyseal hormones, we carried out an immunohistochemical study analysing the presence of receptors for these hormones in the pituitary and adipose cells of male wild-type (WT) mice (Dlk1+/+ ) compared to knockout (KO) mice (Dlk1-/- ). The mRNA expression of these molecules was also determined using the reverse transcriptase-polymerase chain reaction. The results obtained showed that, in WT adipose cells, all of the adenohypophyseal hormone receptors were present, with a higher mRNA expression for growth hormone (GH) receptor and thyroid-stimulating hormone (TSH) receptor. Of the total cells in the anterior pituitary lobe, 17.09±0.9% were leptin receptor (LEPR) immunoreactive (-IR), mainly in GH-IR and prolactin (PRL)-IR cells (41.5±3.8%; 13.5±1.7%, respectively). In Dlk1-/- mice, adipocyte cells showed a significant increase in the TSH receptor mRNA expression level. Moreover, the percentage of LEPR-IR GH cells showed a statistically significant increase compared to controls, from 41.5±3.8% to 53.1±4.0%. By contrast, only 3.0±0.6% of LEP-IR anterior pituitary cells were detected in Dlk1 KO mice, as opposed to 6.8±1.1% observed in WT mice. The results suggest that relationships exist between adipocytes and pituitary GH, PRL and TSH cells, in addition to an influence with respect to the synthesis and release of pituitary leptin, particularly in PRL cells.
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Affiliation(s)
- A. R. Bello
- Cell Biology SectionSchool of Sciences/Institute for Tropical Diseases and Public HealthUniversity of La LagunaTenerifeSpain
| | - R. A. Puertas‐Avendaño
- Cell Biology SectionSchool of Sciences/Institute for Tropical Diseases and Public HealthUniversity of La LagunaTenerifeSpain
| | - M. J. González‐Gómez
- Department of Inorganic and Organic Chemistry and BiochemistrySchool of Medicine/Regional Centre for Biomedical ResearchBiomedicine Unit Spanish National Research Council/University of Castilla‐La ManchaAlbaceteSpain
| | - M. González‐Gómez
- Department of Basic Medical SciencesSchool of MedicineUniversity of La LagunaTenerifeSpain
| | - J. Laborda
- Department of Inorganic and Organic Chemistry and BiochemistrySchool of Medicine/Regional Centre for Biomedical ResearchBiomedicine Unit Spanish National Research Council/University of Castilla‐La ManchaAlbaceteSpain
| | - C. Damas
- Department of PsychobiologySchool of PsychologyUniversity of La LagunaTenerifeSpain
| | - M. Ruiz‐Hidalgo
- Department of Inorganic and Organic Chemistry and BiochemistrySchool of Medicine/Regional Centre for Biomedical ResearchBiomedicine Unit Spanish National Research Council/University of Castilla‐La ManchaAlbaceteSpain
| | - C. Diaz
- Department of Medical SciencesSchool of Medicine/Institute for Research in Neurological DisabilitiesUniversity of Castilla‐La ManchaAlbaceteSpain
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Wu Y, Wang J, Cai W, Shen X. Could tea polyphenols be beneficial for preventing the precocious puberty? Med Hypotheses 2016; 95:24-26. [PMID: 27692159 DOI: 10.1016/j.mehy.2016.07.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 07/18/2016] [Indexed: 11/17/2022]
Abstract
Precocious puberty which impacts children physically and psychologically has become one of the health problem over the world. However, the mechanism and preventive measures of precocious puberty is still not clear. Recent studies suggested that leptin may act as the 'permissive factor' to initiate the puberty by regulating gonadotrophin-releasing hormone secretion. Previous evidence from animal and human studies found that tea polyphenols can reduce serum leptin levels in vivo and inhibit the expression of leptin in adipose tissue. This article focus on whether tea polyphenols could delay the onset of puberty by reducing leptin levels. To verify the possibility of tea polyphenols on preventing precocious puberty, animal experiment can be used. Our hypothesis that tea polyphenols could prevent the precocious puberty may provide important potential way for the prevention and control of children precocious puberty.
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Affiliation(s)
- Youmei Wu
- Department of Nutrition, School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Jialu Wang
- Department of Nutrition, School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Wei Cai
- Department of Nutrition, School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China; Department of Clinical Nutrition, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Xiuhua Shen
- Department of Nutrition, School of Public Health, Shanghai Jiao Tong University, Shanghai 200025, China; Department of Clinical Nutrition, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China.
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11
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McDuffie IA, Akhter N, Childs GV. Regulation of Leptin mRNA and Protein Expression in Pituitary Somatotropes. J Histochem Cytochem 2016; 52:263-73. [PMID: 14729878 DOI: 10.1177/002215540405200214] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Leptin, the ob protein, regulates food intake and satiety and can be found in the anterior pituitary. Leptin antigens and mRNA were studied in the anterior pituitary (AP) cells of male and female rats to learn more about its regulation. Leptin antigens were found in over 40% of cells in diestrous or proestrous female rats and in male rats. Lower percentages of AP cells were seen in the estrous population (21 ± 7%). During peak expression of antigens, co-expression of leptin and growth hormone (GH) was found in 27 ± 4% of AP cells. Affinity cytochemistry studies detected 24 ± 3% of AP cells with leptin proteins and growth hormone releasing hormone (GHRH) receptors. These data suggested that somatotropes were a significant source of leptin. To test regulatory factors, estrous and diestrous AP populations were treated with estrogen (100 pM) and/or GHRH (2 nM) to learn if either would increase leptin expression in GH cells. To rule out the possibility that the immunoreactive leptin was bound to receptors in somatotropes, leptin mRNA was also detected by non-radioactive in situ hybridization in this group of cells. In estrous female rats, 39 ± 0.9% of AP cells expressed leptin mRNA, indicating that the potential for leptin production was greater than predicted from the immunolabeling. Estrogen and GHRH together (but not alone) increased percentages of cells with leptin protein (41 ± 9%) or mRNA (57 ± 5%). Estrogen and GHRH also increased the percentages of AP cells that co-express leptin mRNA and GH antigens from 20 ± 2% of AP cells to 37 ± 5%. Although the significance of leptin in GH cells is not understood, it is clearly increased after stimulation with GHRH and estrogen. Because GH cells also have leptin receptors, this AP leptin may be an autocrine or paracrine regulator of pituitary cell function.
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Affiliation(s)
- Iris A McDuffie
- Department of Nutrition, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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12
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Allensworth-James ML, Odle A, Haney A, Childs G. Sex Differences in Somatotrope Dependency on Leptin Receptors in Young Mice: Ablation of LEPR Causes Severe Growth Hormone Deficiency and Abdominal Obesity in Males. Endocrinology 2015; 156:3253-64. [PMID: 26168341 PMCID: PMC4541611 DOI: 10.1210/en.2015-1198] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Leptin receptor (LEPR) signaling controls appetite and energy expenditure. Somatotrope-specific deletion of the LEPRb signaling isoform causes GH deficiency and obesity. The present study selectively ablated Lepr exon 1 in somatotropes, which removes the signal peptide, causing the loss of all isoforms of LEPR. Excision of Lepr exon 1 was restricted to the pituitary, and mutant somatotropes failed to respond to leptin. Young (2-3 mo) males showed a severe 84% reduction in serum GH levels and more than 60% reduction in immunolabeled GH cells compared with 41%-42% reductions in GH and GH cells in mutant females. Mutant males (35 d) and females (45 d) weighed less than controls and males had lower lean body mass. Image analysis of adipose tissue by magnetic resonance imaging showed that young males had a 2-fold increase in abdominal fat mass and increased adipose tissue density. Young females had only an overall increase in adipose tissue. Both males and females showed lower energy expenditure and higher respiratory quotient, indicating preferential carbohydrate burning. Young mutant males slept less and were more restless during the dark phase, whereas the opposite was true of females. The effects of a Cre-bearing sire on his non-Cre-recombinase bearing progeny are seen by increased respiratory quotient and reduced litter sizes. These studies elucidate clear sex differences in the extent to which somatotropes are dependent on all isoforms of LEPR. These results, which were not seen with the ablation of Lepr exon 17, highlight the severe consequences of ablation of LEPR in male somatotropes.
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Affiliation(s)
- Melody L Allensworth-James
- Department of Neurobiology and Developmental Sciences, College of Medicine University of Arkansas for Medical Sciences, Little Rock, Arkansas 72212
| | - Angela Odle
- Department of Neurobiology and Developmental Sciences, College of Medicine University of Arkansas for Medical Sciences, Little Rock, Arkansas 72212
| | - Anessa Haney
- Department of Neurobiology and Developmental Sciences, College of Medicine University of Arkansas for Medical Sciences, Little Rock, Arkansas 72212
| | - Gwen Childs
- Department of Neurobiology and Developmental Sciences, College of Medicine University of Arkansas for Medical Sciences, Little Rock, Arkansas 72212
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Akhter N, CarlLee T, Syed MM, Odle AK, Cozart MA, Haney AC, Allensworth-James ML, Beneš H, Childs GV. Selective deletion of leptin receptors in gonadotropes reveals activin and GnRH-binding sites as leptin targets in support of fertility. Endocrinology 2014; 155:4027-42. [PMID: 25057790 PMCID: PMC4164926 DOI: 10.1210/en.2014-1132] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The adipokine, leptin (LEP), is a hormonal gateway, signaling energy stores to appetite-regulatory neurons, permitting reproduction when stores are sufficient. Dual-labeling for LEP receptors (LEPRs) and gonadotropins or GH revealed a 2-fold increase in LEPR during proestrus, some of which was seen in LH gonadotropes. We therefore investigated LEPR functions in gonadotropes with Cre-LoxP technology, deleting the signaling domain of the LEPR (Lepr-exon 17) with Cre-recombinase driven by the rat LH-β promoter (Lhβ-cre). Selectivity of the deletion was validated by organ genotyping and lack of LEPR and responses to LEP by mutant gonadotropes. The mutation had no impact on growth, body weight, the timing of puberty, or pregnancy. Mutant females took 36% longer to produce their first litter and had 50% fewer pups/litter. When the broad impact of the loss of gonadotrope LEPR on all pituitary hormones was studied, mutant diestrous females had reduced serum levels of LH (40%), FSH (70%), and GH (54%) and mRNA levels of Fshβ (59%) and inhibin/activin β A and β B (25%). Mutant males had reduced serum levels of GH (74%), TSH (31%), and prolactin (69%) and mRNA levels of Gh (31%), Ghrhr (30%), Fshβ (22%), and glycoprotein α-subunit (Cga) (22%). Serum levels of LEP and ACTH and mRNA levels of Gnrhr were unchanged. However, binding to GnRH receptors was reduced in LEPR-null LH or FSH gonadotropes by 82% or 89%, respectively, in females (P < .0001) and 27% or 53%, respectively, in males (P < .03). This correlated with reductions in GnRH receptor protein immunolabeling, suggesting that LEP's actions may be posttranscriptional. Collectively, these studies highlight the importance of LEP to gonadotropes with GnRH-binding sites and activin as potential targets. LEP may modulate population growth, adjusting the number of offspring to the availability of food supplies.
