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Johnson CS, Mermelstein PG. The interaction of membrane estradiol receptors and metabotropic glutamate receptors in adaptive and maladaptive estradiol-mediated motivated behaviors in females. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:33-91. [PMID: 36868633 DOI: 10.1016/bs.irn.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Estrogen receptors were initially identified as intracellular, ligand-regulated transcription factors that result in genomic change upon ligand binding. However, rapid estrogen receptor signaling initiated outside of the nucleus was also known to occur via mechanisms that were less clear. Recent studies indicate that these traditional receptors, estrogen receptor α and estrogen receptor β, can also be trafficked to act at the surface membrane. Signaling cascades from these membrane-bound estrogen receptors (mERs) can rapidly alter cellular excitability and gene expression, particularly through the phosphorylation of CREB. A principal mechanism of neuronal mER action has been shown to occur through glutamate-independent transactivation of metabotropic glutamate receptors (mGlu), which elicits multiple signaling outcomes. The interaction of mERs with mGlu has been shown to be important in many diverse functions in females, including driving motivated behaviors. Experimental evidence suggests that a large part of estradiol-induced neuroplasticity and motivated behaviors, both adaptive and maladaptive, occurs through estradiol-dependent mER activation of mGlu. Herein we will review signaling through estrogen receptors, both "classical" nuclear receptors and membrane-bound receptors, as well as estradiol signaling through mGlu. We will focus on how the interactions of these receptors and their downstream signaling cascades are involved in driving motivated behaviors in females, discussing a representative adaptive motivated behavior (reproduction) and maladaptive motivated behavior (addiction).
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Affiliation(s)
- Caroline S Johnson
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Paul G Mermelstein
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States.
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2
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Rocha MLM, Fernandes PP, Tenório F, Manhães AC, Barradas PC. Malnourishment during early lactation disrupts the ontogenetic distribution of the CART and α-MSH anorexigenic molecules in the arcuate/paraventricular pathway and lateral hypothalamus in male rats. Brain Res 2020; 1743:146906. [PMID: 32473258 DOI: 10.1016/j.brainres.2020.146906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/20/2020] [Accepted: 05/25/2020] [Indexed: 11/19/2022]
Abstract
Developmental malnourishment impacts the energetic metabolism control throughout life. In rat offspring, a 0% protein diet during the first 10 days of lactation results in leptin resistance and in alterations in: feeding behavior, serum leptin and neuropeptide Y (NPY) levels in the hypothalamic arcuate nucleus (ARC)/paraventricular (PVN) pathway. Here, the distributions of alpha-melanocyte stimulating hormone (α-MSH) and cocaine and amphetamine regulated transcript (CART), anorexigenic molecules, were immunohistochemically assessed in the ARC, PVN and lateral hypothalamus (LH) nuclei. Rat dams were subjected to one of the following diet protocols from postnatal day (P) 1-10: 1) Protein-free (PFG, 0% protein chow); 2) Pair-fed (UFG, normoprotein chow); 3) Control group (CG, normoprotein chow). PFG, UFG and CG male offspring were analyzed at different time points, from P5 to P180. In the ARC, PFG α-MSH and CART were increased from P10 to P45 when compared to CG and UFG. In the PVN, α-MSH and CART peaks in PFG animals were delayed from P20 to P30 when compared to CG. In the LH, CART was more intense in PFG animals than in UFG and CG ones by P20, and, by P30, UFG immunostaining became less intense than in CG. In conclusion, aproteic diet altered the ontogenetic distribution of both anorexigenic molecules. In the PVN, the peak was delayed to P30, which coincides with the leptin peak and follows the previously described NPY (orexigenic) peak in this model. The permanent LH CART and α-MSH increase may be associated with the previously observed PFG hypophagia.
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Affiliation(s)
- Michael L M Rocha
- Laboratório de Neurobiologia do Desenvolvimento, Departamento de Farmacologia e Psicobiologia, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Priscilla P Fernandes
- Laboratório de Neurobiologia do Desenvolvimento, Departamento de Farmacologia e Psicobiologia, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Frank Tenório
- Laboratório de Neurobiologia do Desenvolvimento, Departamento de Farmacologia e Psicobiologia, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alex C Manhães
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Penha C Barradas
- Laboratório de Neurobiologia do Desenvolvimento, Departamento de Farmacologia e Psicobiologia, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
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Molina-Martínez LM, Juárez J. Differential expression of μ-opioid receptors in the nucleus accumbens, amygdala and VTA depends on liking for alcohol, chronic alcohol intake and estradiol treatment. Behav Brain Res 2019; 378:112255. [PMID: 31550484 DOI: 10.1016/j.bbr.2019.112255] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 09/19/2019] [Accepted: 09/20/2019] [Indexed: 10/25/2022]
Abstract
Affectations of the opioid system have been related to exacerbated alcohol consumption. The objectives of this work were to assess whether a deficit of β-endorphinergic neurons differentially affects alcohol intake in female rats with low (LC) and high alcohol consumption (HC), and to determine changes in the μ-opioid receptors (MOR) related to alcohol consumption and chronic exposure to alcohol in structures of the mesolimbic system. Female wild-type rats were selected according to their baseline alcohol intake levels and then exposed to chronic voluntary alcohol consumption after a single injection of either the vehicle or estradiol valerate (EV) to produce a β-endorphin neuronal deficit. Changes in alcohol consumption and MOR expression levels were assessed in the nucleus accumbens (NAc), amygdala (Amy) and ventral tegmental area (VTA) at 5 and 10 weeks after EV treatment. The LC rats increased alcohol intake from baseline to the initial weeks after EV treatment and this consumption remained stable throughout the studied period. In contrast, alcohol consumption increased steadily over time in the HC rats. The HC vehicle rats had a 38% higher MOR protein expression in the NAc than the LC vehicle rats. In addition, chronic alcohol consumption increased MOR expression in the Amy regardless of consumption level, whereas EV treatment produced a decrease in MOR expression in the VTA in all groups. These results suggest intrinsic differences in MOR expression related to alcohol consumption levels. Also, the EV treatment and chronic exposure to alcohol produced adaptive changes in MOR expression.
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Affiliation(s)
- L M Molina-Martínez
- Laboratorio de Farmacología y Conducta, Instituto de Neurociencias, CUCBA, Universidad de Guadalajara, Mexico
| | - J Juárez
- Laboratorio de Farmacología y Conducta, Instituto de Neurociencias, CUCBA, Universidad de Guadalajara, Mexico.
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Yang YM, Sehgal PB. Smooth Muscle-Specific BCL6+/- Knockout Abrogates Sex Bias in Chronic Hypoxia-Induced Pulmonary Arterial Hypertension in Mice. Int J Endocrinol 2018; 2018:3473105. [PMID: 30140283 PMCID: PMC6081567 DOI: 10.1155/2018/3473105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/07/2018] [Accepted: 06/24/2018] [Indexed: 12/18/2022] Open
Abstract
The "estrogen paradox" in pulmonary arterial hypertension (PAH) refers to observations that while there is a higher incidence of idiopathic PAH in women, rodent models of PAH show male dominance and estrogens are protective. To explain these differences, we previously proposed the neuroendocrine-STAT5-BCL6 hypothesis anchored in the sex-biased and species-specific patterns of growth hormone (GH) secretion by the pituitary, the targeting of the hypothalamus by estrogens to feminize GH secretion patterns, and the role of the transcription factors STAT5a/b and BCL6 as downstream mediators of this patterned GH-driven sex bias. As a test of this hypothesis, we previously reported that vascular smooth muscle cell- (SMC-) specific deletion of the STAT5a/b locus abrogated the male-dominant sex bias in the chronic hypoxia model of PAH in mice. In the present study, we confirmed reduced BCL6 expression in pulmonary arterial (PA) segments in both male and female SMC:STAT5a/b-/- mice. In order to test the proposed contribution of BCL6 to sex bias in PAH, we developed mice with SMC-specific deletion of BCL6+/- by crossing SM22α-Cre mice with BCL6-floxed mice and investigated sex bias in these mutant mice in the chronic hypoxia model of PAH. We observed that the male-bias observed in wild-type- (wt-) SM22α-Cre-positive mice was abrogated in the SMC:BCL6+/- knockouts-both males and females showed equivalent enhancement of indices of PAH. The new data confirm BCL6 as a contributor to the sex-bias phenotype observed in hypoxic PAH in mice and support the neuroendocrine-STAT5-BCL6 hypothesis of sex bias in this experimental model of vascular disease.
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Affiliation(s)
- Yang-Ming Yang
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, USA
| | - Pravin B. Sehgal
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, USA
- Department of Medicine, New York Medical College, Valhalla, NY 10595, USA
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Sehgal PB, Yang YM, Miller EJ. Hypothesis: Neuroendocrine Mechanisms (Hypothalamus-Growth Hormone-STAT5 Axis) Contribute to Sex Bias in Pulmonary Hypertension. Mol Med 2015; 21:688-701. [PMID: 26252185 PMCID: PMC4749490 DOI: 10.2119/molmed.2015.00122] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/30/2015] [Indexed: 12/12/2022] Open
Abstract
Pulmonary hypertension (PH) is a disease with high morbidity and mortality. The prevalence of idiopathic pulmonary arterial hypertension (IPAH) and hereditary pulmonary arterial hypertension (HPAH) is approximately two- to four-fold higher in women than in men. Paradoxically, there is an opposite male bias in typical rodent models of PH (chronic hypoxia or monocrotaline); in these models, administration of estrogenic compounds (for example, estradiol-17β [E2]) is protective. Further complexities are observed in humans ingesting anorexigens (female bias) and in rodent models, such as after hypoxia plus SU5416/Sugen (little sex bias) or involving serotonin transporter overexpression or dexfenfluramine administration (female bias). These complexities in sex bias in PH remain incompletely understood. We recently discovered that conditional deletion of signal transducer and activator of transcription 5a/b (STAT5a/b) in vascular smooth muscle cells abrogated the male bias in PH in hypoxic mice and that late-stage obliterative lesions in patients of both sexes with IPAH and HPAH showed reduced STAT5a/b, reduced Tyr-P-STAT5 and reduced B-cell lymphoma 6 protein (BCL6). In trying to understand the significance of these observations, we realized that there existed a well-characterized E2-sensitive central neuroendocrine mechanism of sex bias, studied over the last 40 years, that, at its peripheral end, culminated in species-specific male ("pulsatile") versus female ("more continuous") temporal patterns of circulating growth hormone (GH) levels leading to male versus female patterned activation of STAT5a/b in peripheral tissues and thus sex-biased expression of hundreds of genes. In this report, we consider the contribution of this neuroendocrine mechanism (hypothalamus-GH-STAT5) in the generation of sex bias in different PH situations.
