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Martin H, Coursan A, Lallement J, Di Miceli M, Kandiah J, Raho I, Buttler J, Guilloux JP, De Deurwaerdere P, Layé S, Routh VH, Guiard BP, Magnan C, Cruciani-Guglielmacci C, Fioramonti X. Serotonergic neurons are involved in the counter-regulatory response to hypoglycemia. J Neuroendocrinol 2023; 35:e13344. [PMID: 37857383 DOI: 10.1111/jne.13344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/30/2023] [Accepted: 09/12/2023] [Indexed: 10/21/2023]
Abstract
OBJECTIVES Intensive insulin therapy provides optimal glycemic control in patients with diabetes. However, intensive insulin therapy causes so-called iatrogenic hypoglycemia as a major adverse effect. The ventromedial hypothalamus (VMH) has been described as the primary brain area initiating the counter-regulatory response (CRR). Nevertheless, the VMH receives projections from other brain areas which could participate in the regulation of the CRR. In particular, studies suggest a potential role of the serotonin (5-HT) network. Thus, the objective of this study was to determine the contribution of 5-HT neurons in CRR control. METHODS Complementary approaches have been used to test this hypothesis in quantifying the level of 5-HT in several brain areas by HPLC in response to insulin-induced hypoglycemia, measuring the electrical activity of dorsal raphe (DR) 5-HT neurons in response to insulin or decreased glucose level by patch-clamp electrophysiology; and measuring the CRR hormone glucagon as an index of the CRR to the modulation of the activity of 5-HT neurons using pharmacological or pharmacogenetic approaches. RESULTS HPLC measurements show that the 5HIAA/5HT ratio is increased in several brain regions including the VMH in response to insulin-induced hypoglycemia. Patch-clamp electrophysiological recordings show that insulin, but not decreased glucose level, increases the firing frequency of DR 5-HT neurons in the DR. In vivo, both the pharmacological inhibition of 5-HT neurons by intraperitoneal injection of the 5-HT1A receptor agonist 8-OH-DPAT or the chemogenetic inhibition of these neurons reduce glucagon secretion, suggesting an impaired CRR. CONCLUSION Taken together, these data highlight a new neuronal network involved in the regulation of the CRR. In particular, this study shows that DR 5-HT neurons detect iatrogenic hypoglycemia in response to the increased insulin level and may play an important role in the regulation of CRR.
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Affiliation(s)
- Hugo Martin
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
| | - Adeline Coursan
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
| | | | - Mathieu Di Miceli
- Worcester Biomedical Research Group, School of Science and the Environment, University of Worcester, Worcester, UK
| | - Janany Kandiah
- Université Paris Cité, BFA, UMR 8251, CNRS, Paris, France
| | - Ilyès Raho
- Université Paris Cité, BFA, UMR 8251, CNRS, Paris, France
| | - Jasmine Buttler
- INCIA, UMR CNRS, Bordeaux University, Neurocampus, Bordeaux, France
| | | | | | - Sophie Layé
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, New Jersey, USA
| | - Bruno P Guiard
- Centre de Recherches sur la Cognition Animale (CRCA), Centre de Biologie Intégrative (CBI), Toulouse, France
| | | | | | - Xavier Fioramonti
- Université Bordeaux, INRAE, Bordeaux INP, NutriNeuro, UMR 1286, Bordeaux, France
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2
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Kumar SS, Bouwer GT, Jackson MK, Perkinson MR, McDonald FJ, Brown CH, Augustine RA. Kisspeptin neuron projections to oxytocin neurons are not necessary for parturition in the mouse. Brain Struct Funct 2023; 228:1535-1548. [PMID: 37389617 PMCID: PMC10335956 DOI: 10.1007/s00429-023-02670-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 06/13/2023] [Indexed: 07/01/2023]
Abstract
Oxytocin is synthesized by hypothalamic supraoptic nucleus (SON) and paraventricular nucleus (PVN) neurons and is released from the posterior pituitary gland to trigger uterine contractions during parturition. In rats, oxytocin neuron innervation by periventricular nucleus (PeN) kisspeptin neurons increases over pregnancy and intra-SON kisspeptin administration excites oxytocin neurons only in late pregnancy. To test the hypothesis that kisspeptin neurons excite oxytocin neurons to trigger uterine contractions during birth in C57/B6J mice, double-label immunohistochemistry for kisspeptin and oxytocin first confirmed that kisspeptin neurons project to the SON and PVN. Furthermore, kisspeptin fibers expressed synaptophysin and formed close appositions with oxytocin neurons in the mouse SON and PVN before and during pregnancy. Stereotaxic viral delivery of caspase-3 into the AVPV/PeN of Kiss-Cre mice before mating reduced kisspeptin expression in the AVPV, PeN, SON and PVN by > 90% but did not affect the duration of pregnancy or the timing of delivery of each pup during parturition. Therefore, it appears that AVPV/PeN kisspeptin neuron projections to oxytocin neurons are not necessary for parturition in the mouse.
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Affiliation(s)
- Shalini S Kumar
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Gregory T Bouwer
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Meliame K Jackson
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Michael R Perkinson
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Fiona J McDonald
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Colin H Brown
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Rachael A Augustine
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand.