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Affiliation(s)
- Noor Akhter
- Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
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Orlik B, Madej P, Owczarek A, Skałba P, Chudek J, Olszanecka-Glinianowicz M. Plasma omentin and adiponectin levels as markers of adipose tissue dysfunction in normal weight and obese women with polycystic ovary syndrome. Clin Endocrinol (Oxf) 2014; 81:529-35. [PMID: 24392647 DOI: 10.1111/cen.12381] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 09/22/2013] [Accepted: 12/04/2013] [Indexed: 12/14/2022]
Abstract
OBJECTIVE It is suggested that disturbed adipokines release plays a role in PCOS pathogenesis. The aim of this study was to assess plasma levels of omentin and adiponectin as well as the omentin to adiponectin ratio, as markers of adipose tissue dysfunction in relation to hormonal or metabolic changes in PCOS. STUDY DESIGN, PATIENTS AND MEASUREMENTS A cross-sectional study involved 87 PCOS (48 obese) and 72 non-PCOS women (41 obese). Anthropometric parameters and body composition were determined, and serum glucose, hormones, omentin-1 and adiponectin levels were measured. RESULTS The adiponectin level was similar in PCOS and non-PCOS groups, but, in both, was significantly lower in obese compared with normal weight subgroups, while the omentin-1 level was significantly lower in the PCOS compared with the non-PCOS group, and not related to body mass. The adiponectin to omentin-1 ratio (AOR) was significantly higher in the PCOS than non-PCOS group. Moreover, AOR was significantly higher in the normal weight than in obese subgroups in both PCOS and non-PCOS groups. Multiple regression analyses revealed that AOR variability is explained by oestradiol level and all anthropometric parameters as well as FAI, but not LH to FSH and HOMA-IR values. CONCLUSIONS Our results suggest secondary to insulin resistance and hyperandrogenism impairment of hormonal stroma adipose tissue function in PCOS, independent of nutritional status. Contrarily, the adipocyte hormonal dysfunction is primarily dependent on excessive fat accumulation. It seems that the AOR may be useful in the assessment of adipose tissue dysfunction not only in PCOS.
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Affiliation(s)
- Bartłomiej Orlik
- Health Promotion and Obesity Management Unit, Department of Pathophysiology, Medical University of Silesia, Katowice, Poland
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15
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Duarte S, Gomes-Filho M, Silva D, Silva L, Oliveira C, Rodrigues F, Silva A, Fernandes C, Silva C, Rondina D. Expressão gênica de adipocinas em ovelhas alimentadas com resíduos da indústria do biodiesel da mamona. ARQ BRAS MED VET ZOO 2014. [DOI: 10.1590/1678-6355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A expressão de RNAm para leptina, receptor de leptina (obRb), adiponectina, receptor de adiponectina (AdipoR1) e resistina foi avaliada por meio da técnica de PCR em tempo real, em tecidos ovariano, hipofisário, adiposo do omento e da região perirrenal, em ovelhas alimentadas sem farelo de mamona ou com farelo de mamona detoxificada durante 14 meses. O tipo de dieta não afetou os níveis de RNAm para leptina, obRb, adiponectina, AdipoR1 e resistina nos diferentes tecidos avaliados (P>0,05). Nos tecidos ovariano e hipofisário, não foi verificada a expressão da adiponecina e da resistina, respectivamente. Como consequência, pode-se concluir que o farelo de mamona detoxificada pode ser utilizado como fonte proteica na dieta de ovelhas, sem afetar a expressão do gene resistina e dos genes leptina e adiponectina, bem como de seus receptores.
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Affiliation(s)
| | | | - D.M.F. Silva
- Universidade Federal Rural de Pernambuco, Brasil
| | | | | | | | | | | | | | - D. Rondina
- Universidade Estadual do Ceará, Brazil.; CNPq, Brasil
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16
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Di Yorio MP, Bilbao MG, Faletti AG. Neuropeptide Y regulates the leptin receptors in rat hypothalamic and pituitary explant cultures. ACTA ACUST UNITED AC 2014; 188:13-20. [DOI: 10.1016/j.regpep.2013.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 11/05/2013] [Accepted: 11/19/2013] [Indexed: 01/01/2023]
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17
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Olszanecka-Glinianowicz M, Madej P, Nylec M, Owczarek A, Szanecki W, Skałba P, Chudek J. Circulating apelin level in relation to nutritional status in polycystic ovary syndrome and its association with metabolic and hormonal disturbances. Clin Endocrinol (Oxf) 2013. [PMID: 23199261 DOI: 10.1111/cen.12120] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE The aim of the study was to analyse relationships between plasma apelin-36 and apelin-12 levels, nutritional status, insulin resistance and hormonal disturbances, as well as plasma adiponectin, leptin and resistin concentrations in PCOS women. STUDY DESIGN PATIENTS AND MEASUREMENTS A cross-sectional study involving 87 PCOS (48 obese) and 67 non-PCOS women (36 obese). Anthropometric parameters and body composition were determined. Serum glucose, androgens, FSH, LH, SHBG, insulin, apelin-36, apelin-12, adiponectin, leptin and resistin were measured in the fasting state. RESULTS Plasma apelin-36 and apelin-12 levels were significantly higher in normal weight women than in the obese women with PCOS (3·1 ± 2·2 vs 1·2 ± 0·7 μg/l, P < 0·001; 2·9 ± 2·4 vs 0·5 ± 0·7 μg/l; P < 0·001 respectively). Both plasma apelin-36 and -12 levels correlated positively with adiponectin levels, and inversely with leptin or resistin levels. There was a negative correlation between plasma apelin-36, apelin-12 and serum LH levels. In addition, an inverse correlation between apelin-12 level and LH to FSH ratio was found. In multiple regression analysis 9% of LH variability was explained by apelin-12 levels (β = -0·14; P < 0·001). CONCLUSIONS Nutritional status seems to have different effects on apelin release, particularly, its active isoform, in women with PCOS compared with women without PCOS. This may be partially caused by changes in leptin and resistin secretion and may enhance pituitary-ovarian axis disturbances. The association between both isoforms of apelin and insulin resistance seems to be bidirectional.
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18
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Li C, Ramahi E, Nijland MJ, Choi J, Myers DA, Nathanielsz PW, McDonald TJ. Up-regulation of the fetal baboon hypothalamo-pituitary-adrenal axis in intrauterine growth restriction: coincidence with hypothalamic glucocorticoid receptor insensitivity and leptin receptor down-regulation. Endocrinology 2013; 154:2365-73. [PMID: 23625543 PMCID: PMC3689287 DOI: 10.1210/en.2012-2111] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Intrauterine growth restriction (IUGR) is an important fetal developmental problem resulting from 2 broad causes: maternal undernutrition and/or decreased fetal nutrient delivery to the fetus via placental insufficiency. IUGR is often accompanied by up-regulation of the hypothalamo-pituitary-adrenal axis (HPAA). Sheep studies show fetal HPAA autonomy in late gestation. We hypothesized that IUGR, resulting from poor fetal nutrient delivery, up-regulates the fetal baboon HPAA in late gestation, driven by hypothalamo-pituitary glucocorticoid receptor (GR) insensitivity and decreased fetal leptin in peripheral plasma. Maternal baboons were fed as ad libitum controls or nutrient restricted to produce IUGR (fed 70% of the control diet) from 0.16 to 0.9 gestation. Peripheral ACTH, cortisol, and leptin were measured by immunoassays. CRH, arginine vasopressin (AVP), GR, leptin receptor (ObRb), and pro-opiomelanocortin peptide expression were determined immunohistochemically. IUGR fetal peripheral cortisol and ACTH, but not leptin, were increased (P < .05). IUGR increased CRH peptide expression, but not AVP, in the fetal hypothalamic paraventricular nucleus (PVN) and median eminence (P < .05). PVN ObRb peptide expression, but not GR, was decreased (P < .05) with IUGR. ObRb and pro-opiomelanocortin were robustly expressed in the anterior pituitary gland, but ∼1% of cells showed colocalization. We conclude that (1) CRH, not AVP, is the major releasing hormone driving ACTH and cortisol secretion during primate IUGR, (2) fetal HPAA activation was aided by GR insensitivity and decreased ObRb expression in the PVN, and (3) the anterior pituitary is not a site for ObRb effects on the HPAA.