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Affiliation(s)
- Pravin B Sehgal
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York, United States of America
- Department of Medicine, New York Medical College, Valhalla, New York, United States of America
| | - Yang-Ming Yang
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York, United States of America
| | - Edmund J Miller
- Center for Heart and Lung Research, The Feinstein Institute for Medical Research, Manhasset, New York, United States of America
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Sehgal PB, Yang YM, Yuan H, Miller EJ. STAT5a/b contribute to sex bias in vascular disease: A neuroendocrine perspective. JAKSTAT 2015; 4:1-20. [PMID: 27141328 DOI: 10.1080/21623996.2015.1090658] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 08/25/2015] [Accepted: 08/27/2015] [Indexed: 12/24/2022] Open
Abstract
Previous studies have elucidated a neuroendocrine mechanism consisting of the hypothalamus (growth hormone releasing hormone, GHRH) - pituitary (growth hormone, GH) - STAT5a/b axis that underlies sex-biased gene expression in the liver. It is now established that male vs female patterned secretion of GHRH, and thus of circulating GH levels ("pulsatile" vs "more continuous" respectively), leading to differently patterned activation of PY-STAT5a/b in hepatocytes results in sex-biased gene expression of cohorts of hundreds of downstream genes. This review outlines new data in support of a STAT5a/b-based mechanism of sex bias in the vascular disease pulmonary hypertension (PH). Puzzling observations in PH include its 2-4-fold higher prevalence in women but a male-dominance in many rodent models, and, paradoxically, inhibition of PH development by estrogens in such models. We observed that conditional deletion of STAT5a/b in vascular smooth muscle cells (SMC) in mice converted the male-dominant model of chronic hypoxia-induced PH into a female-dominant phenotype. In human idiopathic PH, there was reduced STAT5a/b and PY-STAT5 in cells in late-stage obliterative pulmonary arterial lesions in both men and women. A juxtaposition of the prior liver data with the newer PH-related data drew attention to the hypothalamus-GH-STAT5 axis, which is the major target of estrogens at the level of the hypothalamus. This hypothesis explains many of the puzzling aspects of sex bias in PH in humans and rodent models. The extension of STAT5-anchored mechanisms of sex bias to vascular disease emphasizes the contribution of central neuroendocrine processes in generating sexual dimorphism in different tissues and cell types.
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Affiliation(s)
- Pravin B Sehgal
- Departments of Cell Biology & Anatomy; New York Medical College; Valhalla, NY USA; Department of Medicine; New York Medical College; Valhalla, NY USA
| | - Yang-Ming Yang
- Departments of Cell Biology & Anatomy; New York Medical College ; Valhalla, NY USA
| | - Huijuan Yuan
- Departments of Cell Biology & Anatomy; New York Medical College ; Valhalla, NY USA
| | - Edmund J Miller
- Center for Heart and Lung Research; The Feinstein Institute for Medical Research ; Manhasset, NY USA
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Nuzzaci D, Laderrière A, Lemoine A, Nédélec E, Pénicaud L, Rigault C, Benani A. Plasticity of the Melanocortin System: Determinants and Possible Consequences on Food Intake. Front Endocrinol (Lausanne) 2015; 6:143. [PMID: 26441833 PMCID: PMC4568417 DOI: 10.3389/fendo.2015.00143] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 08/31/2015] [Indexed: 02/06/2023] Open
Abstract
The melanocortin system is one of the most important neuronal pathways involved in the regulation of food intake and is probably the best characterized. Agouti-related peptide (AgRP) and proopiomelanocortin (POMC) expressing neurons located in the arcuate nucleus of the hypothalamus are the key elements of this system. These two neuronal populations are sensitive to circulating molecules and receive many excitatory and inhibitory inputs from various brain areas. According to sensory and metabolic information they integrate, these neurons control different aspects of feeding behavior and orchestrate autonomic responses aimed at maintaining energy homeostasis. Interestingly, composition and abundance of pre-synaptic inputs onto arcuate AgRP and POMC neurons vary in the adult hypothalamus in response to changes in the metabolic state, a phenomenon that can be recapitulated by treatment with hormones, such as leptin or ghrelin. As described in other neuroendrocrine systems, glia might be determinant to shift the synaptic configuration of AgRP and POMC neurons. Here, we discuss the physiological outcome of the synaptic plasticity of the melanocortin system, and more particularly its contribution to the control of energy balance. The discovery of this attribute has changed how we view obesity and related disorders, and opens new perspectives for their management.
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Affiliation(s)
- Danaé Nuzzaci
- Center for Taste and Feeding Behaviour, CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, Dijon, France
| | - Amélie Laderrière
- Center for Taste and Feeding Behaviour, CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, Dijon, France
| | - Aleth Lemoine
- Center for Taste and Feeding Behaviour, CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, Dijon, France
| | - Emmanuelle Nédélec
- Center for Taste and Feeding Behaviour, CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, Dijon, France
| | - Luc Pénicaud
- Center for Taste and Feeding Behaviour, CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, Dijon, France
| | - Caroline Rigault
- Center for Taste and Feeding Behaviour, CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, Dijon, France
| | - Alexandre Benani
- Center for Taste and Feeding Behaviour, CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, Dijon, France
- *Correspondence: Alexandre Benani, Centre des Sciences du Goût et de l’Alimentation (CSGA), CNRS (UMR6265), INRA (UMR1324), Université de Bourgogne-Franche Comté, 9E Boulevard Jeanne d’Arc, Dijon 21000, France,
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Koch M, Horvath TL. Molecular and cellular regulation of hypothalamic melanocortin neurons controlling food intake and energy metabolism. Mol Psychiatry 2014; 19:752-61. [PMID: 24732669 DOI: 10.1038/mp.2014.30] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 02/17/2014] [Accepted: 02/24/2014] [Indexed: 12/25/2022]
Abstract
The brain receives and integrates environmental and metabolic information, transforms these signals into adequate neuronal circuit activities, and generates physiological behaviors to promote energy homeostasis. The responsible neuronal circuitries show lifetime plasticity and guaranty metabolic health and survival. However, this highly evolved organization has become challenged nowadays by chronic overload with nutrients and reduced physical activity, which results in an ever-increasing number of obese individuals worldwide. Research within the last two decades has aimed to decipher the responsible molecular and cellular mechanisms for regulation of the hypothalamic melanocortin neurons, which have a key role in the control of food intake and energy metabolism. This review maps the central connections of the melanocortin system and highlights its global position and divergent character in physiological and pathological metabolic events. Moreover, recently uncovered molecular and cellular processes in hypothalamic neurons and glial cells that drive plastic morphological and physiological changes in these cells, and account for regulation of food intake and energy metabolism, are brought into focus. Finally, potential functional interactions between metabolic disorders and psychiatric diseases are discussed.
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Affiliation(s)
- M Koch
- 1] Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT, USA [2] Institute of Anatomy, University of Leipzig, Leipzig, Germany
| | - T L Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT, USA
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Wang TJ, Chen JR, Wang WJ, Wang YJ, Tseng GF. Genistein partly eases aging and estropause-induced primary cortical neuronal changes in rats. PLoS One 2014; 9:e89819. [PMID: 24587060 PMCID: PMC3934964 DOI: 10.1371/journal.pone.0089819] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 01/26/2014] [Indexed: 01/11/2023] Open
Abstract
Gonadal hormones can modulate brain morphology and behavior. Recent studies have shown that hypogonadism could result in cortical function deficits. To this end, hormone therapy has been used to ease associated symptoms but the risk may outweigh the benefits. Here we explored whether genistein, a phytoestrogen, is effective in restoring the cognitive and central neuronal changes in late middle age and surgically estropause female rats. Both animal groups showed poorer spatial learning than young adults. The dendritic arbors and spines of the somatosensory cortical and CA1 hippocampal pyramidal neurons were revealed with intracellular dye injection and analyzed. The results showed that dendritic spines on these neurons were significantly decreased. Remarkably, genistein treatment rescued spatial learning deficits and restored the spine density on all neurons in the surgically estropause young females. In late middle age females, genistein was as effective as estradiol in restoring spines; however, the recovery was less thorough than on young OHE rats. Neither genistein nor estradiol rectified the shortened dendritic arbors of the aging cortical pyramidal neurons suggesting that dendritic arbors and spines are differently modulated. Thus, genistein could work at central level to restore excitatory connectivity and appears to be potent alternative to estradiol for easing aging and menopausal syndromes.
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Affiliation(s)
- Tsyr-Jiuan Wang
- Department of Nursing, National Taichung University of Science and Technology, Taichung, Taiwan
| | - Jeng-Rung Chen
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan
| | - Wen-Jay Wang
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan
| | - Yueh-Jan Wang
- Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien, Taiwan
| | - Guo-Fang Tseng
- Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien, Taiwan
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González-Arenas A, Piña-Medina AG, González-Flores O, Galván-Rosas A, Camacho-Arroyo I. Sex hormones and expression pattern of cytoskeletal proteins in the rat brain throughout pregnancy. J Steroid Biochem Mol Biol 2014; 139:154-8. [PMID: 23318880 DOI: 10.1016/j.jsbmb.2013.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 12/20/2012] [Accepted: 01/04/2013] [Indexed: 10/27/2022]
Abstract
Pregnancy involves diverse changes in brain function that implicate a re-organization in neuronal cytoskeleton. In this physiological state, the brain is in contact with several hormones that it has never been exposed, as well as with very high levels of hormones that the brain has been in touch throughout life. Among the latter hormones are progesterone and estradiol which regulate several brain functions, including learning, memory, neuroprotection, and the display of sexual and maternal behavior. These functions involve changes in the structure and organization of neurons and glial cells that require the participation of cytoskeletal proteins whose expression and activity is regulated by estradiol and progesterone. We have found that the expression pattern of Microtubule Associated Protein 2, Tau, and Glial Fibrillary Acidic Protein changes in a tissue-specific manner in the brain of the rat throughout gestation and the start of lactation, suggesting that these proteins participate in the plastic changes observed in the brain during pregnancy. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.