- Department of Physiology, School of Biomedical Sciences, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
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3
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Rock KD, St Armour G, Horman B, Phillips A, Ruis M, Stewart AK, Jima D, Muddiman DC, Stapleton HM, Patisaul HB. Effects of Prenatal Exposure to a Mixture of Organophosphate Flame Retardants on Placental Gene Expression and Serotonergic Innervation in the Fetal Rat Brain. Toxicol Sci 2020; 176:203-223. [PMID: 32243540 PMCID: PMC7357193 DOI: 10.1093/toxsci/kfaa046] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
There is a growing need to understand the potential neurotoxicity of organophosphate flame retardants (OPFRs) and plasticizers because use and, consequently, human exposure, is rapidly expanding. We have previously shown in rats that developmental exposure to the commercial flame retardant mixture Firemaster 550 (FM 550), which contains OPFRs, results in sex-specific behavioral effects, and identified the placenta as a potential target of toxicity. The placenta is a critical coordinator of fetal growth and neurodevelopment, and a source of neurotransmitters for the developing brain. We have shown in rats and humans that flame retardants accumulate in placental tissue, and induce functional changes, including altered neurotransmitter production. Here, we sought to establish if OPFRs (triphenyl phosphate and a mixture of isopropylated triarylphosphate isomers) alter placental function and fetal forebrain development, with disruption of tryptophan metabolism as a primary pathway of interest. Wistar rat dams were orally exposed to OPFRs (0, 500, 1000, or 2000 μg/day) or a serotonin (5-HT) agonist 5-methoxytryptamine for 14 days during gestation and placenta and fetal forebrain tissues collected for analysis by transcriptomics and metabolomics. Relative abundance of genes responsible for the transport and synthesis of placental 5-HT were disrupted, and multiple neuroactive metabolites in the 5-HT and kynurenine metabolic pathways were upregulated. In addition, 5-HTergic projections were significantly longer in the fetal forebrains of exposed males. These findings suggest that OPFRs have the potential to impact the 5-HTergic system in the fetal forebrain by disrupting placental tryptophan metabolism.
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Affiliation(s)
- Kylie D Rock
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
| | - Genevieve St Armour
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
| | - Brian Horman
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
| | - Allison Phillips
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708
| | - Matthew Ruis
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708
| | - Allison K Stewart
- Molecular Education, Technology, and Research Innovation Center, North Carolina State University, Raleigh, North Carolina 27695
| | - Dereje Jima
- Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina 27695
- Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina 27695
| | - David C Muddiman
- Molecular Education, Technology, and Research Innovation Center, North Carolina State University, Raleigh, North Carolina 27695
| | - Heather M Stapleton
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708
| | - Heather B Patisaul
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27619
- Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina 27695
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Thompson Gray AD, Simonetti J, Adegboye F, Jones CK, Zurawski Z, Hamm HE. Sexual Dimorphism in Stress-induced Hyperthermia in SNAP25Δ3 mice, a mouse model with disabled Gβγ regulation of the exocytotic fusion apparatus. Eur J Neurosci 2020; 52:2815-2826. [PMID: 32449556 DOI: 10.1111/ejn.14836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 11/28/2022]
Abstract
Behavioral assays in the mouse can show marked differences between male and female animals of a given genotype. These differences identified in such preclinical studies may have important clinical implications. We recently made a mouse model with impaired presynaptic inhibition through Gβγ-SNARE signaling. Here, we examine the role of sexual dimorphism in the severity of the phenotypes of this model, the SNAP25Δ3 mouse. In males, we already reported that SNAP25Δ3 homozygotes demonstrated phenotypes in motor coordination, nociception, spatial memory and stress processing. We now report that while minimal sexually dimorphic effects were observed for the nociceptive, motor or memory phenotypes, large differences were observed in the stress-induced hyperthermia paradigm, with male SNAP25Δ3 homozygotes exhibiting an increase in body temperature subsequent to handling relative to wild-type littermates, while no such genotype-dependent effect was observed in females. This suggests sexually dimorphic mechanisms of Gβγ-SNARE signaling for stress processing or thermoregulation within the mouse. Second, we examined the effects of heterozygosity with respect to the SNAP25Δ3 mutation. Heterozygote SNAP25Δ3 animals were tested alongside homozygote and wild-type littermates in all of the aforementioned paradigms and displayed phenotypes similar to wild-type animals or an intermediate state. From this, we conclude that the SNAP25Δ3 mutation does not behave in an autosomal dominant manner, but rather displays incomplete dominance for many phenotypes.
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Affiliation(s)
| | - Justice Simonetti
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Feyisayo Adegboye
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
| | - Carrie K Jones
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN, USA
| | - Zack Zurawski
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA.,Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, USA
| | - Heidi E Hamm
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
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5
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Kammel LG, Correa SM. Selective sexual differentiation of neurone populations may contribute to sex-specific outputs of the ventromedial nucleus of the hypothalamus. J Neuroendocrinol 2020; 32:e12801. [PMID: 31605642 PMCID: PMC6982598 DOI: 10.1111/jne.12801] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 09/26/2019] [Accepted: 10/08/2019] [Indexed: 12/11/2022]
Abstract
Sex differences among neurones in the ventrolateral region of the ventromedial hypothalamic nucleus (VMHvl) allow for the display of a diversity of sex-typical behaviours and physiological responses, ranging from mating behaviour to metabolism. Here, we review recent studies that interrogate the relationship between sex-typical responses and changes in cellular phenotypes. We discuss technologies that increase the resolution of molecular profiling or targeting of cell populations, including single-cell transcriptional profiling and conditional viral genetic approaches to manipulate neurone survival or activity. Overall, emerging studies indicate that sex-typical functions of the VMH may be mediated by phenotypically distinct and sexually differentiated neurone populations within the VMHvl. Future studies in this and other brain regions could exploit cell-type-specific tools to reveal the cell populations and molecular mediators that modulate sex-typical responses. Furthermore, cell-type-specific analyses of the effects of sexually differentiating factors, including sex hormones, can test the hypothesis that distinct cell types within a single brain region vary with respect to sexual differentiation.
