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Murakami S, Ohki-Hamazaki H, Uchiyama Y. Somatostatin affects GnRH neuronal development and migration and stimulates olfactory-related fiber fasciculation. Dev Neurobiol 2024; 84:3-17. [PMID: 38072668 DOI: 10.1002/dneu.22931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 11/10/2023] [Accepted: 11/23/2023] [Indexed: 01/19/2024]
Abstract
Transient expression of somatostatin (SST) has been observed in the olfactory epithelium (OE) and nerves of chick embryos. Intense expression of SST in these regions on embryonic days (E) 5-8 coincides with the migration of neurons producing gonadotropin-releasing hormone (GnRH) from the OE to the forebrain (FB), suggesting that SST plays a role in the development of GnRH neurons. Using in ovo electroporation of small interfering RNA, we found that the suppression of SST mRNA in the olfactory placode (OP) of E3.5 chick embryos significantly reduced the number of GnRH and Islet-1-immunoreactive neurons in the nasal region without affecting the entry of GnRH neurons into the FB at E5.5-6. SST knockdown did not lead to changes in the number of apoptotic, proliferating, or HuC/D-positive neuronal cells in the OE; therefore, it is possible that SST is involved in the neurogenesis/differentiation of GnRH neurons and OP-derived GnRH-negative migratory neurons. In whole OP explant cultures, we also found that SST or its analog octreotide treatment significantly increased the number of migratory GnRH neurons and the migratory distance from the explants. The co-application of an SST antagonist blocked the octreotide-induced increase in the number of GnRH neurons. Furthermore, the fasciculation of polysialylated neural cell adhesion molecule-immunoreactive fibers emerging from the explants was dependent on octreotide. Taken together, our results provide evidence that SST exerts facilitatory effects on the development of neurons expressing GnRH or Islet-1 and on GnRH neuronal migration, in addition to olfactory-related fiber fasciculation.
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Affiliation(s)
- Shizuko Murakami
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Hiroko Ohki-Hamazaki
- College of Liberal Arts and Sciences, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Yasuo Uchiyama
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Tokyo, Japan
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2
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Murakami S, Ohki‐Hamazaki H, Uchiyama Y. Olfactory placode generates a diverse population of neurons expressing GnRH, somatostatin mRNA, neuropeptide Y, or calbindin in the chick forebrain. J Comp Neurol 2022; 530:2977-2993. [PMID: 35844047 PMCID: PMC9796302 DOI: 10.1002/cne.25389] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 06/28/2022] [Accepted: 06/30/2022] [Indexed: 01/01/2023]
Abstract
The olfactory placode (OP) of vertebrates generates several classes of migrating cells, including hypothalamic gonadotropin-releasing hormone (GnRH)-producing neurons, which play essential roles in the reproduction system. Previous studies using OP cell labeling have demonstrated that OP-derived non-GnRH cells enter the developing forebrain; however, their final fates and phenotypes are less well understood. In chick embryos, a subpopulation of migratory cells from the OP that is distinct from GnRH neurons transiently expresses somatostatin (SS). We postulated that these cells are destined to develop into brain neurons. In this study, we examined the expression pattern of SS mRNA in the olfactory-forebrain region during development, as well as the destination of OP-derived migratory cells, including SS mRNA-expressing cells. Utilizing the Tol2 genomic integration system to induce long-term fluorescent protein expression in OP cells, we found that OP-derived migratory cells labeled at embryonic day (E) 3 resided in the olfactory nerve and medial forebrain at E17-19. A subpopulation of green fluorescent protein (GFP)-labeled GnRH neurons that remained in the olfactory nerve was considered to comprise terminal nerve neurons. In the forebrain, GFP-labeled cells showed a distribution pattern similar to that of GnRH neurons. A large proportion of GFP-labeled cells expressed the mature neuronal marker NeuN. Among the GFP-labeled cells, the percentage of GnRH neurons was low, while the remaining GnRH-negative neurons either expressed SS mRNA, neuropeptide Y, or calbindin D-28k or did not express any of them. These results indicate that a diverse population of OP-derived neuronal cells, other than GnRH neurons, integrates into the chick medial forebrain.
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Affiliation(s)
- Shizuko Murakami
- Department of Cellular and Molecular NeuropathologyJuntendo University Graduate School of MedicineTokyoJapan
| | | | - Yasuo Uchiyama
- Department of Cellular and Molecular NeuropathologyJuntendo University Graduate School of MedicineTokyoJapan
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Campbell RE, Coolen LM, Hoffman GE, Hrabovszky E. Highlights of neuroanatomical discoveries of the mammalian gonadotropin-releasing hormone system. J Neuroendocrinol 2022; 34:e13115. [PMID: 35502534 PMCID: PMC9232911 DOI: 10.1111/jne.13115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/09/2022] [Accepted: 03/01/2022] [Indexed: 11/17/2022]
Abstract
The anatomy and morphology of gonadotropin-releasing hormone (GnRH) neurons makes them both a joy and a challenge to investigate. They are a highly unique population of neurons given their developmental migration into the brain from the olfactory placode, their relatively small number, their largely scattered distribution within the rostral forebrain, and, in some species, their highly varied individual anatomical characteristics. These unique features have posed technological hurdles to overcome and promoted fertile ground for the establishment and use of creative approaches. Historical and more contemporary discoveries defining GnRH neuron anatomy remain critical in shaping and challenging our views of GnRH neuron function in the regulation of reproductive function. We begin this review with a historical overview of anatomical discoveries and developing methodologies that have shaped our understanding of the reproductive axis. We then highlight significant discoveries across specific groups of mammalian species to address some of the important comparative aspects of GnRH neuroanatomy. Lastly, we touch on unresolved questions and opportunities for future neuroanatomical research on this fascinating and important population of neurons.
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Affiliation(s)
- Rebecca E. Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinNew Zealand
| | - Lique M. Coolen
- Department of Biological SciencesKent State UniversityKentOhioUSA
| | | | - Erik Hrabovszky
- Laboratory of Reproductive NeurobiologyInstitute of Experimental MedicineBudapestHungary
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4
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Duittoz AH, Forni PE, Giacobini P, Golan M, Mollard P, Negrón AL, Radovick S, Wray S. Development of the gonadotropin-releasing hormone system. J Neuroendocrinol 2022; 34:e13087. [PMID: 35067985 PMCID: PMC9286803 DOI: 10.1111/jne.13087] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 12/02/2021] [Accepted: 12/22/2021] [Indexed: 11/29/2022]
Abstract
This review summarizes the current understanding of the development of the neuroendocrine gonadotropin-releasing hormone (GnRH) system, including discussion on open questions regarding (1) transcriptional regulation of the Gnrh1 gene; (2) prenatal development of the GnRH1 system in rodents and humans; and (3) paracrine and synaptic communication during migration of the GnRH cells.
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Affiliation(s)
| | - Paolo E. Forni
- Department of Biological SciencesUniversity at AlbanyAlbanyNYUSA
- The RNA InstituteUniversity at AlbanyAlbanyNYUSA
| | - Paolo Giacobini
- Laboratory of Development and Plasticity of the Postnatal BrainLille Neuroscience & Cognition, UMR‐S1172, Inserm, CHU LilleUniversity of LilleLilleFrance
| | - Matan Golan
- Institute of Animal SciencesAgricultural Research Organization – Volcani CenterRishon LetziyonIsrael
| | - Patrice Mollard
- Institute of Functional GenomicsCNRS, InsermMontpellier UniversityMontpellierFrance
| | - Ariel L. Negrón
- Clinical and Translational ResearchRutgers Robert Wood Johnson Medical SchoolNew BrunswickNJUSA
| | - Sally Radovick
- Clinical and Translational ResearchRutgers Robert Wood Johnson Medical SchoolNew BrunswickNJUSA
| | - Susan Wray
- Cellular and Developmental Neurobiology SectionNational Institute of Neurological Disorders and Stroke/National Institutes of HealthBethesdaMDUSA
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5
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Ogawa S, Parhar IS. Heterogeneity in GnRH and kisspeptin neurons and their significance in vertebrate reproductive biology. Front Neuroendocrinol 2022; 64:100963. [PMID: 34798082 DOI: 10.1016/j.yfrne.2021.100963] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/11/2021] [Accepted: 10/31/2021] [Indexed: 02/07/2023]
Abstract
Vertebrate reproduction is essentially controlled by the hypothalamus-pituitary-gonadal (HPG) axis, which is a central dogma of reproductive biology. Two major hypothalamic neuroendocrine cell groups containing gonadotropin-releasing hormone (GnRH) and kisspeptin are crucial for control of the HPG axis in vertebrates. GnRH and kisspeptin neurons exhibit high levels of heterogeneity including their cellular morphology, biochemistry, neurophysiology and functions. However, the molecular foundation underlying heterogeneities in GnRH and kisspeptin neurons remains unknown. More importantly, the biological and physiological significance of their heterogeneity in reproductive biology is poorly understood. In this review, we first describe the recent advances in the neuroendocrine functions of kisspeptin-GnRH pathways. We then view the recent emerging progress in the heterogeneity of GnRH and kisspeptin neurons using morphological and single-cell transcriptomic analyses. Finally, we discuss our views on the significance of functional heterogeneity of reproductive endocrine cells and their potential relevance to reproductive health.
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Affiliation(s)
- Satoshi Ogawa
- Brain Research Institute, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia
| | - Ishwar S Parhar
- Brain Research Institute, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia.
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Keen KL, Petersen AJ, Figueroa AG, Fordyce BI, Shin J, Yadav R, Erdin S, Pearce RA, Talkowski ME, Bhattacharyya A, Terasawa E. Physiological Characterization and Transcriptomic Properties of GnRH Neurons Derived From Human Stem Cells. Endocrinology 2021; 162:6298609. [PMID: 34125902 PMCID: PMC8294693 DOI: 10.1210/endocr/bqab120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Indexed: 12/23/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus play a key role in the regulation of reproductive function. In this study, we sought an efficient method for generating GnRH neurons from human embryonic and induced pluripotent stem cells (hESC and hiPSC, respectively). First, we found that exposure of primitive neuroepithelial cells, rather than neuroprogenitor cells, to fibroblast growth factor 8 (FGF8), was more effective in generating GnRH neurons. Second, addition of kisspeptin to FGF8 further increased the efficiency rates of GnRH neurogeneration. Third, we generated a fluorescent marker mCherry labeled human embryonic GnRH cell line (mCh-hESC) using a CRISPR-Cas9 targeting approach. Fourth, we examined physiological characteristics of GnRH (mCh-hESC) neurons: similar to GnRH neurons in vivo, they released the GnRH peptide in a pulsatile manner at ~60 min intervals; GnRH release increased in response to high potassium, kisspeptin, estradiol, and neurokinin B challenges; and injection of depolarizing current induced action potentials. Finally, we characterized developmental changes in transcriptomes of GnRH neurons using hESC, hiPSC, and mCh-hESC. The developmental pattern of transcriptomes was remarkably similar among the 3 cell lines. Collectively, human stem cell-derived GnRH neurons will be an important tool for establishing disease models to understand diseases, such as idiopathic hypothalamic hypogonadism, and testing contraceptive drugs.