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Affiliation(s)
- Aliesha González-Arenas
- Facultad de Química, Departamento de Biología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán 04510, México, D.F., México
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Chowen JA, Argente J, Horvath TL. Uncovering novel roles of nonneuronal cells in body weight homeostasis and obesity. Endocrinology 2013; 154:3001-7. [PMID: 23798599 PMCID: PMC3749483 DOI: 10.1210/en.2013-1303] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Glial cells, which constitute more than 50% of the mass of the central nervous system and greatly outnumber neurons, are at the vanguard of neuroendocrine research in metabolic control and obesity. Historically relegated to roles of structural support and protection, diverse functions have been gradually attributed to this heterogeneous class of cells with their protagonism in crescendo in all areas of neuroscience during the past decade. However, this dramatic increase in attention bestowed upon glial cells has also emphasized our vast lack of knowledge concerning many aspects of their physiological functions, let alone their participation in numerous pathologies. This minireview focuses on the recent advances in our understanding of how glial cells participate in the physiological regulation of appetite and systemic metabolism as well as their role in the pathophysiological response to poor nutrition and secondary complications associated with obesity. Moreover, we highlight some of the existing lagoons of knowledge in this increasingly important area of investigation.
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Affiliation(s)
- Julie A Chowen
- Hospital Infantil Universitario Niño Jesús, Department of Endocrinology, Instituto de Investigación La Princesa, 28009 Madrid, Spain.
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Arimoto JM, Wong A, Rozovsky I, Lin SW, Morgan TE, Finch CE. Age increase of estrogen receptor-α (ERα) in cortical astrocytes impairs neurotrophic support in male and female rats. Endocrinology 2013; 154:2101-13. [PMID: 23515288 PMCID: PMC3740484 DOI: 10.1210/en.2012-2046] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Rodent models show decreased neuronal responses to estradiol (E2) during aging (E2-desensitization) in association with reduced neuronal estrogen receptor (ER)-α, but little is known about age changes of E2-dependent astrocytic neurotrophic support. Because elevated expression of astrocyte glial fibrillary acidic protein (GFAP) is associated with impaired neurotrophic activity and because the GFAP promoter responds to ERα, we investigated the role of astrocytic ERα and ERβ in impaired astrocyte neurotrophic activity during aging. In vivo and in vitro, ERα was increased greater than 50% with age in astrocytes from the cerebral cortex of male rats (24 vs 3 months), whereas ERβ did not change. In astrocytes from 3-month-old males, experimentally increasing the ERα to ERβ ratio induced the aging phenotype of elevated GFAP and impaired E2-dependent neurite outgrowth. In 24-month-old male astrocytes, lowering ERα reversed the age elevation of GFAP and partially restored E2-dependent neurite outgrowth. Mixed glia (astrocytes to microglia, 3:1) of both sexes also showed these age changes. In a model of perimenopause, mixed glia from 9- to 15-month rats showed E2 desensitization: 9-month regular cyclers retained young-like ERα to ERβ ratios and neurotrophic activity, whereas 9-month noncyclers had elevated ERα and GFAP but low E2-dependent neurotrophic activity. In vivo, ERα levels in cortical astrocytes were also elevated. The persisting effects of ovarian acyclicity in vitro are hypothesized to arise from steroidal perturbations during ovarian senescence. These findings suggest that increased astrocyte ERα expression during aging contributes to the E2 desensitization of the neuronal responses in both sexes.
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Affiliation(s)
- Jason M Arimoto
- Department of Biological Sciences, University of Southern California, 3715 McClintock Avenue, Los Angeles, California 90089-0191, USA
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Micevych P, Christensen A. Membrane-initiated estradiol actions mediate structural plasticity and reproduction. Front Neuroendocrinol 2012; 33:331-41. [PMID: 22828999 PMCID: PMC3496015 DOI: 10.1016/j.yfrne.2012.07.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/11/2012] [Accepted: 07/13/2012] [Indexed: 12/17/2022]
Abstract
Over the years, our ideas about estrogen signaling have greatly expanded. In addition to estradiol having direct nuclear actions that mediate transcription and translation, more recent experiments have demonstrated membrane-initiated signaling. Both direct nuclear and estradiol membrane signaling can be mediated by the classical estrogen receptors, ERα and ERβ, which are two of the numerous putative membrane estrogen receptors. Thus far, however, only ERα has been shown to play a prominent role in regulating female reproduction and sexual behavior. Because ERα is a ligand-gated transcription factor and not a typical membrane receptor, trafficking to the cell membrane requires post-translational modifications. Two necessary modifications are palmitoylation and association with caveolins, a family of scaffolding proteins. In addition to their role in trafficking, caveolin proteins also serve to determine ERα interactions with metabotropic glutamate receptors (mGluRs). It is through these complexes that ERα, which cannot by itself activate G proteins, is able to initiate intracellular signaling. Various combinations of ERα-mGluR interactions have been demonstrated throughout the nervous system from hippocampus to striatum to hypothalamus to dorsal root ganglion (DRG) in both neurons and astrocytes. These combinations of ER and mGluR allow estradiol to have both facilitative and inhibitory actions in neurons. In hypothalamic astrocytes, the estradiol-mediated release of intracellular calcium stores regulating neurosteroid synthesis requires ERα-mGluR1a interaction. In terms of estradiol regulation of female sexual receptivity, activation of ERα-mGluR1a signaling complex leads to the release of neurotransmitters and alteration of neuronal morphology. This review will examine estradiol membrane signaling (EMS) activating a limbic-hypothalamic lordosis regulating circuit, which involves ERα trafficking, internalization, and modifications of neuronal morphology in a circuit that underlies female sexual receptivity.
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Affiliation(s)
- Paul Micevych
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1763, United States.
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14
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Membrane-initiated estradiol signaling induces spinogenesis required for female sexual receptivity. J Neurosci 2012; 31:17583-9. [PMID: 22131419 DOI: 10.1523/jneurosci.3030-11.2011] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Estrogens have profound actions on the structure of the nervous system during development and in adulthood. One of the signature actions of estradiol is to alter the morphology of neural processes. In the hippocampus, estradiol modulates spines and cellular excitability that affect cognitive behaviors. In the hypothalamus, estradiol increases spine density in mediobasal hypothalamic nuclei that regulate reproduction. The hypothalamic arcuate nucleus (ARH), an important site for modulation of female sexual receptivity, has a sexual dimorphism in dendritic spine density that favors females. In the present study, we used both β-actin immunostaining and Golgi staining to visualize estradiol-induced changes in spine density in Long-Evans rats. Golgi impregnation was used to visualize spine shape, and then β-actin immunoreactivity was used as a semiquantitative measure of spine plasticity since actin forms the core of dendritic spines. At 4 h after estradiol treatment, both β-actin immunofluorescence and filopodial spines were increased (from 70.57 ± 1.09% to 78.01 ± 1.05%, p < 0.05). Disruption of estradiol-induced β-actin polymerization with cytochalasin D attenuated lordosis behavior, indicating the importance of estradiol-mediated spinogenesis for female sexual receptivity (81.43 ± 7.05 to 35.00 ± 11.76, p < 0.05). Deactivation of cofilin, an actin depolymerizing factor is required for spinogenesis. Membrane-initiated estradiol signaling involving the metabotropic glutamate receptor 1a was responsible for the phosphorylation and thereby deactivation of cofilin. These data demonstrate that estradiol-induced spinogenesis in the ARH is an important cellular mechanism for the regulation of female sexual behavior.
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15
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Sanathara NM, Moraes J, Kanjiya S, Sinchak K. Orphanin FQ in the mediobasal hypothalamus facilitates sexual receptivity through the deactivation of medial preoptic nucleus mu-opioid receptors. Horm Behav 2011; 60:540-8. [PMID: 21872598 PMCID: PMC3210402 DOI: 10.1016/j.yhbeh.2011.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 08/02/2011] [Accepted: 08/10/2011] [Indexed: 02/04/2023]
Abstract
Sexual receptivity, lordosis, can be induced by sequential estradiol and progesterone or extended exposure to high levels of estradiol in the female rat. In both cases estradiol initially inhibits lordosis through activation of β-endorphin (β-END) neurons of the arcuate nucleus of the hypothalamus (ARH) that activate μ-opioid receptors (MOP) in the medial preoptic nucleus (MPN). Subsequent progesterone or extended estradiol exposure deactivates MPN MOP to facilitate lordosis. Opioid receptor-like receptor-1 (ORL-1) is expressed in ARH and ventromedial hypothalamus (VMH). Infusions of its endogenous ligand, orphanin FQ (OFQ/N, aka nociceptin), into VMH-ARH region facilitate lordosis. Whether OFQ/N acts in ARH and/or VMH and whether OFQ/N is necessary for steroid facilitation of lordosis are unclear. In Exp I, OFQ/N infusions in VMH and ARH that facilitated lordosis also deactivated MPN MOP indicating that OFQ/N facilitation of lordosis requires deactivation of ascending ARH-MPN projections by directly inhibiting ARH β-END neurons and/or through inhibition of excitatory VMH-ARH pathways to proopiomelanocortin neurons. It is unclear whether OFQ/N activates the VMH output motor pathways directly or via the deactivation of MPN MOP. In Exp II we tested whether ORL-1 activation is necessary for estradiol-only or estradiol+progesterone lordosis facilitation. Blocking ORL-1 with UFP-101 inhibited estradiol-only lordosis and MPN MOP deactivation but had no effect on estradiol+progesterone facilitation of lordosis and MOP deactivation. In conclusion, steroid facilitation of lordosis inhibits ARH β-END neurons to deactivate MPN MOP, but estradiol-only and estradiol+progesterone treatments appear to use different neurotransmitter systems to inhibit ARH-MPN signaling.
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Affiliation(s)
- Nayna M Sanathara
- Department of Biological Sciences, California State University, Long Beach, Long Beach, CA 90840-9502, USA
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16
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Changes in the content of GFAP in the rat brain during pregnancy and the beginning of lactation. Neurosci Lett 2010; 484:197-200. [DOI: 10.1016/j.neulet.2010.08.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 07/08/2010] [Accepted: 08/17/2010] [Indexed: 11/23/2022]
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17
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Abstract
Food intake is a major physiological function in animals and must be entrained to the circadian oscillations in food availability. In the last two decades a growing number of reports have shed light on the hormonal, cellular and molecular mechanisms involved in the regulation of food intake. Brain areas located in the hypothalamus have been shown to play a pivotal role in the regulation of energy metabolism, controlling energy balance. In these areas, neuronal plasticity has been reported that is dependent upon key hormones, such as leptin and ghrelin, that are produced by peripheral organs. This review will provide an overview of recent discoveries relevant to understanding these issues.
