1
|
Zhou X, Jiang D, Xu Y, Pan J, Xu D, Tian Y, Shen X, Huang Y. Endocrine and molecular regulation mechanisms of follicular development and egg-laying in quails under different photoperiods. Anim Biotechnol 2023; 34:4809-4818. [PMID: 37022011 DOI: 10.1080/10495398.2023.2196551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Photoperiod is a key environmental factor in regulating bird reproduction and induces neuroendocrine changes through the hypothalamic-pituitary-gonadal (HPG) axis. OPN5, as a deep-brain photoreceptor, transmits light signals to regulate follicular development through TSH-DIO2/DIO3. However, the mechanism among OPN5, TSH-DIO2/DIO3, and VIP/PRL in the HPG axis underlying the photoperiodic regulation of bird reproduction is unclear. In this study, 72 laying quails with 8-week-old were randomly divided into the long-day (LD) group [16 light (L): 8 dark (D)] and the short-day (SD) group (8 L:16 D), and then samples were collected on d 1, d 11, d 22, and d 36 of the experiment. The results showed that compared with the LD group, the SD group significantly inhibited follicular development (P < 0.05), decreased the P4, E2, LH, and PRL in serum (P < 0.05), downregulated the expression of GnRHR, VIP, PRL, OPN5, DIO2, and LHβ (P < 0.05), reduced the expression of GnRH and TSHβ (P > 0.05), and promoted DIO3, GnIH gene expression (P < 0.01). The short photoperiod downregulates OPN5, TSHβ, and DIO2 and upregulates DIO3 expression to regulate the GnRH/GnIH system. The downregulation of GnRHR and upregulation of GnIH resulted in a decrease in LH secretion, which withdrew the gonadotropic effects on ovarian follicles development. Slow down of follicular development and egg laying may also arise from lack of PRL potentiation to small follicle development under short days.
Collapse
Affiliation(s)
- Xiaoli Zhou
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| | - Danli Jiang
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| | - Yanglong Xu
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| | - Jianqiu Pan
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| | - Danning Xu
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| | - Yunbo Tian
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| | - Xu Shen
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| | - Yunmao Huang
- College of Animal Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, China
- College of Animal Science & Technology, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, Guangzhou, China
| |
Collapse
|
2
|
Butruille L, Vancamp P, Demeneix BA, Remaud S. Thyroid hormone regulation of adult neural stem cell fate: A comparative analysis between rodents and primates. Vitam Horm 2021; 116:133-192. [PMID: 33752817 DOI: 10.1016/bs.vh.2021.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Thyroid hormone (TH) signaling, a highly conserved pathway across vertebrates, is crucial for brain development and function throughout life. In the adult mammalian brain, including that of humans, multipotent neural stem cells (NSCs) proliferate and generate neuronal and glial progenitors. The role of TH has been intensively investigated in the two main neurogenic niches of the adult mouse brain, the subventricular and the subgranular zone. A key finding is that T3, the biologically active form of THs, promotes NSC commitment toward a neuronal fate. In this review, we first discuss the roles of THs in the regulation of adult rodent neurogenesis, as well as how it relates to functional behavior, notably olfaction and cognition. Most research uncovering these roles of TH in adult neurogenesis was conducted in rodents, whose genetic background, brain structure and rate of neurogenesis are considerably different from that of humans. To bridge the phylogenetic gap, we also explore the similarities and divergences of TH-dependent adult neurogenesis in non-human primate models. Lastly, we examine how photoperiodic length changes TH homeostasis, and how that might affect adult neurogenesis in seasonal species to increase fitness. Several aspects by which TH acts on adult NSCs seem to be conserved among mammals, while we only start to uncover the molecular pathways, as well as how other in- and extrinsic factors are intertwined. A multispecies approach delivering more insights in the matter will pave the way for novel NSC-based therapies to combat neurological disorders.
Collapse
Affiliation(s)
- Lucile Butruille
- UMR 7221 Phyma, CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Pieter Vancamp
- UMR 7221 Phyma, CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Barbara A Demeneix
- UMR 7221 Phyma, CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Sylvie Remaud
- UMR 7221 Phyma, CNRS/Muséum National d'Histoire Naturelle, Paris, France.
| |
Collapse
|
3
|
|
4
|
Geng A, Zhang Y, Zhang J, Wang H, Chu Q, Liu H. Effects of lighting pattern and photoperiod on egg production and egg quality of a native chicken under free-range condition. Poult Sci 2018; 97:2378-2384. [DOI: 10.3382/ps/pey104] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
5
|
Abstract
The isolation of melatonin was first reported in 1958. Since the demonstration that pineal melatonin synthesis reflects both daily and seasonal time, melatonin has become a key element of chronobiology research. In mammals, pineal melatonin is essential for transducing day-length information into seasonal physiological responses. Due to its lipophilic nature, melatonin is able to cross the placenta and is believed to regulate multiple aspects of perinatal physiology. The endogenous daily melatonin rhythm is also likely to play a role in the maintenance of synchrony between circadian clocks throughout the adult body. Pharmacological doses of melatonin are effective in resetting circadian rhythms if taken at an appropriate time of day, and can acutely regulate factors such as body temperature and alertness, especially when taken during the day. Despite the extensive literature on melatonin physiology, some key questions remain unanswered. In particular, the amplitude of melatonin rhythms has been recently associated with diseases such as type 2 diabetes mellitus but understanding of the physiological significance of melatonin rhythm amplitude remains poorly understood.