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Affiliation(s)
- Kim L Keen
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI, USA
| | - Andrew J Petersen
- Waisman Center, Graduate School, University of Wisconsin, Madison, WI, USA
| | - Alexander G Figueroa
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Benjamin I Fordyce
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI, USA
| | - Jaeweon Shin
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Rachita Yadav
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA, USA
| | - Serkan Erdin
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA, USA
| | - Robert A Pearce
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Michael E Talkowski
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA, USA
| | - Anita Bhattacharyya
- Waisman Center, Graduate School, University of Wisconsin, Madison, WI, USA
- Department of Cell and Regenerative Medicine, University of Wisconsin, Madison, WI, USA
| | - Ei Terasawa
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI, USA
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- Correspondence: Ei Terasawa, PhD, Wisconsin National Primate Research Center, University of Wisconsin, 1223 Capitol Court, Madison, WI 53715-1299, USA.
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7
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Katreddi RR, Forni PE. Mechanisms underlying pre- and postnatal development of the vomeronasal organ. Cell Mol Life Sci 2021; 78:5069-5082. [PMID: 33871676 PMCID: PMC8254721 DOI: 10.1007/s00018-021-03829-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/17/2021] [Accepted: 03/29/2021] [Indexed: 02/06/2023]
Abstract
The vomeronasal organ (VNO) is sensory organ located in the ventral region of the nasal cavity in rodents. The VNO develops from the olfactory placode during the secondary invagination of olfactory pit. The embryonic vomeronasal structure appears as a neurogenic area where migratory neuronal populations like endocrine gonadotropin-releasing hormone-1 (GnRH-1) neurons form. Even though embryonic vomeronasal structures are conserved across most vertebrate species, many species including humans do not have a functional VNO after birth. The vomeronasal epithelium (VNE) of rodents is composed of two major types of vomeronasal sensory neurons (VSNs): (1) VSNs distributed in the apical VNE regions that express vomeronasal type-1 receptors (V1Rs) and the G protein subunit Gαi2, and (2) VSNs in the basal territories of the VNE that express vomeronasal type-2 receptors (V2Rs) and the G subunit Gαo. Recent studies identified a third subclass of Gαi2 and Gαo VSNs that express the formyl peptide receptor family. VSNs expressing V1Rs or V2Rs send their axons to distinct regions of the accessory olfactory bulb (AOB). Together, VNO and AOB form the accessory olfactory system (AOS), an olfactory subsystem that coordinates the social and sexual behaviors of many vertebrate species. In this review, we summarize our current understanding of cellular and molecular mechanisms that underlie VNO development. We also discuss open questions for study, which we suggest will further enhance our understanding of VNO morphogenesis at embryonic and postnatal stages.
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Affiliation(s)
- Raghu Ram Katreddi
- Department of Biological Sciences, Center for Neuroscience Research, The RNA Institute, University At Albany, State University of New York, Albany, NY, USA
| | - Paolo E Forni
- Department of Biological Sciences, Center for Neuroscience Research, The RNA Institute, University At Albany, State University of New York, Albany, NY, USA.
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8
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Luo G, Hou M, Wang B, Liu Z, Liu W, Han T, Zhang D, Zhou X, Jia W, Tan Y, Wu Y, Wang J, Zhang X. Tsga10 is essential for arrangement of mitochondrial sheath and male fertility in mice. Andrology 2021; 9:368-375. [PMID: 32790169 DOI: 10.1111/andr.12889] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 07/31/2020] [Accepted: 08/10/2020] [Indexed: 01/06/2023]
Abstract
BACKGROUND Male infertility is a major issue in human reproduction health, yet known genetic factors are only responsible for a small fraction of cases. TSGA10 is a testis-specific protein that is highly conserved among different species. A previous study has reported a homozygous mutation in TSGA10 in a male infertile patient; however, function analysis of Tsga10 genes in knockout mice has not yet been undertaken. OBJECTIVES The aim of the present work was to analyse the function of TSGA10 protein in the spermatogenesis of Tsga10+/- mice. MATERIALS AND METHODS Tsga10+/- mice were generated by CRISPR/Cas9 technology, in vitro fertilization (IVF), western blot, co-immunoprecipitation and other methods were used to the function analysis. RESULTS Heterozygous Tsga10 male mice created by CRISPR/Cas9 were infertile and presented significantly reduced sperm motility because of disordered mitochondrial sheath formation. Furthermore, TSGA10 can interact with GRP78 and NSUN2, which are associated with peri-implantation lethality and the gonadotropin-releasing hormone (GnRH) network. DISCUSSION AND CONCLUSION We demonstrate that deficiency of Tsga10 gene can lead to male infertility in mice. TSGA10 is involved in the correct arrangement of mitochondrial sheath in spermatozoa. Future studies on TSGA10 include an in-depth exploration of the underlying mechanisms of TSGA10 in spermatogenesis, early embryonic development and GnRH network.
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Affiliation(s)
- Geng Luo
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Meiqi Hou
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Bo Wang
- Department of Clinical Laboratory, Maternal and Child Health Hospital of Hubei Province, Wuhan, China
| | - Zhenxing Liu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Wenqiang Liu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Tiantian Han
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Dazhi Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaopei Zhou
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Weimin Jia
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Yang Tan
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Yanling Wu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Jiarui Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
| | - Xianqin Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan, China
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9
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Palaniappan TK, Slekiene L, Gunhaga L, Patthey C. Extensive apoptosis during the formation of the terminal nerve ganglion by olfactory placode-derived cells with distinct molecular markers. Differentiation 2019; 110:8-16. [PMID: 31539705 DOI: 10.1016/j.diff.2019.09.003] [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: 04/24/2019] [Revised: 08/30/2019] [Accepted: 09/02/2019] [Indexed: 12/20/2022]
Abstract
The terminal nerve ganglion (TNG) is a well-known structure of the peripheral nervous system in cartilaginous and teleost fishes. It derives from the olfactory placode during embryonic development. While the differentiation and migration of gonadotropin releasing hormone (GnRH)-expressing neurons from the olfactory placode has been well documented, the TNG has been neglected in birds and mammals, and its development is less well described. Here we describe the formation of a ganglion-like structure from migratory olfactory placodal cells in chicken. The TNG is surrounded by neural crest cells, but in contrast to other cranial sensory ganglia, we observed no neural crest corridor, and olfactory unsheathing cells appear only after the onset of neuronal migration. We identified Isl1 and Lhx2 as two transcription factors that label neuronal subpopulations in the forming TNG, distinct from GnRH1+ cells, thereby revealing a diversity of cell types during the formation of the TNG. We also provide evidence for extensive apoptosis in the terminal nerve ganglion shortly after its formation, but not in other cranial sensory ganglia. Moreover, at later stages placode-derived neurons expressing GnRH1, Isl1 and/or Lhx2 become incorporated in the telencephalon. The integration of TNG neurons into the telencephalon together with the earlier widespread apoptosis in the TNG might be an explanation why the TNG in mammals and birds is much smaller compared to other vertebrates.
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Affiliation(s)
| | - Lina Slekiene
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden
| | - Cedric Patthey
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden.
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Cho HJ, Shan Y, Whittington NC, Wray S. Nasal Placode Development, GnRH Neuronal Migration and Kallmann Syndrome. Front Cell Dev Biol 2019; 7:121. [PMID: 31355196 PMCID: PMC6637222 DOI: 10.3389/fcell.2019.00121] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/14/2019] [Indexed: 12/22/2022] Open
Abstract
The development of Gonadotropin releasing hormone-1 (GnRH) neurons is important for a functional reproduction system in vertebrates. Disruption of GnRH results in hypogonadism and if accompanied by anosmia is termed Kallmann Syndrome (KS). From their origin in the nasal placode, GnRH neurons migrate along the olfactory-derived vomeronasal axons to the nasal forebrain junction and then turn caudally into the developing forebrain. Although research on the origin of GnRH neurons, their migration and genes associated with KS has identified multiple factors that influence development of this system, several aspects still remain unclear. This review discusses development of the olfactory system, factors that regulate GnRH neuron formation and development of the olfactory system, migration of the GnRH neurons from the nose into the brain, and mutations in humans with KS that result from disruption of normal GnRH/olfactory systems development.
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Affiliation(s)
- Hyun-Ju Cho
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Yufei Shan
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Niteace C Whittington
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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11
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Song Y, Tao B, Chen J, Jia S, Zhu Z, Trudeau VL, Hu W. GABAergic Neurons and Their Modulatory Effects on GnRH3 in Zebrafish. Endocrinology 2017; 158:874-886. [PMID: 28324056 DOI: 10.1210/en.2016-1776] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/17/2017] [Indexed: 01/11/2023]
Abstract
γ-Aminobutyric acid (GABA) is a major amino acid neurotransmitter in the vertebrate brain. To provide detailed information on the distribution of the GABA in zebrafish (Danio rerio), neurons were labeled with mCherry driven by the glutamic acid decarboxylase 67 (gad67) promoter. In the transgenic line Tg(gad67:mCherry), mCherry-positive gad67 cell bodies were predominantly localized to the olfactory bulb, pallial zones, subpallium zones, parvocellular preoptic nucleus, periventricular gray zone of optic tectum, torus semicircularis, posterior tuberculum, medial longitudinal fascicle, caudal zone of periventricular hypothalamus, and oculomotor nucleus. mCherry-positive fibers were widely distributed in the olfactory bulbs, subpallium, thalamus, ventral hypothalamic zone, tectum opticum, mesencephalon, and rhombencephalon. mCherry-positive neurons were also observed in the retina and the spinal cord. The anatomical relationships between GABAergic and gonadotrophin-releasing hormone 3 (GnRH3) neurons were investigated by crossing Tg(gad67:mCherry) fish with the previously established Tg(gnrh3:EGFP) transgenic line. GnRH3 cell bodies and fibers were contacted by GABAergic fibers directly in the ventral telencephalon and anterior tuberal nucleus. A subpopulation of GnRH3 neurons in the ventral telencephalic area was also labeled with mCherry, so some GnRH3 neurons are also GABAergic. GABAB receptor agonist (baclofen) and antagonist (CGP55845) treatments indicated that GABAB receptor signaling inhibited gnrh3 expression in larval fish but was stimulatory in adult fish. The expression of pituitary lhβ and fshβ was stimulated by intraperitoneal injection of baclofen in adult fish. We conclude that GABA via GABAB receptors regulates GnRH3 neurons in a developmentally dependent manner in zebrafish.