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Affiliation(s)
- Laura G Kammel
- Department of Integrative Biology and Physiology, Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, CA, USA
- Molecular, Cellular, Integrative Physiology Graduate Program, University of California, Los Angeles, CA, USA
| | - Stephanie M Correa
- Department of Integrative Biology and Physiology, Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, CA, USA
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6
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Neurobiological characteristics underlying metabolic differences between males and females. Prog Neurobiol 2018; 176:18-32. [PMID: 30194984 DOI: 10.1016/j.pneurobio.2018.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/22/2018] [Accepted: 09/01/2018] [Indexed: 12/24/2022]
Abstract
The hypothalamus is the main integrating center for metabolic control. Our understanding of how hypothalamic circuits function to control appetite and energy expenditure has increased dramatically in recent years, due to the rapid rise in the incidence of obesity and the search for effective treatments. Increasing evidence indicates that these treatments will most likely differ between males and females. Indeed, sex differences in metabolism have been demonstrated at various levels, including in two of the most studied neuronal populations involved in metabolic control: the anorexigenic proopiomelanocortin neurons and the orexigenic neuropeptide Y/Agouti-related protein neurons. Here we review what is known to date regarding the sex differences in these two neuronal populations, as well as other neuronal populations involved in metabolic control and glial cells.
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7
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Seymour AJ, Scott V, Augustine RA, Bouwer GT, Campbell RE, Brown CH. Development of an excitatory kisspeptin projection to the oxytocin system in late pregnancy. J Physiol 2016; 595:825-838. [PMID: 27589336 DOI: 10.1113/jp273051] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 08/23/2016] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Oxytocin release from the posterior pituitary gland stimulates uterine contraction during birth but the central mechanisms that activate oxytocin neurones for birth are not well characterized. We found that that kisspeptin fibre density around oxytocin neurones increases in late-pregnant rats. These kisspeptin fibres originated from hypothalamic periventricular nucleus neurones that upregulated kisspeptin expression in late pregnancy. Oxytocin neurones were excited by central kisspeptin administration in late-pregnant rats but not in non-pregnant rats or early- to mid-pregnant rats. Our results reveal the emergence of a new excitatory kisspeptin projection to the oxytocin system in late pregnancy that might contribute to oxytocin neurone activation for birth. ABSTRACT The hormone oxytocin promotes uterine contraction during parturition. Oxytocin is synthesized by magnocellular neurones in the hypothalamic supraoptic and paraventricular nuclei and is released into the circulation from the posterior pituitary gland in response to action potential firing. Systemic kisspeptin administration increases oxytocin neurone activity to elevate plasma oxytocin levels. Here, immunohistochemistry revealed that rats on the expected day of parturition (day 21 of gestation) had a higher density of kisspeptin-positive fibres in the perinuclear zone surrounding the supraoptic nucleus (which provides dense glutamatergic and GABAergic innervation to the supraoptic nucleus) than was evident in non-pregnant rats. Retrograde tracing showed the kisspeptin projections to the perinuclear zone originated from the hypothalamic periventricular nucleus. Quantitative RT-PCR showed that kisspeptin receptor mRNA, Kiss1R mRNA, was expressed in the perinuclear zone-supraoptic nucleus and that the relative Kiss1R mRNA expression does not change over the course of pregnancy. Finally, intracerebroventricular administration of kisspeptin increased the firing rate of oxytocin neurones in anaesthetized late-pregnant rats (days 18-21 of gestation) but not in non-pregnant rats, or in early- or mid-pregnant rats. Taken together, these results suggest that kisspeptin expression is upregulated in the periventricular nucleus projection to the perinuclear zone of the supraoptic nucleus towards the end of pregnancy. Hence, this input might activate oxytocin neurones during parturition.
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Affiliation(s)
- Alexander J Seymour
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Centre for Neuroendocrinology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Victoria Scott
- Centre for Neuroendocrinology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Rachael A Augustine
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Centre for Neuroendocrinology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Gregory T Bouwer
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Centre for Neuroendocrinology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Colin H Brown
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand.,Centre for Neuroendocrinology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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8
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Shimogawa Y, Sakuma Y, Yamanouchi K. Efferent and afferent connections of the ventromedial hypothalamic nucleus determined by neural tracer analysis: Implications for lordosis regulation in female rats. Neurosci Res 2015; 91:19-33. [DOI: 10.1016/j.neures.2014.10.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 10/08/2014] [Accepted: 10/11/2014] [Indexed: 12/14/2022]
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9
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Ito H, Shimogawa Y, Kohagura D, Moriizumi T, Yamanouchi K. Inhibitory role of the serotonergic system on estrogen receptor α expression in the female rat hypothalamus. Neurosci Lett 2014; 583:194-8. [DOI: 10.1016/j.neulet.2014.09.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/10/2014] [Accepted: 09/22/2014] [Indexed: 01/07/2023]
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10
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Ito H, Moriizumi T, Shimogawa Y, Yamanouchi K. Postnatal changes in the number of serotonin-immunoreactive cells in midbrain raphe nuclei of male rats. Anat Sci Int 2013; 89:199-206. [PMID: 24293189 DOI: 10.1007/s12565-013-0217-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 11/13/2013] [Indexed: 10/26/2022]
Abstract
To clarify the developmental changes in serotonergic neurons in the subdivisions of the dorsal (DR) and median raphe (MR) nuclei before puberty, the extent of the nuclei and the number of serotonin (5-HT) immunoreactive (ir) cells were measured in 5-, 15-, and 30-day-old rats and 8-week-old (adult) castrated male rats. The brains were fixed and 50 μm frozen sections prepared. After immunostaining for 5-HT, the number of 5-HT-ir cells in a 0.2 × 0.2 mm frame in the dorsal, ventral and lateral subdivisions of the DR (dDR, vDR and lDR, respectively) and MR were counted. Total numbers of 5-HT-ir cells counted in the frame of three sections in each rat were expressed as the number of cells per cubic millimeter (density). The results indicated that the densities of 5-HT-ir cells in the MR were almost the same in all age groups. On the other hand, among the subdivisions of the DR, the mean density of 5-HT-ir cells in 15-day-old rats was higher than that in the 5-day-old group in the lDR only. The area of the three sections of the DR and of the MR was also measured. The area of the DR in 15-day-old rats was found to be twice that in the 5-day-old rats, and differed from the area in 30-day-old rats and adults. There were no differences among the age groups in the areas of the MR. The results indicate that the expression of 5-HT in the lDR and extent of the DR increased to adult levels from days 5 to 15 after birth. In the dDR, vDR and MR, expression of 5-HT at postnatal day 5 was at adult levels already.