Collapse
Affiliation(s)
- Jonathan D Johnston
- Faculty of Health and Medical SciencesUniversity of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Debra J Skene
- Faculty of Health and Medical SciencesUniversity of Surrey, Guildford, Surrey GU2 7XH, UK
| |
Collapse
|
6
|
Christian HC, Imirtziadis L, Tortonese D. Ultrastructural changes in lactotrophs and folliculo-stellate cells in the ovine pituitary during the annual reproductive cycle. J Neuroendocrinol 2015; 27:277-84. [PMID: 25650820 DOI: 10.1111/jne.12261] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 01/30/2015] [Accepted: 01/30/2015] [Indexed: 11/26/2022]
Abstract
In seasonal mammals living in temperate zones, photoperiod regulates prolactin secretion, such that prolactin plasma concentrations peak during the summer months and are lowest during the winter. In sheep, a short-day breeder, circulating prolactin has important modulatory effects on the reproductive system via inhibitory actions on pituitary gonadotrophs and hypothalamic gonadotrophin-releasing hormone release. The exact cellular mechanisms that account for the chronic hypersecretion of prolactin during the summer is not known, although evidence supports an intrapituitary mechanism regulated by melatonin. Folliculo-stellate (FS) cells are non-endocrine cells that play a crucial role in paracrine communication within the pituitary and produce factors controlling prolactin and gonadotrophin release. The present study examined the morphology of the FS and lactotroph cell populations and their distribution in the sheep pituitary during the annual reproductive cycle. Ovine pituitary glands were collected in the winter (breeding season; BS) and summer (nonbreeding season; NBS) and were prepared for quantitative electron microscopy to assess the effects of season on FS and lactotroph cell density, morphology and distribution, as well as on junctional contacts between cells. It was found that lactotrophs in the NBS are larger in size and contain more numerous PRL granules than lactotrophs in the BS. FS cells were also larger in the NBS compared to BS and showed altered morphology such that, in the BS, long cell processes surrounded clusters of adjacent secretory cells. Although no significant change in the number of junctions was observed between lactotrophs and FS cells, or lactotrophs and gonadotrophs, there was a significant increase in the number of adherens junctions between lactotrophs and between FS cells. These findings demonstrate seasonal plasticity in the morphology of lactotrophs and FS cells that reflect changes in PRL secretion.
Collapse
Affiliation(s)
- H C Christian
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | | |
Collapse
|
7
|
Geng AL, Xu SF, Zhang Y, Zhang J, Chu Q, Liu HG. Effects of photoperiod on broodiness, egg-laying and endocrine responses in native laying hens. Br Poult Sci 2014; 55:264-9. [PMID: 24404878 DOI: 10.1080/00071668.2013.878782] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
1. The effects of photoperiod on broodiness, egg-laying and endocrine responses in native laying hens were investigated. A total of 648, 18-week-old native laying hens (Beijing You Chicken, BYC) were randomly allocated to 6 groups with 3 replicates. The birds were exposed to 1 of 6 different photoperiods, including 16L:8D (06:00 to 22:00 h) for group 1; 12L:2D:4L:6D for group 2; 8L:4D:4L:8D for group 3; 16L:8D (03:00 to 19:00 h) for group 4; 14L:10D for group 5; and 18L:6D for group 6. 2. The broodiness rate and egg-laying rate for weeks 20-26, 27-33, 34-40, 41-47, 48-54 and 55-61 were calculated, and serum prolactin (PRL), luteinising hormone (LH), 17-beta-oestradiol (E2), melatonin (Mel) and progesterone (P4) concentrations were measured at the end of each stage. 3. Significant effects were observed on the rate of broodiness by the photoperiod and stage, but the interaction of photoperiod and stage was not significant. The rate of broodiness for group 3 (5.9%) was significantly higher than other groups, with group 2 being the lowest (2.8%). Broodiness rate was the highest for weeks 41-47 (9.9%). Significant effects were observed on average egg-laying rate by photoperiod and stage: the rate of egg-laying of groups 2 and 5 were significantly higher than groups 1, 4 and 6. 4. There were no significant effects of photoperiod on PRL, LH and Mel concentrations at 26, 33, 40 and 54 weeks of age (P > 0.05), but at 47 weeks of age, PRL and LH concentrations of group 1 were significantly lower than those in other groups. 5. The study suggests that the photoperiod of group 2 (12L:2D:4L:6D) is optimal for the birds' performance to give the lowest broodiness rate and the highest egg-laying rate during the whole laying period, and 41-47 weeks may be a key stage for the photomodulation of broodiness.
Collapse
Affiliation(s)
- A L Geng
- a Institute of Animal Husbandry and Veterinary Medicine , Beijing Academy of Agricultural and Forestry Sciences , Beijing 100097 , P. R. China
| | | | | | | | | | | |
Collapse
|
8
|
Abstract
Living organisms show seasonality in a wide array of functions such as reproduction, fattening, hibernation, and migration. At temperate latitudes, changes in photoperiod maintain the alignment of annual rhythms with predictable changes in the environment. The appropriate physiological response to changing photoperiod in mammals requires retinal detection of light and pineal secretion of melatonin, but extraretinal detection of light occurs in birds. A common mechanism across all vertebrates is that these photoperiod-regulated systems alter hypothalamic thyroid hormone (TH) conversion. Here, we review the evidence that a circadian clock within the pars tuberalis of the adenohypophysis links photoperiod decoding to local changes of TH signaling within the medio-basal hypothalamus (MBH) through a conserved thyrotropin/deiodinase axis. We also focus on recent findings which indicate that, beyond the photoperiodic control of its conversion, TH might also be involved in longer-term timing processes of seasonal programs. Finally, we examine the potential implication of kisspeptin and RFRP3, two RF-amide peptides expressed within the MBH, in seasonal rhythmicity.