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Affiliation(s)
- Yanlong Song
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Binbin Tao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Ji Chen
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Shaoting Jia
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Zuoyan Zhu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | | | - Wei Hu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
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12
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Zhu J, Xu XH, Knight GE, He C, Burnstock G, Xiang Z. A subpopulation of gonadotropin-releasing hormone neurons in the adult mouse forebrain is γ-Aminobutyric acidergic. J Neurosci Res 2015; 93:1611-21. [DOI: 10.1002/jnr.23610] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/30/2015] [Accepted: 06/01/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Jiao Zhu
- Department of Neurobiology; Key Laboratory of Molecular Neurobiology; Ministry of Education; Second Military Medical University; Shanghai People's Republic of China
| | - Xiao-hui Xu
- School of Life Science; Shanghai University; Shanghai People's Republic of China
| | - Gillian E. Knight
- Autonomic Neuroscience Centre; University College Medical School; London United Kingdom
| | - Cheng He
- Department of Neurobiology; Key Laboratory of Molecular Neurobiology; Ministry of Education; Second Military Medical University; Shanghai People's Republic of China
| | - Geoffrey Burnstock
- Autonomic Neuroscience Centre; University College Medical School; London United Kingdom
- Department of Pharmacology and Therapeutics; The University of Melbourne; Melbourne Australia
| | - Zhenghua Xiang
- Department of Neurobiology; Key Laboratory of Molecular Neurobiology; Ministry of Education; Second Military Medical University; Shanghai People's Republic of China
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13
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Forni PE, Wray S. GnRH, anosmia and hypogonadotropic hypogonadism--where are we? Front Neuroendocrinol 2015; 36:165-77. [PMID: 25306902 PMCID: PMC4703044 DOI: 10.1016/j.yfrne.2014.09.004] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 09/08/2014] [Accepted: 09/25/2014] [Indexed: 11/19/2022]
Abstract
Gonadotropin releasing hormone (GnRH) neurons originate the nasal placode and migrate into the brain during prenatal development. Once within the brain, these cells become integral components of the hypothalamic-pituitary-gonadal axis, essential for reproductive function. Disruption of this system causes hypogonadotropic hypogonadism (HH). HH associated with anosmia is clinically defined as Kallman syndrome (KS). Recent work examining the developing nasal region has shed new light on cellular composition, cell interactions and molecular cues responsible for the development of this system in different species. This review discusses some developmental aspects, animal models and current advancements in our understanding of pathologies affecting GnRH. In addition we discuss how development of neural crest derivatives such as the glia of the olfactory system and craniofacial structures control GnRH development and reproductive function.
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Affiliation(s)
- Paolo E Forni
- Department of Biological Sciences and the Center for Neuroscience Research, University at Albany, State University of New York, Albany, NY 12222, United States.
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, United States.
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14
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Watanabe M, Fukuda A, Nabekura J. The role of GABA in the regulation of GnRH neurons. Front Neurosci 2014; 8:387. [PMID: 25506316 PMCID: PMC4246667 DOI: 10.3389/fnins.2014.00387] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 11/12/2014] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons form the final common pathway for the central regulation of reproduction. Gamma-amino butyric acid (GABA) has long been implicated as one of the major players in the regulation of GnRH neurons. Although GABA is typically an inhibitory neurotransmitter in the mature adult central nervous system, most mature GnRH neurons show the unusual characteristic of being excited by GABA. While many reports have provided much insight into the contribution of GABA to the activity of GnRH neurons, the precise physiological role of the excitatory action of GABA on GnRH neurons remains elusive. This brief review presents the current knowledge of the role of GABA signaling in GnRH neuronal activity. We also discuss the modulation of GABA signaling by neurotransmitters and neuromodulators and the functional consequence of GABAergic inputs to GnRH neurons in both the physiology and pathology of reproduction.
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Affiliation(s)
- Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine Hamamatsu, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine Hamamatsu, Japan
| | - Junichi Nabekura
- Department of Developmental Physiology, National Institute for Physiological Sciences Okazaki, Japan ; Core Research for Evolutionary Science and Technology, Japan Science and Technology Corporation Saitama, Japan ; Department of Physiological Sciences, The Graduate School for Advanced Study Hayama, Japan
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15
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Vastagh C, Schwirtlich M, Kwakowsky A, Erdélyi F, Margolis FL, Yanagawa Y, Katarova Z, Szabó G. The spatiotemporal segregation of GAD forms defines distinct GABA signaling functions in the developing mouse olfactory system and provides novel insights into the origin and migration of GnRH neurons. Dev Neurobiol 2014; 75:249-70. [PMID: 25125027 DOI: 10.1002/dneu.22222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/18/2014] [Accepted: 08/06/2014] [Indexed: 01/26/2023]
Abstract
Gamma-aminobutyric acid (GABA) has a dual role as an inhibitory neurotransmitter in the adult central nervous system (CNS) and as a signaling molecule exerting largely excitatory actions during development. The rate-limiting step of GABA synthesis is catalyzed by two glutamic acid decarboxylase isoforms GAD65 and GAD67 coexpressed in the GABAergic neurons of the CNS. Here we report that the two GADs show virtually nonoverlapping expression patterns consistent with distinct roles in the developing peripheral olfactory system. GAD65 is expressed exclusively in undifferentiated neuronal progenitors confined to the proliferative zones of the sensory vomeronasal and olfactory epithelia In contrast GAD67 is expressed in a subregion of the nonsensory epithelium/vomeronasal organ epithelium containing the putative Gonadotropin-releasing hormone (GnRH) progenitors and GnRH neurons migrating from this region through the frontonasal mesenchyme into the basal forebrain. Only GAD67+, but not GAD65+ cells accumulate detectable GABA. We further demonstrate that GAD67 and its embryonic splice variant embryonic GAD (EGAD) concomitant with GnRH are dynamically regulated during GnRH neuronal migration in vivo and in two immortalized cell lines representing migratory (GN11) and postmigratory (GT1-7) stage GnRH neurons, respectively. Analysis of GAD65/67 single and double knock-out embryos revealed that the two GADs play complementary (inhibitory) roles in GnRH migration ultimately modulating the speed and/or direction of GnRH migration. Our results also suggest that GAD65 and GAD67/EGAD characterized by distinct subcellular localization and kinetics have disparate functions during olfactory system development mediating proliferative and migratory responses putatively through specific subcellular GABA pools.
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Affiliation(s)
- Csaba Vastagh
- Division of Medical Gene Technology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary; Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
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16
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Henkin RI, Potolicchio SJ, Levy LM. Olfactory Hallucinations without Clinical Motor Activity: A Comparison of Unirhinal with Birhinal Phantosmia. Brain Sci 2013; 3:1483-553. [PMID: 24961619 PMCID: PMC4061890 DOI: 10.3390/brainsci3041483] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/11/2013] [Accepted: 10/12/2013] [Indexed: 01/14/2023] Open
Abstract
Olfactory hallucinations without subsequent myoclonic activity have not been well characterized or understood. Herein we describe, in a retrospective study, two major forms of olfactory hallucinations labeled phantosmias: one, unirhinal, the other, birhinal. To describe these disorders we performed several procedures to elucidate similarities and differences between these processes. From 1272, patients evaluated for taste and smell dysfunction at The Taste and Smell Clinic, Washington, DC with clinical history, neurological and otolaryngological examinations, evaluations of taste and smell function, EEG and neuroradiological studies 40 exhibited cyclic unirhinal phantosmia (CUP) usually without hyposmia whereas 88 exhibited non-cyclic birhinal phantosmia with associated symptomology (BPAS) with hyposmia. Patients with CUP developed phantosmia spontaneously or after laughing, coughing or shouting initially with spontaneous inhibition and subsequently with Valsalva maneuvers, sleep or nasal water inhalation; they had frequent EEG changes usually ipsilateral sharp waves. Patients with BPAS developed phantosmia secondary to several clinical events usually after hyposmia onset with few EEG changes; their phantosmia could not be initiated or inhibited by any physiological maneuver. CUP is uncommonly encountered and represents a newly defined clinical syndrome. BPAS is commonly encountered, has been observed previously but has not been clearly defined. Mechanisms responsible for phantosmia in each group were related to decreased gamma-aminobutyric acid (GABA) activity in specific brain regions. Treatment which activated brain GABA inhibited phantosmia in both groups.
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Affiliation(s)
- Robert I Henkin
- Center for Molecular Nutrition and Sensory Disorders, The Taste and Smell Clinic, 5125 MacArthur Blvd, NW, Suite 20, Washington, DC 20016, USA.
| | - Samuel J Potolicchio
- Department of Neurology, The George Washington University Medical Center, 2150 Pennsylvania Avenue, NW, 7th Floor, Washington, DC 20037, USA.
| | - Lucien M Levy
- Department of Radiology, The George Washington University Medical Center, 900 23rd Street, NW, Washington, DC 20037, USA.
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17
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Hrabovszky E, Liposits Z. Afferent neuronal control of type-I gonadotropin releasing hormone neurons in the human. Front Endocrinol (Lausanne) 2013; 4:130. [PMID: 24062728 PMCID: PMC3778916 DOI: 10.3389/fendo.2013.00130] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/03/2013] [Indexed: 12/30/2022] Open
Abstract
Understanding the regulation of the human menstrual cycle represents an important ultimate challenge of reproductive neuroendocrine research. However, direct translation of information from laboratory animal experiments to the human is often complicated by strikingly different and unique reproductive strategies and central regulatory mechanisms that can be present in even closely related animal species. In all mammals studied so far, type-I gonadotropin releasing hormone (GnRH) synthesizing neurons form the final common output way from the hypothalamus in the neuroendocrine control of the adenohypophysis. Under various physiological and pathological conditions, hormonal and metabolic signals either regulate GnRH neurons directly or act on upstream neuronal circuitries to influence the pattern of pulsatile GnRH secretion into the hypophysial portal circulation. Neuronal afferents to GnRH cells convey important metabolic-, stress-, sex steroid-, lactational-, and circadian signals to the reproductive axis, among other effects. This article gives an overview of the available neuroanatomical literature that described the afferent regulation of human GnRH neurons by peptidergic, monoaminergic, and amino acidergic neuronal systems. Recent studies of human genetics provided evidence that central peptidergic signaling by kisspeptins and neurokinin B (NKB) play particularly important roles in puberty onset and later, in the sex steroid-dependent feedback regulation of GnRH neurons. This review article places special emphasis on the topographic distribution, sexual dimorphism, aging-dependent neuroanatomical changes, and plastic connectivity to GnRH neurons of the critically important human hypothalamic kisspeptin and NKB systems.
