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Merchán M, Plaza I, Nieto J, Plaza J, Abecia JA, Palacios C. Densitometric analysis of GnRH and IBA1 immunocytochemistry in the basal ventromedial hypothalamus of the ewe. Theriogenology 2024; 227:112-119. [PMID: 39053287 DOI: 10.1016/j.theriogenology.2024.07.012] [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: 03/22/2024] [Revised: 06/29/2024] [Accepted: 07/15/2024] [Indexed: 07/27/2024]
Abstract
Gonadotropin releasing hormone (GnRH) synthesis and secretion regulates seasonal fertility. In the brain, the distribution of GnRH-positive neurons is diffuse, hindering efforts to monitor variations in its cellular and tissue levels. Here, we aim at assessing GnRH immunoreactivity in nuclei responsible for seasonal fertility regulation (SFR) within the posterior, anterior, and preoptic areas of the basal hypothalamus during estrous in ewes. We detected reaction products in the ventromedial basal hypothalamus in neurons, nerve fibers, non-neuronal immunoreactive bodies, and diffuse interstitial areas. Immunoreactivity correlated with the distribution of the main SFR nuclei in the arcuate, retrochiasmatic, periventricular, medial preoptic, supraoptic, and preoptic areas. By independent component analysis density segmentation and by interferential contrast, we identified GnRH non-neuronal positive bodies as microglial cells encapsulated within a dense halo of reaction products. These GnRH-positive microglial cells were distributed in patches and rows throughout the basal ventromedial hypothalamus, suggesting their role in paracrine or juxtacrine signaling. Moreover, as shown by ionized calcium-binding adaptor molecule 1 (IBA1) immunocytochemistry, the distribution of GnRH reaction products overlapped with the microglial dense reactive zones. Therefore, our findings support the assertion that a combined densitometric analysis of GnRH and IBA1 immunocytochemistry enables activity mapping for monitoring seasonal changes following experimental interventions.
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Affiliation(s)
- M Merchán
- Animal Production Area, Department of Construction and Agronomy, Faculty of Agricultural and Environmental Sciences, University of Salamanca, Avda. Filiberto Villalobos, 119, 37007, Salamanca, Spain
| | - I Plaza
- Auditory Neuroplasticity Laboratory, Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca. Salamanca. Calle del Pintor Fernando Gallego, 2, 37007, Spain
| | - J Nieto
- Animal Production Area, Department of Construction and Agronomy, Faculty of Agricultural and Environmental Sciences, University of Salamanca, Avda. Filiberto Villalobos, 119, 37007, Salamanca, Spain
| | - J Plaza
- Animal Production Area, Department of Construction and Agronomy, Faculty of Agricultural and Environmental Sciences, University of Salamanca, Avda. Filiberto Villalobos, 119, 37007, Salamanca, Spain
| | - J A Abecia
- IUCA. Departamento de Producción Animal y Ciencia de los Alimentos, Universidad de Zaragoza, Miguel Servet, 177, 50013, Zaragoza, Spain
| | - C Palacios
- Animal Production Area, Department of Construction and Agronomy, Faculty of Agricultural and Environmental Sciences, University of Salamanca, Avda. Filiberto Villalobos, 119, 37007, Salamanca, Spain.
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Merchán M, Coveñas R, Plaza I, Abecia JA, Palacios C. Anatomy of hypothalamic and diencephalic nuclei involved in seasonal fertility regulation in ewes. Front Vet Sci 2023; 10:1101024. [PMID: 36876003 PMCID: PMC9978410 DOI: 10.3389/fvets.2023.1101024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/31/2023] [Indexed: 02/18/2023] Open
Abstract
In this study, we describe in detail the anatomy of nuclei involved in seasonal fertility regulation (SFR) in ewes. For this purpose, the intergeniculate leaflet of the visual thalamus, the caudal hypothalamic arcuate nucleus, and suprachiasmatic, paraventricular and supraoptic nuclei of the rostral hypothalamus were morphometrically and qualitatively analyzed in Nissl-stained serial sections, in the three anatomical planes. In addition, data were collected on calcium-binding proteins and cell phenotypes after immunostaining alternate serial sections for calretinin, parvalbumin and calbindin. For a complete neuroanatomical study, glial architecture was assessed by immunostaining and analyzing alternate sections for glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (IBA1). The results showed a strong microglial and astroglia reaction around the hypothalamic nuclei of interest and around the whole 3rd ventricle of the ewe brain. Moreover, we correlated cytoarchitectonic coordinates of panoramic serial sections with their macroscopic localization and extension in midline sagittal-sectioned whole brain to provide guidelines for microdissecting nuclei involved in SFR.