Collapse
Affiliation(s)
- Hugues Dardente
- Physiologie de la Reproduction et des Comportements, INRA, UMR085, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais de Tours, Tours, France
- Institut français du cheval et de l’équitation, Nouzilly, France
- *Correspondence: Hugues Dardente, INRA, UMR85 Physiologie de la Reproduction et des Comportements, CNRS, UMR7247, Université François Rabelais de Tours, IFCE, F-37380 Nouzilly, France e-mail:
| | - David G. Hazlerigg
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
| | | |
Collapse
|
9
|
Persichetti A, Sciuto R, Rea S, Basciani S, Lubrano C, Mariani S, Ulisse S, Nofroni I, Maini CL, Gnessi L. Prevalence, mass, and glucose-uptake activity of ¹⁸F-FDG-detected brown adipose tissue in humans living in a temperate zone of Italy. PLoS One 2013; 8:e63391. [PMID: 23667608 DOI: 10.1371/journal.pone.0063391] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 04/03/2013] [Indexed: 11/25/2022] Open
Abstract
Background The 18F-fluorodeoxyglucose (18F-FDG)-detected brown adipose tissue (BAT), is enhanced by cold stimulus and modulated by other factors that still have to be disentangled. We investigated the prevalence, mass, and glucose-uptake activity of 18F-FDG-detected BAT in a population of adults living in the temperate climatic zone of the Rome area. Methods and Findings We retrospectively analyzed 6454 patients who underwent 18F-FDG positron emission tomography/computed tomography (PET/CT) examinations. We found 18F-FDG BAT in 217 of the 6454 patients (3.36%). Some of them underwent more than one scan and the positive scans were 278 among 8004 (3.47%). The prevalence of patients with at least one positive scan was lower in men (1.77%; 56 of 3161) compared with women (4.88%; 161 of 3293). The BAT positive patients were most frequently younger, thinner and with lower plasma glucose levels compared with BAT negative patients. The amount of BAT in the defined region of interest, the activity of BAT and the number of positive sites of active BAT were similar in both sexes. The prevalence of patients with 18F-FDG positive PET/CT was highest in December-February, lower in March-May and September-November, and lowest in June-August and was positively correlated with night length and negatively correlated with ambient temperature. Changes in day length and variations of temperature, associated with the prevalence of positive BAT patients. Among the patients who had multiple scans, outdoor temperature was significantly lower and day length was shorter on the occasion when BAT was detected. Conclusions This study identifies day length, outdoor temperature, age, sex, BMI, and plasma glucose levels as major determinants of the prevalence, mass, and activity of 18F-FDG-detected BAT.
Collapse
|
10
|
Affiliation(s)
- J. Raynaud
- Institute of Evolutionary Biology and Environmental Studies; University of Zurich; Zurich Switzerland
| | - C. Schradin
- Université de Strasbourg; IPHC-DEPE; CNRS; Strasbourg France
- School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Johannesburg South Africa
| |
Collapse
|
11
|
Molik E, Misztal T, Romanowicz K, Zieba D. Short-day and melatonin effects on milking parameters, prolactin profiles and growth-hormone secretion in lactating sheep. Small Rumin Res 2013; 109:182-7. [DOI: 10.1016/j.smallrumres.2012.10.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
12
|
Bowyer JF, Thomas M, Patterson TA, George NI, Runnells JA, Levi MS. A visual description of the dissection of the cerebral surface vasculature and associated meninges and the choroid plexus from rat brain. J Vis Exp 2012. [PMID: 23183685 PMCID: PMC3523424 DOI: 10.3791/4285] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
This video presentation was created to show a method of harvesting the two most important highly vascular structures, not residing within the brain proper, that support forebrain function. They are the cerebral surface (superficial) vasculature along with associated meninges (MAV) and the choroid plexus which are necessary for cerebral blood flow and cerebrospinal fluid (CSF) homeostasis. The tissue harvested is suitable for biochemical and physiological analysis, and the MAV has been shown to be sensitive to damage produced by amphetamine and hyperthermia. As well, the major and minor cerebral vasculatures harvested in MAV are of potentially high interest when investigating concussive types of head trauma. The MAV dissected in this presentation consists of the pial and some of the arachnoid membrane (less dura) of the meninges and the major and minor cerebral surface vasculature. The choroid plexus dissected is the structure that resides in the lateral ventricles as described by Oldfield and McKinley. The methods used for harvesting these two tissues also facilitate the harvesting of regional cortical tissue devoid of meninges and larger cerebral surface vasculature, and is compatible with harvesting other brain tissues such as striatum, hypothalamus, hippocampus, etc. The dissection of the two tissues takes from 5 to 10 min total. The gene expression levels for the dissected MAV and choroid plexus, as shown and described in this presentation can be found at GSE23093 (MAV) and GSE29733 (choroid plexus) at the NCBI GEO repository. This data has been, and is being, used to help further understand the functioning of the MAV and choroid plexus and how neurotoxic events such as severe hyperthermia and AMPH adversely affect their function.