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Affiliation(s)
- Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- *Correspondence: Erik Hrabovszky, Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, 43 Szigony Street, Budapest 1083, Hungary e-mail:
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
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18
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Hall JA, Decatur WA, Daukss DM, Hayes MK, Marquis TJ, Morin SJ, Kelleher TF, Sower SA. Expression of three GnRH receptors in specific tissues in male and female sea lampreys Petromyzon marinus at three distinct life stages. Front Neurosci 2013; 7:88. [PMID: 23754972 PMCID: PMC3664763 DOI: 10.3389/fnins.2013.00088] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 05/10/2013] [Indexed: 11/17/2022] Open
Abstract
Two recently cloned gonadotropin-releasing hormone (GnRH) receptors (lamprey GnRH-R-2 and lamprey GnRH-R-3) along with lamprey (l) GnRH-R-1 were shown to share similar structural features and amino acid motifs common to other vertebrate receptors. Here we report on our findings of RNA expression of these three GnRH receptors in the three major life stages (larval, parasitic, and adult phases) of the sea lamprey, Petromyzon marinus, a basal vertebrate. For each stage, we examined the expression of messenger RNA encoding the receptors in the brain, pituitary, gonad, heart, muscle, liver, eye, intestine, kidney, skin, thyroid, gill, and endostyle by RT-PCR. In adult lampreys, the spatial expression of the three receptors in the brain and pituitary was investigated by in situ hybridization. In general, the receptors were more widely expressed in adult tissues as compared to parasitic-phase tissues and least widely expressed in the larval tissues. There were noted differences in male and female lampreys in the adult and parasitic phases for all three receptors. The data showed the presence of all three receptor transcripts in brain tissues for adult and parasitic phases and all three receptor transcripts were expressed in the adult pituitaries, but not in the parasitic pituitaries. However, in the larval phase, only lGnRH-R-1 was expressed in the larval brain and pituitary. In situ hybridization revealed that lGnRH-R-2 and -3 were expressed in the pineal tissue of adult female lampreys while lGnRH-R-1 was expressed in the pineal in adult male lampreys, all restricted to the pineal pellucida. In summary, these data provide an initial comparative analysis of expression of three lamprey GnRH receptors suggesting differential regulation within males and females at three different life/reproductive stages.
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Affiliation(s)
- Jeffrey A Hall
- Department of Molecular, Cellular and Biomedical Sciences, Center for Molecular and Comparative Endocrinology, University of New Hampshire Durham, NH, USA
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19
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Meczekalski B, Podfigurna-Stopa A, Smolarczyk R, Katulski K, Genazzani AR. Kallmann syndrome in women: from genes to diagnosis and treatment. Gynecol Endocrinol 2013; 29:296-300. [PMID: 23368665 DOI: 10.3109/09513590.2012.752459] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Kallmann syndrome (KS) can be characterized as genetic disorder marked by hypogonadotropic hypogonadism and anosmia. Franz Jozef Kallmann was the first who described this disease in 1944. He suggested, that this disease has hereditary background. At present, six genes are regarded as causal genes of KS. These genes can be listed in chronological order: KAL1, FGFR1, FGF8, CHD7, PROKR2 and PROK2. The sensitivity of molecular testing of KS is only about 30%. Diagnosis based on clinical findings is therefore such important. Cardinal features of patients with KS include hypogonadotropic hypogonadism and anosmia or hyposmia. Some non-reproductive, non-olfactory symptoms can also be present, depending on the genetic form of disease. Some patients with KS present midline cranial anomalies (cleft lip, cleft palate and imperfect fusion). Sometimes patients can also suffer from missing teeth (dental agenesis). Optic problems, such as colour blindness or optic atrophy also can occur in KS patients. Very characteristic symptom in KS patients is mirror movements of the upper limbs (imitation synkinesis for contralateral limbs). The type of treatment in women with KS depends on the goal of therapy. After the diagnosis of syndrome, the main goal of the treatment is to induce and maintain secondary sex characteristic (estrogen-progestin therapy). The further goal in some patients can be related to enable fertility (gonadotropin, gonadotropin-releasing hormone therapy).
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Affiliation(s)
- Blazej Meczekalski
- Department of Gynecological Endocrinology, Poznan University of Medical Sciences, Poznan, Poland.
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20
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Casoni F, Hutchins BI, Donohue D, Fornaro M, Condie BG, Wray S. SDF and GABA interact to regulate axophilic migration of GnRH neurons. J Cell Sci 2012; 125:5015-25. [PMID: 22976302 DOI: 10.1242/jcs.101675] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Stromal derived growth factor (SDF-1) and gamma-aminobutyric acid (GABA) are two extracellular cues that regulate the rate of neuronal migration during development and may act synergistically. The molecular mechanisms of this interaction are still unclear. Gonadotropin releasing hormone-1 (GnRH) neurons are essential for vertebrate reproduction. During development, these neurons emerge from the nasal placode and migrate through the cribriform plate into the brain. Both SDF-1 and GABA have been shown to regulate the rate of GnRH neuronal migration by accelerating and slowing migration, respectively. As such, this system was used to explore the mechanism by which these molecules act to produce coordinated cell movement during development. In the present study, GABA and SDF-1 are shown to exert opposite effects on the speed of cell movement by activating depolarizing or hyperpolarizing signaling pathways, GABA via changes in chloride and SDF-1 via changes in potassium. GABA and SDF-1 were also found to act synergistically to promote linear rather than random movement. The simultaneous activation of these signaling pathways, therefore, results in tight control of cellular speed and improved directionality along the migratory pathway of GnRH neurons.
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Affiliation(s)
- Filippo Casoni
- Cellular and Developmental Neurobiology Section, NINDS/NIH, Bethesda, MD 20892, USA
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21
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Diaczok D, DiVall S, Matsuo I, Wondisford FE, Wolfe AM, Radovick S. Deletion of Otx2 in GnRH neurons results in a mouse model of hypogonadotropic hypogonadism. Mol Endocrinol 2011; 25:833-46. [PMID: 21436260 DOI: 10.1210/me.2010-0271] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
GnRH is the central regulator of reproductive function responding to central nervous system cues to control gonadotropin synthesis and secretion. GnRH neurons originate in the olfactory placode and migrate to the forebrain, in which they are found in a scattered distribution. Congenital idiopathic hypogonadotropic hypogonadism (CIHH) has been associated with mutations or deletions in a number of genes that participate in the development of GnRH neurons and expression of GnRH. Despite the critical role of GnRH in mammalian reproduction, a comprehensive understanding of the developmental factors that are responsible for regulating the establishment of mature GnRH neurons and the expression of GnRH is lacking. orthodenticle homeobox 2 (OTX2), a homeodomain protein required for the formation of the forebrain, has been shown to be expressed in GnRH neurons, up-regulated during GnRH neuronal development, and responsible for increased GnRH promoter activity in GnRH neuronal cell lines. Interestingly, mutations in Otx2 have been associated with human hypogonadotropic hypogonadism, but the mechanism by which Otx2 mutations cause CIHH is unknown. Here we show that deletion of Otx2 in GnRH neurons results in a significant decrease in GnRH neurons in the hypothalamus, a delay in pubertal onset, abnormal estrous cyclicity, and infertility. Taken together, these data provide in vivo evidence that Otx2 is critical for GnRH expression and reproductive competence.
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Affiliation(s)
- Daniel Diaczok
- Division of Pediatric Endocrinology, The Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, Maryland 21287, USA
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22
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Pombal MA, Alvarez-Otero R, Pérez-Fernández J, Solveira C, Megías M. Development and organization of the lamprey telencephalon with special reference to the GABAergic system. Front Neuroanat 2011; 5:20. [PMID: 21442003 PMCID: PMC3062466 DOI: 10.3389/fnana.2011.00020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Accepted: 03/07/2011] [Indexed: 12/12/2022] Open
Abstract
Lampreys, together with hagfishes, represent the sister group of gnathostome vertebrates. There is an increasing interest for comparing the forebrain organization observed in lampreys and gnathostomes to shed light on vertebrate brain evolution. Within the prosencephalon, there is now a general agreement on the major subdivisions of the lamprey diencephalon; however, the organization of the telencephalon, and particularly its pallial subdivisions, is still a matter of controversy. In this study, recent progress on the development and organization of the lamprey telencephalon is reviewed, with particular emphasis on the GABA immunoreactive cell populations trying to understand their putative origin. First, we describe some early general cytoarchitectonic events by searching the classical literature as well as our collection of embryonic and prolarval series of hematoxylin-stained sections. Then, we comment on the cell proliferation activity throughout the larval period, followed by a detailed description of the early events on the development of the telencephalic GABAergic system. In this context, lampreys apparently do not possess the same molecularly distinct subdivisions of the gnathostome basal telencephalon because of the absence of a Nkx2.1-expressing domain in the developing subpallium; a fact that has been related to the absence of a medial ganglionic eminence as well as of its derived nucleus in gnathostomes, the pallidum. Therefore, these data raise interesting questions such as whether or not a different mechanism to specify telencephalic GABAergic neurons exists in lampreys or what are their migration pathways. Finally, we summarize the organization of the adult lamprey telencephalon by analyzing the main proposed conceptions, including the available data on the expression pattern of some developmental regulatory genes which are of importance for building its adult shape.
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Affiliation(s)
- Manuel A Pombal
- Neurolam Group, Department of Functional Biology and Health Sciences, Faculty of Biology, University of Vigo Vigo, Spain
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23
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Wierman ME, Kiseljak-Vassiliades K, Tobet S. Gonadotropin-releasing hormone (GnRH) neuron migration: initiation, maintenance and cessation as critical steps to ensure normal reproductive function. Front Neuroendocrinol 2011; 32:43-52. [PMID: 20650288 PMCID: PMC3008544 DOI: 10.1016/j.yfrne.2010.07.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/08/2010] [Accepted: 07/14/2010] [Indexed: 12/23/2022]
Abstract
GnRH neurons follow a carefully orchestrated journey from their birth in the olfactory placode area. Initially, they migrate along with the vomeronasal nerve into the brain at the cribriform plate, then progress caudally to sites within the hypothalamus where they halt and send projections to the median eminence to activate pituitary gonadotropes. Many factors controlling this precise journey have been elucidated by the silencing or over-expression of candidate genes in mouse models. Importantly, a number of these factors may not only play a role in normal physiology of the hypothalamic-pituitary-gonadal axis but also be mis-expressed to cause human disorders of GnRH deficiency, presenting as a failure to undergo normal pubertal development. This review outlines the current cadre of candidates thought to modulate GnRH neuronal migration. The further elucidation and characterization of these factors that impact GnRH neuron development may shed new light on human reproductive disorders and provide potential targets to develop new pro-fertility or contraceptive agents.
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Affiliation(s)
- Margaret E Wierman
- Department of Medicine, University of Colorado-Denver, Aurora, CO 80045, USA
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24
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Abstract
Gonadotrophin-releasing hormone-1 (GnRH-1) is essential for mammalian reproduction, controlling release of gonadotrophins from the anterior pituitary. GnRH-1 neurones migrate from the nasal placode into the forebrain during development. Although first located within the nasal placode, the embryonic origin/lineage of GnRH-1 neurones is still unclear. The migration of GnRH-1 cells is the best characterised example of neurophilic/axophilic migration, with the cells using a subset of olfactory-derived vomeronasal axons as their pathway and numerous molecules to guide their movement into the forebrain. Exciting work in this area is beginning to identify intersecting pathways that orchestrate the movement of these critical neuroendocrine cells into the central nervous system, both spatially and temporally, through a diverse and changing terrain. Once within the forebrain, little is known about how the axons target the median eminence and ultimately secrete GnRH-1 in a pulsatile fashion.