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Affiliation(s)
- Hiroyuki Ito
- Department of Anatomy, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan
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11
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Ayala C, Pennacchio GE, Soaje M, Carreño NB, Bittencourt JC, Jahn GA, Celis ME, Valdez SR. Effects of thyroid status on NEI concentration in specific brain areas related to reproduction during the estrous cycle. Peptides 2013; 49:74-80. [PMID: 24028792 DOI: 10.1016/j.peptides.2013.08.016] [Citation(s) in RCA: 6] [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: 06/14/2013] [Revised: 08/21/2013] [Accepted: 08/21/2013] [Indexed: 01/10/2023]
Abstract
We previously showed that short-term hypo- and hyperthyroidism induce changes in neuropeptide glutamic-acid-isoleucine-amide (NEI) concentrations in discrete brain areas in male rats. To investigate the possible effects of hypo- and hyperthyroidism on NEI concentrations mainly in hypothalamic areas related to reproduction and behavior, female rats were sacrificed at different days of the estrous cycle. Circulating luteinizing hormone (LH), estradiol and progesterone concentrations were measured in control, hypothyroid (hypoT, treated with PTU during 7-9 days) and hyperthyroid (hyperT, l-T4 during 4-7 days) animals. Both treatments blunted the LH surge. Hypo- and hyperthyroidism increased estradiol concentrations during proestrus afternoon (P-PM), although hypoT rats showed lower values compared to control during proestrus morning (P-AM). Progesterone levels were higher in all groups at P-PM and in the hyperT during diestrus morning (D2). NEI concentrations were lower in hypoT rats during the estrous cycle except in estrus (E) in the peduncular part of the lateral hypothalamus (PLH). They were also reduced by both treatments in the perifornical part of the lateral hypothalamus (PeFLH) during P-PM. Hypothyroidism led to higher NEI concentrations during P-PM in the organum vasculosum of the lamina terminalis and anteroventral periventricular nucleus (OVLT+AVPV). The present results indicate that NEI concentration is regulated in a complex manner by hypo- and hyperthyroidism in the different areas studied, suggesting a correlation between NEI values and the variations of gonadal steroid levels during estrous cycle. These changes could be, in part, responsible for the alterations observed in the hypothalamic-pituitary-gonadal axis in these pathologies.
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Affiliation(s)
- Carolina Ayala
- Laboratorio de Ciencias Fisiológicas, Cátedra de Bacteriología y Virología Médicas, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, CP 5000 Córdoba, Argentina; Sección de Desarrollo Cerebral Perinatal (SPBD), Instituto de Histología y Embriología Mendoza (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Parque General San Martín, CP 5500 Mendoza, Argentina.
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12
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Yang CF, Chiang MC, Gray DC, Prabhakaran M, Alvarado M, Juntti SA, Unger EK, Wells JA, Shah NM. Sexually dimorphic neurons in the ventromedial hypothalamus govern mating in both sexes and aggression in males. Cell 2013; 153:896-909. [PMID: 23663785 PMCID: PMC3767768 DOI: 10.1016/j.cell.2013.04.017] [Citation(s) in RCA: 457] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/11/2013] [Accepted: 04/05/2013] [Indexed: 02/06/2023]
Abstract
Sexual dimorphisms in the brain underlie behavioral sex differences, but the function of individual sexually dimorphic neuronal populations is poorly understood. Neuronal sexual dimorphisms typically represent quantitative differences in cell number, gene expression, or other features, and it is unknown whether these dimorphisms control sex-typical behavior exclusively in one sex or in both sexes. The progesterone receptor (PR) controls female sexual behavior, and we find many sex differences in number, distribution, or projections of PR-expressing neurons in the adult mouse brain. Using a genetic strategy we developed, we have ablated one such dimorphic PR-expressing neuronal population located in the ventromedial hypothalamus (VMH). Ablation of these neurons in females greatly diminishes sexual receptivity. Strikingly, the corresponding ablation in males reduces mating and aggression. Our findings reveal the functions of a molecularly defined, sexually dimorphic neuronal population in the brain. Moreover, we show that sexually dimorphic neurons can control distinct sex-typical behaviors in both sexes.