Collapse
Affiliation(s)
- John F Bowyer
- Division of Neurotoxicology, National Center for Toxicological Research.
| | | | | | | | | | | |
Collapse
|
13
|
Matzkin ME, Ambao V, Carino MH, Rossi SP, González L, Turyn D, Campo S, Calandra RS, Frungieri MB. Prolactin (PRL) induction of cyclooxygenase 2 (COX2) expression and prostaglandin (PG) production in hamster Leydig cells. Mol Cell Endocrinol 2012; 348:33-46. [PMID: 21803118 DOI: 10.1016/j.mce.2011.07.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 06/08/2011] [Accepted: 07/12/2011] [Indexed: 12/14/2022]
Abstract
Serum prolactin (PRL) variations play a crucial role in the photoperiodic-induced testicular regression-recrudescence transition in hamsters. We have previously shown that cyclooxygenase 2 (COX2), a key enzyme in the biosynthesis of prostaglandins (PGs), is expressed mostly in Leydig cells of reproductively active hamsters with considerable circulating and pituitary levels of PRL. In this study, we describe a stimulatory effect of PRL on COX2/PGs in hamster Leydig cells, which is mediated by IL-1β and prevented by P38-MAPK and JAK2 inhibitors. Furthermore, by preparative isoelectric focusing (IEF), we isolated PRL charge analogues from pituitaries of active [isoelectric points (pI): 5.16, 4.61, and 4.34] and regressed (pI: 5.44) hamsters. More acidic PRL charge analogues strongly induced COX2 expression, while less acidic ones had no effect. Our studies suggest that PRL induces COX2/PGs in hamster Leydig cells through IL-1β and activation of P38-MAPK and JAK2. PRL microheterogeneity detected in active/inactive hamsters may be responsible for the photoperiodic variations of COX2 expression in Leydig cells.
Collapse
Affiliation(s)
- María Eugenia Matzkin
- Laboratorio de Esteroides, Instituto de Biología y Medicina Experimental, CONICET, Vuelta de Obligado 2490 (1428), Ciudad de Buenos Aires, Argentina
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Abstract
In mammals, the nocturnal melatonin signal is well established as a key hormonal indicator of seasonal changes in day-length, providing the brain with an internal representation of the external photoperiod. The pars tuberalis (PT) of the pituitary gland is the major site of expression of the G-coupled receptor MT1 in the brain and is considered as the main site of integration of the photoperiodic melatonin signal. Recent studies have revealed how the photoperiodic melatonin signal is encoded and conveyed by the PT to the brain and the pituitary, but much remains to be resolved. The development of new animal models and techniques such as cDNA arrays or high throughput sequencing has recently shed the light onto the regulatory networks that might be involved. This review considers the current understanding of the mechanisms driving photoperiodism in the mammalian PT with a particular focus on the seasonal prolactin secretion.
Collapse
Affiliation(s)
- Sandrine M Dupré
- University of Manchester, Faculty of Life Sciences, Manchester, UK.
| |
Collapse
|
15
|
Richardson G, Wang-Weigand S. Effects of long-term exposure to ramelteon, a melatonin receptor agonist, on endocrine function in adults with chronic insomnia. Hum Psychopharmacol 2009; 24:103-11. [PMID: 19090503 DOI: 10.1002/hup.993] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE To evaluate the effects of ramelteon, an MT(1)/MT(2) melatonin receptor agonist used to treat insomnia, on endocrine function in adults with chronic insomnia. METHODS This was a double-blind, placebo-controlled, trial of adults (18-45 years) with chronic insomnia. Subjects received either ramelteon 16 mg or placebo nightly for 6 months. Hormonal measures of the thyroid, reproductive, and adrenal axes were analyzed monthly and compared with baseline and placebo values. RESULTS While isolated changes were detected at some time points, there were no consistent statistically significant differences between treatments on measures of thyroid function (total T4, free T4, TSH, and total T3), adrenal function (AM cortisol, and ACTH), or on most reproductive endocrine measures [LH, FSH, estradiol (women), total, and free testosterone (men)]. Prolactin concentrations were increased overall in women in the ramelteon group compared with placebo (p = 0.003). No clinical effects of elevated prolactin were reported; average menstrual cycle length, duration of menses, and ovulation probability did not differ between groups. CONCLUSIONS Long-term exposure to ramelteon 16 mg, a potent melatonin receptor agonist, resulted in mild, transient increase in prolactin, in women only, that were not associated with measurable reproductive effects. There were no consistent changes in other endocrine measures.
Collapse
Affiliation(s)
- Gary Richardson
- Henry Ford Hospital, Sleep Disorders and Research Center, Detroit, MI 48202, USA.
| | | |
Collapse
|
16
|
Agez L, Laurent V, Guerrero HY, Pévet P, Masson-Pévet M, Gauer F. Endogenous melatonin provides an effective circadian message to both the suprachiasmatic nuclei and the pars tuberalis of the rat. J Pineal Res 2009; 46:95-105. [PMID: 19090912 DOI: 10.1111/j.1600-079x.2008.00636.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The suprachiasmatic nuclei (SCN) distribute the circadian neural message to the pineal gland which transforms it into a humoral circadian message, the nocturnal melatonin synthesis, which in turn modulates tissues expressing melatonin receptors such as the SCN or the pars tuberalis (PT). Nuclear orphan receptors (NOR), including rorbeta and rev-erbalpha, have been presented as functional links between the positive and negative loops of the molecular clock. Recent findings suggest that these NOR could be the initial targets of melatonin's chronobiotic message within the SCN. We investigated the role of these NOR in the physiological effect of endogenous melatonin on these tissues. We monitored rorbeta and rev-erbalpha mRNA expression levels by quantitative in situ hybridization after pinealectomy. Pinealectomy had no effect on NOR circadian expression rhythms in the SCN in 8-day pinealectomized (PX) animals. However in animals PX for 3 months, significant desynchronization between per1 and per2 transcription patterns appeared. These results suggest that endogenous melatonin could sustain the circadian rhythmicity and the phase relationship between the molecular partners of the SCN circadian system on a long-term basis. On the other hand, pinealectomy decreased the level and abolished the rhythmicity of NOR mRNA expression in the PT. These effects were partially prevented by daily melatonin administration in the drinking water. These results show that NOR can be regulated by the melatonin circadian rhythm in the PT and could be the link between the physiological action of melatonin and the core of the molecular circadian clock in this tissue.