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Affiliation(s)
- Miguel Merchán
- Animal Production Area, Department of Construction and Agronomy, Faculty of Agricultural and Environmental Sciences, University of Salamanca, Salamanca, Spain.,Laboratory of Neuroanatomy of the Peptidergic Systems, Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain.,Recognized Research Group - Molecular Bases of Development (Grupo de Investigación Reconocido - Bases Moleculares del Desarrollo - GIR-BMD), University of Salamanca, Salamanca, Spain
| | - Rafael Coveñas
- Laboratory of Neuroanatomy of the Peptidergic Systems, Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain.,Recognized Research Group - Molecular Bases of Development (Grupo de Investigación Reconocido - Bases Moleculares del Desarrollo - GIR-BMD), University of Salamanca, Salamanca, Spain
| | - Ignacio Plaza
- Auditory Neuroplasticity Laboratory, Institute for Neuroscience of Castilla y León (INCYL), University of Salamanca, Salamanca, Spain
| | - José Alfonso Abecia
- Environmental Science Institute (IUCA), University of Zaragoza, Zaragoza, Spain
| | - Carlos Palacios
- Animal Production Area, Department of Construction and Agronomy, Faculty of Agricultural and Environmental Sciences, University of Salamanca, Salamanca, Spain
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Mariani MM, Mojziszek K, Curley E, Thornton JE. Lowering luteinizing hormone (LH) reverses spatial memory deficits associated with neurotoxin infusion into the hippocampus of ovx rats. Horm Behav 2020; 119:104631. [PMID: 31759942 DOI: 10.1016/j.yhbeh.2019.104631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 10/24/2019] [Accepted: 10/28/2019] [Indexed: 01/14/2023]
Affiliation(s)
- Monica M Mariani
- Neuroscience Department, Oberlin College, 119 Woodland Street, Oberlin, OH 44074, USA.
| | - Kirsten Mojziszek
- Neuroscience Department, Oberlin College, 119 Woodland Street, Oberlin, OH 44074, USA
| | - Emily Curley
- Neuroscience Department, Oberlin College, 119 Woodland Street, Oberlin, OH 44074, USA
| | - Janice E Thornton
- Neuroscience Department, Oberlin College, 119 Woodland Street, Oberlin, OH 44074, USA
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Barabás K, Szabó-Meleg E, Ábrahám IM. Effect of Inflammation on Female Gonadotropin-Releasing Hormone (GnRH) Neurons: Mechanisms and Consequences. Int J Mol Sci 2020; 21:ijms21020529. [PMID: 31947687 PMCID: PMC7014424 DOI: 10.3390/ijms21020529] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 02/06/2023] Open
Abstract
: Inflammation has a well-known suppressive effect on fertility. The function of gonadotropin-releasing hormone (GnRH) neurons, the central regulator of fertility is substantially altered during inflammation in females. In our review we discuss the latest results on how the function of GnRH neurons is modified by inflammation in females. We first address the various effects of inflammation on GnRH neurons and their functional consequences. Second, we survey the possible mechanisms underlying the inflammation-induced actions on GnRH neurons. The role of several factors will be discerned in transmitting inflammatory signals to the GnRH neurons: cytokines, kisspeptin, RFamide-related peptides, estradiol and the anti-inflammatory cholinergic pathway. Since aging and obesity are both characterized by reproductive decline our review also focuses on the mechanisms and pathophysiological consequences of the impact of inflammation on GnRH neurons in aging and obesity.