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Affiliation(s)
- Cindy F Yang
- Program in Neuroscience, University of California, San Francisco, San Francisco, CA 94158, USA
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13
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Patisaul HB, Losa-Ward SM, Todd KL, McCaffrey KA, Mickens JA. Influence of ERβ selective agonism during the neonatal period on the sexual differentiation of the rat hypothalamic-pituitary-gonadal (HPG) axis. Biol Sex Differ 2012; 3:2. [PMID: 22260364 PMCID: PMC3292502 DOI: 10.1186/2042-6410-3-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 01/19/2012] [Indexed: 12/24/2022] Open
Abstract
Background It is well established that sexual differentiation of the rodent hypothalamic-pituitary-gonadal (HPG) axis is principally orchestrated by estrogen during the perinatal period. Here we sought to better characterize the mechanistic role the beta form of the estrogen receptor (ERβ) plays in this process. Methods To achieve this, we exposed neonatal female rats to three doses (0.5, 1 and 2 mg/kg) of the ERβ selective agonist diarylpropionitrile (DPN) using estradiol benzoate (EB) as a positive control. Measures included day of vaginal opening, estrous cycle quality, GnRH and Fos co-localization following ovariectomy and hormone priming, circulating luteinizing hormone (LH) levels and quantification of hypothalamic kisspeptin immunoreactivity. A second set of females was then neonatally exposed to DPN, the ERα agonist propyl-pyrazole-triol (PPT), DPN+PPT, or EB to compare the impact of ERα and ERβ selective agonism on kisspeptin gene expression in pre- and post-pubescent females. Results All three DPN doses significantly advanced the day of vaginal opening and induced premature anestrus. GnRH and Fos co-labeling, a marker of GnRH activation, following ovariectomy and hormone priming was reduced by approximately half at all doses; the magnitude of which was not as large as with EB or what we have previously observed with the ERα agonist PPT. LH levels were also correspondingly lower, compared to control females. No impact of DPN was observed on the density of kisspeptin immunoreactive (-ir) fibers or cell bodies in the arcuate (ARC) nucleus, and kisspeptin-ir was only significantly reduced by the middle (1 mg/kg) DPN dose in the preoptic region. The second experiment revealed that EB, PPT and the combination of DPN+PPT significantly abrogated preoptic Kiss1 expression at both ages but ARC expression was only reduced by EB. Conclusion Our results indicate that selective agonism of ERβ is not sufficient to completely achieve male-typical HPG organization observed with EB or an ERα agonist.
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Affiliation(s)
- Heather B Patisaul
- Department of Biology, North Carolina State University, Raleigh, NC 27695, USA.
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Cao J, Patisaul HB. Sexually dimorphic expression of hypothalamic estrogen receptors α and β and Kiss1 in neonatal male and female rats. J Comp Neurol 2011; 519:2954-77. [PMID: 21484804 PMCID: PMC3874381 DOI: 10.1002/cne.22648] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Release of gonadotropins in adult rodents is sex specific and dependent upon kisspeptin (Kiss1) neurons. This crucial pathway within the hypothalamic-pituitary-gonadal (HPG) axis is profoundly influenced by neonatal estrogens, which induce a male-like phenotype. Classically, estrogen activity is mediated via the estrogen receptors α and β (ERα and ERβ), but the relative roles each plays in organizing the sex-specific ontogeny of kisspeptin signaling pathways remain unresolved. Thus, the present study used in situ hybridization histochemistry (ISHH) to map the temporal and sexually dimorphic neonatal mRNA expression profiles of ERα, ERβ, and Kiss1 in the anterioventral periventricular nucleus (AVPV), medial preoptic area (MPOA), ventromedial nucleus (VMN), and arcuate nucleus (ARC), all regions critical for kisspeptin regulation of gonadotropin secretion. In general, females had higher levels of ERα, in all regions examined, a sex difference that persisted until postnatal day (PND) 19 except in the ARC. Males had significantly more ERβ expression in the AVPV at birth, but this sex difference was lost and then re-emerged on PND 19, with females having more than males. VMN ERβ levels were higher in females until PND 19. Kiss1 was not detectable until PND 11 in the anterior hypothalamus, but expression levels were equivalent at birth in the ARC. By PND 2, ARC ERα and Kiss1 levels were abundant, sexually dimorphic (higher in females), and, respectively, showed a U- and a bell-shaped pattern with age. Sex differences in ARC Kiss1 expression provide evidence that Kiss1 may play a role in the sexual dimorphic organization of the neonatal brain. These detailed profiles of neonatal Kiss1 and ERs mRNA levels will help elucidate the relative roles each plays in the sex-specific, estrogen-dependent organization of gonadotropin signaling pathways.
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Affiliation(s)
- Jinyan Cao
- Department of Biology, North Carolina State University, Raleigh, North Carolina 27695
| | - Heather B. Patisaul
- Department of Biology, North Carolina State University, Raleigh, North Carolina 27695
- Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina 27695
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15
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Laalaoui A, Fèvre-Montange M, Ahboucha S, Gamrani H. Proopiomelanocortin in the arcuate nucleus of the rodent Meriones shawi: effects of dehydration. Acta Histochem 2011; 113:369-74. [PMID: 20447683 DOI: 10.1016/j.acthis.2010.01.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Revised: 01/20/2010] [Accepted: 01/21/2010] [Indexed: 11/24/2022]
Abstract
Proopiomelanocortin (POMC) is a 36kDa glycoprotein implicated in homeostatic balance. We used in situ hybridization histochemistry coupled with quantitative autoradiography to determine the anatomical distribution of POMC mRNA-expressing neurons in the arcuate nucleus (AN) and to examine the effects of prolonged dehydration on POMC gene expression in a semi-desert rodent, Meriones shawi (Shaw's Jird). In the hypothalamus of control animals, POMC mRNA-expressing neurons were exclusively localized in the AN and they showed a differential distribution and density along its rostro-caudal subdivisions. In dehydrated animals, water deprivation caused a decrease in POMC mRNA labeling in the AN. These results suggest that dehydration stress can induce negative regulation of POMC gene expression in this species. A comparative study of weight variation between control and dehydrated animals showed a weight loss followed by stabilization of weight during prolonged dehydration.