Collapse
Affiliation(s)
- Laurence Agez
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UMR 7168, Université Louis Pasteur, Strasbourg, France
| | | | | | | | | | | |
Collapse
|
17
|
Abstract
The pars tuberalis (PT) is a distinct subdivision of the anterior pituitary gland that plays a central role in regulating seasonal prolactin release. In sheep, there is compelling evidence that seasonal changes in light, transformed into a melatonin signal, are interpreted by the PT to modulate the release of a factor which affects prolactin release. The identity of this factor(s) is unknown but has been preemptively called 'tuberalin'. In the present study, we report on an initial immunocytochemical investigation where we have identified that many ovine PT cells are immunoreactive for the tachykinin substance P (SP). Few cells in the pars distalis immunoreact for SP. The SP-immunoreactive cells did not colocalize with beta-luteinizing hormone. RT-PCR confirmed the presence of preprotachykinin A mRNA in the PT. We hypothesize that SP, and possibly other preprotachykinin A-derived tachykinins, may play a role in the seasonal regulation of prolactin secretion in sheep.
Collapse
Affiliation(s)
- Donal C Skinner
- Department of Zoology and Physiology, and Neurobiology Program, University of Wyoming, Laramie, Wyo. 82071, USA.
| | | | | | | |
Collapse
|
18
|
Abstract
Recent evidence based on studies in hypothalamo-pituitary disconnected Soay sheep suggests that the generation of circannual rhythms may be local to specific tissues or physiological systems. Now, the authors present a physiological model of a circannual rhythm generator centered in the pituitary gland based on the interaction between melatonin-responsive cells in the pars tuberalis that act to decode photoperiod, and lactotroph cells of the adjacent pars distalis that secrete prolactin. The model produces a self-sustained, circannual rhythm in endocrine output that the authors explore by mathematical modeling. The circannual oscillation requires a delayed negative feedback mechanism. The authors highlight specific features of the pituitary dynamics as a guide to future research on circannual rhythms.
Collapse
Affiliation(s)
- Duncan J Macgregor
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | | |
Collapse
|
19
|
Jurkevich A, Berghman LR, Cornett LE, Kuenzel WJ. Immunohistochemical characterization of chicken pituitary cells containing the vasotocin VT2 receptor. Cell Tissue Res 2008; 333:253-62. [DOI: 10.1007/s00441-008-0636-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Accepted: 05/02/2008] [Indexed: 10/22/2022]
|
20
|
Abstract
In seasonal species, various physiological processes including reproduction are organized by photoperiod via melatonin, but the mechanisms of melatonin action are still unknown. In birds, the peptide gonadotropin-inhibiting hormone (GnIH) has been shown to have inhibitory effects on reproductive activity and displays seasonal changes of expression. Here we present evidence in mammals that the gene orthologous to GnIH, the RFamide-related peptide (RFRP) gene, expressed in the mediobasal hypothalamus, is strongly regulated by the length of the photoperiod, via melatonin. The level of RFRP mRNA and the number of RFRP-immunoreactive cell bodies were reduced in sexually quiescent Syrian and Siberian hamsters acclimated to short-day photoperiod (SD) compared with sexually active animals maintained under long-day photoperiod (LD). This was contrasted in the laboratory Wistar rat, a non-photoperiodic breeder, in which no evidence for RFRP photoperiodic modulation was seen. In Syrian hamsters, the reduction of RFRP expression in SD was independent from secondary changes in gonadal steroids. By contrast, the photoperiodic variation of RFRP expression was abolished in pinealectomized hamsters, and injections of LD hamsters with melatonin for 60 d provoked inhibition of RFRP expression down to SD levels, indicating that the regulation is dependent on melatonin. Altogether, these results demonstrate that in these hamster species, the RFRP neurons are photoperiodically modulated via a melatonin-dependent process. These observations raise questions on the role of RFRP as a general inhibitor of reproduction and evoke new perspectives for understanding how melatonin controls seasonal processes via hypothalamic targets.
Collapse
Affiliation(s)
- Florent G Revel
- Département de Neurobiologie des Rythmes, Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université Louis Pasteur-Institut Fédératif de Recherche des Neurosciences, Strasbourg, France
| | | | | | | | | |
Collapse
|
21
|
Abstract
Animals have evolved many season-specific behavioural and physiological adaptations that allow them to both cope with and exploit the cyclic annual environment. Two classes of endogenous annual timekeeping mechanisms enable animals to track, anticipate and prepare for the seasons: a timer that measures an interval of several months and a clock that oscillates with a period of approximately a year. Here, we discuss the basic properties and biological substrates of these timekeeping mechanisms, as well as their reliance on, and encoding of environmental cues to accurately time seasonal events. While the separate classification of interval timers and circannual clocks has elucidated important differences in their underlying properties, comparative physiological investigations, especially those regarding seasonal prolactin secretions, hint at the possibility of common substrates.
Collapse
Affiliation(s)
- Matthew J Paul
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
| | | | | |
Collapse
|
22
|
Abstract
The pars tuberalis (PT) of the adenohypophysis expresses a high density of melatonin receptors and is thought to be a crucial relay for the actions of melatonin on seasonal rhythmicity of prolactin secretion by the pars distalis (PD). In common with the suprachiasmatic nucleus of the hypothalamus and most other peripheral tissues, the PT rhythmically expresses a range of 'clock genes'. Interestingly, this expression is highly dependent upon melatonin/photoperiod, with several aspects unique to the PT. These observations led to the establishment of a conceptual framework for the encoding of seasonal timing in this tissue. This review summarises current knowledge of the morphological, functional and molecular aspects of the PT and considers its role in seasonal timing. The strengths and weaknesses of current hypotheses that link melatonin action in the PT to its seasonal effect on lactotrophs of the PD are discussed and alternative working hypotheses are suggested.