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Affiliation(s)
- S Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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25
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The generation of an array of clonal, immortalized cell models from the rat hypothalamus: analysis of melatonin effects on kisspeptin and gonadotropin-inhibitory hormone neurons. Neuroscience 2009; 162:1134-40. [DOI: 10.1016/j.neuroscience.2009.05.026] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 04/30/2009] [Accepted: 05/14/2009] [Indexed: 12/15/2022]
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26
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Jasoni CL, Porteous RW, Herbison AE. Anatomical location of mature GnRH neurons corresponds with their birthdate in the developing mouse. Dev Dyn 2009; 238:524-31. [DOI: 10.1002/dvdy.21869] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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27
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The influence of catecholamine on the migration of gonadotropin-releasing hormone-producing neurons in the rat foetuses. Brain Struct Funct 2008; 213:289-300. [PMID: 18841392 DOI: 10.1007/s00429-008-0197-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 09/16/2008] [Indexed: 10/21/2022]
Abstract
Catecholamines (CA) play an important role in the regulation of GnRH neurons in adults, and it is probable that they control GnRH-neuron development. Migration of GnRH neurons was evaluated in male and female rats at the 17th embryonic day (E17) and E21, following the daily treatment of their pregnant mothers from the 11th to the 16th and 20th day of gestation with alpha-methyl-para-tyrosine (alphaMPT), an inhibitor of catecholamine synthesis. High-performance liquid chromatography with electrochemical detection (HPLC-ED) was used to specify the alphaMPT-induced CA depletion. There was a 50-70% decrease in dopamine and noradrenaline content in the nose and in the brain of alphaMPT-treated foetuses, proving the efficacy of this pharmacological model. Immunohistochemistry was used to evaluate the percentage (%) of GnRH neurons along their migration pathway from the vomeronasal organ (VNO) in the nose to the septo-preoptic area in the forebrain which is considered as an index of neuron migration. Special attention was paid to the topographic relationships of GnRH neurons with catecholaminergic fibres. These were observed in apposition with GnRH neurons in the entrance to the forebrain. In CA-deficient foetuses, the percentage of GnRH neurons located in the rostral regions extending from the VNO to the septum was greater than in controls. However, no statistically significant difference was found in the forebrain which extended from the septum to the retrochiasmatic area. In conclusion, these data suggest that endogenous catecholamines stimulate the GnRH neuron migration in ontogenesis.
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28
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Gill JC, Wadas B, Chen P, Portillo W, Reyna A, Jorgensen E, Mani S, Schwarting GA, Moenter SM, Tobet S, Kaiser UB. The gonadotropin-releasing hormone (GnRH) neuronal population is normal in size and distribution in GnRH-deficient and GnRH receptor-mutant hypogonadal mice. Endocrinology 2008; 149:4596-604. [PMID: 18499748 PMCID: PMC2553368 DOI: 10.1210/en.2008-0403] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hypothalamic GnRH neurons are essential for initiation and regulation of reproductive function. In addition to pituitary gonadotrope stimulation, activity of GnRH through its receptor (GnRHR) has been suggested to include autocrine regulation of the GnRH neuron. Two hypogonadal mouse strains, the Gnrh1 mutant (hpg) mice and Gnrhr mutant mice were used to investigate the potential role of GnRH signaling in the proper development and maintenance of GnRH neurons. Immunocytochemical analysis of heterozygous hpg mice revealed a GnRH neuron population that was normal in size and distribution, indicating no effect from reduced Gnrh1 gene dosage on the neurons themselves. To visualize GnRH neurons in homozygous GnRH-deficient hpg mice, heterozygous hpg mice were crossed with GnRH-green fluorescent protein (GFP) transgenic mice with targeted expression of the GFP reporter gene in GnRH neurons. Analysis of forebrains of homozygous hpg/GFP-positive mice immunostained for GFP revealed a normal population size and appropriate distribution of GnRH neurons in hpg mice, with immunoreactive neuronal processes present at the median eminence. Similarly, adult mice deficient in functional GnRHR possessed a full complement of GnRH neurons in the basal forebrain that was indistinguishable from the distribution of GnRH neurons in their wild-type counterparts. Moreover, hpg/GFP neurons retained the ability to generate spontaneous bursts of action potential firing activity, suggesting that GnRH peptide is not required for this function. These data establish that autocrine-paracrine GnRH-signaling is not a prerequisite for the developmental migration of GnRH neurons into the brain or for the projection of GnRH neurosecretory axons.
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Affiliation(s)
- John C Gill
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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Lee JM, Tiong J, Maddox DM, Condie BG, Wray S. Temporal migration of gonadotrophin-releasing hormone-1 neurones is modified in GAD67 knockout mice. J Neuroendocrinol 2008; 20:93-103. [PMID: 18081557 DOI: 10.1111/j.1365-2826.2007.01623.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gonadotrophin-releasing hormone (GnRH-1) neurones reside in the forebrain and regulate gonadal function via the hypothalamic-pituitary-gonadal axis. Disruption of this axis results in reproductive dysfunction. During embryonic development, GnRH-1 neurones migrate from the nasal pit through the nasal/forebrain junction (NFJ) into the developing brain. Prenatally gamma-aminobutyric acid (GABA) is excitatory and has been shown to play a role in nervous system development. Both in vivo and in vitro experiments suggest that GABA inhibits migration of GnRH-1 neurones. The present study examines the migration of GnRH-1 neurones in GAD67 knockout (KO) mice to further elucidate the role of GABA on GnRH-1 neuronal development. Three stages were examined, embryonic day (E)12.5, E14.5 and E17.5. GnRH-1 cell number and location were analysed by immunocytochemistry and in situ hybridisation histochemistry. The total number of GnRH-1 immunopositive cells was similar between wild-type (WT) and KO mice. However, significant differences were found in the overall distribution of GnRH-1 immunopositive cells in GAD67 KO compared to WT mice at all stages. Subsequent analysis by area revealed differences occurred at the NFJ with an increase in GnRH-1 cells in GAD67 KO at E14.5 and a decrease in GnRH-1 cells in GAD67 KO at E17.5. Comparable counts for cells expressing GnRH-1 transcript and protein were obtained. These data indicate that attenuated levels of GABA accelerate GnRH-1 cell migration in nasal areas as well as movement of GnRH-1 cells into the central nervous system at the NFJ.
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Affiliation(s)
- J M Lee
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, MD, USA
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McClellan KM, Calver AR, Tobet SA. GABAB receptors role in cell migration and positioning within the ventromedial nucleus of the hypothalamus. Neuroscience 2007; 151:1119-31. [PMID: 18248902 DOI: 10.1016/j.neuroscience.2007.11.048] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 11/20/2007] [Accepted: 11/28/2007] [Indexed: 12/16/2022]
Abstract
The ventromedial (VMN) and arcuate (ARC) nuclei of the hypothalamus are bilateral nuclear groups at the base of the hypothalamus that are organized through the aggregation of neurons born along the third ventricle that migrate laterally. During development, GABAergic neurons and fibers surround the forming (or primordial) VMN while neurons containing GABA receptors are found within the boundaries of the emerging nucleus. To investigate the role that GABAB receptors play in establishing the VMN, Thy-1 yellow fluorescent protein (YFP) mice were utilized for live video microscopy studies. The Thy-1 promoter drives YFP expression in regions of the hypothalamus during development. Administration of the GABAB receptor antagonist saclofen and the GABAA receptor antagonist bicuculline selectively increased the rate of VMN cell movement in slices placed in vitro at embryonic day 14, when cells that form both the ARC and VMN are migrating away from the proliferative zone surrounding the third ventricle. To further test the role of GABAB receptors in VMN development, GABAB receptor knockout mice were used to examine changes in the positions of phenotypically identified cells within the VMN. Cells containing immunoreactive estrogen receptors (ER) alpha were located in the ventrolateral quadrant of the wild type VMN. In GABABR1 knockout mice, these ERalpha positive neurons were located in more dorsal positions at postnatal day (P) 0 and P4. We conclude that GABA alters cell migration and its effect on final cell positioning may lead to changes in the circuitry and connections within specific nuclei of the developing hypothalamus.
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Affiliation(s)
- K M McClellan
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523, USA
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31
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Schwarting GA, Henion TR, Nugent JD, Caplan B, Tobet S. Stromal cell-derived factor-1 (chemokine C-X-C motif ligand 12) and chemokine C-X-C motif receptor 4 are required for migration of gonadotropin-releasing hormone neurons to the forebrain. J Neurosci 2006; 26:6834-40. [PMID: 16793890 PMCID: PMC6673820 DOI: 10.1523/jneurosci.1728-06.2006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons migrate from the vomeronasal organ (VNO) in the nasal compartment to the basal forebrain in mice, beginning on embryonic day 11 (E11). These neurons use vomeronasal axons as guides to migrate through the nasal mesenchyme. Most GnRH neurons then migrate along the caudal branch of the vomeronasal nerve to reach the hypothalamus. We show here that stromal cell-derived factor-1 [SDF-1, also known as chemokine C-X-C motif ligand 12 (CXCL12)] is expressed in the embryonic nasal mesenchyme from as early as E10 in an increasing rostral to caudal gradient that is most intense at the border of the nasal mesenchyme and the telencephalon. Chemokine C-X-C motif receptor 4 (CXCR4), the receptor for SDF-1, is expressed by neurons in the olfactory epithelium and VNO. Cells derived from these sensory epithelia, including migrating GnRH neurons and ensheathing glial precursors of the migrating mass (MM), also express CXCR4, suggesting that they may use SDF-1 as a chemokine. In support of this, most GnRH neurons of CXCR4-/- mice fail to exit the VNO at E13, and comparatively few GnRH neurons reach the forebrain. There is also a significant decrease in the total number of GnRH neurons in CXCR4-/- mice and an increase in cell death within the VNO relative to controls. The MM is smaller in CXCR4-/- mice, suggesting that some MM cells also require SDF-1/CXCR4 function for migration and survival.
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Affiliation(s)
- Gerald A Schwarting
- Shriver Center/University of Massachusetts Medical Center, Waltham, Massachusetts 02452, USA.
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Izvolskaia M, Duittoz AH, Ugrumov MV, Tillet Y. Tyrosine hydroxylase expression in the olfactory/respiratory epithelium in early sheep fetuses (Ovis aries). Brain Res 2006; 1083:29-38. [PMID: 16556435 DOI: 10.1016/j.brainres.2006.01.130] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 01/26/2006] [Accepted: 01/30/2006] [Indexed: 11/26/2022]
Abstract
Transient expression of tyrosine hydroxylase (TH, the first enzyme in catecholamine synthesis) has been shown in different brain and peripheral structures of various species. TH-immunoreactive neurons have been reported in the nasal region of human and rat fetuses migrating to the forebrain with GnRH neurons during embryogenesis. In the present study, immunohistochemical analysis and in situ hybridization were performed in fetal sheep and in vitro sheep embryo olfactory placode cultures to confirm this population in this species. On embryonic days 33 to 35, TH-immunoreactive cells as well as TH cDNA-hybridized cells were found in the olfactory and respiratory epithelium and were spatially separated from GnRH-immunoreactive neurons. In days 40 to 44 of gestation, TH-immunoreactive neurons were no longer observed in the olfactory epithelium, and TH-immunoreactive fibers were found on the trajectories of the olfactory nerves. At this stage, some TH-immunoreactive fibers were also labeled for GnRH. TH-immunoreactive cells were also found in primary cultures of olfactory placodes of fetal sheep at 10 to 18 days in vitro. Some of them coexpressed GnRH. These results imply that olfactory epithelium is also able to give rise to TH expressing cells in fetal sheep, but this expression is suppressed earlier in ontogenesis than in humans due to some unidentified factors not present in the primary cultures of olfactory placode. The role of TH expression remains unclear as in other previously described examples.