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Majdic G, Tobet S. Cooperation of sex chromosomal genes and endocrine influences for hypothalamic sexual differentiation. Front Neuroendocrinol 2011; 32:137-45. [PMID: 21338619 PMCID: PMC3085655 DOI: 10.1016/j.yfrne.2011.02.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 02/11/2011] [Accepted: 02/15/2011] [Indexed: 02/04/2023]
Abstract
There is little debate that mammalian sexual differentiation starts from the perspective of two primary sexes that correspond to differential sex chromosomes (X versus Y) that lead to individuals with sex typical characteristics. Sex steroid hormones account for most aspects of brain sexual differentiation, however, a growing literature has raised important questions about the role of sex chromosomal genes separate from sex steroid actions. Several important model animals are being used to address these issues and, in particular, they are taking advantage of molecular genetic approaches using different mouse strains. The current review examines the cooperation of genetic and endocrine influences from the perspective of behavioral and morphological hypothalamic sexual differentiation, first in adults and then in development. In the final analysis, there is an ongoing need to account for the influence of hormones in the context of underlying genetic circumstances and null hormone conditions.
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Affiliation(s)
- Gregor Majdic
- Veterinary Faculty, University of Ljubljana, Ljubljana, Slovenia and Medical Faculty, University of Maribor, Maribor, Slovenia
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Flanagan-Cato LM. Sex differences in the neural circuit that mediates female sexual receptivity. Front Neuroendocrinol 2011; 32:124-36. [PMID: 21338620 PMCID: PMC3085563 DOI: 10.1016/j.yfrne.2011.02.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 02/05/2011] [Accepted: 02/14/2011] [Indexed: 01/28/2023]
Abstract
Female sexual behavior in rodents, typified by the lordosis posture, is hormone-dependent and sex-specific. Ovarian hormones control this behavior via receptors in the hypothalamic ventromedial nucleus (VMH). This review considers the sex differences in the morphology, neurochemistry and neural circuitry of the VMH to gain insights into the mechanisms that control lordosis. The VMH is larger in males compared with females, due to more synaptic connections. Another sex difference is the responsiveness to estradiol, with males exhibiting muted, and in some cases reverse, effects compared with females. The lack of lordosis in males may be explained by differences in synaptic organization or estrogen responsiveness, or both, in the VMH. However, given that damage to other brain regions unmasks lordosis behavior in males, a male-typical VMH is unlikely the main factor that prevents lordosis. In females, key questions remain regarding the mechanisms whereby ovarian hormones modulate VMH function to promote lordosis.
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Affiliation(s)
- Loretta M Flanagan-Cato
- Department of Psychology and Mahoney Institute of Neurological Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA.
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18
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Adewale HB, Todd KL, Mickens JA, Patisaul HB. The impact of neonatal bisphenol-A exposure on sexually dimorphic hypothalamic nuclei in the female rat. Neurotoxicology 2011; 32:38-49. [PMID: 20696184 PMCID: PMC3030630 DOI: 10.1016/j.neuro.2010.07.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 07/29/2010] [Accepted: 07/29/2010] [Indexed: 11/23/2022]
Abstract
Now under intense scrutiny, due to its endocrine disrupting properties, the potential threat the plastics component bisphenol-A (BPA) poses to human health remains unclear. Found in a multitude of polycarbonate plastics, food and beverage containers, and medical equipment, BPA is thought to bind to estrogen receptors (ERs), thereby interfering with estrogen-dependent processes. Our lab has previously shown that exposure to BPA (50mg/kg bw or 50μg/kg bw) during the neonatal critical period is associated with advancement of puberty, early reproductive senescence and ovarian malformations in female Long Evans rats. Here, using neural tissue obtained from the same animals, we explored the impact of neonatal BPA exposure on the development of sexually dimorphic hypothalamic regions critical for female reproductive physiology and behavior. Endpoints included quantification of oxytocin-immunoreactive neurons (OT-ir) in the paraventricular nucleus (PVN), serotonin (5-HT-ir) fiber density in the ventrolateral subdivision of the ventromedial nucleus (VMNvl) as well as ERα-ir neuron number in the medial preoptic area (MPOA), the VMNvl, and the arcuate nucleus (ARC). Both doses of BPA increased the number of OT-ir neurons within the PVN, but no significant effects were seen on 5-HT-ir fiber density or ERα-ir neuron number in any of the areas analyzed. In addition to hypothalamic development, we also assessed female sex behavior and body weight. No effect of BPA on sexual receptivity or proceptive behavior in females was observed. Females treated with BPA, however, weighed significantly more than control females by postnatal day 99. This effect of BPA on weight is critical because alterations in metabolism, are frequently associated with reproductive dysfunction. Collectively, the results of this and our prior study indicate that the impact of neonatal BPA exposure within the female rat hypothalamus is region specific and support the hypothesis that developmental BPA exposure may adversely affect reproductive development in females.
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Affiliation(s)
- Heather B Adewale
- Department of Biology, NC State University, Raleigh, NC 27695, United States
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Sá SI, Pereira PA, Paula-Barbosa MM, Madeira MD. Role of neural afferents as mediators of estrogen effects on the hypothalamic ventromedial nucleus. Brain Res 2010; 1366:60-70. [DOI: 10.1016/j.brainres.2010.10.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 10/13/2010] [Accepted: 10/13/2010] [Indexed: 01/20/2023]
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Clotfelter ED, McNitt MM, Carpenter RE, Summers CH. Modulation of monoamine neurotransmitters in fighting fish Betta splendens exposed to waterborne phytoestrogens. FISH PHYSIOLOGY AND BIOCHEMISTRY 2010; 36:933-943. [PMID: 20012186 DOI: 10.1007/s10695-009-9370-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2009] [Accepted: 11/29/2009] [Indexed: 05/28/2023]
Abstract
Endogenous estrogens are known to affect the activity of monoamine neurotransmitters in vertebrate animals, but the effects of exogenous estrogens on neurotransmitters are relatively poorly understood. We exposed sexually mature male fighting fish Betta splendens to environmentally relevant and pharmacological doses of three phytoestrogens that are potential endocrine disruptors in wild fish populations: genistein, equol, and β-sitosterol. We also exposed fish to two doses of the endogenous estrogen 17β-estradiol, which we selected as a positive control because phytoestrogens are putative estrogen mimics. Our results were variable, but the effects were generally modest. Genistein increased dopamine levels in the forebrains of B. splendens at both environmentally relevant and pharmacological doses. The environmentally relevant dose of equol increased dopamine levels in B. splendens forebrains, and the pharmacological dose decreased norepinephrine (forebrain), dopamine (hindbrain), and serotonin (forebrain) levels. The environmentally relevant dose of β-sitosterol decreased norepinephrine and dopamine in the forebrain and hindbrain, respectively. Our results suggest that sources of environmental phytoestrogens, such as runoff or effluent from agricultural fields, wood pulp mills, and sewage treatment plants, have the potential to modulate neurotransmitter activity in free-living fishes in a way that could interfere with normal behavioral processes.