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Affiliation(s)
- Marcelo O Dietrich
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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18
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Subcellular dynamics of somatostatin receptor subtype 1 in the rat arcuate nucleus: receptor localization and synaptic connectivity vary in parallel with the ultradian rhythm of growth hormone secretion. J Neurosci 2009; 29:8198-205. [PMID: 19553459 DOI: 10.1523/jneurosci.0336-09.2009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Growth hormone (GH) secretion in male rats exhibits a 3.3 h ultradian rhythm generated by the reciprocal interaction of GH-releasing hormone (GHRH) and somatostatin (SRIF). SRIF receptor subtypes sst(1) and sst(2) are highly expressed in GHRH neurons of the hypothalamic arcuate nucleus (ARC). We previously demonstrated an ultradian oscillation in binding of SRIF analogs to the ARC in relation to GH peaks and troughs. Here we tested the hypothesis that these ultradian changes in SRIF binding are due to differential plasma membrane targeting of sst(1) receptors in ARC neurons using immunocytochemistry and electron microscopy. We found that 87% of sst(1)-positive ARC neurons also synthesized GHRH. Subcellularly, 80% of sst(1) receptors were located intracellularly and 20% at the plasma membrane regardless of GH status. However, whereas 30% of the cell-surface sst(1) receptors were located perisynaptically or subsynaptically following exposure to high GH secretion, this fraction was increased to 42% following a GH trough period (p = 0.05). Furthermore, the relative abundance of symmetric and asymmetric synapses on sst(1)-positive dendrites also varied significantly, depending on the GH cycle, from approximately equal numbers following GH troughs to 70:30 in favor of symmetric, i.e., inhibitory, inputs after GH peaks (p < 0.02). These findings suggest that postsynaptic localization of sst(1) receptors and synaptic connectivity in the ARC undergo pronounced remodeling in parallel with the GH rhythm. Such synaptic plasticity may be an important mechanism by which sst(1) mediates SRIF's cyclical effects on ARC GHRH neurons to generate the ultradian rhythm of GH secretion.
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19
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Arias C, Zepeda A, Hernández-Ortega K, Leal-Galicia P, Lojero C, Camacho-Arroyo I. Sex and estrous cycle-dependent differences in glial fibrillary acidic protein immunoreactivity in the adult rat hippocampus. Horm Behav 2009; 55:257-63. [PMID: 19056393 DOI: 10.1016/j.yhbeh.2008.10.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 10/28/2008] [Accepted: 10/29/2008] [Indexed: 11/21/2022]
Abstract
Sex differences in the morphology and function of the hippocampus have been reported in several species, but it is unknown whether a sexual dimorphism exists in glial fibrillary acidic protein (GFAP) expression in the rat hippocampus. We analyzed GFAP immunoreactivity in the hippocampus of intact adult male rats as well as in females during diestrus and proestrus phases of the estrous cycle. We found that in CA1, CA3, and dentate gyrus, GFAP immunoreactivity was higher in proestrus females as compared with males and diestrus females. In CA1, a similar GFAP immunoreactivity was found in males and in diestrus females, but in dentate gyrus, males presented the lowest GFAP content. Interestingly, differences in astrocyte morphology were also found. Rounded cells with numerous and short processes were mainly observed in the hippocampus during proestrus whereas cells with stellate shape with few and long processes were present in the hippocampus of males and diestrus females. The marked sex and estrous cycle-dependent differences in GFAP immunoreactivity density and in astrocyte number and morphology found in the rat hippocampus, suggest the involvement of sex steroid hormones in the sexually dimorphic functions of the hippocampus, and in the change in its activity during the estrous cycle.
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Affiliation(s)
- Clorinda Arias
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico
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20
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Martinez L, de Lacalle S. Astrocytic reaction to a lesion, under hormonal deprivation. Neurosci Lett 2007; 415:190-3. [PMID: 17267125 PMCID: PMC1876749 DOI: 10.1016/j.neulet.2007.01.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Revised: 12/19/2006] [Accepted: 01/09/2007] [Indexed: 11/27/2022]
Abstract
Gonadal hormones can influence the morphology and function of glial cells, particularly astrocytes. Here we explore the hypothesis that 17beta-estradiol (E2) exerts a positive effect on astrocytes within the region of the cholinergic neurons of the basal forebrain, an area heavily implicated in memory and attentional processes. Female rats were ovariectomized at 3 months of age and lesioned with the immunotoxin 192 IgG-saporin before receiving a subcutaneous pellet containing 0.25mg of estrogen or placebo, released over 60 days. The control, non-ovariectomized group was treated identically. At the end of the treatment, we used image analysis procedures to evaluate changes in the levels of glial fibrillary acidic protein (GFAP) expression in the area of the lesion. Infusion of the immunotoxin induced a slight increase in GFAP expression in some subjects, compared to the contralateral side. However, when differences within animals where factored in, GFAP expression in ovariectomized animals treated with E2 was undistinguishable from intact controls. By contrast, in ovariectomized animals treated with placebo, GFAP expression was significantly higher. These results suggest that E2 deprivation may exacerbate the effects of an immunotoxic lesion, and, more importantly, that E2 administration may contribute to structural recovery of lesioned cholinergic neurons by blocking GFAP expression in the area. These results are particularly relevant in the context of female aging and postmenopausal dementia, and further highlight other potential levels at which to design interventions to preserve an intact cholinergic system, which may be crucial to prevent Alzheimer's disease.
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Affiliation(s)
- Lizeth Martinez
- Department of Biomedical Sciences, Charles R. Drew University of Medicine and Sciences, 1731 East 120th Street, Los Angeles, CA 90059, USA
| | - Sonsoles de Lacalle
- Department of Biomedical Sciences, Charles R. Drew University of Medicine and Sciences, 1731 East 120th Street, Los Angeles, CA 90059, USA
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21
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Etgen AM, González-Flores O, Todd BJ. The role of insulin-like growth factor-I and growth factor-associated signal transduction pathways in estradiol and progesterone facilitation of female reproductive behaviors. Front Neuroendocrinol 2006; 27:363-75. [PMID: 16904171 DOI: 10.1016/j.yfrne.2006.06.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 06/12/2006] [Indexed: 12/24/2022]
Abstract
We are examining the role of insulin-like growth factor-I (IGF-I) and downstream signal transduction pathways associated with growth factors (e.g., mitogen-activated protein kinase, MAPK) in estradiol and progesterone facilitation of female reproductive behavior in rats. Brain IGF-I receptor activity is required for the long-term, priming actions of estradiol on the female reproductive axis. Infusions of an IGF-I receptor antagonist during estradiol priming blocks induction of hypothalamic alpha(1B)-adrenergic receptors and luteinizing hormone surges, and attenuates lordosis behavior. Infusion of MAPK and phosphatidylinositol-3-kinase inhibitors inhibitors during estradiol priming completely blocks hormone-facilitated lordosis. Because progestin receptors (PRs) can be phosphorylated and activated by MAPKs, growth factor signaling pathways may also participate in progesterone facilitation of reproductive behaviors. Infusion of a MAPK inhibitor in estradiol-primed rats blocks progestin facilitation and sequential inhibition of lordosis and proceptive behaviors. Interference with MAPK signaling also inhibits behavioral responses to cGMP and a delta-opioid agonist, both of which can activate MAPK in some cells. Thus MAPK is involved in the facilitation of lordosis and proceptive behaviors, perhaps by phosphorylation of hypothalamic PRs.
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Affiliation(s)
- Anne M Etgen
- Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA.
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22
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López M, Lage R, Mendieta H, González R, Diéguez C. Effects of perinatal overfeeding on mechanisms controlling food intake and body weight homeostasis. Expert Rev Endocrinol Metab 2006; 1:651-659. [PMID: 30754095 DOI: 10.1586/17446651.1.5.651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The prevalence of overweight and obesity in most developed countries has markedly increased during the last several decades. In addition to genetic, hormonal and metabolic influences, epigenetic environmental factors, such as fetal and neonatal nutrition, play a key role in the development of obesity. Interestingly, becoming overweight during critical developmental periods of fetal and/or neonatal life has been shown to continue throughout juvenile life into adulthood. In spite of this evidence, the specific biological mechanisms underlying this fetal/neonatal programming are not perfectly understood. However, it is clear that circulating hormones, such as insulin, leptin and ghrelin, play a critical role in the development and programming of hypothalamic circuits regulating food intake and bodyweight homeostasis.
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Affiliation(s)
- Miguel López
- a Postdoctoral Research Associate, University of Santiago de Compostela, Department of Physiology, School of Medicine, c/ San Francisco s/n 15782. Santiago de Compostela (A Coruña), Spain.
| | - Ricardo Lage
- b Student, University of Santiago de Compostela, Department of Physiology, School of Medicine, c/ San Francisco s/n 15782. Santiago de Compostela (A Coruña), Spain.
| | - Hugo Mendieta
- c PhD Student, University of Santiago de Compostela, Department of Physiology, School of Medicine, c/ San Francisco s/n 15782. Santiago de Compostela (A Coruña), Spain.
| | - Ruth González
- d PhD Student, University of Santiago de Compostela, Department of Physiology, School of Medicine, c/ San Francisco s/n 15782. Santiago de Compostela (A Coruña), Spain.
| | - Carlos Diéguez
- e Professor, University of Santiago de Compostela, Department of Physiology, School of Medicine, C/ San Francisco s/n 15782, Santiago de Compostela, (A Coruña), Spain.
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23
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Abstract
Leptin regulates energy balance, in part, by modulating the activity of neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons in the hypothalamic arcuate nucleus. Leptin-deficient (ob/ob) mice differ from wild-type mice in the number of excitatory and inhibitory post-synaptic densities and currents onto NPY and POMC neurons. When leptin was delivered to ob/ob mice, the synaptic density rapidly normalized, an effect detectable within 6 hours, several hours before leptin's effect on food intake. Synaptic currents were also shifted toward wild-type values in leptin-replaced ob/ob mice. These data suggest that leptin-mediated plasticity in the ob/ob hypothalamus may underlie some of the hormone's behavioral effects. In an effort to determine whether the observed synaptic plasticity is leptin specific, we analyzed the effects of an orexigenic hormone, ghrelin, and anorexigenic hormone, estradiol. Ghrelin rearranged synapses in wild type animals to support suppressed POMC tone, whereas the estradiol triggered a robust increase in the number of excitatory, glutamate inputs of POMC neurons. The rearrangement of synapses by estradiol was leptin independent, because it was also evident in leptin- (ob/ob) and leptin receptor-deficient (db/db) mice and was paralleled with decreased food intake and increased energy expenditure in these mutant, obese animals. Such plasticity was also observed in other hypothalamic regions and extrahypothalamic sites. These observations raise the notion that synaptic plasticity is a major way through which peripheral metabolic hormones influence brain functions.