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Affiliation(s)
- Marina Izvolskaia
- Laboratory of Hormonal Regulations, Institute of Developmental Biology, Russian Academy of Sciences, Vavilov str., 26,119991 Moscow, Russia
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33
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Abstract
Neurons that synthesize GnRH are critical brain regulators of the reproductive axis, yet they originate outside the brain and must migrate over long distances and varied environments to get to their appropriate positions during development. Many studies, past and present, are providing clues for the types of molecules encountered and movements expected along the migratory route. Recent studies provide real-time views of the behavior of GnRH neurons in the context of in vitro preparations that model those in vivo. Live images provide direct evidence of the changing behavior of GnRH neurons in their different environments, showing that GnRH neurons move with greater frequency and with more alterations in direction after they enter the brain. The heterogeneity of molecular phenotypes for GnRH neurons likely ensures that multiple external factors will be found that regulate the migration of different portions of the GnRH neuronal population at different steps along the route. Molecules distributed in gradients both in the peripheral olfactory system and basal forebrain may be particularly influential in directing the appropriate movement of GnRH neurons along their arduous migration. Molecules that mediate the adhesion of GnRH neurons to changing surfaces may also play critical roles. It is likely that the multiple external factors converge on selective signal transduction pathways to engage the mechanical mechanisms needed to modulate GnRH neuronal movement and ultimately migration.
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Affiliation(s)
- Stuart A Tobet
- Colorado State University, Department of Biomedical Sciences, 1617 Campus Delivery, Fort Collins, Colorado 80523, USA
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Von Bartheld CS. The terminal nerve and its relation with extrabulbar "olfactory" projections: lessons from lampreys and lungfishes. Microsc Res Tech 2005; 65:13-24. [PMID: 15570592 DOI: 10.1002/jemt.20095] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The definition of the terminal nerve has led to considerable confusion and controversy. This review analyzes the current state of knowledge as well as diverging opinions about the existence, components, and definition of terminal nerves or their components, with emphasis on lampreys and lungfishes. I will argue that the historical terminology regarding this cranial nerve embraces a definition of a terminal nerve that is compatible with its existence in all vertebrate species. This review further summarizes classical and more recent anatomical, developmental, neurochemical, and molecular evidence suggesting that a multitude of terminalis cell types, not only those expressing gonadotropin-releasing hormone, migrate various distances into the forebrain. This results in numerous morphological and neurochemically distinct phenotypes of neurons, with a continuum spanning from olfactory receptor-like neurons in the olfactory epithelium to typical large ganglion cells that accompany the classical olfactory projections. These cell bodies may lose their peripheral connections with the olfactory epithelium, and their central projections or cell bodies may enter the forebrain at several locations. Since "olfactory" marker proteins can be expressed in bona fide nervus terminalis cells, so-called extrabulbar "olfactory" projections may be a collection of disguised nervus terminalis components. If we do not allow this pleiomorphic collection of nerves to be considered within a terminal nerve framework, then the only alternative is to invent a highly species- and stage-specific, and, ultimately, thoroughly confusing nomenclature for neurons and nerve fibers that associate with the olfactory nerve and forebrain.
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Affiliation(s)
- Christopher S Von Bartheld
- Department of Physiology and Cell Biology, Mailstop 352, University of Nevada School of Medicine, Reno, NV 89557, USA.
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Bless EP, Walker HJ, Yu KW, Knoll JG, Moenter SM, Schwarting GA, Tobet SA. Live view of gonadotropin-releasing hormone containing neuron migration. Endocrinology 2005; 146:463-8. [PMID: 15486219 DOI: 10.1210/en.2004-0838] [Citation(s) in RCA: 41] [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: 11/19/2022]
Abstract
Neurons that synthesize GnRH control the reproductive axis and migrate over long distances and through different environments during development. Prior studies provided strong clues for the types of molecules encountered and movements expected along the migratory route. However, our studies provide the first real-time views of the behavior of GnRH neurons in the context of an in vitro preparation that maintains conditions comparable to those in vivo. The live views provide direct evidence of the changing behavior of GnRH neurons in their different environments, showing that GnRH neurons move with greater frequency and with more changes in direction after they enter the brain. Perturbations of guiding fibers distal to moving GnRH neurons in the nasal compartment influenced movement without detectable changes in the fibers in the immediate vicinity of moving GnRH neurons. This suggests that the use of fibers by GnRH neurons for guidance may entail selective signaling in addition to mechanical guidance. These studies establish a model to evaluate the influences of specific molecules that are important for their migration.
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Affiliation(s)
- Elizabeth P Bless
- The Shriver Center at the University of Massachusetts Medical School, Waltham, Massachusetts 02254, USA
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Hrabovszky E, Turi GF, Kalló I, Liposits Z. Expression of vesicular glutamate transporter-2 in gonadotropin-releasing hormone neurons of the adult male rat. Endocrinology 2004; 145:4018-21. [PMID: 15205380 DOI: 10.1210/en.2004-0589] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Isoforms of the recently cloned vesicular glutamate transporters (VGLUT1-3) selectively accumulate glutamic acid into synaptic vesicles in excitatory axon terminals and are viewed as reliable markers for glutamatergic neurons. Our present studies provided dual-label in situ hybridization evidence that virtually all (99.5%) GnRH neurons express VGLUT2 mRNA in the preoptic region of the adult male rat. Dual-label immunofluorescent experiments were carried out to examine the presence of VGLUT2 protein in GnRH axon terminals. Confocal laser microscopic analysis of the organum vasculosum of the lamina terminalis and the external zone of the median eminence, the major termination fields for GnRH-secreting axons, demonstrated the frequent occurrence of VGLUT2 immunoreactivity in GnRH axon terminals. Together these mRNA hybridization and immunocytochemical data indicate that GnRH neurons of the adult male rat possess marked glutamatergic characteristics. The physiological significance of endogenous glutamate in the regulation of gonadotropin secretion requires clarification.
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Affiliation(s)
- Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest 1083, Hungary.
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Kimura F, Shinohara K, Funabashi T, Daikoku S, Suyama K, Mitsushima D, Sano A. Nicotine inhibition of pulsatile GnRH secretion is mediated by GABAA receptor system in the cultured rat embryonic olfactory placode. Psychoneuroendocrinology 2004; 29:749-56. [PMID: 15110924 DOI: 10.1016/s0306-4530(03)00119-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2003] [Revised: 04/04/2003] [Accepted: 04/07/2003] [Indexed: 11/30/2022]
Abstract
In past work, we suggested that nicotine inhibition of in vivo pulsatile LH release is not mediated by opiate receptors known to be involved in the inhibition of LH release. In the present study, we examined whether nicotine inhibits the pulsatile gonadotropin-releasing hormone (GnRH) release, and whether this inhibition of GnRH release by nicotine is mediated by the GABA receptor system, by checking in vitro pulsatile GnRH release from cultured GnRH neurons obtained from olfactory placodes of rat embryos at E13.5. The mean interpulse interval of pulsatile GnRH release into the medium was 34.2+/-2.0 min in the control period and increased to 95.3+/-19.0 min (n=6) in the period of nicotine treatment at a concentration of 500 nM, showing an inhibitory effect of nicotine on pulsatile GnRH release. The GABA(A) receptor antagonist bicuculline used alone at a concentration of 20 microM caused no significant changes in the pulsatile GnRH release, but when used in combination with 500 nM of nicotine, bicuculline blocked the nicotine inhibition of GnRH release. In a separate experiment, nicotine treatment at a concentration of 500 nM significantly increased GABA release. These results suggest that, in the cultured embryonic olfactory placode, nicotine stimulates GABA release, which then inhibits GnRH release through GABA(A) receptor system.
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Affiliation(s)
- Fukuko Kimura
- Department of Neuroendocrinology, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan.
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Heger S, Seney M, Bless E, Schwarting GA, Bilger M, Mungenast A, Ojeda SR, Tobet SA. Overexpression of glutamic acid decarboxylase-67 (GAD-67) in gonadotropin-releasing hormone neurons disrupts migratory fate and female reproductive function in mice. Endocrinology 2003; 144:2566-79. [PMID: 12746320 DOI: 10.1210/en.2002-221107] [Citation(s) in RCA: 46] [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: 11/19/2022]
Abstract
gamma-Aminobutyric acid (GABA) inhibits the embryonic migration of GnRH neurons and regulates hypothalamic GnRH release. A subset of GnRH neurons expresses GABA along their migratory route in the nasal compartment before entering the brain, suggesting that GABA produced by GnRH neurons may help regulate the migratory process. To examine this hypothesis and the possibility that persistence of GABA production by GnRH neurons may affect subsequent reproductive function, we generated transgenic mice in which the expression of glutamic acid decarboxylase-67 (GAD-67), a key enzyme in GABA synthesis, is targeted to GnRH neurons under the control of the GnRH gene promoter. On embryonic d 15, when GnRH neurons are still migrating, the transgenic animals had more GnRH neurons in aberrant locations in the cerebral cortex and fewer neurons reaching the hypothalamic-preoptic region, whereas migration into the brain was not affected. Hypothalamic GnRH content in mutant mice was low during the first week of postnatal life, increasing to normal values during infantile development (second week after birth) in the presence of increased pulsatile GnRH release. Consistent with these changes, serum LH and FSH levels were also elevated. Gonadotropin release returned to normal values by the time steroid negative feedback became established (fourth week of life). Ovariectomy at this time demonstrated an enhanced gonadotropin response in transgenic animals. Although the onset of puberty, as assessed by the age at vaginal opening and first ovulation, was not affected in the mutant mice, estrous cyclicity and adult reproductive capacity were disrupted. Mutant mice had reduced litter sizes, increased time intervals between deliveries of litters, and a shorter reproductive life span. Thus, GABA produced within GnRH neurons does not delay GnRH neuronal migration, but instead serves as a developmental cue that increases the positional diversity of these neurons within the basal forebrain. In addition, the results suggest that the timely termination of GABA production within the GnRH neuronal network is a prerequisite for normal reproductive function. The possibility arises that similar abnormalities in GABA homeostasis may contribute to syndromes of hypothalamic amenorrhea/oligomenorrhea in humans.