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Affiliation(s)
- Cun Li
- The University of Texas Health Science Center San Antonio, Center for Pregnancy and Newborn Research, Department of Obstetrics and Gynecology San Antonio, TX 78229, USA
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Bilbao MG, Di Yorio MP, Faletti AG. Different levels of leptin regulate different target enzymes involved in progesterone synthesis. Fertil Steril 2013; 99:1460-6. [PMID: 23332974 DOI: 10.1016/j.fertnstert.2012.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/29/2012] [Accepted: 12/10/2012] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To study the effects of different doses of leptin on the expression of proteins involved in P synthesis, such as steroidogenic acute regulatory protein (StAR), cytochrome P450 side chain cleavage (P450scc), and 3β-hydroxysteroid dehydrogenase (3βHSD). DESIGN Experimental studies. SETTING Research laboratory. ANIMAL(S) Immature rats primed with gonadotropins to induce ovulation. INTERVENTION(S) In vivo studies: rats received either an acute or daily treatment with leptin. In vitro studies: ovarian explants were cultured in the absence or presence of leptin (0.3-500 ng/mL). MAIN OUTCOME MEASURE(S) The expression of both messenger RNA and protein of StAR, P450scc, and 3βHSD were measured by reverse transcription-polymerase chain reaction (PCR) and Western blot, respectively. RESULT(S) The acute treatment with leptin, which inhibits the ovulatory process, caused a significant reduction in the ovarian expression of P450scc without changes in StAR or 3βHSD. In contrast, the daily treatment, which induces the ovulatory process, showed an increased expression of the ovarian 3βHSD protein, without differences in the other proteins measured. We also found that leptin increased the protein of both P450scc and 3βHSD at physiological levels and inhibited both messenger RNA and protein of 3βHSD at higher concentrations. CONCLUSION(S) The results indicate that 1) leptin is able to regulate the expression of the 3βHSD protein in a dose-dependent manner; and 2) leptin seems to exert its dual effects on P synthesis on different targets in a dose-dependent manner.
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Affiliation(s)
- María Guillermina Bilbao
- Centro de Estudios Farmacológicos y Botánicos (CEFYBO-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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Calvino C, Souza LL, Costa-e-Sousa RH, Almeida NAS, Trevenzoli IH, Pazos-Moura CC. Hypothyroidism reduces ObRb-STAT3 leptin signalling in the hypothalamus and pituitary of rats associated with resistance to leptin acute anorectic action. J Endocrinol 2012; 215:129-35. [PMID: 22875962 DOI: 10.1530/joe-11-0476] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Leptin has been shown to regulate the hypothalamus-pituitary-thyroid axis, acting primarily through the STAT3 pathway triggered through the binding of leptin to the long-chain isoform of the leptin receptor, ObRb. We previously demonstrated that although hyperthyroid rats presented leptin effects on TSH secretion, those effects were abolished in hypothyroid rats. We addressed the hypothesis that changes in the STAT3 pathway might explain the lack of TSH response to leptin in hypothyroidism by evaluating the protein content of components of leptin signalling via the STAT3 pathway in the hypothalamus and pituitary of hypothyroid (0·03% methimazole in the drinking water/21 days) and hyperthyroid (thyroxine 5 μg/100 g body weight /5 days) rats. Hypothyroid rats exhibited decreased ObRb and phosphorylated STAT3 (pSTAT3) protein in the hypothalamus, and in the pituitary gland they exhibited decreased ObRb, total STAT3, pSTAT3 and SOCS3 (P<0·05). Except for a modest decrease in pituitary STAT3, no other alterations were observed in hyperthyroid rats. Moreover, unlike euthyroid rats, the hypothyroid rats did not exhibit a reduction in food ingestion after a single injection of leptin (0·5 mg/kg body weight). Therefore, hypothyroidism decreased ObRb-STAT3 signalling in the hypothalamus and pituitary gland, which likely contributes to the loss of leptin action on food intake and TSH secretion, as previously observed in hypothyroid rats.
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Affiliation(s)
- Camila Calvino
- Laboratório de Endocrinologia Molecular, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Edificio do Centro de Ciencias da Saude, Bloco G CEP 21941-902, Rio de Janeiro, Brazil
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21
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Akhter N, Odle AK, Allensworth-James ML, Haney AC, Syed MM, Cozart MA, Chua S, Kineman R, Childs GV. Ablation of leptin signaling to somatotropes: changes in metabolic factors that cause obesity. Endocrinology 2012; 153:4705-15. [PMID: 22865370 PMCID: PMC3512011 DOI: 10.1210/en.2012-1331] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 07/12/2012] [Indexed: 01/22/2023]
Abstract
Mice with somatotrope-specific deletion of the Janus kinase binding site in leptin receptors are GH deficient as young adults and become obese by 6 months of age. This study focused on the metabolic status of young (3-4.5 month old) preobese mutant mice. These mutants had normal body weights, lean body mass, serum leptin, glucose, and triglycerides. Mutant males and females showed significantly higher respiratory quotients (RQ) and lower energy output, resulting from a higher volume of CO(2) output and lower volume of O(2) consumption. Deletion mutant females were significantly less active than controls; they had higher levels of total serum ghrelin and ate more food. Mutant females also had lower serum insulin and higher glucagon. In contrast, deletion mutant males were not hyperphagic, but they were more active and spent less time sleeping. Adiponectin and resistin, both products of adipocytes, were increased in male and female mutant mice. In addition, mutant males showed an increase in circulating levels of the potent lipogenic hormone, glucose-dependent insulinotropic peptide. Taken together, these results indicate that mutant mice may become obese due to a reduction in lipid oxidation and energy expenditure. This may stem from GH deficiency. Reduced fat oxidation and enhanced insulin sensitivity (in females) are directly related to GH deficiency in mutant mice because GH has been shown by others to increase insulin sensitivity and fat oxidation and reduce carbohydrate oxidation. Gender-dependent alterations in metabolic signals may further exacerbate the future obese phenotype and affect the timing of its onset. Females show a delay in onset of obesity, perhaps because of their low serum insulin, which is lipogenic, whereas young males already have higher levels of the lipogenic hormone, glucose-dependent insulinotropic peptide. These findings signify that leptin signals to somatotropes are vital for the normal metabolic activity needed to optimize body composition.
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Affiliation(s)
- Noor Akhter
- Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
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22
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Roubos EW, Dahmen M, Kozicz T, Xu L. Leptin and the hypothalamo-pituitary-adrenal stress axis. Gen Comp Endocrinol 2012; 177:28-36. [PMID: 22293575 DOI: 10.1016/j.ygcen.2012.01.009] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/20/2022]
Abstract
Leptin is a 16-kDa protein mainly produced and secreted by white adipose tissue and informing various brain centers via leptin receptor long and short forms about the amount of fat stored in the body. In this way leptin exerts a plethora of regulatory functions especially related to energy intake and metabolism, one of which is controlling the activity of the hypothalamo-pituitary-adrenal (HPA) stress axis. First, this review deals with the basic properties of leptin's structure and signaling at the organ, cell and molecule level, from lower vertebrates to humans but with emphasis on rodents because these have been investigated in most detail. Then, attention is given to the various interactions of adipose leptin with the HPA-axis, at the levels of the hypothalamus (especially the paraventricular nucleus), the anterior lobe of the pituitary gland (action on corticotropes) and the adrenal gland, where it releases corticosteroids needed for adequate stress adaptation. Also, possible local production and autocrine and paracrine actions of leptin at the hypothalamic and pituitary levels of the HPA-axis are being considered. Finally, a schematic model is presented showing the ways peripherally and centrally produced leptin may modulate, via the HPA-axis, stress adaptation in conjunction with the control of energy homeostasis.
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Affiliation(s)
- Eric W Roubos
- Department of Cellular Animal Physiology, Faculty of Science, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands.
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23
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Childs GV, Akhter N, Haney A, Syed M, Odle A, Cozart M, Brodrick Z, Gaddy D, Suva LJ, Akel N, Crane C, Benes H, Charlesworth A, Luque R, Chua S, Kineman RD. The somatotrope as a metabolic sensor: deletion of leptin receptors causes obesity. Endocrinology 2011; 152:69-81. [PMID: 21084451 PMCID: PMC3033057 DOI: 10.1210/en.2010-0498] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 10/07/2010] [Indexed: 01/01/2023]
Abstract
Leptin, the product of the Lep gene, reports levels of adiposity to the hypothalamus and other regulatory cells, including pituitary somatotropes, which secrete GH. Leptin deficiency is associated with a decline in somatotrope numbers and function, suggesting that leptin may be important in their maintenance. This hypothesis was tested in a new animal model in which exon 17 of the leptin receptor (Lepr) protein was selectively deleted in somatotropes by Cre-loxP technology. Organ genotyping confirmed the recombination of the floxed LepR allele only in the pituitary. Deletion mutant mice showed a 72% reduction in pituitary cells bearing leptin receptor (LEPR)-b, a 43% reduction in LEPR proteins and a 60% reduction in percentages of immunopositive GH cells, which correlated with reduced serum GH. In mutants, LEPR expression by other pituitary cells was like that of normal animals. Leptin stimulated phosphorylated Signal transducer and activator of transcription 3 expression in somatotropes from normal animals but not from mutants. Pituitary weights, cell numbers, IGF-I, and the timing of puberty were not different from control values. Growth curves were normal during the first 3 months. Deletion mutant mice became approximately 30-46% heavier than controls with age, which was attributed to an increase in fat mass. Serum leptin levels were either normal in younger animals or reflected the level of obesity in older animals. The specific ablation of the Lepr exon 17 gene in somatotropes resulted in GH deficiency with a consequential reduction in lipolytic activity normally maintained by GH and increased adiposity.