Collapse
Affiliation(s)
- H Dardente
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, UK.
| |
Collapse
|
23
|
Johnston JD, Schuster C, Barrett P, Hazlerigg DG. Regulation of the ovine MT1 melatonin receptor promoter: interaction between multiple pituitary transcription factors at different phases of development. Mol Cell Endocrinol 2007; 268:59-66. [PMID: 17337323 DOI: 10.1016/j.mce.2007.01.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2006] [Revised: 12/16/2006] [Accepted: 01/24/2007] [Indexed: 11/22/2022]
Abstract
Pineal secretion of melatonin provides a neuroendocrine representation of the light-dark cycle, which is used to synchronise daily and annual rhythms of physiology and behaviour. In mammals, melatonin primarily acts through MT(1) melatonin receptors that exhibit a highly restricted tissue distribution. Expression of MT(1) receptors is subject to developmental and circadian control, which likely modulates the physiological actions of melatonin. To investigate the mechanisms controlling MT(1) expression we cloned the proximal 1.5kb region of the ovine MT(1) promoter. Sequence analysis revealed putative cis-elements for transcription factors involved in pituitary development, namely Pitx-1 and Egr-1, and multiple putative E-boxes, which are involved in both circadian and developmental gene regulation. Nuclear protein from ovine pars tuberalis (PT) cells, a site of high endogenous MT(1) expression, stimulated gene expression from a MT(1) expression construct, indicating the presence of a functional promoter. Pitx-1 was strongly expressed in the ovine PT and stimulated MT(1) promoter activity in transfection assays. Co-transfection with Egr-1 induced promoter-specific effects: Pitx-1-stimulated MT(1) activity was inhibited, whereas betaLH promoter activity was enhanced. In addition to Pitx-1 the circadian clock genes Clock and Bmal1 were also expressed in the PT. However, despite multiple putative E-boxes in the MT(1) promoter, transfected Clock and Bmal1 were unable to regulate either basal or Pitx-1-stimulated MT(1) promoter activity. The current data, in conjunction with our previous study of the rat MT(1) promoter, suggests a general model in which melatonin receptor expression in the mammalian pituitary is determined by the developmentally changing balance between stimulatory and inhibitory transcription factors. Furthermore, our data suggest that circadian variation in MT(1) gene expression does not depend upon the direct action of circadian clock genes on E-box cis-elements.
Collapse
Affiliation(s)
- Jonathan D Johnston
- School of Biomedical and Molecular Sciences, University of Surrey, Guildford GU2 7XH, UK.
| | | | | | | |
Collapse
|
24
|
Wagner GC, Johnston JD, Tournier BB, Ebling FJP, Hazlerigg DG. Melatonin induces gene-specific effects on rhythmic mRNA expression in the pars tuberalis of the Siberian hamster (Phodopus sungorus). Eur J Neurosci 2007; 25:485-90. [PMID: 17284190 DOI: 10.1111/j.1460-9568.2006.05291.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In mammals, circadian and photoperiodic information is encoded in the pineal melatonin signal. The pars tuberalis (PT) of the pituitary is a melatonin target tissue, which transduces photoperiodic changes and drives seasonal changes in prolactin secretion from distal lactotroph cells. Measurement of photoperiodic time in the PT is believed to occur through melatonin dependent changes in clock gene expression, although it is unclear whether the PT should be considered a melatonin sensitive peripheral oscillator. We tested this hypothesis in the Siberian hamster (Phodopus sungorus) firstly by investigating the effects of melatonin injection, and secondly by determining whether temporal variation in gene expression within the PT persists in the absence of a rhythmic melatonin signal. Hamsters preconditioned to long days were treated with melatonin during the late light phase, to advance the timing of the nocturnal melatonin peak, or placed in constant light for one 24 h cycle, thereby suppressing endogenous melatonin secretion. Gene expression in the PT was measured by in situ hybridization. We show that melatonin rapidly induces cry1 mRNA expression without the need for a prolonged melatonin-free interval, acutely inhibits mt1 expression, advances the timing of peak rev-erb alpha expression and modulates per1 expression. With the exception of cry1, these genes continue to show temporal changes in expression over a first cycle in the absence of a melatonin signal. Our data are consistent with the hypothesis that the hamster PT contains a damped endogenous circadian oscillator, which requires a rhythmic melatonin signal for long-term synchronization.