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Affiliation(s)
- Sabine Heger
- Division of Neuroscience, Oregon National Regional Primate Research Center, Oregon Health & Science University, Beaverton, Oregon 97006, USA
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Pronina T, Ugrumov M, Adamskaya E, Kuznetsova T, Shishkina I, Babichev V, Calas A, Tramu G, Mailly P, Makarenko I. Influence of serotonin on the development and migration of gonadotropin-releasing hormone neurones in rat foetuses. J Neuroendocrinol 2003; 15:549-58. [PMID: 12716405 DOI: 10.1046/j.1365-2826.2003.01029.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study used a pharmacological approach to evaluate the consequences of the metabolic perturbations of neurotransmitters on brain development. Pregnant rats received p-chlorophenylalanine (pCPA), an inhibitor of serotonin (5-hydroxytryptamine, 5-HT) synthesis, or saline (control) from the 11th day of gestation once or daily up to the 15th, 17th and 20th day, followed by processing of the forebrain and/or nasal cranium of foetal males and females for high-performance liquid chromatography of monoamines, radioimmunoassay of gonadotropin-releasing hormone (GnRH) and quantitative and semiquantitative immunocytochemistry for GnRH. The pCPA treatment resulted in a 50-70% depletion of 5-HT in the nasal crania and forebrains at any studied age. Radioimmunoassay showed no change in GnRH content in 5-HT deficient foetuses at E16 compared to controls, being higher in both cases in the rostral forebrain than in the hypothalamus. In controls at E21, the GnRH content in the hypothalamus exceeded that in the rostral forebrain, whereas in the 5-HT deficient group the opposite was found. These data suggest that 5-HT provided a stimulating effect on GnRH neurone migration, and this was confirmed by quantification of GnRH-immunoreactive neurones in the forebrain along the trajectory of their migration. At E18 and E21, the fractions of GnRH neurones in the rostral part of the trajectory in pCPA-treated foetuses were greater than those in control foetuses but the opposite was true for the caudal part of the trajectory. Moreover, 5-HT appeared to control the proliferation of the precursor cells of GnRH neurones and their differentiation, as derived from the observations of the increased number of GnRH neurones in the forebrain of foetuses of both sexes, as well as the region-specific decreased neuronal size and content of GnRH in 5-HT-deficient females. Thus, 5-HT appears to contribute to the regulation of the origin, differentiation and migration of GnRH neurones.
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Affiliation(s)
- T Pronina
- Laboratory of Hormonal Regulations, Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilov str., Moscow 117808, Russia
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Corradi A, Croci L, Broccoli V, Zecchini S, Previtali S, Wurst W, Amadio S, Maggi R, Quattrini A, Consalez GG. Hypogonadotropic hypogonadism and peripheral neuropathy in Ebf2-null mice. Development 2003; 130:401-10. [PMID: 12466206 DOI: 10.1242/dev.00215] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Olf/Ebf transcription factors have been implicated in numerous developmental processes, ranging from B-cell development to neuronal differentiation. We describe mice that carry a targeted deletion within the Ebf2 (O/E3) gene. In Ebf2-null mutants, because of defective migration of gonadotropin releasing hormone-synthesizing neurons, formation of the neuroendocrine axis (which is essential for pubertal development) is impaired, leading to secondary hypogonadism. In addition, Ebf2(-/-) peripheral nerves feature defective axon sorting, hypomyelination, segmental dysmyelination and axonal damage, accompanied by a sharp decrease in motor nerve conduction velocity. Ebf2-null mice reveal a novel genetic cause of hypogonadotropic hypogonadism and peripheral neuropathy in the mouse, disclosing an important role for Ebf2 in neuronal migration and nerve development.
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Davis AM, Henion TR, Tobet SA. Gamma-aminobutyric acidB receptors and the development of the ventromedial nucleus of the hypothalamus. J Comp Neurol 2002; 449:270-80. [PMID: 12115679 DOI: 10.1002/cne.10293] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Gamma-aminobutyric acid (GABA) is a highly abundant neurotransmitter in the brain and the ligand for GABA(A), GABA(B), and GABA(C) receptors. Unlike GABA(A) and GABA(C) receptors, which are chloride channels, GABA(B) receptors are G-protein linked and alter cell-signaling pathways. Electrophysiological studies have found GABA(B) receptors in cultured embryonic hypothalamus, but the distribution of these receptors remains unknown. In the present study, we examined the expression of GABA(B) receptors in the ventromedial nucleus of the hypothalamus (VMH) during embryonic mouse development. GABA(B) receptors were present in the VMH at all ages examined, from embryonic day 13 to postnatal day 6. Using a brain slice preparation, we examined the effect of GABA(B) receptor activation on cell movement in the embryonic VMH as the nucleus forms in vitro. The GABA(B) receptor agonist baclofen decreased the rate of cell movement in a dose-dependent manner. Baclofen reduced cell movement by up to 56% compared with vehicle-treated controls. The percentage of cells moving per field and the angles of cell movement were not affected. With our previous findings of GABA(A) receptor activation, it is likely that GABA influences VMH development via multiple mechanisms.
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Affiliation(s)
- Aline M Davis
- The Shriver Center, University of Massachusetts Medical School, 200 Trapelo Road, Waltham, MA 02452, USA
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Nunemaker CS, DeFazio RA, Moenter SM. Estradiol-sensitive afferents modulate long-term episodic firing patterns of GnRH neurons. Endocrinology 2002; 143:2284-92. [PMID: 12021193 DOI: 10.1210/endo.143.6.8869] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GnRH neurons comprise the final common pathway of an estrogen-sensitive pattern generator controlling fertility. To determine estradiol effects on GnRH neuron firing patterns, adult transgenic mice were ovariectomized (OVX), and half were treated with estradiol (OVX+E). One week later targeted single-unit extracellular recordings were made from GnRH neurons identified by green fluorescent protein expression. Estradiol markedly affected GnRH neuron firing patterns, increasing the percentage and duration of time these cells were quiescent (< or = 1 action current/min). Estradiol increased the interval between episodes of increased firing rate determined by Cluster analysis of recordings more than 45 min (OVX+E 38.8 +/- 7.2 min, OVX 16.7 +/- 2.1 min, n = 6 each). Possible mechanisms of estradiol modulation were examined by simultaneously blocking ionotropic secretion of gamma-aminobutyric acid and glutamatergic receptors. This treatment had no effect on cells from OVX mice (n = 10), indicating episodic firing of GnRH neurons is not driven by activation of these receptors. Receptor blockade eliminated estradiol effects on GnRH neurons in the midventral preoptic area (n = 7) but not elsewhere (n = 7). Individual GnRH neurons thus display episodic firing patterns at intervals previously reported for secretory pulses. Estradiol modulates episode frequency to exert feedback control; in a substantial subset of GnRH neurons, estradiol feedback is enforced via GABAergic and/or glutamatergic afferents.
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Affiliation(s)
- Craig S Nunemaker
- Department of Internal Medicine and National Science Foundation Center for Biological Timing, University of Virginia, Charlottesville, Virginia 22908, USA
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Deleted in colorectal cancer (DCC) regulates the migration of luteinizing hormone-releasing hormone neurons to the basal forebrain. J Neurosci 2001. [PMID: 11157077 DOI: 10.1523/jneurosci.21-03-00911.2001] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Luteinizing hormone-releasing hormone (LHRH) neurons migrate from the vomeronasal organ (VNO) to the forebrain in all mammals studied. In mice, most LHRH neuron migration is dependent on axons that originate in the VNO but bypass the olfactory bulb and project into the basal forebrain. Thus, cues that regulate the trajectories of these vomeronasal axons are candidates for determining the destination of LHRH neurons. Using in situ hybridization techniques, we examined the expression of Deleted in colorectal cancer (DCC), a vertebrate receptor for the guidance molecule netrin-1, during development of the olfactory system. DCC is expressed by cells in the olfactory epithelium (OE) and VNO, and in cells migrating from the OE and VNO from embryonic day 11 (E11) to E14. Some DCC(+) cells on vomeronasal axons in the nose also express LHRH. However, DCC expression is downregulated beginning at E12, so few if any LHRH neurons in the forebrain also express DCC. In rat, DCC is expressed on TAG-1(+) axons that guide migrating LHRH neurons. We therefore examined LHRH neuron migration in DCC(-/-) mice and found that trajectories of the caudal vomeronasal nerve and positions of LHRH neurons are abnormal. Fewer than the normal number of LHRH neurons are found in the basal forebrain, and many LHRH neurons are displaced into the cerebral cortex of DCC(-/-) mice. These results are consistent with the idea that DCC regulates the trajectories of a subset of vomeronasal axons that guide the migration of LHRH neurons. Loss of DCC function results in the migration of many LHRH neurons to inappropriate destinations.
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Abstract
An increase in pulsatile release of LHRH is essential for the onset of puberty. However, the mechanism controlling the pubertal increase in LHRH release is still unclear. In primates the LHRH neurosecretory system is already active during the neonatal period but subsequently enters a dormant state in the juvenile/prepubertal period. Neither gonadal steroid hormones nor the absence of facilitatory neuronal inputs to LHRH neurons is responsible for the low levels of LHRH release before the onset of puberty in primates. Recent studies suggest that during the prepubertal period an inhibitory neuronal system suppresses LHRH release and that during the subsequent maturation of the hypothalamus this prepubertal inhibition is removed, allowing the adult pattern of pulsatile LHRH release. In fact, y-aminobutyric acid (GABA) appears to be an inhibitory neurotransmitter responsible for restricting LHRH release before the onset of puberty in female rhesus monkeys. In addition, it appears that the reduction in tonic GABA inhibition allows an increase in the release of glutamate as well as other neurotransmitters, which contributes to the increase in pubertal LHRH release. In this review, developmental changes in several neurotransmitter systems controlling pulsatile LHRH release are extensively reviewed.
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Affiliation(s)
- E Terasawa
- Department of Pediatrics, Wisconsin Regional Primate Research Center, and University of Wisconsin-Madison, 53715-1299, USA.
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45
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Simonian SX, Skynner MJ, Sieghart W, Essrich C, Luscher B, Herbison AE. Role of the GABA(A) receptor gamma2 subunit in the development of gonadotropin-releasing hormone neurons in vivo. Eur J Neurosci 2000; 12:3488-96. [PMID: 11029618 DOI: 10.1046/j.1460-9568.2000.00225.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have employed transgenic mouse models to examine the functional significance of the gamma2 subunit of the GABA(A) (gamma-aminobutyric acid) receptor to the correct development of gonadotropin-releasing hormone (GnRH) neurons in vivo. In the first experiment, the expression of gamma2 subunit protein by the GnRH phenotype was determined using transgenic mice in which GnRH gene sequences direct the expression of the LacZ reporter to the nucleus of the GnRH neurons. This greatly facilitates the immunocytochemical identification of non-nuclear-located antigens within GnRH neurons and revealed that approximately 25% of juvenile GnRH neurons were immunoreactive for the gamma2 subunit and that this increased to 40% in pubertal mice. In the second experiment, GnRH mRNA expression was examined in the brains of gamma2 subunit knockout mice (gamma2(0/0)) and their wild-type (gamma2+/+) littermates at embryonic day 15 and postnatal days (P) 0 and 11-16 using in situ hybridization. The distribution and numbers of cells expressing GnRH mRNA in gamma2+/+ and gamma2(0/0) mice were not found to differ at any age. However, the GnRH mRNA content of medial septal cells was significantly lower in gamma2(0/0) compared with gamma2+/+ mice at P11-16 (P<0.05) and the same trend was observed for preoptic area neurons. These results demonstrate that while the gamma2 subunit of the GABA(A) receptor is expressed by postnatal GnRH neurons, their embryonic development does not require a functional gamma2 subunit. In contrast, postnatal GnRH mRNA expression was found to be dependent upon signalling through the GABA(A) receptor.