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Affiliation(s)
- Gwen V Childs
- Professor and Chair, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
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Rodrigues AL, de Moura EG, Passos MCF, Dutra SCP, Lisboa PC. Postnatal early overnutrition changes the leptin signalling pathway in the hypothalamic-pituitary-thyroid axis of young and adult rats. J Physiol 2009; 587:2647-61. [PMID: 19403617 DOI: 10.1113/jphysiol.2009.169045] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Postnatal early overnutrition (EO) is a risk factor for obesity in adult life. Rats raised in a small litter can develop hyperinsulinaemia, hyperphagia, hyperleptinaemia and hypertension as adults. Since leptin regulates the hypothalamic-pituitary-thyroid axis and the metabolism of thyroid hormones, we studied the leptin signalling pathway in pituitary and thyroid glands of the postnatal EO model. To induce EO, at the third day of lactation the litter size was reduced to three pups per litter (SL group). In control litters (NL group), the litter size was adjusted to 10 pups per litter. Body weight and food intake were monitored. Rat offspring were killed at 21 (weaning) and 180 days old (adulthood). Plasma thyroid hormones, thyroid-stimulating hormone (TSH) and leptin were measured by radioimmunoassay. Proteins of the leptin signalling pathway were analysed by Western blotting. Body weight of offspring in the SL group was higher from the seventh day of lactation (+33%, P < 0.05) until 180 days old (+18%, P < 0.05). Offspring in the SL group showed higher visceral fat mass at 21 and 180 days old (+176 and +52%, respectively, P < 0.05), but plasma leptin was higher only at 21 days (+88%, P < 0.05). The SL offspring showed higher plasma TSH, 3,5,3'-triiodothronine (T(3)) and thyroxine (T(4)) at 21 days (+60, +91 and +68%, respectively, P < 0.05), while the opposite was observed at 180 days regarding thyroid hormones (T(3), -10%; and T(4), -30%, P < 0.05), with no difference in TSH levels. In hypothalamus, no change was observed in the leptin signalling pathway at 21 days. However, lower janus thyrosine kinase 2 (JAK2) and phosphorilated-signal transducer and activator of transcription-3 (p-STAT3) content were detected in adulthood. In pituitary, the SL group presented higher leptin receptors (Ob-R), JAK2 and p-STAT3 content at 21 days and lower JAK2 and STAT3 content at 180 days old. In contrast, in thyroid, the Ob-R expression was lower in young SL rats, while the adult SL group presented higher Ob-R and JAK2 content. We showed that postnatal EO induces short- and long-term effects upon the hypothalamic-pituitary-thyroid axis. These changes may help to explain future development of metabolic and endocrine dysfunctions, such as metabolic syndrome and hypothyroidism.
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Affiliation(s)
- Ananda Lages Rodrigues
- Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
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Ogasawara H, Ohwada S, Nagai Y, Taketa Y, Matsuzaki M, Tanaka S, Watanabe K, Aso H, Yamaguchi T. Localization of leptin and leptin receptor in the bovine adenohypophysis. Domest Anim Endocrinol 2008; 35:8-15. [PMID: 18367366 DOI: 10.1016/j.domaniend.2008.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 01/04/2008] [Accepted: 01/08/2008] [Indexed: 11/29/2022]
Abstract
The present study was carried out to detail the cellular localization of leptin (Lep) and the leptin receptor (LepR) in the bovine adenohypophysis. Lep immunoreactivity (Lep-ir) was found in about 30% of adenohypophysial cells in the gland. Immunochemistry of Lep and specific hormones using serial sections revealed that Lep-ir was present in 60.4% of somatotrophs, 15.9% of gonadotrophs, 6.5% of mammotrophs, 6.5% of thyrotrophs and 2.4% of corticotrophs. Both the common short isoform (OBRa) and the long isoform (OBRb) of LepR mRNA were expressed in the bovine adenohypophysis. LepR immunoreactivity (LepR-ir) was found in only 2.8% of the adenohypophysial cells and over 50% of LepR-ir cells were gonadotrophs, in which most of the cells were distributed in the zona tuberalis. The findings on Lep and LepR in the adenohypophysial cells indicate that Lep may regulate gonadotroph function through autocrine/paracrine pathway in the bovine adenohypophysis.
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Affiliation(s)
- Hideki Ogasawara
- Laboratory of Functional Morphology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, 981-8555 Sendai, Japan
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26
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Shimizu F, Matsuzaki T, Iwasa T, Tanaka N, Minakuchi M, Kuwahara A, Yasui T, Furumoto H, Irahara M. Transition of leptin receptor expression during pubertal development in female rat pituitary. Endocr J 2008; 55:191-8. [PMID: 18250539 DOI: 10.1507/endocrj.k07e-029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Leptin is thought to play important roles in pubertal development and reproductive function in the female. Leptin receptor is expressed in various tissues including the pituitary and hypothalamus. We investigated the transition of leptin receptor (Ob-R) expression in female rat pituitary during pubertal development. Real-time RT-PCR was performed for long-form leptin receptor (Ob-Rb) and short-form leptin receptor (Ob-Ra) in the pituitary and cerebrum of the rats aged 4 (juvenile), 6 (pubertal), and 8 weeks (adult). Double immunohistochemical colocalization of Ob-R and luteinizing hormone (LH) was performed in pituitaries from 4-week-old female rats. Serum leptin concentrations of 4-, 6-, and 8-week-old rats were measured by radioimmunoassay. In the pituitary, expression of Ob-Rb mRNA in 4-week-old rats (1.00 +/- 0.16) was significantly higher than in 8-week-old rats (0.61 +/- 0.07, p<0.05), although expression of Ob-Ra mRNA did not differ among 4-, 6-, and 8-week-old rats. In cerebrum, Ob-Ra and Ob-Rb mRNA expressions did not differ significantly among 4-, 6-, and 8-week-old rats. Intense staining of Ob-R and colocalization of Ob-R and LH were seen in 4-week-old rat pituitary. On the other hand, serum concentrations of leptin in 6- and 8-week-old rats were significantly higher than those in 4-week-old rats (p<0.05, p<0.01, respectively). In conclusion, since the pituitary gonadotroph is a potential target of leptin, the juvenile rat pituitary might prepare for a subsequent increase of serum leptin concentration by expressing Ob-Rb.
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Affiliation(s)
- Fumi Shimizu
- Department of Obstetrics and Gynecology, Institute of Health Biosciences, The University of Tokushima Graduate School, Japan
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Kus I, Colakoglu N, Ogeturk M, Kus MA, Ozen OA, Sarsilmaz M. Effects of testosterone on leptin production in anterior pituitary cells of rats: an immunohistochemical study. ACTA ACUST UNITED AC 2007; 53:79-82. [PMID: 17453686 DOI: 10.1080/01485010601164024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The aim of this study was to immunohistochemically examine the effects of orchidectomy and administration of testosterone hormone on leptin production in the rat anterior pituitary. Twenty-one male Wistar rats were divided into three groups. Group I and group II were designated as control (sham-orchidectomized) and orchidectomized rats, respectively. Rats in group III were orchidectomized and injected daily with testosterone propionate for 1 month. At the end of the experimental period, all animals were sacrificed by decapitation. The pituitary glands of all rats were removed and processed for semi-quantitative evaluation of immunohistochemical leptin staining. Intensity of immunostaining was determined on a scale between 0 (no staining) and 5 (heavy staining). Immunostaining of leptin was moderate (3+) in control rats, heavy (5+) in orchidectomized rats, and low (1+) in testosterone-treated orchidectomized rats, respectively. These findings indicate that orchidectomy increases leptin secretion in anterior pituitary cells, and this increase of leptin synthesis can be prevented by administration of testosterone propionate. Thus, testosterone seems to affect leptin production in the anterior pituitary of male rats.
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Affiliation(s)
- I Kus
- Department of Anatomy, Faculty of Medicine, Firat University, Elazig, Turkey
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28
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Passos MCF, Lins MC, Lisboa PC, Toste FP, Bonomo IT, de Moura EG. Maternal leptin treatment during lactation programs the thyroid function of adult rats. Life Sci 2007; 80:1754-8. [PMID: 17349662 DOI: 10.1016/j.lfs.2007.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 01/23/2007] [Accepted: 02/05/2007] [Indexed: 11/16/2022]
Abstract
Recently, we showed that both maternal malnutrition during lactation and leptin treatment during the neonatal period program thyroid function. In this study we evaluate whether maternal leptin treatment during lactation programs thyroid function of the offspring in the adulthood. The dams were divided into 2 groups: Lep-daily sc single injected with 8 microg/100 g of body weight with recombinant rat leptin during the last 3 days of lactation and control group (C) that received the same volume of saline. The 180 day-old animals received a single i.p. injection of (125)I (2.22x10(4) Bq) and they were killed 2 h after the injection. Triiodothyronine (T3), thyroxine (T4), thyrotropin (TSH) and leptin concentrations were measured by radioimmunoassay. The milk of leptin-treated mothers on the last day of treatment had higher leptin (p<0.05) concentration. The pups of the leptin-treated mothers had at 21 days an unchanged T3, T4 and leptin serum concentrations with higher TSH (p<0.05). The offspring of Lep mothers had at 180 days a higher T3 (p<0.05) with normal thyroid (125)I uptake, T4 and TSH serum concentrations compared to the controls. So, the mother's hyperleptinaemia during lactation programs to a higher T3 serum concentration on the offspring, probably by a higher leptin transfer through the milk.
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Affiliation(s)
- Magna Cottini Fonseca Passos
- Department of Applied Nutrition, Nutrition Institute, State University of Rio de Janeiro, 20550-030, Rio de Janeiro, RJ, Brazil.