Collapse
Affiliation(s)
- Gabriela C Wagner
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, UK
| | | | | | | | | |
Collapse
|
25
|
Abstract
In seasonal species, photoperiod organizes various physiological processes, including reproduction. Recent data indicate that the expression of type 2 iodothyronine deiodinase (Dio2) is modulated by photoperiod in the mediobasal hypothalamus of some seasonal species. Dio2 is believed to control the local synthesis of bioactive T(3) to regulate gonadal response. Here we used in situ hybridization to study Dio2 expression in the hypothalamus of a photoperiodic rodent, the Syrian hamster. Dio2 was highly expressed in reproductively active hamsters in long day, whereas it was dramatically reduced in sexually inhibited hamsters maintained in short day. This contrasted with the laboratory rat, a nonphotoperiodic species, in which no evidence for Dio2 photoperiodic modulation was seen. We also demonstrate that photoperiodic variations of Dio2 expression in hamsters are independent from secondary changes in gonadal steroids. Studies in pinealectomized hamsters showed that the photoperiodic variation of Dio2 expression is melatonin dependent, and injections of long day hamsters with melatonin for only 7 d were sufficient to inhibit Dio2 expression to that of short day levels. Finally, because in some seasonal species thyroid hormones are involved in photorefractoriness, we examined Dio2 expression in short day-refractory hamsters and found that Dio2 mRNA levels remained low despite full reproductive recrudescence. Altogether, these results demonstrate that in the Syrian hamster Dio2 is photoperiodically modulated via a melatonin-dependent process. Furthermore, refractoriness to photoperiod in hamsters appears to occur independently of Dio2. These results raise new perspectives for understanding how thyroid hormones are involved in the control of photoperiodic neuroendocrine processes.
Collapse
Affiliation(s)
- Florent G Revel
- Département de Neurobiologie des Rythmes, Centre National de la Recherche Scientifique Unité Mixte de Recherche, 7168/LC2, Institut des Neurosciences Cellulaires et Intégratives, Université Louis Pasteur, 67084 Strasbourg Cedex, France
| | | | | | | | | |
Collapse
|
26
|
Abstract
Melatonin effects are discussed by reviewing results from mice with intact or disrupted melatonin signaling. Melatonin, the neuroendocrine hand of the clock produced in the pineal gland during night, acts upon two receptor subtypes. Melatonin receptors are found in the suprachiasmatic nuclei (SCN), hypophysial pars tuberalis (PT) and adrenal gland. In SCN, melatonin interacts with PACAP, a neuropeptide of the retinohypothalamic tract. Moreover, melatonin acts on the SCN to modulate the activity of the sympathetic nervous system. Melatonin is not required to maintain rhythmic clock gene expression in SCN. By contrast, the rhythmic clock gene expression in PT depends on a melatonin signal interacting with adenosine. Melatonin may also affect clock gene protein levels in the adrenal cortex and influence adrenal functions. In conclusion, melatonin may serve the synchronization of peripheral oscillators by interacting with other neuroactive substances. A stress-reducing potency of melatonin needs to be explored in further studies.
Collapse
Affiliation(s)
- H W Korf
- Dr. Senckenbergische Anatomie, Fachbereich Medizin, J.W.-Goethe Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt/Main, Germany.
| | | |
Collapse
|
27
|
Johnston JD, Tournier BB, Andersson H, Masson-Pévet M, Lincoln GA, Hazlerigg DG. Multiple effects of melatonin on rhythmic clock gene expression in the mammalian pars tuberalis. Endocrinology 2006; 147:959-65. [PMID: 16269454 DOI: 10.1210/en.2005-1100] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In mammals, changing day length modulates endocrine rhythms via nocturnal melatonin secretion. Studies of the pituitary pars tuberalis (PT) suggest that melatonin-regulated clock gene expression is critical to this process. Here, we considered whether clock gene rhythms continue in the PT in the absence of melatonin and whether the effects of melatonin on the expression of these genes are temporally gated. Soay sheep acclimated to long photoperiod (LP) were transferred to constant light for 24 h, suppressing endogenous melatonin secretion. Animals were infused with melatonin at 4-h intervals across the final 24 h, and killed 3 h after infusion. The expression of five clock genes (Per1, Per2, Cry1, Rev-erbalpha, and Bmal1) was measured by in situ hybridization. In sham-treated animals, PT expression of Per1, Per2, and Rev-erbalpha showed pronounced temporal variation despite the absence of melatonin, with peak times occurring earlier than predicted under LP. The time of peak Bmal1 expression remained LP-like, whereas Cry1 expression was continually low. Melatonin infusion induced Cry1 expression at all times and suppressed other genes, but only when they showed high expression in sham-treated animals. Hence, 3 h after melatonin treatment, clock gene profiles were driven to a similar state, irrespective of infusion time. In contrast to the PT, melatonin infusions had no clear effect on clock gene expression in the suprachiasmatic nuclei. Our results provide the first example of acute sensitivity of multiple clock genes to one endocrine stimulus and suggest that rising melatonin levels may reset circadian rhythms in the PT, independently of previous phase.
Collapse
|
28
|
Abstract
The pineal hormone melatonin is mainly secreted during night-time which, in humans, is the normal time of sleep. It has been proposed that, during this period, melatonin exerts an inhibitory influence on secretory activity of the hypothalamic-pituitary-adrenal (HPA) system, although there is little evidence for this view in humans. In blind humans, a single oral dose of melatonin at bed time suppressed nocturnal cortisol secretion. However, suppression could have been secondary to an improved sleep after melatonin in these experiments. In the present study, we examined whether melatonin exerts a similar inhibitory effect on HPA activity in waking subjects. Fourteen healthy young men were tested at bed time, but kept awake throughout the experimental epoch. Thirty minutes after oral ingestion of 5 mg melatonin, activity of the HPA-system was stimulated through a standard insulin-induced hypoglycaemia. Adrenocorticotrophin hormone and cortisol concentrations under basal conditions before insulin injection, as well as in response to insulin-induced hypoglycaemia, were almost identical for the melatonin and placebo control conditions (P > 0.5). However, melatonin increased plasma prolactin concentrations (P < 0.01) and reduced systolic blood pressure in the time interval following hypoglycaemia (P < 0.05). Based on a review of the literature and our results, we conclude that melatonin per se has no substantially suppressing effect on HPA secretory activity, although such an effect can be gated by sleep-related processes.