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Affiliation(s)
- Tamas L Horvath
- Section of Comparative Medicine, Yale University School of Medicine, 375 Congress Ave. LSOG 117, PO Box 208016, New Haven, CT 06510-8016, USA.
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24
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Horvath TL. Synaptic plasticity mediating leptin's effect on metabolism. PROGRESS IN BRAIN RESEARCH 2006; 153:47-55. [PMID: 16876567 DOI: 10.1016/s0079-6123(06)53002-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Tamas L Horvath
- Section of Comparative Medicine, and Department of Ob./Gyn., Yale University School of Medicine, New Haven, CT 06520, USA.
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25
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Parducz A, Hajszan T, Maclusky NJ, Hoyk Z, Csakvari E, Kurunczi A, Prange-Kiel J, Leranth C. Synaptic remodeling induced by gonadal hormones: neuronal plasticity as a mediator of neuroendocrine and behavioral responses to steroids. Neuroscience 2005; 138:977-85. [PMID: 16310961 DOI: 10.1016/j.neuroscience.2005.07.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Revised: 07/04/2005] [Accepted: 07/12/2005] [Indexed: 11/21/2022]
Abstract
During recent decades, it has become a generally accepted view that structural neuroplasticity is remarkably involved in the functional adaptation of the CNS. Thus, cellular morphology in the brain is in continuous transition throughout the life span, as a response to environmental stimuli. The effects of the environment on neuroplasticity are mediated by, to some extent, the changing levels of circulating gonadal steroid hormones. Today, it is clear that the function of gonadal steroids in the brain extends beyond simply regulating reproductive and/or neuroendocrine events. In addition, or even more importantly, gonadal steroids participate in the shaping of the developing brain, while their actions during adult life are implicated in higher brain functions such as cognition, mood and memory. A large body of evidence indicates that gonadal steroid-induced functional changes are accompanied by alterations in neuron and synapse numbers, as well as in dendritic and synaptic morphology. These structural modifications are believed to serve as a morphological basis for changes in behavior and cellular activity. Due to their growing functional and clinical significance, the specificity, timeframe, as well as the molecular and cellular mechanisms of hormone-induced neuroplasticity have become the focus of many studies. In this review, we briefly summarize current knowledge and the most significant recent discoveries from our laboratories on estrogen- and dehydroepiandrosterone-induced synaptic remodeling in the hypothalamus and hippocampus, two important brain areas heavily involved in autonomic and cognitive operations, respectively.
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Affiliation(s)
- A Parducz
- Laboratory of Molecular Neurobiology, Biological Research Center, Hungarian Academy of Sciences, Szeged.
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26
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Horvath TL. The hardship of obesity: a soft-wired hypothalamus. Nat Neurosci 2005; 8:561-5. [PMID: 15856063 DOI: 10.1038/nn1453] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2005] [Accepted: 03/11/2005] [Indexed: 11/09/2022]
Abstract
Food intake and energy expenditure are determinants of metabolic phenotype and are regulated by the CNS. Although humans have a well-balanced homeostatic feedback loop, obesity and metabolic disorders are spreading rapidly and carry a heavy toll of morbidity and mortality. The past decade has witnessed major advances in the understanding of basic metabolic processes, the brain circuitry that determines appropriate and, but, inappropriate behavioral and humoral responses to changing metabolic cues remains largely ill defined. This review summarizes current knowledge of the brain anatomy that supports food intake and energy expenditure and discusses cellular mechanisms such as synaptic plasticity that may provide clues toward the development of successful central therapies to combat metabolic disorders, including obesity and diabetes.
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Affiliation(s)
- Tamas L Horvath
- Department of Obstetrics, Gynecology & Reproductive Sciences, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06510, USA.
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27
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Becker JB, Arnold AP, Berkley KJ, Blaustein JD, Eckel LA, Hampson E, Herman JP, Marts S, Sadee W, Steiner M, Taylor J, Young E. Strategies and methods for research on sex differences in brain and behavior. Endocrinology 2005; 146:1650-73. [PMID: 15618360 DOI: 10.1210/en.2004-1142] [Citation(s) in RCA: 599] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Female and male brains differ. Differences begin early during development due to a combination of genetic and hormonal events and continue throughout the lifespan of an individual. Although researchers from a myriad of disciplines are beginning to appreciate the importance of considering sex differences in the design and interpretation of their studies, this is an area that is full of potential pitfalls. A female's reproductive status and ovarian cycle have to be taken into account when studying sex differences in health and disease susceptibility, in the pharmacological effects of drugs, and in the study of brain and behavior. To investigate sex differences in brain and behavior there is a logical series of questions that should be answered in a comprehensive investigation of any trait. First, it is important to determine that there is a sex difference in the trait in intact males and females, taking into consideration the reproductive cycle of the female. Then, one must consider whether the sex difference is attributable to the actions of gonadal steroids at the time of testing and/or is sexually differentiated permanently by the action of gonadal steroids during development. To answer these questions requires knowledge of how to assess and/or manipulate the hormonal condition of the subjects in the experiment appropriately. This article describes methods and procedures to assist scientists new to the field in designing and conducting experiments to investigate sex differences in research involving both laboratory animals and humans.
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Affiliation(s)
- Jill B Becker
- Department of Psychology, University of Michigan, 525 East University, Ann Arbor, MI 48109, USA.
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28
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Furman S, Hill JM, Vulih I, Zaltzman R, Hauser JM, Brenneman DE, Gozes I. Sexual dimorphism of activity-dependent neuroprotective protein in the mouse arcuate nucleus. Neurosci Lett 2005; 373:73-8. [PMID: 15555780 DOI: 10.1016/j.neulet.2004.09.077] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Accepted: 09/27/2004] [Indexed: 11/20/2022]
Abstract
Activity-dependent neuroprotective protein (ADNP) is a highly conserved vasoactive intestinal peptide (VIP) responsive gene that is expressed abundantly in the brain and in the body and is essential for brain formation and embryonic development. Since, VIP exhibits sexual dimorphism in the hypothalamus, the potential differential expression of ADNP in male and female mice was investigated. Real-time polymerase chain reaction revealed sexual dimorphism in ADNP mRNA expression as well as fluctuations within the estrus cycle. Immunohistochemistry with an antibody to ADNP showed specific staining in the arcuate nucleus of the hypothalamus. ADNP-like immunoreactivity in the arcuate nucleus also exhibited fluctuations during the estrus cycle. Here, brain sections at proestrus were the most immunoreactive and brain sections at estrus--the least. Furthermore, male arcuate nucleus ADNP-like immunoreactivity was significantly lower than that of the female estrus. Many neuropeptides, neurotransmitters and proteins are localized to the arcuate nucleus where they contribute to the regulation of reproductive cyclicity and energy homeostasis. The results presented here suggest that ADNP has a part in the estrus cycle as an affecter or an effector.
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Affiliation(s)
- Sharon Furman
- Department of Clinical Biochemistry, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
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29
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Affiliation(s)
- Tamas L Horvath
- Department of Obstetrics, Gynecology & Reproductive Sciences, Yale University School of Medicine, 333 Cedar Street FMB 339, New Haven, Connecticut 06520, USA.
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30
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Pinto S, Roseberry AG, Liu H, Diano S, Shanabrough M, Cai X, Friedman JM, Horvath TL. Rapid rewiring of arcuate nucleus feeding circuits by leptin. Science 2004; 304:110-5. [PMID: 15064421 DOI: 10.1126/science.1089459] [Citation(s) in RCA: 708] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The fat-derived hormone leptin regulates energy balance in part by modulating the activity of neuropeptide Y and proopiomelanocortin neurons in the hypothalamic arcuate nucleus. To study the intrinsic activity of these neurons and their responses to leptin, we generated mice that express distinct green fluorescent proteins in these two neuronal types. Leptin-deficient (ob/ob) mice differed from wild-type mice in the numbers of excitatory and inhibitory synapses and postsynaptic currents onto neuropeptide Y and proopiomelanocortin neurons. When leptin was delivered systemically to ob/ob mice, the synaptic density rapidly normalized, an effect detectable within 6 hours, several hours before leptin's effect on food intake. These data suggest that leptin-mediated plasticity in the ob/ob hypothalamus may underlie some of the hormone's behavioral effects.
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Affiliation(s)
- Shirly Pinto
- Laboratory of Molecular Genetics, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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31
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Etgen AM. Ovarian Steroid and Growth Factor Regulation of Female Reproductive Function Involves Modification of Hypothalamic α1-Adrenoceptor Signaling. Ann N Y Acad Sci 2003; 1007:153-61. [PMID: 14993049 DOI: 10.1196/annals.1286.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The ovarian steroids estradiol (E(2)) and progesterone (P) act on target neurons in the hypothalamus and preoptic area to coordinate the expression of female reproductive behaviors with the timing of the preovulatory luteinizing hormone (LH) surge. This chapter will summarize evidence that E(2) and P facilitation of the receptive component of female reproductive behavior, lordosis, involves changes in both the expression of and intracellular signal transduction pathways engaged by alpha(1)-adrenergic receptors in the hypothalamus and preoptic area. The alpha(1)-adrenoceptors are thought to mediate the facilitatory effects of the catecholamine neurotransmitter norepinephrine on both lordosis behavior and LH release. E(2) first induces the expression of the alpha(1B)-adrenergic receptor subtype in the hypothalamus and preoptic area. P then acts in an E(2)-dependent manner to promote linkage of hypothalamic alpha(1)-adrenoceptors to an intracellular signaling pathway involving nitric oxide and cyclic GMP. This chapter will also describe recent findings that implicate brain insulin-like growth factor-I (IGF-I) receptors as obligatory co-mediators of hormonal regulation of hypothalamic alpha(1)-adrenoceptors and female neuroendocrine function. Additional studies suggest that E(2) and IGF-I facilitate lordosis behavior by activating kinases traditionally associated with growth factor signal transduction (mitogen-activated protein kinases and phosphatidlyinositol-3-kinases). These molecular events are proposed to help coordinate the timing of ovulation with the expression of sexual receptivity, thereby maximizing reproductive success.