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29
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Akhter N, Johnson BW, Crane C, Iruthayanathan M, Zhou YH, Kudo A, Childs GV. Anterior pituitary leptin expression changes in different reproductive states: in vitro stimulation by gonadotropin-releasing hormone. J Histochem Cytochem 2007; 55:151-66. [PMID: 17046838 PMCID: PMC1780073 DOI: 10.1369/jhc.6a7072.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
This study was designed to learn more about the changes in expression of rat anterior pituitary (AP) leptin during the estrous cycle. QRT-PCR assays of cycling rat AP leptin mRNA showed 2-fold increases from metestrus to diestrus followed by an 86% decrease on the morning of proestrus. Percentages of leptin cells increased in proestrus and pregnancy to 55-60% of AP cells. Dual labeling for leptin proteins and growth hormone (GH) or gonadotropins showed that the rise in leptin protein-bearing cells from diestrus to proestrus was mainly in GH cells. Only 10-20% of leptin cells in male or cycling female rats coexpress gonadotropins. In contrast, 50-73% of leptin cells from pregnant or lactating females coexpress gonadotropins and only 19% coexpress GH, indicating plasticity in the distribution of leptin. Leptin cells expressed GnRH receptors, and estrogen and GnRH together increased the coexpression of leptin mRNA and gonadotropins. GnRH increased cellular leptin proteins three to four times and mRNA 9.8 times in proestrous rats and stimulated leptin secretion in cultures from diestrous, proestrous, and pregnant rats. These regulatory influences, and the high expression of AP leptin during proestrus and pregnancy, suggest a supportive role for leptin during key events involved with reproduction.
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Affiliation(s)
- Noor Akhter
- Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, 4301 W. Markham St., Slot 510, Little Rock, AR 72205, USA.
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30
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Wilkinson M, Brown R, Imran SA, Ur E. Adipokine gene expression in brain and pituitary gland. Neuroendocrinology 2007; 86:191-209. [PMID: 17878708 DOI: 10.1159/000108635] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Accepted: 12/04/2006] [Indexed: 12/20/2022]
Abstract
The brain has been recognized as a prominent site of peptide biosynthesis for more than 30 years, and many neuropeptides are now known to be common to gut and brain. With these precedents in mind it is remarkable that adipose-derived peptides like leptin have attracted minimal attention as brain-derived putative neuromodulators of energy balance. This review outlines the evidence that several adipose-specific genes are also expressed in the central nervous system and pituitary gland. We, and others, confirmed that the genes for leptin, resistin, adiponectin, FIAF (fasting-induced adipose factor) and adiponutrin are expressed and regulated in these tissues. For example, leptin mRNA was readily detectable in human, rat, sheep and pig brain, but not in the mouse. Leptin expression in rat brain and pituitary was regulated through development, by food restriction, and following traumatic brain injury. In contrast, hypothalamic resistin mRNA was unaffected by age or by fasting, but was significantly depleted by food restriction in mouse pituitary gland. Similar results were seen in the ob/ob mouse, and we noted a marked reduction in resistin-positive hypothalamic nerve fibres. Resistin and fiaf mRNA were also upregulated in hypoxic/ischaemic mouse brain. Our studies on the regulation of neuronal adipokines were greatly aided by the availability of clonal hypothalamic neuronal cell lines. One of these, N-1, expresses both rstn and fiaf together with several other neuropeptides and receptors involved in energy homeostasis. Selective silencing of rstn revealed an autocrine/paracrine regulatory system, mediated through socs-3 expression that may influence the feedback effects of insulin and leptin in vivo. A similar convergence of signals in the pituitary gland could also influence anterior pituitary hormone secretion. In conclusion, the evidence is suggestive that brain and pituitary-derived adipokines represent a local regulatory circuit that may fine tune the feedback effects of adipose hormones in the control of energy balance.
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Affiliation(s)
- Michael Wilkinson
- Department of Obstetrics and Gynaecology, Dalhousie University, Halifax, N.S., Canada.
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31
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Malendowicz LK, Rucinski M, Belloni AS, Ziolkowska A, Nussdorfer GG. Leptin and the regulation of the hypothalamic-pituitary-adrenal axis. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 263:63-102. [PMID: 17725965 DOI: 10.1016/s0074-7696(07)63002-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Leptin, the product of the obesity gene (ob) predominantly secreted from adipocytes, plays a major role in the negative control of feeding and acts via a specific receptor (Ob-R), six isoforms of which are known at present. Evidence has been accumulated that leptin, like other peptides involved in the central regulation of food intake, controls the function of the hypothalamic-pituitary-adrenal (HPA) axis, acting on both its central and peripheral branches. Leptin, along with Ob-R, is expressed in the hypothalamus and pituitary gland, where it modulates corticotropin-releasing hormone and ACTH secretion, probably acting in an autocrine-paracrine manner. Only Ob-R is expressed in the adrenal gland, thereby making it likely that leptin affects it by acting as a circulating hormone. Although in vitro and in vivo findings could suggest a glucocorticoid secretagogue action in the rat, the bulk of evidence indicates that leptin inhibits steroid-hormone secretion from the adrenal cortex. In keeping with this, leptin was found to dampen the HPA axis response to many kinds of stress. In contrast, leptin enhances catecolamine release from the adrenal medulla. This observation suggests that leptin activates the sympathoadrenal axis and does not appear to agree with its above-mentioned antistress action. Leptin and/or Ob-R are also expressed in pituitary and adrenal tumors, but little is known about the role of this cytokine in the pathophysiology.
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Affiliation(s)
- Ludwik K Malendowicz
- Department of Histology and Embryology, School of Medicine, Karol Marcinkowski University of Medical Sciences, PL-60781 Poznan, Poland
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Wong AOL, Zhou H, Jiang Y, Ko WKW. Feedback regulation of growth hormone synthesis and secretion in fish and the emerging concept of intrapituitary feedback loop. Comp Biochem Physiol A Mol Integr Physiol 2006; 144:284-305. [PMID: 16406825 DOI: 10.1016/j.cbpa.2005.11.021] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 11/21/2005] [Accepted: 11/21/2005] [Indexed: 11/21/2022]
Abstract
Growth hormone (GH) is known to play a key role in the regulation of body growth and metabolism. Similar to mammals, GH secretion in fish is under the control of hypothalamic factors. Besides, signals generated within the pituitary and/or from peripheral tissues/organs can also exert a feedback control on GH release by effects acting on both the hypothalamus and/or anterior pituitary. Among these feedback signals, the functional role of IGF is well conserved from fish to mammals. In contrast, the effects of steroids and thyroid hormones are more variable and appear to be species-specific. Recently, a novel intrapituitary feedback loop regulating GH release and GH gene expression has been identified in fish. This feedback loop has three functional components: (i) LH induction of GH release from somatotrophs, (ii) amplification of GH secretion by GH autoregulation in somatotrophs, and (iii) GH feedback inhibition of LH release from neighboring gonadotrophs. In this article, the mechanisms for feedback control of GH synthesis and secretion are reviewed and functional implications of this local feedback loop are discussed. This intrapituitary feedback loop may represent a new facet of pituitary research with potential applications in aquaculture and clinical studies.
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Affiliation(s)
- Anderson O L Wong
- Department of Zoology, University of Hong Kong, Pokfulam Road, Hong Kong, PR China.
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Kappeler L, Gautron L, Layé S, Dantzer R, Zizzari P, Epelbaum J, Bluet-Pajot MT. Pituitary cocaine- and amphetamine-regulated transcript expression depends on the strain, sex and oestrous cycle in the rat. J Neuroendocrinol 2006; 18:426-33. [PMID: 16684132 DOI: 10.1111/j.1365-2826.2006.01435.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) mRNA and peptides are abundant in the adenohypophysis, but their role in pituitary function has not yet been elucidated. CART peptides were recently shown to colocalise with luteinising hormone (LH) or prolactin in rat anterior pituitary, and contradictory results concerning the peptide effects on pituitary hormonal secretions were obtained in vitro from pituitary cell cultures. Thus, we reinvestigated the expression of CART mRNA within the pituitary. Immunohistochemistry for pituitary hormones was performed on sections from adult male Wistar rats followed by in situ hybridisation using CART mRNA antisense 35S-labelled probes. The most represented CART-expressing cells were lactotrophs (42 +/- 1% of CART cells) and gonadotrophs (32 +/- 3%), followed by thyrotrophs (10 +/- 2%), corticotrophs (7 +/- 2%) and somatotrophs (6 +/- 1%). In the pars tuberalis, CART mRNA was easily detectable in gonadotrophs and lactotrophs and, to a lesser extent, in corticotrophs and thyrotrophs. CART peptide was quickly and potently released from perifused pituitary by depolarisation (K+ 30 mM for 15 min; 465 +/- 37% over basal release, n = 5). Gonadotrophin-releasing hormone and thyrotrophin-releasing hormone (0.1 microM) were also active to a lesser extent (138 +/- 11% and 71 +/- 17, n = 7, respectively). CART (0.1 microM) did not modify basal LH or prolactin release but selectively inhibited K+-induced LH release without affecting K+-induced prolactin secretion. Pituitary CART mRNA and content were sex dependent and varied during the oestrous cycle, being lower in dioestrous 2. Pituitary CART content also varied widely amongst rat strains being five to six-fold higher in Wistar and Fischer rats compared to Brown Norway and Lou C rats. Ageing differentially affected pituitary CART mRNA and content, resulting in a marked decrease in Lou C and an increase in Wistar and Sprague-Dawley rats. Taken together, these results suggest that pituitary CART expression is dependent of the sex steroid environment and may be physiologically involved in LH secretion.