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Sex and regional differences in decrease of serotonin-immunoreactive cells by parachlorophenylalanine in rat raphe nuclei. Neurosci Res 2010; 67:33-9. [PMID: 20144667 DOI: 10.1016/j.neures.2010.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Revised: 01/29/2010] [Accepted: 02/01/2010] [Indexed: 11/23/2022]
Abstract
To determine sex and regional differences in the properties of serotonin (5-HT) neurons of the raphe nuclei, the responsiveness to parachlorophenylalanine (PCPA) of 5-HT neurons in the dorsal and median raphe nuclei (DR and MR) and the nucleus raphe magnus (RMg) was analyzed by counting 5-HT-immunoreactive (5-HT-ir) cells. Gonadectomized male (OCX) and female (OVX) rats were treated with 100mg/kg b.wt PCPA or saline daily for 4 days. The brains were removed and fixed one day after the last injection. Frozen sections were stained with serotonin antibody and the numbers of 5-HT-ir cells in the raphe nuclei were counted. As a result, in female rats, the densities of 5-HT-ir cells in these 3 raphe nuclei were almost the same when compared the PCPA-treated and saline-treated groups. On the other hand, in male rats, the densities of 5-HT-ir cells in the DR and MR of PCPA-treated rats were lower than in saline-treated rats. In the male RMg, no difference was seen. These results suggest that responsiveness of 5-HT neurons to PCPA in the DR and MR, but not in the RMg, were sexually dimorphic.
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22
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Adewale HB, Jefferson WN, Newbold RR, Patisaul HB. Neonatal bisphenol-a exposure alters rat reproductive development and ovarian morphology without impairing activation of gonadotropin-releasing hormone neurons. Biol Reprod 2009; 81:690-9. [PMID: 19535786 DOI: 10.1095/biolreprod.109.078261] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Developmental exposure to endocrine-disrupting compounds is hypothesized to adversely affect female reproductive physiology by interfering with the organization of the hypothalamic-pituitary-gonadal axis. Here, we compared the effects of neonatal exposure to two environmentally relevant doses of the plastics component bisphenol-A (BPA; 50 microg/kg and 50 mg/kg) with the ESR1 (formerly known as ERalpha)-selective agonist 4,4',4''-(4-propyl-[(1)H]pyrazole-1,3,5-triyl)trisphenol (PPT; 1 mg/kg) on the development of the female rat hypothalamus and ovary. An oil vehicle and estradiol benzoate (EB; 25 microg) were used as negative and positive controls. Exposure to EB, PPT, or the low dose of BPA advanced pubertal onset. A total of 67% of females exposed to the high BPA dose were acyclic by 15 wk after vaginal opening compared with 14% of those exposed to the low BPA dose, all of the EB- and PPT-treated females, and none of the control animals. Ovaries from the EB-treated females were undersized and showed no evidence of folliculogenesis, whereas ovaries from the PPT-treated females were characterized by large antral-like follicles, which did not appear to support ovulation. Severity of deficits within the BPA-treated groups increased with dose and included large antral-like follicles and lower numbers of corpora lutea. Sexual receptivity, examined after ovariectomy and hormone replacement, was normal in all groups except those neonatally exposed to EB. FOS induction in hypothalamic gonadotropic (GnRH) neurons after hormone priming was impaired in the EB- and PPT-treated groups but neither of the BPA-treated groups. Our data suggest that BPA disrupts ovarian development but not the ability of GnRH neurons to respond to steroid-positive feedback.
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Affiliation(s)
- Heather B Adewale
- Department of Biology, North Carolina State University, Raleigh, North Carolina, USA
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23
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Patisaul HB, Todd KL, Mickens JA, Adewale HB. Impact of neonatal exposure to the ERalpha agonist PPT, bisphenol-A or phytoestrogens on hypothalamic kisspeptin fiber density in male and female rats. Neurotoxicology 2009; 30:350-7. [PMID: 19442818 DOI: 10.1016/j.neuro.2009.02.010] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 02/11/2009] [Accepted: 02/13/2009] [Indexed: 11/16/2022]
Abstract
Neonatal exposure to endocrine disrupting compounds (EDCs) can impair reproductive physiology, but the specific mechanisms by which this occurs remain largely unknown. Growing evidence suggests that kisspeptin (KISS) neurons play a significant role in the regulation of pubertal onset and ovulation, therefore disruption of KISS signaling could be a mechanism by which EDCs impair reproductive maturation and function. We have previously demonstrated that neonatal exposure to phytoestrogens decreases KISS fiber density in the anterior hypothalamus of female rats, an effect which was associated with early persistent estrus and the impaired activation gonadotropin releasing hormone (GnRH) neurons. The goals of the present study were to (1) determine if an ERalpha selective agonist (PPT) or bisphenol-A (BPA) could produce similar effects on hypothalamic KISS content in female rats and (2) to determine if male KISS fiber density was also vulnerable to disruption by EDCs. We first examined the effects of neonatal exposure to PPT, a low (50 microg/kg bw) BPA dose, and a high (50 mg/kg bw) BPA dose on KISS immunoreactivity (-ir) in the anterior ventral periventricular (AVPV) and arcuate (ARC) nuclei of adult female rats, using estradiol benzoate (EB) and a sesame oil vehicle as controls. AVPV KISS-ir, following ovariectomy (OVX) and hormone priming, was significantly lower in the EB and PPT groups but not the BPA groups. ARC KISS-ir levels were significantly diminished in the EB and high dose BPA groups, and there was a nonsignificant trend for lower KISS-ir in the PPT group. We next examined effects of neonatal exposure to a low (50 microg/kg bw) dose of BPA and the phytoestrogens genistein (GEN) and equol (EQ) on KISS-ir in the AVPV and ARC of adult male rats, using OVX females as an additional control group. None of the compounds affected KISS-ir in the male hypothalamus. Our results suggest that the organization of hypothalamic KISS fibers may be vulnerable to disruption by EDC exposure and that females might be more sensitive than males.