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Affiliation(s)
- Anne M Etgen
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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Tsai CL, Wang LH, Fang LS. Estradiol and para-chlorophenylalanine downregulate the expression of brain aromatase and estrogen receptor-alpha mRNA during the critical period of feminization in tilapia (Oreochromis mossambicus). Neuroendocrinology 2001; 74:325-34. [PMID: 11694764 DOI: 10.1159/000054699] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The period of maximal feminizing action of 17beta-estradiol (E(2)) upon sex ratio is before 10 days posthatching in tilapia (Oreochromis mossambicus). The effect of E(2) at this time is mimicked by para-chlorophenylalanine (p-CPA), a serotonin (5-hydroxytryptamine; 5-HT) synthesis inhibitor. The effect of E(2) on sexual differentiation may be mediated by the 5-HT system, which is consistent with the suggestion in mammals. The masculinizing actions of 17alpha-methyltestosterone (MT) are most potent later at up to day 20 of age, and may depend on MT induction of aromatase activity. In the present study, the effects of gonadal steroids and p-CPA on brain aromatase and estrogen receptor (ER) mRNA expression during the critical period of sexual differentiation were investigated. Treatment of tilapia with E(2) resulted in a significant decrease in the expression of brain aromatase and ERalpha between days 0 and 10, but not subsequently. The effect of E(2) at this time can be mimicked by p-CPA. Treatment of tilapia with MT, by contrast, resulted in a significant increase in brain aromatase, ERalpha and ERbeta mRNA expression when given between days 10 and 20. The downregulation of brain aromatase and ERalpha mRNA expression by E(2) before 10 days of age and, in turn, the upregulation of brain aromatase and ERalpha and ERbeta mRNA expression by MT at up to day 20 of age coincide with the period in which E(2) and MT have the maximal effect on gonadal feminization and masculinization, respectively.
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Affiliation(s)
- C L Tsai
- Department of Marine Resources, National Sun Yat-sen University, Kaohsiung, Taiwan 80424, ROC.
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Cardona-Gómez GP, Mendez P, DonCarlos LL, Azcoitia I, Garcia-Segura LM. Interactions of estrogens and insulin-like growth factor-I in the brain: implications for neuroprotection. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2001; 37:320-34. [PMID: 11744097 DOI: 10.1016/s0165-0173(01)00137-0] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Data from epidemiological studies suggest that the decline in estrogen following menopause could increase the risk of neurodegenerative diseases. Furthermore, experimental studies on different animal models have shown that estrogen is neuroprotective. The mechanisms involved in the neuroprotective effects of estrogen are still unclear. Anti-oxidant effects, activation of different membrane-associated intracellular signaling pathways, and activation of classical nuclear estrogen receptors (ERs) could contribute to neuroprotection. Interactions with neurotrophins and other growth factors may also be important for the neuroprotective effects of estradiol. In this review we focus on the interaction between insulin-like growth factor-I (IGF-I) and estrogen signaling in the brain and on the implications of this interaction for neuroprotection. During the development of the nervous system, IGF-I promotes the differentiation and survival of specific neuronal populations. In the adult brain, IGF-I is a neuromodulator, regulates synaptic plasticity, is involved in the response of neural tissue to injury and protects neurons against different neurodegenerative stimuli. As an endocrine signal, IGF-I represents a link between the growth and reproductive axes and the interaction between estradiol and IGF-I is of particular physiological relevance for the regulation of growth, sexual maturation and adult neuroendocrine function. There are several potential points of convergence between estradiol and IGF-I receptor (IGF-IR) signaling in the brain. Estrogen activates the mitogen-activated protein kinase (MAPK) pathway and has a synergistic effect with IGF-I on the activation of Akt, a kinase downstream of phosphoinositol-3 kinase. In addition, IGF-IR is necessary for the estradiol induced expression of the anti-apoptotic molecule Bcl-2 in hypothalamic neurons. The interaction of ERs and IGF-IR in the brain may depend on interactions between neural cells expressing ERs with neural cells expressing IGF-IR, or on direct interactions of the signaling pathways of alpha and beta ERs and IGF-IR in the same cell, since most neurons expressing IGF-IR also express at least one of the ER subtypes. In addition, studies on adult ovariectomized rats given intracerebroventricular (i.c.v.) infusions with antagonists for ERs or IGF-IR or with IGF-I have shown that there is a cross-regulation of the expression of ERs and IGF-IR in the brain. The interaction of estradiol and IGF-I and their receptors may be involved in different neural events. In the developing brain, ERs and IGF-IR are interdependent in the promotion of neuronal differentiation. In the adult, ERs and IGF-IR interact in the induction of synaptic plasticity. Furthermore, both in vitro and in vivo studies have shown that there is an interaction between ERs and IGF-IR in the promotion of neuronal survival and in the response of neural tissue to injury, suggesting that a parallel activation or co-activation of ERs and IGF-IR mediates neuroprotection.
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Affiliation(s)
- G P Cardona-Gómez
- Instituto Cajal, C.S.I.C., Avenida Doctor Arce 37, E-28002, Madrid, Spain
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Abstract
For decades, sexual behavior has been a valuable model system for behavioral neuroscientists studying the neural basis of motivated behaviors. One striking example of a change in motivation is the binary switch in sexual receptivity that occurs during the estrous cycle in female rats. Investigations of the neural basis of this change in behavior have fundamentally advanced our understanding of both behaviorally relevant neural pathways and basic mechanisms of steroid action in the brain. These advances have made this behavioral model system a staple of neuroendocrinology. A challenge that remains before us, given our current understanding of the circuitry and chemistry, is to develop a coherent model of how neural plasticity in the hypothalamus contributes to the dependence of this behavior on motivational state. This review will focus on the ventromedial nucleus of the hypothalamus, especially its ventrolateral subdivision. First, the anatomical, neurochemical, and functional aspects of the macro- and microcircuitry of this brain region will be discussed, followed by a discussion of the likely mechanisms of estrogen action within the ventrolateral VMH. Then, the evidence for estrogen-induced neural plasticity will be considered, including a comparison with the effects of estrogen on synaptic organization in other brain regions. Finally, a working model of neural plasticity within the ventrolateral VMH microcircuitry will be presented as a starting point for future experiments to verify or, more likely, revise and expand.
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Affiliation(s)
- L M Flanagan-Cato
- Department of Psychology, Institute for Neurological Sciences, Philadelphia, Pennsylvania, 19104-6196, USA
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Nacher J, Rosell DR, McEwen BS. Widespread expression of rat collapsin response-mediated protein 4 in the telencephalon and other areas of the adult rat central nervous system. J Comp Neurol 2000; 424:628-39. [PMID: 10931485 DOI: 10.1002/1096-9861(20000904)424:4<628::aid-cne5>3.0.co;2-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The rat collapsin response-mediated protein 4 (rCRMP-4) is a member of a family of proteins that are involved in axonal growth. It is found transiently in postmitotic neurons, such as those that are generated in the adult hippocampus. The authors used immunocytochemistry to investigate whether areas of the rat central nervous system (CNS) that retain postnatal neurogenesis express this protein. They found pronounced rCRMP-4 immunoreactivity in recently generated cells in the dentate granular layer, the subventricular zone, the olfactory bulbs, and the rostral migratory stream, four areas in which the production or migration of neurons occurs in adulthood. However, rCRMP-4 immunoreactivity also is expressed in many other regions of the rat brain in which there is no record of adult neurogenesis or neuronal migration, e.g., in the olfactory glomeruli and in neurons of the cerebral cortex. In the hypothalamus, intensely rCRMP-4-labeled neurons populated the supraoptic, paraventricular, and periventricular nuclei as well as the median eminence and the arcuate nucleus. Immunoreactivity for rCRMP-4 also was present in certain neurons of the interpeduncular nucleus, median raphe, superior colliculus, and scattered granule cerebellar neurons. Many of these regions are known to display axonal outgrowth and/or synaptic rearrangement in adulthood and to coexpress the polysialylated form of the neural cell adhesion molecule. Thus, the results of this study suggest that rCRMP-4 expression in the CNS is associated with cells that are migrating or are undergoing axonal growth. Nevertheless, small, rCRMP-4-immunoreactive cells were seen throughout the brain. These cells did not express neuronal, astroglial, or microglial markers, although some of them also were immunoreactive for rip antibody, suggesting an oligodendroglial lineage.
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Affiliation(s)
- J Nacher
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, New York 10021, USA.
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Chowen JA, Azcoitia I, Cardona-Gomez GP, Garcia-Segura LM. Sex steroids and the brain: lessons from animal studies. J Pediatr Endocrinol Metab 2000; 13:1045-66. [PMID: 11085182 DOI: 10.1515/jpem.2000.13.8.1045] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Gonadal steroid hormones have multiple effects throughout development on steroid responsive tissues in the brain. The belief that the cellular morphology of the adult brain cannot be modulated or that the synaptic connectivity is "hard-wired" is being rapidly refuted by abundant and growing evidence. Indeed, the brain is capable of undergoing many morphological changes throughout life and gonadal steroids play an important role in many of these processes. Gonadal steroids are implicated in the development of sexually dimorphic structures in the brain, in the control of physiological behaviors and functions and the brain's response to physiological or harmful substances. The effect of sex steroids on neuroprotection and neuroregeneration is an important and expanding area of investigation. Astroglia are targets for estrogen and testosterone and are apparently involved in the actions of sex steroids on the central nervous system. Sex hormones induce changes in the expression of glial fibrillary acidic protein, the growth of astrocytic processes and the extent to which neuronal membranes are covered by astroglial processes. These changes are linked to modifications in the number of synaptic inputs to neurons and suggest that astrocytes may participate in the genesis of gonadal steroid-induced sex differences in synaptic connectivity and synaptic plasticity in the adult brain. Astrocytes and tanycytes may also participate in the cellular effects of sex steroids by releasing neuroactive substances and by regulating the local accumulation of specific growth factors, such as insulin-like growth factor-I, that are involved in estrogen-induced synaptic plasticity and estrogen-mediated neuroendocrine control. Astroglia may also be involved in the regenerative and neuroprotective effects of sex steroids since astroglial activation after brain injury or after peripheral nerve axotomy is regulated by sex hormones.