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Affiliation(s)
- L Kappeler
- UMR 549 Inserm, Université-Paris-René-Descartes, Faculté de Médecine, Paris, France
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34
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França LR, Suescun MO, Miranda JR, Giovambattista A, Perello M, Spinedi E, Calandra RS. Testis structure and function in a nongenetic hyperadipose rat model at prepubertal and adult ages. Endocrinology 2006; 147:1556-63. [PMID: 16339210 DOI: 10.1210/en.2005-0640] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There are few data for hormonal levels and testis structure and function during postnatal development in rats neonatally treated with monosodium L-glutamate (MSG). In our study, newborn male pups were ip injected with MSG (4 mg/g body weight) every 2 d up to 10 d of age and investigated at prepubertal and adult ages. Plasma levels of leptin, LH, FSH, prolactin, testosterone (T), corticosterone, and free T4 (FT4) were measured. MSG rats displayed elevated circulating levels of corticosterone and hyperadiposity/hyperleptinemia, regardless of the age examined; conversely, circulating prolactin levels were not affected. Moreover, prepubertal MSG rats revealed a significant (P < 0.05) reduction in testis weight and the number of Sertoli (SC) and Leydig cells per testis. Leptin plasma levels were severalfold higher (2.41 vs. 8.07; P < 0.05) in prepubertal MSG rats, and these animals displayed plasma LH, FSH, T, and FT4 levels significantly decreased (P < 0.05). Taken together, these data indicate that testis development, as well as SC and Leydig cell proliferation, were disturbed in prepubertal MSG rats. Adult MSG rats also displayed significantly higher leptin plasma levels (7.26 vs. 27.04; P < 0.05) and lower (P < 0.05) LH and FSH plasma levels. However, T and FT4 plasma levels were normal, and no apparent alterations were observed in testis structure of MSG rats. Only the number of SCs per testis was significantly (P < 0.05) reduced in the adult MSG rats. In conclusion, although early installed hyperadipose/hyperleptinemia phenotype was probably responsible for the reproductive axis damages in MSG animals, it remains to be investigated whether this condition is the main factor for hypothalamus-pituitary-gonadal axis dysfunction in MSG rats.
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Affiliation(s)
- L R França
- Laboratory of Cellular Biology, Department of Morphology, Institute of Biological Sciences/Federal University of Minas Gerais, Belo Horizonte-MG, Brazil.
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de Moura EG, Passos MCF. Neonatal programming of body weight regulation and energetic metabolism. Biosci Rep 2006; 25:251-69. [PMID: 16283556 DOI: 10.1007/s10540-005-2888-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Programming is an epigenetic phenomena by which nutritional, hormonal, physical psychological and other stressful events acting in a critical period of life, such as gestation and lactation, modifies in a prolonged way certain physiological functions. This process was preserved by natural selection as an important adaptive tool for survival of organisms living in nutritional impaired areas. So, malnutrition during gestation and lactation turns on different genes that provide the organism with a thrifty phenotype. In the case of an abundant supply of nutrients after this period, those organisms that were adapted to a low metabolic waste and higher energy utilization will be in a higher risk of developing metabolic diseases, such as obesity, hyperlipidemia, diabetes mellitus and hypertension. The kind of malnutrition, duration and intensity are important for the type of programming obtained. We discuss some of the hormonal and metabolic changes that occur in gestation or lactation, when malnutrition is applied to the mothers and their offspring. Some of these changes, such as an increase of maternal triiodothyronine (T(3)), leptin and glucocorticoids (GC) and decrease in prolactin are by itself potential programming factors. Most of these hormones can be transfer through the milk that has other important macronutrients composition changes in malnourished dams. We discuss the programming effects of some of these hormones upon body weight and composition, leptin, thyroid and adrenal functions, and their effects on liver, muscle and adipose tissue metabolism and the consequences on thermogenesis.
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Affiliation(s)
- Egberto Gaspar de Moura
- Dept. Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brasil.
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36
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Oge A, Bayraktar F, Saygili F, Guney E, Demir S. TSH influences serum leptin levels independent of thyroid hormones in hypothyroid and hyperthyroid patients. Endocr J 2005; 52:213-7. [PMID: 15863950 DOI: 10.1507/endocrj.52.213] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Leptin is considered to play a role in maintenance of energy balance and body weight by neuroendocrine mechanisms. The physiological mechanisms for thyroid hormone-induced alteration in serum leptin are not well known. In the present study, the relationship between thyroid hormones and leptin levels was investigated in patients with overt hypothyroidism and hyperthyroidism before and after successful treatment. Leptin levels were determined by radioimmunoassay and body mass index (BMI) was calculated for each subject. Serum leptin levels of 26 hypothyroid and 22 hyperthyroid patients were compared with those of 20 healthy volunteers who comprised the controls. Serum leptin levels of hypothyroid patients (28.4 +/- 4.1 ng/ml) were found to be significantly higher than the controls (19.1 +/- 3.2 ng/ml) (p<0.01), whereas hyperthyroid patients had lower levels (10.7 +/- 1.2 ng/ml) (p<0.01). In hypothyroid patients, serum leptin levels were decreased significantly to 20.6 +/- 2.1 ng/ml with thyroxin treatment (p<0.05). However, in hyperthyroid group, serum leptin levels were increased to 12.4 +/- 2.2 ng/ml by treatment (p>0.05). BMI was not changed with the treatment in either group. The serum leptin levels were correlated with BMI and thyrotropin (TSH) in both hypothyroid and hyperthyroid patients. Serum leptin levels are affected in thyroid disorders and the correlation of leptin with TSH is independent of thyroid hormones.
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Affiliation(s)
- Aysin Oge
- Department of Internal Medicine, Division of Endocrinology and Metabolism, Adnan Menderes University School of Medicine, Aydin, Turkey
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Chowdhury I, Chien JT, Chatterjee A, Yu JYL. Effects of leptin and neuropeptide-Y on transcript levels of thyrotropin beta and common alpha subunits of rat pituitary cells in vitro. Life Sci 2004; 75:2897-909. [PMID: 15454341 DOI: 10.1016/j.lfs.2004.04.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2003] [Accepted: 04/15/2004] [Indexed: 10/26/2022]
Abstract
Leptin and neuropeptide-Y (NPY) are indicated to play a role in hypothalamo-pituitary-thyroid (HPT) axis in relation to regulation of energy homeostasis mediated through acting at hypothalamic synthesis and release of thyrotropin (TSH)-releasing hormone (TRH). Whether leptin and NPY also act at pituitary level in HPT axis remains unknown. This study aimed at investigating whether or not leptin and NPY exert actions at pituitary in modulation of transcript levels of TSHbeta and the common pituitary glycoprotein hormone alpha (PGHalpha) subunits. The dispersed pituitary cells from 6 wk old male Wistar rats were incubated with or without TRH, leptin or NPY of 10(-8) M and 10(-10) M for 6 h at 37 degrees C in medium-199 under aeration of 95% O2 and 5% CO2. The mRNA levels of TSHbeta and PGHalpha subunits of the incubated cells were measured by reverse transcription-polymerase chain reaction. The results revealed that leptin stimulated, while NPY inhibited, TSHbeta mRNA levels in a dose-related manner. Both leptin and NPY increased alpha subunit mRNA levels. It is demonstrated for the first time that both leptin and NPY exert a direct action at rat pituitary affecting steady-state levels of mRNA of TSHbeta and PGHalpha subunits. The present study supports that both leptin and NPY act at the pituitary as well besides the hypothalamus in HPT axis in relation to regulation of energy homeostasis.
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Affiliation(s)
- Indrajit Chowdhury
- Endocrinology Laboratory, Institute of Zoology, Academia Sinica, Academia Rd., Taipei, Taiwan115, ROC
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Vicente LL, de Moura EG, Lisboa PC, Monte Alto Costa A, Amadeu T, Mandarim-de-Lacerda CA, Passos MCF. Malnutrition during lactation in rats is associated with higher expression of leptin receptor in the pituitary of adult offspring. Nutrition 2004; 20:924-8. [PMID: 15474883 DOI: 10.1016/j.nut.2004.06.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Recent studies have shown that leptin receptor is expressed in human and rat pituitary glands. The expression of leptin receptor in rats whose dams were malnourished during lactation has not been previously reported. METHODS We examined leptin receptor expression in the pituitary gland of adult rats whose dams were assigned to one of the following groups during lactation: control diet, protein-restricted diet (8% protein), or energy-restricted diet (the control diet fed in restricted quantities that were calculated according to the mean ingestion of the protein-restricted group). After weaning, all pups had free access to the control diet until they reached adult age, at which time leptin receptor expression in the pituitary was analyzed by immunohistochemistry. RESULTS Adult animals from protein- and energy-restricted dams had a higher expression of leptin receptor in pituitary tissue, normal serum leptin concentrations, higher serum tri-iodothyronine concentrations, and lower thyroid-stimulating hormone concentrations than did the control rats. CONCLUSIONS In the fed state, leptin has a stimulatory effect on release of thyroid-stimulating hormone. The higher expression of leptin receptor in the pituitary of animals from protein- and energy-restricted dams may suggest a postreceptor failure in leptin action. This higher receptor expression may have allowed a greater inhibition of release of thyroid-stimulating hormone.