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Affiliation(s)
- Heather B Patisaul
- Department of Biology, North Carolina State University, 127 David Clark Labs, Raleigh, NC 27695, USA.
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Patisaul HB, Adewale HB, Mickens JA. Neonatal agonism of ERalpha masculinizes serotonergic (5-HT) projections to the female rat ventromedial nucleus of the hypothalamus (VMN) but does not impair lordosis. Behav Brain Res 2008; 196:317-22. [PMID: 18950659 DOI: 10.1016/j.bbr.2008.09.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 08/28/2008] [Accepted: 09/13/2008] [Indexed: 02/01/2023]
Abstract
Serotonin (5-HT) is known to play a role in the suppression of the lordosis response in males. We have previously shown that there is a sex difference in the density of 5-HT immunoreactive (5-HT-ir) fibers in the ventrolateral division of the adult ventromedial nucleus of the hypothalamus (VMNvl) and that neonatal administration of estradiol (E2) increases 5-HT-ir in the female VMNvl to male-typical levels. Here we demonstrate that postnatal administration of the ERalpha agonist 1,3,5-tris(4-Hydroxyphenyl)-4-propyl-1H-pyrazole (PPT), but not the ERbeta agonist diarylpropionitrile (DPN), also masculinizes 5-HT-ir in the female VMNvl, suggesting a mechanistic role for ERalpha in this process. Sexual receptivity, as ascertained by the lordosis quotient, was unaffected by either PPT or DPN treatment but nearly abolished by estradiol benzoate (EB), a synthetic estrogen with high affinity for both ERalpha and ERbeta. Collectively, these observations show that postnatal estrogens increase the density of 5-HT projections to the VMNvl via an ERalpha dependent mechanism, but that this increased inhibitory input is not sufficient to suppress the lordosis response.
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Affiliation(s)
- Heather B Patisaul
- Department of Biology, North Carolina State University, Raleigh, NC 27695, USA.
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Imbesi R, Castrogiovanni P. Embryonic and postnatal development in experimental tryptophan deprived rats. A preliminary study. J Mol Histol 2008; 39:487-98. [DOI: 10.1007/s10735-008-9188-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Accepted: 07/24/2008] [Indexed: 10/21/2022]
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Bateman HL, Patisaul HB. Disrupted female reproductive physiology following neonatal exposure to phytoestrogens or estrogen specific ligands is associated with decreased GnRH activation and kisspeptin fiber density in the hypothalamus. Neurotoxicology 2008; 29:988-97. [PMID: 18656497 DOI: 10.1016/j.neuro.2008.06.008] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Revised: 06/04/2008] [Accepted: 06/18/2008] [Indexed: 01/20/2023]
Abstract
It is well established that estrogen administration during neonatal development can advance pubertal onset and prevent the maintenance of regular estrous cycles in female rats. This treatment paradigm also eliminates the preovulatory rise of gonadotropin releasing hormone (GnRH). It remains unclear, however, through which of the two primary forms of the estrogen receptor (ERalpha or ERbeta) this effect is mediated. It is also unclear whether endocrine disrupting compounds (EDCs) can produce similar effects. Here we compared the effect of neonatal exposure to estradiol benzoate (EB), the ERalpha specific agonist 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT), the ERbeta specific agonist diarylpropionitrile (DPN) and the naturally occurring EDCs genistein (GEN) and equol (EQ) on pubertal onset, estrous cyclicity, GnRH activation, and kisspeptin content in the anteroventral periventricular (AVPV) and arcuate (ARC) nuclei. Vaginal opening was significantly advanced by EB and GEN. By 10 weeks post-puberty, irregular estrous cycles were observed in all groups except the control group. GnRH activation, as measured by the percentage of immunopositive GnRH neurons that were also immunopositive for Fos, was significantly lower in all treatment groups except the DPN group compared to the control group. GnRH activation was absent in the PPT group. These data suggest that neonatal exposure to EDCs can suppress GnRH activity in adulthood, and that ERalpha plays a pivotal role in this process. Kisspeptins (KISS) have recently been characterized to be potent stimulators of GnRH secretion. Therefore we quantified the density of KISS immunolabeled fibers in the AVPV and ARC. In the AVPV, KISS fiber density was significantly lower in the EB and GEN groups compared to the control group but only in the EB and PPT groups in the ARC. The data suggest that decreased stimulation of GnRH neurons by KISS could be a mechanism by which EDCs can impair female reproductive function.
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Affiliation(s)
- Heather L Bateman
- Department of Zoology, North Carolina State University, Raleigh, NC 27695, USA.
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