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Affiliation(s)
- J A Chowen
- Unit of Investigation, Hospital Niño Jesús, Madrid, Spain.
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37
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Nappi RE, Sinforiani E, Mauri M, Bono G, Polatti F, Nappi G. Memory functioning at menopause: impact of age in ovariectomized women. Gynecol Obstet Invest 2000; 47:29-36. [PMID: 9852389 DOI: 10.1159/000010058] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Estrogens are known to act selectively on some components of memory, exerting beneficial effects on cognitive performances. However, there are few data on the long-term effect of the lack of estrogen in postmenopausal women. Therefore, we investigated attentive and verbal memory performances in physiological and surgical menopause, drawing attention to the impact of age at menopause, and we compared a well-known aging and estrogen-dependent index, the entity of bone mass loss to memory functioning. No significant differences were found in the mean scores of attentive and psychomotor performances between physiological and surgical menopause, whereas a lower number of recalled words (recency effect = PS2) was found in surgical menopause (p < 0.001) in comparison to physiological menopause. In addition, both the age at the time of ovariectomy (r = 0.47; p = 0. 014) and the years since surgery (r = -0.64; p = 0.000) correlated to short-term verbal memory performance (PS2) with better scores when surgery occurred later in women's lives. Surgical menopause is able to affect short-term verbal memory more than physiological menopause and seems to represent a critical negative event within the female brain, in particular when it occurs prematurely.
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Affiliation(s)
- R E Nappi
- Department of Obstetrics and Gynecology, IRCCS S. Matteo, IRCCS Mondino, University Center of Adaptive Disorders and Headache, University of Pavia, Italy.
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Laming PR, Kimelberg H, Robinson S, Salm A, Hawrylak N, Müller C, Roots B, Ng K. Neuronal-glial interactions and behaviour. Neurosci Biobehav Rev 2000; 24:295-340. [PMID: 10781693 DOI: 10.1016/s0149-7634(99)00080-9] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Both neurons and glia interact dynamically to enable information processing and behaviour. They have had increasingly intimate, numerous and differentiated associations during brain evolution. Radial glia form a scaffold for neuronal developmental migration and astrocytes enable later synapse elimination. Functionally syncytial glial cells are depolarised by elevated potassium to generate slow potential shifts that are quantitatively related to arousal, levels of motivation and accompany learning. Potassium stimulates astrocytic glycogenolysis and neuronal oxidative metabolism, the former of which is necessary for passive avoidance learning in chicks. Neurons oxidatively metabolise lactate/pyruvate derived from astrocytic glycolysis as their major energy source, stimulated by elevated glutamate. In astrocytes, noradrenaline activates both glycogenolysis and oxidative metabolism. Neuronal glutamate depends crucially on the supply of astrocytically derived glutamine. Released glutamate depolarises astrocytes and their handling of potassium and induces waves of elevated intracellular calcium. Serotonin causes astrocytic hyperpolarisation. Astrocytes alter their physical relationships with neurons to regulate neuronal communication in the hypothalamus during lactation, parturition and dehydration and in response to steroid hormones. There is also structural plasticity of astrocytes during learning in cortex and cerebellum.
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Affiliation(s)
- P R Laming
- School of Biology and Biochemistry, Medical Biology Centre, 97 Lisburn Road, Belfast, UK.
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Donahue JE, Stopa EG, Chorsky RL, King JC, Schipper HM, Tobet SA, Blaustein JD, Reichlin S. Cells containing immunoreactive estrogen receptor-alpha in the human basal forebrain. Brain Res 2000; 856:142-51. [PMID: 10677621 DOI: 10.1016/s0006-8993(99)02413-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The distribution of estrogen receptor protein-alpha (ER-alpha)-containing cells in the human hypothalamus and adjacent regions was studied using a monoclonal antibody (H222) raised against ER-alpha derived from MCF-7 human breast cancer cells. Reaction product was found in restricted populations of neurons and astrocyte-like cells. Neurons immunoreactive for ER-alpha were diffusely distributed within the basal forebrain and preoptic area, infundibular region, central hypothalamus, basal ganglia and amygdala. Immunoreactive astrocyte-like cells were noted within specific brain regions, including the lamina terminalis and subependymal peri-third-ventricular region. These data are consistent with the location of estrogen receptors in the basal forebrain of other species and the known effects of estrogens on the cellular functions of both neurons and supporting elements within the human hypothalamus and basal forebrain.
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Affiliation(s)
- J E Donahue
- Department of Pathology, Neuropathology Division, Rhode Island Hospital, Brown University School of Medicine, APC 12th Floor, 593 Eddy St., Providence, RI, USA
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40
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Castagna C, Obole A, Viglietti-Panzica C, Balthazart J, Panzica GC. Effects of testosterone on the synaptology of the medial preoptic nucleus of male Japanese quail. Brain Res Bull 1999; 50:241-9. [PMID: 10582522 DOI: 10.1016/s0361-9230(99)00193-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The medial preoptic nucleus (POM) of male Japanese quail is a sexually dimorphic testosterone-dependent structure that plays a key role in the activation of male sexual behavior. Both the total volume of the nucleus and the size of the dorsolateral neurons are decreased in gonadectomized males. Immunocytochemical studies have revealed a complex pattern of innervation: immunopositive fibers for several neuropeptides and neurotransmitters have been detected in the POM; some of them (e.g. vasotocin-immunoreactive fibers) are sexually dimorphic and testosterone-dependent To understand the anatomical bases of these testosterone-dependent neurochemical changes, we performed an ultrastructural study of the POM neuropil in intact sexually mature, gonadectomized, or testosterone-treated gonadectomized males. A complex synaptic organization of the POM neuropil was observed in intact male quail reflecting the heterogeneity of the neurotransmitters and neuropeptides present in this nucleus. Changes in this organization were observed after the endocrine manipulations. The number of axosomatic synapses per cell body decreased after gonadectomy and was restored to the level observed in the intact group after the administration of testosterone. By contrast, no significant change was observed in the density of axodendritic and axospinal synapses after hormonal manipulations which suggests that the total number of synapses in the nucleus should be affected by testosterone (constant density in a changing total volume). The cross-sectional area of synaptic boutons was also decreased by castration and restored to intact level by testosterone. The action of testosterone on the activation of male copulatory behavior in gonadectomized birds is hence paralleled by an extensive rearrangement of neuropil in the POM.
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Affiliation(s)
- C Castagna
- Department of Anatomy, Pharmacology and Forensic Medicine, University of Torino, Italy
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41
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42
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Hebb MO, Denovan-Wright EM, Robertson HA. Expression of the Huntington's disease gene is regulated in astrocytes in the arcuate nucleus of the hypothalamus of postpartum rats. FASEB J 1999; 13:1099-106. [PMID: 10336893 DOI: 10.1096/fasebj.13.9.1099] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Huntington's disease (HD) is one of a number of neurodegenerative disorders caused by expansion of polyglutamine-encoding CAG repeats within specific genes. Huntingtin, the protein product of the HD gene, is widely expressed in neural and nonneural human and rodent tissue. The function of the wild-type or mutated form of huntingtin is currently unknown. We have observed that relative to naive and male animals, huntingtin protein was significantly increased in the arcuate nucleus of postpartum rats. Using an oligonucleotide probe, in situ and Northern blot hybridization confirmed the expression of huntingtin mRNA. Quantification of the in situ hybridization signal in the arcuate nucleus revealed an approximate sevenfold increase in the expression of huntingtin mRNA in postpartum, lactating animals compared with naive female or male animals. Emulsion autoradiography and immunohistochemistry revealed that the cells with elevated huntingtin expression had a stellate conformation that morphologically resembled astrocytes. Dual label immunofluorescence immunohistochemistry demonstrated the colocalization of huntingtin and glial fibrillary acidic protein in these cells, confirming that they were astrocytes. Astrocytes expressing huntingtin were consistently found in close apposition to neuronal soma, suggesting interactions between these cell types. During the perinatal and postnatal period, the hypothalamus undergoes alterations in metabolic function. Our results support the idea of glia-induced metabolic changes in the hypothalamus. These results provide the first demonstration of naturally occurring changes in the expression of the Huntington's disease gene in the brain and suggest that huntingtin may play an important role in the processes that regulate neuroendocrine function.
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Affiliation(s)
- M O Hebb
- Laboratory of Molecular Neurobiology, Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7
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Hutchison JB, Wozniak A, Beyer C, Karolczak M, Hutchison RE. Steroid metabolising enzymes in the determination of brain gender. J Steroid Biochem Mol Biol 1999; 69:85-96. [PMID: 10418982 DOI: 10.1016/s0960-0760(99)00057-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The neurotrophic effects of oestrogen formed in the brain are important in brain sexual differentiation of the central nervous system and behaviour. Aromatase, converting testosterone to oestradiol-17beta, is a key enzyme involved in brain development. In primary cell cultures of foetal hypothalamus, we have found that male neurones consistently have higher aromatase activity than in the female. Using a specific antibody to the mouse aromatase, immunoreactivity was localized in the neural soma and neurites in hypothalamic cultures. Additionally more male foetal hypothalamus neurones express aromatase than in the female. Testosterone increases aromatase activity in parallel with a greater number of aromatase-immunoreactive neurones. Testosterone also increases soma size, neurite length, and branching of cultured hypothalamic neurones. The neuronal aromatase activity appears to be sensitive to the inductive effects of androgen only during the later stages of foetal development. Endogenous inhibitors of the aromatase are also likely to have a regulatory role. This work suggests that regulation of a network of aromatase neurones, sensitive to the hormonal environment of the hypothalamus, may determine when oestrogens are available for neurotrophic effects underlying brain differentiation.
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Affiliation(s)
- J B Hutchison
- MRC Neuroendocrine Development and Behaviour Group, The Babraham Institute, Cambridge, UK.