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MESH Headings
- Animals
- Cell Count
- Female
- Fetus
- Genes, Reporter/genetics
- Gonadotropin-Releasing Hormone/genetics
- Gonadotropin-Releasing Hormone/metabolism
- Hypothalamus, Anterior/cytology
- Hypothalamus, Anterior/metabolism
- Lac Operon/genetics
- Mice
- Mice, Knockout/genetics
- Mice, Knockout/metabolism
- Mice, Transgenic/genetics
- Mice, Transgenic/metabolism
- Neurons/cytology
- Neurons/metabolism
- Phenotype
- Preoptic Area/cytology
- Preoptic Area/metabolism
- Prosencephalon/cytology
- Prosencephalon/embryology
- Prosencephalon/metabolism
- RNA, Messenger/metabolism
- Receptors, GABA-A/genetics
- Receptors, GABA-A/metabolism
- Septal Nuclei/cytology
- Septal Nuclei/metabolism
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Affiliation(s)
- S X Simonian
- Laboratory of Neuroendocrinology, The Babraham Institute, Babraham, Cambridge, UK
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46
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Kramer PR, Guerrero G, Krishnamurthy R, Mitchell PJ, Wray S. Ectopic expression of luteinizing hormone-releasing hormone and peripherin in the respiratory epithelium of mice lacking transcription factor AP-2alpha. Mech Dev 2000; 94:79-94. [PMID: 10842061 DOI: 10.1016/s0925-4773(00)00316-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The vertebrate transcription factor activator protein-2 (AP-2alpha) is involved in craniofacial morphogenesis. In the nasal placode AP-2alpha expression delineates presumptive respiratory epithelia from olfactory epithelia, with AP-2alpha expression restricted to the anterior region of the respiratory epithelium (absent from the olfactory epithelium) at later stages. To address the role AP-2alpha plays in differentiation of cell groups in the nasal placode, the spatiotemporal expression pattern of four markers normally associated with olfactory epithelial structures was analyzed in mice lacking AP-2alpha. These markers were the intermediate filament protein peripherin, the neuropeptide luteinizing hormone-releasing hormone (LHRH), the neural cell adhesion molecule (NCAM) and the olfactory transcription factor Olf-1. Development of cells expressing these markers was similar in both genotypes until embryonic day 12.5 (E12.5), indicating that the main olfactory epithelium and olfactory pit formation was normal. At E13.5 in mutant mice, ectopic LHRH neurons and peripherin axons were detected in respiratory epithelial areas, areas devoid of Olf-1 and NCAM staining. Over the next few days, an increase in total nasal LHRH neurons occurred. The increase in nasal LHRH neurons could be accounted for by LHRH neurons arising and migrating out of respiratory epithelial regions on peripherin-positive fibers. These results indicate that AP-2alpha is not essential for the separation of the olfactory and respiratory epithelium from the nasal placode and is consistent with AP-2alpha preventing recapitulation of developmental programs within the respiratory epithelium that lead to expression of LHRH and peripherin phenotypes.
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Affiliation(s)
- P R Kramer
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20895, USA
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47
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Kramer PR, Krishnamurthy R, Mitchell PJ, Wray S. Transcription factor activator protein-2 is required for continued luteinizing hormone-releasing hormone expression in the forebrain of developing mice. Endocrinology 2000; 141:1823-38. [PMID: 10803593 DOI: 10.1210/endo.141.5.7452] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
LHRH is the neuropeptide responsible for reproductive function. Prenatally, LHRH expression begins when neurons are in the olfactory pit and continues as these cells migrate into the brain. Thus, LHRH neurons maintain neuropeptide expression through very distinct environments. The regulatory interactions that control onset and continued expression of the LHRH phenotype are unknown. To begin to address this question primary LHRH neurons were removed from nasal explants at different ages. A complementary DNA (cDNA) subtraction screen was performed comparing a 3.5-days in vitro LHRH neuron [approximately embryonic day 15 (E15) in vivo] to two 10.5-days in vitro LHRH neurons (approximately postnatal day 1 in vivo). The transcription factor activator protein-2 (AP-2alpha) was differentially expressed and was present in the developmentally younger LHRH neuron. In vivo analysis revealed that LHRH neurons expressed AP-2 as they migrated across the cribriform plate and into the forebrain beginning on E13.5, but that coexpression of LHRH and AP-2 was no longer detected in postnatal day 1 animals. This suggested a regulatory role for AP-2 in LHRH neurons. Analysis of animals lacking AP-2alpha revealed a dramatic decrease in forebrain LHRH neurons between E13.5 and E14.5, correlating with normal onset of AP-2 expression in LHRH neurons as they entered the central nervous system. Nasal cells robustly expressing LHRH were still present on E 14.5. The continued presence of forebrain LHRH cells is proposed based on a second marker, galanin, and lack of increased apoptotic/necrotic cells in this region. A decrease in LHRH messenger RNA in forebrain neurons indicates regulation of LHRH occurred at the transcriptional or posttranscriptional level in mutant animals. These results indicate a developmentally restricted involvement of the transcription factor AP-2 in LHRH expression once the LHRH neurons have migrated into the forebrain, but before establishment of an adult-like distribution.
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Affiliation(s)
- P R Kramer
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-4156, USA
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48
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Kim KH, Patel L, Tobet SA, King JC, Rubin BS, Stopa EG. Gonadotropin-releasing hormone immunoreactivity in the adult and fetal human olfactory system. Brain Res 1999; 826:220-9. [PMID: 10224299 DOI: 10.1016/s0006-8993(99)01271-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Studies in fetal brain tissue of rodents, nonhuman primates and birds have demonstrated that cells containing gonadotropin-releasing hormone (GnRH) migrate from the olfactory placode across the nasal septum into the forebrain. The purpose of this study was to examine GnRH neurons in components of the adult and fetal human olfactory system. In the adult human brain (n=4), immunoreactive GnRH was evident within diffusely scattered cell bodies and processes in the olfactory bulb, olfactory nerve, olfactory cortex, and nervus terminalis located on the anterior surface of the gyrus rectus. GnRH-immunoreactive structures showed a similar distribution in 20-week human fetal brains (n=2), indicating that the migration of GnRH neurons is complete at this time. In 10-11-week fetal brains (n=2), more cells were noted in the nasal cavity than in the brain. Our data are consistent with observations made in other species, confirming olfactory derivation and migration of GnRH neurons into the brain from the olfactory placode.
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Affiliation(s)
- K H Kim
- Department of Pathology, Division of Neuropathology, Brown University, School of Medicine, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA
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49
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Abstract
Gonadotropin releasing hormone (GnRH) is produced and secreted by neurons dispersed throughout the septal-preoptic and anterior hypothalamic areas in adult birds and mammals. These neurons, essential for a functional brain-pituitary-gonadal axis, differentiate in the olfactory placode, the superior aspect of which forms the olfactory epithelium. To reach their final placement within the brain, GnRH neurons migrate out of the epithelium and along the olfactory nerve to the CNS. This nerve is essential for the entrance of GnRH neurons into the CNS. Due to the importance of the nerve for the proper migration of these neurons, we have used immunocytochemistry, DiI labeling and 1 microm serial plastic-embedded sections to characterize the nerve's earliest development in the embryonic chick (stages 17-21). Initially (stage 17) the zone between the placode and prosencephalon is a cellular mass contiguous with the placode. This cluster, known as epithelioid cells, is positive for some but not all neuronal markers studied. The epithelium itself is negative for all neuronal and glial markers at this early stage. By stage 18, the first neurites emerge from the epithelium; this was confirmed at stage 19 by examination of serial 1 microm plastic sections. There is sequential acquisition of immunoreactivity to neuronal markers from stage 18 to 21. The glial component of the nerve appears at stage 21. Axons originating from epithelium, extend to the border of the CNS as confirmed by DiI labeling at stage 21. Small fascicles have entered the CNS at this stage. As previously reported, GnRH neurons begin their migration between stages 20-21 and have also arrived at the border of the brain at stage 21. Despite the penetration of neurites from the olfactory nerve into the CNS, GnRH neurons pause at the nerve-brain junction until stage 29 (2 1/2 days later) before entering the brain. Subsequent studies will examine the nature of the impediment to continued GnRH neuronal migration.
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Affiliation(s)
- P T Drapkin
- Columbia University, College of Physicians and Surgeons, Department of Anatomy and Cell Biology, New York, New York 10032, USA
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50
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Tobet SA, Henderson RG, Whiting PJ, Sieghart W. Special relationship of gamma-aminobutyric acid to the ventromedial nucleus of the hypothalamus during embryonic development. J Comp Neurol 1999; 405:88-98. [PMID: 10022198 DOI: 10.1002/(sici)1096-9861(19990301)405:1<88::aid-cne7>3.0.co;2-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The ventromedial nucleus of the hypothalamus (VMH) is a key nucleus for regulating homeostatic, neuroendocrine, and behavioral functions. We conducted immunocytochemical analyses by using antisera directed against gamma-aminobutyric acid (GABA), its synthetic enzyme glutamic acid decarboxylase (GAD67), GABA-A receptor subunits (alpha2, beta3, epsilon), estrogen receptor-alpha, and Neuropeptide Y (NPY) in the region of the VMH in embryonic mice to identify potential patterning elements for VMH formation. Cells and fibers containing GABA and GAD67 encircled the primordial VMH as early as embryonic day 13 (E13) when the cytoarchitecture of the VMH was not recognizable by Nissl stain. At E16-17 the cytoarchitecture of the VMH became recognizable by Nissl stain as GABAergic fibers invaded the nucleus, continued postnatally, and by adulthood the density of GABAergic fibers was greater inside than outside the VMH. GABA-A receptor subunit expression (beta3 by E13 and alpha2 by E15) within the primordial VMH suggested potential sensitivity to the surrounding GABA signal. Brain slices were used to test whether fibers from distal or proximal sites influenced VMH development. Coronal Vibratome slices were prepared and maintained in vitro for 0-3 days. Nissl stain analyses showed a uniform distribution of cells in the region of the VMH on the day of plating (E15). After 3 days in vitro, cellular aggregation suggesting VMH formation was seen. Nuclear formation in vitro suggests that key factors resided locally within the coronal plane of the slices. It is suggested that either GABA intrinsic to the region nearby the VMH directly influences the development and organization of the VMH, or along with other markers provides an early indicator of pattern determination that precedes the cellular organization of the VMH.
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Affiliation(s)
- S A Tobet
- Program in Neuroscience, The Shriver Center and Harvard Medical School, Waltham, Massachusetts 02154, USA.
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