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Affiliation(s)
- Luciana Leão Vicente
- Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
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Chowdhury I, Chien JT, Chatterjee A, Yu JYL. In vitro effects of mammalian leptin, neuropeptide-Y, β-endorphin and galanin on transcript levels of thyrotropin β and common α subunit mRNAs in the pituitary of bighead carp (aristichthys nobilis). Comp Biochem Physiol B Biochem Mol Biol 2004; 139:87-98. [PMID: 15364291 DOI: 10.1016/j.cbpc.2004.06.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2003] [Revised: 06/09/2004] [Accepted: 06/15/2004] [Indexed: 11/18/2022]
Abstract
Thyrotropin (thyroid stimulating hormone, TSH) is a member of the pituitary glycoprotein hormones, consisting of two dissimilar subunits, alpha and beta. The two subunits are produced by different genes and are regulated independently. We have previously cloned a TSHbeta cDNA from bighead carp pituitary and investigated its gene regulation. We report here the direct effects of mammalian TSH-releasing hormone (TRH), leptin, neuropeptide-Y (NPY), beta-endorphin and galanin on mRNA levels of both TSHbeta and alpha-subunits in the pituitary of bighead carp in vitro. The dispersed pituitary cells of bighead carp were incubated at 25 degrees C for 6 h with different doses of these factors. The relative mRNA levels of TSHbeta and alpha-subunits were estimated by traditional polymerase chain reaction (PCR) analysis and fluorescence real-time PCR analysis. The results revealed that mammalian TRH, leptin and beta-endorphin produced dose-dependent stimulatory effects on mRNA levels of both TSHbeta and alpha-subunits while thyroxine (T4) and mammalian galanin suppressed mRNA levels of both TSHbeta and alpha-subunits. NPY suppressed TSHbeta mRNA level, but stimulated alpha-subunit mRNA level. This study has demonstrated that mammalian TRH, leptin, NPY, beta-endorphin and galanin were active in modulating the steady-state mRNA levels of TSHbeta and alpha-subunits of bighead carp pituitary in vitro. The results suggest that endogenous TRH, leptin, NPY, beta-endorphin and galanin may modulate transcript levels of TSHbeta and alpha-subunits in pituitary of bighead carp.
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Affiliation(s)
- I Chowdhury
- Institute of Zoology, Academia Sinica, Endocrinology Laboratory, No. 128, Sec. 2, Academic Rd., Nan., Taipei, Taiwan 115, ROC
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Glavaski-Joksimovic A, Rowe EW, Jeftinija K, Scanes CG, Anderson LL, Jeftinija S. Effects of leptin on intracellular calcium concentrations in isolated porcine somatotropes. Neuroendocrinology 2004; 80:73-82. [PMID: 15528950 DOI: 10.1159/000081843] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Accepted: 08/09/2004] [Indexed: 01/03/2023]
Abstract
Leptin, the product of the obese gene, is a protein that is secreted primarily from adipocytes. Leptin can influence the function of the pituitary gland through its action on the hypothalamus, but it can also directly act at the level of the pituitary gland. The ability of leptin to induce an increase in intracellular Ca2+ concentration ([Ca2+]i) in somatotropes was examined in dispersed porcine pituitary cells using a calcium imaging system. Somatotropes were functionally identified by the application of human growth hormone releasing hormone. Leptin increased [Ca2+]i in porcine somatotropes in a dose-dependent manner. The application of 100 nM leptin for 3 min did not have a significant effect on [Ca2+]i, while a 3-min application of 1 microM leptin increased [Ca2+]i in about 50% of the somatotropes (p < 0.01). The application of a second leptin challenge (1 microM) evoked a response in only 18% of the observed somatotropes. The stimulatory effect of leptin was abolished in low calcium saline and blocked by nifedipine, an L-calcium channel blocker, suggesting an involvement of calcium channels. Pretreatment of the cultures with AG 490, a specific Janus kinase inhibitor, and with SB 203580, a mitogen-activated protein kinase (MAP kinase) inhibitor, abolished the increase in [Ca2+]i evoked by leptin. In the presence of N(omega)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, the magnitude of the increase in [Ca2+]i evoked by 1 microM leptin was not significantly changed. However, in the presence of L-NAME only 24% of the somatotropes responded to leptin, while in parallel control cultures 70% of the somatotropes responded to leptin. These results imply an involvement of Janus kinase/signal transducer and activator or transcription, MAP kinase and NOS-signaling pathways in the stimulatory effect of leptin on porcine somatotropes.
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Watanobe H, Yoneda M. Evaluation of the role of melanocortin 3 and 4 receptors in leptin-stimulated and spontaneous growth hormone secretion in rats. Neuroendocrinology 2003; 78:331-8. [PMID: 14688446 DOI: 10.1159/000074886] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2003] [Accepted: 10/13/2003] [Indexed: 11/19/2022]
Abstract
It has been reported that the melanocortin 4-receptor (MC4-R) may act downstream of leptin to mediate its effects on food intake and several neuroendocrine functions (the reproductive system, the hypothalamo-pituitary-thyroid axis, and prolactin secretion). However, no previous study examined whether MC4-R mediates leptin stimulatory actions on growth hormone (GH) secretion, or whether MC4-R signaling is involved in spontaneous pulsatile GH release in fed rats. Therefore in this study we examined the involvement of both MC3-R and MC4-R (the predominant MC-R subtypes expressed in the brain) in these two aspects of GH secretion in freely-moving male rats. In both fed and 3-day fasted rats, plasma GH levels were determined every 15 min over 5 h after single intracerebroventricular injections of the following substances or vehicle. Fasting diminished and leptin (0.3 nmol) reinstated the GH pulse amplitude without affecting the pulse frequency. Neither HS014 (1.0 nmol, a selective MC4-R antagonist) nor agouti-related peptide (1.0 nmol, a non-selective MC3/4-R antagonist) was effective in altering leptin-stimulated or spontaneous GH secretion. In addition, neither melanotan-II (1.0 nmol, a non-selective MC3/4-R agonist) nor gamma(1)-melanocyte-stimulating hormone (10 nmol, a selective MC3-R agonist) affected significantly GH release in fasted rats. We have previously demonstrated that stimulation or blockade of MC4-R, achieved by the same drug dosage as in this study, significantly affect luteinizing hormone and prolactin secretion in rats. The present results thus suggest that neither MC4-R nor MC3-R is involved in leptin-stimulated or spontaneous GH secretion, or at least that the level of MC4-R involvement in GH secretion is much lower than that in luteinizing hormone and prolactin release regulation.
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Affiliation(s)
- Hajime Watanobe
- Division of Internal Medicine, Clinical Research Center, International University of Health and Welfare, Otawara, Tochigi, Japan.
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Morash BA, Imran A, Wilkinson D, Ur E, Wilkinson M. Leptin receptors are developmentally regulated in rat pituitary and hypothalamus. Mol Cell Endocrinol 2003; 210:1-8. [PMID: 14615055 DOI: 10.1016/j.mce.2003.09.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have previously reported that leptin is expressed in adult rat brain and pituitary gland, though the role of leptin in these sites has not been determined. Leptin mRNA is developmentally regulated in the brain and pituitary of male and female rats during early postnatal development, suggesting a role in the maturation of the brain-pituitary system. Here, we sought to extend our previous studies by evaluating (1) the ontogeny of leptin receptor mRNA levels in rat brain and pituitary and (2) pituitary leptin protein levels in neonatal and pre-pubertal rats. Pituitary leptin concentration was highest shortly after birth (postnatal day (PD) 4, 25 ng/mg protein) and fell significantly throughout postnatal development and into adulthood (PD 60, 3.5 ng/mg protein; P<0.005) coincident with a decline in pituitary leptin mRNA levels. Significant age-related effects on leptin receptor mRNA levels were also observed in the pituitary and the hypothalamus of male and female rats using semi-quantitative RT-PCR analysis. In the pituitary, the short form (OBRa) mRNA levels were highest in neonatal rats (PD 4) but declined throughout postnatal development (PD 4-22) paralleling the fall in pituitary leptin mRNA and protein levels. The long form (OBRb) mRNA levels were unaffected by age between PD 4 and 22. In contrast, hypothalamic, levels of OBRb mRNA were very low to undetectable shortly after birth (PD 4) and rose significantly between PD 4 and 14/22 while levels of OBRa mRNA were not significantly different between PD 4 and 22. Immunohistochemical detection of leptin receptor immunoreactivity (all forms) revealed the presence of OBR-like protein in pituitary and hypothalamus as early as PD 4. Cortical leptin receptor mRNA levels were similar throughout early postnatal development. No gender-related differences in leptin receptor mRNA levels were noted in brain or pituitary. In conclusion, these data, together with our previous work, indicate that the neonatal pituitary gland expresses leptin and leptin receptors at levels far in excess of those observed in mature rats. The pituitary is thus quite different from adipose tissue, hypothalamus and cerebral cortex, in which neonatal leptin expression is lowest at birth. Since neonatal pituitary leptin receptor expression is also elevated, it is possible that pituitary-derived leptin plays some role in the development of the hypothalamic-pituitary system.
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Affiliation(s)
- Barbara A Morash
- Department of Obstetrics, IWK Grace Health Centre, 5980 University Avenue, P.O. Box 3070, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada B3J 3G9
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Archanco M, Muruzábal FJ, Llopiz D, Garayoa M, Gómez-Ambrosi J, Frühbeck G, Burrell MA. Leptin expression in the rat ovary depends on estrous cycle. J Histochem Cytochem 2003; 51:1269-77. [PMID: 14500694 DOI: 10.1177/002215540305101003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Leptin is a hormone originally identified in adipocytes. It is involved in the regulation of fat deposition and energy expenditure and in other functions, such as reproduction. The presence of leptin has been reported in several reproductive organs. However, few studies have addressed its expression in the ovary. Moreover, the existing information is not consistent with regard to the particular cell types responsible for leptin expression. In this work we studied the distribution of leptin in the rat ovary by immunohistochemistry (IHC) and in situ hybridization (ISH). Leptin staining was found in steroid-producing cells: thecal, luteal, and interstitial cells. The strongest signal with both techniques was found in the cytoplasm of oocytes. A weak reaction for leptin mRNA was detected in granulosa of all growing follicles, although leptin protein was found only in the mature follicle. Western blotting analysis detects a strongly reactive 16-kD band, giving further support to the presence of leptin in the rat ovary. Variations in this immunoreactive band were found throughout the estrous cycle. Localization of leptin in the ovary may contribute to a better understanding of female reproductive function.