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Miller MM, Bennett HP, Billiar RB, Franklin KB, Joshi D. Estrogen, the ovary, and neutotransmitters: factors associated with aging. Exp Gerontol 1998; 33:729-57. [PMID: 9951619 DOI: 10.1016/s0531-5565(98)00018-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Our studies in the C57BL/6J mouse have been designed to examine the interactions of aging and the ovary, and their mutual effects on neuroendocrine function. In the pituitary, ovarian status and not age determines responsiveness to gonadotropin hormone releasing hormone (GnRH), but estrogen (E2) is an important mediator in CNS changes, and removal of the ovary (OVX) is deleterious to the neuroendocrine hypothalamus. OVX for just six days in young animals results in synaptic loss between noradrenergic terminals and gonadotropin hormone releasing hormone (GnRH) neurons. Long-term OVX, hypothesized to protect against neuroendocrine aging, fails to guard against any studied age-related changes. Some age-related changes occur as early as midlife. Although neuron number remains constant at middle age, opiatergic neurons undergo significant functional changes by producing opiate antagonist peptides. This change appears to be caused by alterations in the prohormone convertases, which cleave propeptide to peptide. Altered peptides may trigger the loss of reproductive capacity. The midlife shift in opiate peptide production is a component of natural developmental processes that begin in the neonate and continue through old age. In the cholinergic system, E2 mediates numbers of cholinergic receptors, cholinergic neurons, and cholinergic-modulated memory systems in both young and old animals. Regardless of age, ovarian steroids, if present at physiologic levels, are beneficial to the neuroendocrine CNS, and long-term deprivation from ovarian-produced factors is deleterious in the systems we have examined. Our studies have shown that deprivation from ovarian steroid hormones in the female appears to be a major factor in the health of the CNS and in events associated with aging.
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Affiliation(s)
- M M Miller
- Department of Obstetrics and Gynecology, McGill University, Montreal, Quebec, Canada.
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45
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Ostrowski NL. Oxytocin receptor mRNA expression in rat brain: implications for behavioral integration and reproductive success. Psychoneuroendocrinology 1998; 23:989-1004. [PMID: 9924748 DOI: 10.1016/s0306-4530(98)00070-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The nonapeptide, oxytocin (OT), has been implicated in a wide range of physiological, behavioral and pharmacological effects related to learning and memory, parturition and lactation, maternal and sexual behavior, and the formation of social attachments. Specific G-protein linked membrane bound OT receptors mediate OTs effects. The unavailability of highly selective pharmacological ligands that discriminate the OT receptor from the highly homologous vasopressin receptors (V1a, V1b and V2 subtypes) has made it difficult to confirm specific effects of oxytocin, particularly in brain regions where OT and multiple AVP receptor subtypes may be coexpressed. Here, data on the oxytocin receptor (OTR) messenger ribonucleic acid (mRNA) localization in brain are presented in the context of a model that proposes a reproductive state-dependent role for steroid-hormone restructuring of neural circuits, and a role for oxytocin in the integration of neural transmission in pathways subserving: (1) steroid-sensitive reproductive behaviors; (2) learning; and (3) reinforcement. It is hypothesized that social attachments emerge as a consequence of a conditioned association between OT-related activity in these pathways and the eliciting stimulus.
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Affiliation(s)
- N L Ostrowski
- Eli Lilly and Company, Lilly Corporate Headquarters, Indianapolis, IN 46285, USA.
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46
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Abstract
Light and electron microscopic studies have shown that ovarian steroids regulate the density and number of excitatory synaptic inputs to hippocampal pyramidal cells in the adult female rat; elevated levels of estradiol are associated with a higher density of dendritic spine synapses on CA1 pyramidal cells. Electrophysiological analyses indicate that these hormone-induced synapses increase hippocampal excitability as well as the potential for synaptic plasticity. Importantly, correlation of dendritic spine density and sensitivity to synaptic input of individual CA1 pyramidal cells from estradiol-treated and control animals suggests that synapses induced by estradiol may be a specialized subpopulation that contains primarily the NMDA subtype of glutamate receptor. The apparent NMDA receptor specificity of these synapses may be key to understanding their functional significance. Currently, the behavioral consequences of additional spine synapses are unknown. Numerous studies have aimed at correlating hormone-induced changes in hippocampal connectivity with differences in hippocampus-dependent spatial learning ability in mazes, but the results of these efforts have been equivocal. Anatomical, electrophysiological, and behavioral studies of estradiol-mediated hippocampal plasticity are reviewed. In conclusion, it is suggested that standard behavioral tests of hippocampal function are not sufficient to reveal the behavioral consequences of hormone-induced hippocampal plasticity. Rather, understanding the behavioral consequences of estradiol and progesterone effects on hippocampal connectivity may require analysis of the hippocampus' cognitive and spatial information processing functions in relation to alternative biologically relevant behaviors. A (nonexclusive) proposal that hormone-induced hippocampal plasticity may facilitate appropriate prepartum/maternal behavior is discussed.
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Affiliation(s)
- C S Woolley
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208, USA
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47
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Moore CT, Leuschen MP. Synaptic density in the arcuate nucleus of female rats approaching middle age. Neurosci Lett 1998; 254:73-6. [PMID: 9779923 DOI: 10.1016/s0304-3940(98)00645-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Synaptic number and synapses/neuronal cell membrane were evaluated from ultrastructural micrographs of the arcuate nucleus from 90-, 120-, 180-, and 240-day female rats grouped into ovary-intact or ovariectomized animals treated with peanut oil vehicle or estradiol benzoate (10 microg/100 g body weight) for 3 days. In ovary-intact rats, synaptic density was significantly less in middle aged 240 day animals than in 90-, 120-, or 180-day animals with greatest decrease occurring between 180- and 240-day animals. Ovary-intact and ovariectomized animals treated with estradiol benzoate had significantly higher sera estradiol levels, but the estradiol was ineffective in increasing synaptic density in the middle aged animals. Logistical regression confirmed a correlation between a decrease in synapses and increasing age but not estradiol treatment.
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Affiliation(s)
- C T Moore
- Department of Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha 68198-1205, USA
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Wagner CK, Silverman AJ, Morrell JI. Evidence for estrogen receptor in cell nuclei and axon terminals within the lateral habenula of the rat: Regulation during pregnancy. J Comp Neurol 1998. [DOI: 10.1002/(sici)1096-9861(19980316)392:3<330::aid-cne4>3.0.co;2-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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49
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Abstract
1. Both the neuroendocrine system and the brain mechanisms underlying gender-specific behavior are known to be organized by steroid sex hormones, androgen and estrogen, during specific sensitive phases of early fetal and perinatal development. The factors that control these phasic effects of the hormones on brain development are still not understood. Processes of masculinization and defeminization are thought to be involved in the sex differentiation of mammalian reproductive behavior. 2. The P450 aromatase, converting androgen to estrogen, is a key enzyme in the development of neural systems, and the activity of this enzyme is likely to be one of the factors determining brain sex differentiation. 3. We have examined the localization and regulation of brain aromatase using the mouse as a model. Measurement of testosterone conversion to estradiol-17 beta, using a sensitive radiometric 3H2O assay, indicates that estrogens are formed more actively in the male mouse brain than in the female during both the prenatal and the neonatal periods. In primary cell cultures of embryonic mouse hypothalamus there are sex differences in aromatase activity during early and late embryogenesis, with a higher capacity for estrogen formation in the male than the female. These sex differences are regionally specific in the brain, since on gender differences in aromatase activity are detectable in cortical cells. 4. Aromatase activity in the mouse brain is neuronal rather than glial. Using a specific antibody to the mouse aromatase, immunoreactivity is restricted to neuronal soma and neurites in hypothalamic cultures. There are more neurons containing expressed aromatase in the male hypothalamus than in the female. Therefore, gender-specific differences in embryonic aromatase activity are neuronal. 5. Testosterone increases aromatase activity specifically in hypothalamic neurons, but has no effect on cortical cells. The neuronal aromatase activity appears to be sensitive to the inductive effects of androgen only in the later stages of embryonic development. Androgen also increases the numbers of aromatase-immunoreactive neurons in the hypothalamus. 6. This work suggests that the embryonic male hypothalamus and other androgen target areas contain a network of neurons which has the capacity to provide estrogen for the sexual differentiation of brain mechanisms of behavior. The phasic activity of the key enzyme, aromatase, during development is influenced by androgen. What determines the developmental action of androgen and the other factors involved in the regulation and expression of this neuronal enzyme still have to be established.
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Affiliation(s)
- J B Hutchison
- MRC Neuroendocrine Development and Behaviour Group, Babraham Institute, Cambridge, U.K
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50
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Mulders WH, Meek J, Hafmans TG, Cools AR. Plasticity in the stress-regulating circuit: decreased input from the bed nucleus of the stria terminalis to the hypothalamic paraventricular nucleus in Wistar rats following adrenalectomy. Eur J Neurosci 1997; 9:2462-71. [PMID: 9464940 DOI: 10.1111/j.1460-9568.1997.tb01663.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The bed nucleus of the stria terminalis is involved in the stress-regulating circuit by funnelling limbic information to the hypothalamic paraventricular nucleus. Since adrenalectomy influences both limbic structures (by inducing cell death in the hippocampus) and the hypothalamic paraventricular nucleus (by increased corticotrophin-releasing hormone synthesis), we investigated whether the bed nucleus of the stria terminalis is also influenced by adrenalectomy. For this purpose, we analysed and compared the projections from the bed nucleus of the stria terminalis to the hypothalamic paraventricular nucleus in normal and adrenalectomized rats by anterograde tracer injections in the bed nucleus of the stria terminalis. Quantitative analysis of the fibre pattern in the hypothalamic paraventricular nucleus of normal rats revealed a homogeneous distribution of fibres of the bed nucleus of the stria terminalis over the different subdivisions of the hypothalamic paraventricular nucleus. In adrenalectomized rats, the absolute fibre density was significantly lower in the whole hypothalamic paraventricular nucleus (1.17 +/- 0.27 10(-3) microm/microm3 in adrenalectomized rats versus 2.59 +/- 0.24 10(-3) microm/microm3 in normal rats; P < 0.01) and all its subdivisions. The largest decrease of fibre density was found in the corticotrophin-releasing hormone-rich part of the hypothalamic paraventricular nucleus (relative fibre density; adrenalectomized rats: 0.602 +/- 0.106, versus 1.095 +/- 0.019 in normal rats, P < 0.01). These results show a loss of input from the bed nucleus of the stria terminalis to the hypothalamic paraventricular nucleus, and particularly to the corticotrophin-releasing hormone neurons, following adrenalectomy. The data suggest that this pathway within the stress-regulating circuit is functionally affected by corticosteroids in adult rats and may imply that human disorders associated with corticosteroid imbalance are allied to a changed circuitry in the brain.
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Affiliation(s)
- W H Mulders
- Department of Anatomy and Embryology, University of Nijmegen, The Netherlands
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