Collapse
Affiliation(s)
- B Perras
- Department of Internal Medicine I, University of Lübeck, Germany.
| | | | | | | |
Collapse
|
29
|
Abstract
Melatonin, dubbed the hormone of darkness, is known to regulate a wide variety of physiological processes in mammals. This review describes well-defined functional responses mediated through activation of high-affinity MT1 and MT2 G protein-coupled receptors viewed as potential targets for drug discovery. MT1 melatonin receptors modulate neuronal firing, arterial vasocon-striction, cell proliferation in cancer cells, and reproductive and metabolic functions. Activation of MT2 melatonin receptors phase shift circadian rhythms of neuronal firing in the suprachiasmatic nucleus, inhibit dopamine release in retina, induce vasodilation and inhibition of leukocyte rolling in arterial beds, and enhance immune responses. The melatonin-mediated responses elicited by activation of MT1 and MT2 native melatonin receptors are dependent on circadian time, duration and mode of exposure to endogenous or exogenous melatonin, and functional receptor sensitivity. Together, these studies underscore the importance of carefully linking each melatonin receptor type to specific functional responses in target tissues to facilitate the design and development of novel therapeutic agent.
Collapse
Affiliation(s)
- Margarita L Dubocovich
- Department of Molecular Pharmacology & Biological Chemistry, Northwestern University Feinberg School of Medicine Center for Drug Discovery and Chemical Biology, Chicago, IL 60611, USA.
| | | |
Collapse
|
30
|
Johnston JD, Ebling FJP, Hazlerigg DG. Photoperiod regulates multiple gene expression in the suprachiasmatic nuclei and pars tuberalis of the Siberian hamster (Phodopus sungorus). Eur J Neurosci 2005; 21:2967-74. [PMID: 15978008 DOI: 10.1111/j.1460-9568.2005.04148.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photoperiod regulates the seasonal physiology of many mammals living in temperate latitudes. Photoperiodic information is decoded by the master circadian clock in the suprachiasmatic nuclei (SCN) of the hypothalamus and then transduced via pineal melatonin secretion. This neurochemical signal is interpreted by tissues expressing melatonin receptors (e.g. the pituitary pars tuberalis, PT) to drive physiological changes. In this study we analysed the photoperiodic regulation of the circadian clockwork in the SCN and PT of the Siberian hamster. Female hamsters were exposed to either long or short photoperiod for 8 weeks and sampled at 2-h intervals across the 24-h cycle. In the SCN, rhythmic expression of the clock genes Per1, Per2, Cry1, Rev-erbalpha, and the clock-controlled genes arginine vasopressin (AVP) and d-element binding protein (DBP) was modulated by photoperiod. All of these E-box-containing genes tracked dawn, with earlier peak mRNA expression in long, compared to short, photoperiod. This response occurred irrespective of the presence of additional regulatory cis-elements, suggesting photoperiodic regulation of SCN gene expression through a common E-box-related mechanism. In long photoperiod, expression of Cry1 and Per1 in the PT tracked the onset and offset of melatonin secretion, respectively. However, whereas Cry1 tracked melatonin onset in short period, Per1 expression was not detectably rhythmic. We therefore propose that, in the SCN, photoperiodic regulation of clock gene expression primarily occurs via E-boxes, whereas melatonin-driven signal transduction drives the phasing of a subset of clock genes in the PT, independently of the E-box.
Collapse
Affiliation(s)
- Jonathan D Johnston
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK.
| | | | | |
Collapse
|
31
|
Sheynzon P, Karolczak M, Dehghani F, Korf HW. Diurnal variation in CREB phosphorylation and PER1 protein levels in lactotroph cells of melatonin-proficient C3H and melatonin-deficient C57BL mice: similarities and differences. Cell Tissue Res 2005; 321:211-7. [PMID: 15947965 DOI: 10.1007/s00441-005-1150-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Accepted: 04/12/2005] [Indexed: 12/15/2022]
Abstract
The pineal hormone melatonin plays an important role in the maintenance of rhythmic functions of the hypophyseal pars tuberalis, which controls the lactotroph cells of the pars distalis. To analyze the effects of melatonin deficiency on the activity state of these cells, we have investigated the levels of Ser133-phosphorylated (p)CREB and PER1 protein in immunocytochemically identified lactotroph cells of melatonin-proficient C3H and melatonin-deficient C57BL mice at four different time points of a 12/12 LD cycle. At night, the percentage of lactotroph cells showing a positive nuclear pCREB and PER1 immunoreaction is significantly smaller in C57BL than in C3H mice. In both mouse strains, the percentage of pCREB-immunoreactive cells is minimal in the early morning and gradually increases to reach a maximum in the late night. PER1 levels show a parallel temporal variation in C3H, but in C57BL, they are drastically reduced in the early afternoon. The observation that, during darkness, the percentage of lactotroph cells with nuclear pCREB immunoreaction is significantly higher in C3H than in C57BL mice suggests the existence of a distinct cell population that is under the control of melatonin-dependent intrapituitary signaling. Interestingly, the percentage of pCREB- and PER1-immunoreactive lactotroph cells reaches minimal and maximal values at the same time points. This suggests that the correlation between CREB phosphorylation and PER1 induction differs between these cells and other neuroendocrine centers, e.g., the pineal organ and suprachiasmatic nucleus, displaying a temporal gap between CREB phosphorylation and PER1 induction.
Collapse
Affiliation(s)
- Pjotr Sheynzon
- Dr. Senckenbergische Anatomie, Institut für Anatomie II, Fachbereich Medizin der J.W. Goethe-Universität Frankfurt, Germany
| | | | | | | |
Collapse
|