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Affiliation(s)
- Klaudia Barabás
- Molecular Neuroendocrinology Research Group, Institute of Physiology, Medical School, Centre for Neuroscience, Szentágothai Research Institute, University of Pécs, H-7624 Pécs, Hungary;
| | - Edina Szabó-Meleg
- Departement of Biophysics, Medical School, University of Pécs, H-7624 Pécs, Hungary;
| | - István M. Ábrahám
- Molecular Neuroendocrinology Research Group, Institute of Physiology, Medical School, Centre for Neuroscience, Szentágothai Research Institute, University of Pécs, H-7624 Pécs, Hungary;
- Correspondence:
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Fujioka H, Funabashi T, Akema T. Prostaglandin E2 modulates presynaptic regulation of GnRH neurons via EP4 receptors in accordance with estrogen milieu. Neuroscience 2017; 360:139-145. [PMID: 28736136 DOI: 10.1016/j.neuroscience.2017.07.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 07/11/2017] [Accepted: 07/12/2017] [Indexed: 01/15/2023]
Abstract
Prostaglandin E2 (PGE2) promotes gonadotropin secretion by regulating the activity of neurons that release gonadotropin-releasing hormone (GnRH) in the hypothalamus. However, the mechanisms of action of PGE2 at these neurons have yet to be fully explored. We examined the effects of PGE2 on the generation of miniature excitatory postsynaptic currents (mEPSCs) at GnRH neurons as measured by whole-cell, patch-clamp recordings. GnRH neurons were identified in slices prepared from the preoptic areas of female GnRH-EGFP rats. Exposure to PGE2 significantly increased the frequency, but not the amplitude, of the mEPSCs generated on the day of proestrus, but neither frequency nor amplitude was altered on day 1 of diestrus. These data suggest that the action of PGE2 on mEPSC frequency varies depending on the stage of estrous. An estrogen-dependence of PGE2's action was further supported by the increased frequency, but not amplitude, of mEPSCs generated at GnRH neurons prepared from estrogen-primed ovariectomized rats. Conversely, PGE2 had no effect on mEPSC frequency or amplitude at GnRH neurons in cholesterol-treated rats. Subsequent experiments to identify candidate receptors for PG2E's action revealed that exposure to a PGE2 receptor 4 (EP4) agonist, but not EP1 or EP2 agonists, mimicked the effects achieved by PGE2 exposure. These effects of mEPSCs could be reversed using an EP4 antagonist, illustrating the specificity of the effect. Collectively, these data demonstrate that PGE2 can alter excitatory synaptic neurotransmission at GnRH neurons via EP4 signaling at presynaptic site(s) in an estrogen-dependent fashion during proestrus.
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Affiliation(s)
- Hitomi Fujioka
- Department of Physiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 226-8511, Japan.
| | - Toshiya Funabashi
- Department of Physiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 226-8511, Japan
| | - Tatsuo Akema
- Department of Physiology, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 226-8511, Japan
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Vastagh C, Rodolosse A, Solymosi N, Farkas I, Auer H, Sárvári M, Liposits Z. Differential Gene Expression in Gonadotropin-Releasing Hormone Neurons of Male and Metestrous Female Mice. Neuroendocrinology 2015; 102:44-59. [PMID: 25925152 DOI: 10.1159/000430818] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/20/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Gonadotropin-releasing hormone (GnRH) neurons play a pivotal role in the regulation of the hypothalamic-pituitary gonadal axis in a sex-specific manner. We hypothesized that the differences seen in reproductive functions of males and females are associated with a sexually dimorphic gene expression profile of GnRH neurons. METHODS AND RESULTS We compared the transcriptome of GnRH neurons obtained from intact metestrous female and male GnRH-green fluorescent protein transgenic mice. About 1,500 individual GnRH neurons from each sex were sampled with laser capture microdissection followed by whole-transcriptome amplification for gene expression profiling. Under stringent selection criteria (fold change >1.6, adjusted p value 0.01), Affymetrix Mouse Genome 430 PM array analysis identified 543 differentially expressed genes. Sexual dimorphism was most apparent in gene clusters associated with synaptic communication, signal transduction, cell adhesion, vesicular transport and cell metabolism. To validate microarray results, 57 genes were selected, and 91% of their differential expression was confirmed by real-time PCR. Similarly, 88% of microarray results were confirmed with PCR from independent samples obtained by patch pipette harvesting and pooling of 30 GnRH neurons from each sex. We found significant differences in the expression of genes involved in vesicle priming and docking (Syt1, Cplx1), GABAergic (Gabra3, Gabrb3, Gabrg2) and glutamatergic (Gria1, Grin1, Slc17a6) neurotransmission, peptide signaling (Sstr3, Npr2, Cxcr4) and the regulation of intracellular ion homeostasis (Cacna1, Cacnb1, Cacng5, Kcnq2, Kcnc1). CONCLUSION The striking sexual dimorphism of the GnRH neuron transcriptome we report here contributes to a better understanding of the differences in cellular mechanisms of GnRH neurons in the two sexes.