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Affiliation(s)
- Marta Archanco
- Department of Histology and Pathology, University of Navarra, Pamplona, Spain
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44
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Peyon P, Vega-Rubín de Celis S, Gómez-Requeni P, Zanuy S, Pérez-Sánchez J, Carrillo M. In vitro effect of leptin on somatolactin release in the European sea bass (Dicentrarchus labrax): dependence on the reproductive status and interaction with NPY and GnRH. Gen Comp Endocrinol 2003; 132:284-92. [PMID: 12812777 DOI: 10.1016/s0016-6480(03)00097-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The aim of the present work was to investigate the neuroendocrine control of pituitary somatolactin (SL) release using dispersed pituitary cell culture obtained from male European sea bass (Dicentrarchus labrax) at different stages of sexual development. The effect of mouse recombinant leptin, sea bream gonadotropin releasing-hormone (sbGnRH) and porcine neuropeptide Y (pNPY) and their potential interaction on the SL release were investigated. High doses of leptin (10(-8)-10(-6)M) were differentially effective in inducing SL release depending on the sexual developmental stage. Porcine NPY alone was not effective on basal SL release, but it dose-dependently (0.1 and 1 nM) enhanced SL release induced by leptin (10(-6) and 10(-8)M) in late pre-pubertal but not in post-pubertal stages. No effect of sbGnRH in association or not with leptin was observed on SL release. These findings are the first evidences that leptin and pNPY can play an important role in the neuroendocrine control of pars intermedia function and SL release in fish. In addition, the sensitivity of SL producing cells to leptin and NPY only in prepubertal and pubertal stages, provides the potential role of SL in the nutritional control of the onset of puberty.
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Affiliation(s)
- Pierre Peyon
- Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Cientificas, 12595 Ribera de Cabanes, Castellón, Spain
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Lin J, Barb CR, Kraeling RR, Rampacek GB. Growth hormone releasing factor decreases long form leptin receptor expression in porcine anterior pituitary cells. Domest Anim Endocrinol 2003; 24:95-101. [PMID: 12586311 DOI: 10.1016/s0739-7240(02)00209-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pituitary cells from six pigs, 180-200 days of age, were studied in primary culture to determine if growth hormone releasing factor (GRF) affects long form leptin receptor (Ob-Rl) expression. On Day 4 of culture, 10(5) live cells per well were challenged with either 0, 10(-6), 10(-7) or 10(-8)M [Ala15]-hGRF-(1-29)NH(2) (3 wells per treatment per pig). Secretion of growth hormone (GH) into the media and pituitary Ob-Rl mRNA expression were determined at 4 h after treatment. Media were analyzed for GH by radioimmunoassay, and total RNA was isolated from cells for determination of Ob-Rl expression by semi quantitative reverse transcription PCR. Basal GH concentration was 32+/-2 ng per 10(5) cells per well (n=18 wells) for 4 h. Relative to control at 4 h, 10(-6),10(-7) and 10(-8)M GRF increased (P<0.01) GH secretion by 151, 129 and 120%, but decreased (P<0.05) Ob-Rl expression by 32, 50 and 38%, respectively. These results indicate that GRF directly modulates Ob-Rl expression at the level of the pituitary, and thereby playing a role in regulating pituitary sensitivity to leptin.
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Affiliation(s)
- J Lin
- Department of Animal and Dairy Science, University of Georgia, Athens, GA 30602, USA
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Abstract
Peptides originally described in other tissues have been located in the anterior pituitary gland. Detection of their encoding mRNAs and specific receptors, together with demonstration of peptide local action led to the postulation of the existence of a paracrine/autocrine regulation of pituitary function. Direct evidence for the role of endogenous peptides has come from studies aiming to block their action through immunoneutralization or pharmacologic blockade. Here we review evidence of pituitary produced peptides as potential candidates as local regulators of thyrotropin secretion. Few studies have approached the subject and most data are not conclusive. Until now, the most consistent data relate to neuromedin B, a bombesin-like peptide. The combined observation of high peptide concentration in rat thyrotrophs, the ability of the exogenous peptide to inhibit thyrotropin (TSH) release in physiologic doses plus the effect of the specific neuromedin B antiserum to increase basal TSH release from isolated pituitaries suggest that neuromedin B acts as a constitutive autocrine TSH-release inhibitor. Neuromedin B is upregulated by thyroid hormones and downregulated by thyrotropin-releasing hormone (TRH) that is consistent with proposed role of local factors, namely to partially mediate or modulate the effects of hormones on pituitary function. However, future studies will certainly confirm other candidates as local regulators of TSH secretion, as well as their relevance at physiologic and pathologic conditions.
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Affiliation(s)
- Carmen C Pazos-Moura
- Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Bloco G, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Brasil.
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Watanobe H. Leptin directly acts within the hypothalamus to stimulate gonadotropin-releasing hormone secretion in vivo in rats. J Physiol 2002; 545:255-68. [PMID: 12433965 PMCID: PMC2290656 DOI: 10.1113/jphysiol.2002.023895] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
It is still not known whether leptin, an adipocyte-derived hormone, acts directly within the hypothalamus to stimulate the gonadotropin-releasing hormone (GnRH)-luteinizing hormone (LH) system. In order to address this question, the present study examined the effects of direct intrahypothalamic perfusions with leptin on the in vivo release of GnRH in ovarian steroid-primed ovariectomized rats utilizing the push-pull perfusion technique. Both alpha-melanocyte-stimulating hormone (alpha-MSH) and neuropeptide Y were also measured in the hypothalamic perfusates. In normally fed animals, the leptin infusion was without effect on the release of these three hypothalamic peptides and also without effect on plasma LH and prolactin (PRL), whether leptin was infused into the medial preoptic area (where the majority of GnRH neuronal cell bodies exist) or the median eminence-arcuate nucleus complex (where axon terminals of GnRH neurons are located). In contrast, in 3-day fasted rats leptin was effective in stimulating the secretion of GnRH, alpha-MSH, and LH, regardless of the site of perfusion. These three hormones were increased in a temporal order of alpha-MSH, GnRH and LH. Irrespective of the site of perfusion, leptin was without effect on the release of neuropeptide Y. Only when leptin was infused into the median eminence-arcuate nucleus complex was PRL secretion also stimulated, although its onset was 1 h behind that of LH. The leptin-induced elevations of GnRH, alpha-MSH, LH and PRL were all dose-dependently stimulated by subnormal (1.0 ng ml(-1)) and normal (3.0 ng ml(-1)) concentrations of leptin, but at higher concentrations (10 ng ml(-1)) it did not produce additional effects. Leptin infusion into the anterior hypothalamic area, a control site equidistant from both the medial preoptic area and the median eminence-arcuate nucleus complex, did not produce a significant change in any of the hormones in either the fed or fasted rats. These results demonstrate for the first time that leptin can act at both the cell bodies and axon terminals of GnRH neurons to stimulate the release of the neurohormone in vivo, and they also suggest that alpha-MSH may play a significant intermediary role in linking leptin and GnRH secretion.
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Affiliation(s)
- Hajime Watanobe
- Division of Internal Medicine, Clinical Research Center, International University of Health and Welfare, Otawara, Tochigi, Japan
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Sullivan SD, Howard LC, Clayton AH, Moenter SM. Serotonergic activation rescues reproductive function in fasted mice: does serotonin mediate the metabolic effects of leptin on reproduction? Biol Reprod 2002; 66:1702-6. [PMID: 12021050 DOI: 10.1095/biolreprod66.6.1702] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Negative energy balance inhibits reproduction by restraining GnRH secretion. Leptin is a permissive metabolic signal for reproduction, but GnRH neurons do not appear to express leptin receptors, suggesting that interneurons transmit leptin signals to these cells. Serotonin (5HT) has satiety effects similar to those of leptin and alters LH release, and serotonergic neurons, which have been shown to express leptin receptors, terminate on GnRH neurons. We hypothesized that serotonergic neurons convey leptin signals to the reproductive neuroendocrine axis. To test this, mice were fasted for 48 h beginning on Diestrous Day 1. While fasting, mice received saline or leptin every 12 h or the 5HT-selective reuptake-inhibitor fluoxetine once at the start of the fast. Estrous cycles of fasted mice were longer (mean +/- SEM, 10.2 +/- 0.5 days; P < 0.0001) than those of fed mice (4.5 +/- 0.2 days). As previously reported, leptin prevented fasting-induced cycle lengthening (4.6 +/- 0.7 days). Fluoxetine also rescued estrous cycles in fasted mice (4.7 +/- 0.6 days), suggesting that 5HT and leptin have similar positive effects on reproduction. Coadministration of the 5HT 1/2/7 receptor-antagonist metergoline blocked rescue of cycle length by fluoxetine and by leptin. Treating leptin-deficient ob/ob and leptin receptor-deficient db/db mice with fluoxetine did not normalize body weight or rescue fertility, perhaps due to altered serotonergic tone in these animals. Together, these data demonstrate a permissive role for serotonergic systems in the metabolic control of reproduction and are consistent with the hypothesis that serotonergic neurons convey leptin signals to GnRH neurons.
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Affiliation(s)
- Shannon D Sullivan
- Department of Medicine, University of Virginia, Charlottesville, Virginia 22908, USA
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