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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Fujioka H, Kakehashi C, Funabashi T, Akema T. Immunohistochemical evidence for the relationship between microglia and GnRH neurons in the preoptic area of ovariectomized rats with and without steroid replacement. Endocr J 2013; 60:191-6. [PMID: 23090753 DOI: 10.1507/endocrj.ej12-0280] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Prostaglandins (PGs), whose synthesis is catalyzed by the rate-limiting enzyme cyclooxygenase (COX) including COX-1 and COX-2, are among the important mediators involved in the regulation of gonadotropin-releasing hormone (GnRH) secretion. However, the cellular origin of PGs remains obscure in terms of its relationship to GnRH neurons. The present study was therefore aimed to clarify the anatomical relationship between COX-1-producing microglia and GnRH neurons in the preoptic area (POA), and to examine possible influence of ovarian steroids. We performed a triple labeled immunofluorescent histochemistry of COX-1, CD11b (a specific marker for microglia) and GnRH in the POA of ovarian steroid-primed and non-primed ovariectomized rats. The result confirmed our previous study suggesting COX-1 immunoreactivity in the vicinity of, but not within, GnRH neurons in the POA. COX-1 around GnRH cells was entirely (100%) localized in cells containing CD11b regardless of steroid replacement in ovariectomized rats. These CD11b-immunoreactive cells had small cell bodies and highly branched fibers characteristic of ramified microglia. Three-dimensional reconstruction of confocal images revealed close proximity of some COX-1-containing microglia and GnRH neurons. These results showed selective and constitutive expression of COX-1 in ramified microglia in the vicinity of GnRH neurons, providing evidence for intercellular communication, mediated by PGs, from microglia to GnRH cells.
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Affiliation(s)
- Hitomi Fujioka
- Department of Physiology, St. Marianna University School of Medicine, Kawasaki 216-8511, Japan
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Lenz KM, Nugent BM, McCarthy MM. Sexual differentiation of the rodent brain: dogma and beyond. Front Neurosci 2012; 6:26. [PMID: 22363256 PMCID: PMC3282918 DOI: 10.3389/fnins.2012.00026] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 02/04/2012] [Indexed: 11/20/2022] Open
Abstract
Steroid hormones of gonadal origin act on the neonatal brain to produce sex differences that underlie adult reproductive physiology and behavior. Neuronal sex differences occur on a variety of levels, including differences in regional volume and/or cell number, morphology, physiology, molecular signaling, and gene expression. In the rodent, many of these sex differences are determined by steroid hormones, particularly estradiol, and are established by diverse downstream effects. One brain region that is potently organized by estradiol is the preoptic area (POA), a region critically involved in many behaviors that show sex differences, including copulatory and maternal behaviors. This review focuses on the POA as a case study exemplifying the depth and breadth of our knowledge as well as the gaps in understanding the mechanisms through which gonadal hormones produce lasting neural and behavioral sex differences. In the POA, multiple cell types, including neurons, astrocytes, and microglia are masculinized by estradiol. Multiple downstream molecular mediators are involved, including prostaglandins, various glutamate receptors, protein kinase A, and several immune signaling molecules. Moreover, emerging evidence indicates epigenetic mechanisms maintain sex differences in the POA that are organized perinatally and thereby produce permanent behavioral changes. We also review emerging strategies to better elucidate the mechanisms through which genetics and epigenetics contribute to brain and behavioral sex differences.
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Affiliation(s)
- Kathryn M Lenz
- Program in Neuroscience and Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
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