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Ruqa WA, Pennacchia F, Rusi E, Zoccali F, Bruno G, Talarico G, Barbato C, Minni A. Smelling TNT: Trends of the Terminal Nerve. Int J Mol Sci 2024; 25:3920. [PMID: 38612730 PMCID: PMC11011448 DOI: 10.3390/ijms25073920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 03/29/2024] [Accepted: 03/30/2024] [Indexed: 04/14/2024] Open
Abstract
There is very little knowledge regarding the terminal nerve, from its implications in the involvement and pathogenesis of certain conditions, to its embryological origin. With this review, we try to summarize the most important evidence on the terminal nerve, aiming to clarify its anatomy and the various functions attributed to it, to better interpret its potential involvement in pathological processes. Recent studies have also suggested its potential role in the control of human reproductive functions and behaviors. It has been hypothesized that it plays a role in the unconscious perception of specific odors that influence autonomic and reproductive hormonal systems through the hypothalamic-pituitary-gonadal axis. We used the PubMed database and found different articles which were then selected independently by three authors. We found 166 articles, of which, after careful selection, only 21 were analyzed. The terminal nerve was always thought to be unimportant in our body. It was well studied in different types of animals, but few studies have been completed in humans. For this reason, its function remains unknown. Studies suggest a possible implication in olfaction due to the anatomical proximity with the olfactive nerve. Others suggest a more important role in reproduction and sexual behaviors. New emerging information suggests a possible role in Kallmann syndrome and COVID-19.
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Affiliation(s)
- Wael Abu Ruqa
- Department of Sense Organs, Sapienza University of Rome, Policlinico Umberto I, 00161 Roma, Italy; (W.A.R.); (F.P.); (F.Z.)
| | - Fiorenza Pennacchia
- Department of Sense Organs, Sapienza University of Rome, Policlinico Umberto I, 00161 Roma, Italy; (W.A.R.); (F.P.); (F.Z.)
| | - Eqrem Rusi
- Department of Human Neuroscience, Sapienza University of Rome, 00185 Rome, Italy; (E.R.); (G.B.); (G.T.)
| | - Federica Zoccali
- Department of Sense Organs, Sapienza University of Rome, Policlinico Umberto I, 00161 Roma, Italy; (W.A.R.); (F.P.); (F.Z.)
| | - Giuseppe Bruno
- Department of Human Neuroscience, Sapienza University of Rome, 00185 Rome, Italy; (E.R.); (G.B.); (G.T.)
| | - Giuseppina Talarico
- Department of Human Neuroscience, Sapienza University of Rome, 00185 Rome, Italy; (E.R.); (G.B.); (G.T.)
| | - Christian Barbato
- Institute of Biochemistry and Cell Biology (IBBC-CNR), Sapienza University Rome, Policlinico Umberto I, 00161 Roma, Italy
| | - Antonio Minni
- Department of Sense Organs, Sapienza University of Rome, Policlinico Umberto I, 00161 Roma, Italy; (W.A.R.); (F.P.); (F.Z.)
- Division of Otolaryngology-Head and Neck Surgery, ASL Rieti-Sapienza University, Ospedale San Camillo de Lellis, 02100 Rieti, Italy
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López-Ojeda W, Hurley RA. Cranial Nerve Zero (CN 0): Multiple Names and Often Discounted yet Clinically Significant. J Neuropsychiatry Clin Neurosci 2022; 34:A4-99. [PMID: 35491548 DOI: 10.1176/appi.neuropsych.22010021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wilfredo López-Ojeda
- Veterans Affairs Mid-Atlantic Mental Illness Research, Education, and Clinical Center and Research and Academic Affairs Service Line, W.G. Hefner Veterans Affairs Medical Center, Salisbury, N.C. (López-Ojeda, Hurley); Departments of Psychiatry and Behavioral Medicine (López-Ojeda, Hurley) and Radiology (Hurley), Wake Forest School of Medicine, Winston-Salem, N.C.; Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston (Hurley)
| | - Robin A Hurley
- Veterans Affairs Mid-Atlantic Mental Illness Research, Education, and Clinical Center and Research and Academic Affairs Service Line, W.G. Hefner Veterans Affairs Medical Center, Salisbury, N.C. (López-Ojeda, Hurley); Departments of Psychiatry and Behavioral Medicine (López-Ojeda, Hurley) and Radiology (Hurley), Wake Forest School of Medicine, Winston-Salem, N.C.; Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston (Hurley)
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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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Bilinska K, von Bartheld CS, Butowt R. Expression of the ACE2 Virus Entry Protein in the Nervus Terminalis Reveals the Potential for an Alternative Route to Brain Infection in COVID-19. Front Cell Neurosci 2021; 15:674123. [PMID: 34290590 PMCID: PMC8287262 DOI: 10.3389/fncel.2021.674123] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/09/2021] [Indexed: 12/11/2022] Open
Abstract
Previous studies suggested that the SARS-CoV-2 virus may gain access to the brain by using a route along the olfactory nerve. However, there is a general consensus that the obligatory virus entry receptor, angiotensin converting enzyme 2 (ACE2), is not expressed in olfactory receptor neurons, and the timing of arrival of the virus in brain targets is inconsistent with a neuronal transfer along olfactory projections. We determined whether nervus terminalis neurons and their peripheral and central projections should be considered as a potential alternative route from the nose to the brain. Nervus terminalis neurons in postnatal mice were double-labeled with antibodies against ACE2 and two nervus terminalis markers, gonadotropin-releasing hormone (GnRH) and choline acetyltransferase (CHAT). We show that a small fraction of CHAT-labeled nervus terminalis neurons, and the large majority of GnRH-labeled nervus terminalis neurons with cell bodies in the region between the olfactory epithelium and the olfactory bulb express ACE2 and cathepsins B and L. Nervus terminalis neurons therefore may provide a direct route for the virus from the nasal epithelium, possibly via innervation of Bowman's glands, to brain targets, including the telencephalon and diencephalon. This possibility needs to be examined in suitable animal models and in human tissues.
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Affiliation(s)
- Katarzyna Bilinska
- L. Rydygier Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Christopher S. von Bartheld
- Department of Physiology and Cell Biology, Reno School of Medicine, University of Nevada, Reno, NV, United States
| | - Rafal Butowt
- L. Rydygier Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
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Bilinska K, von Bartheld CS, Butowt R. Expression of the ACE2 virus entry protein in the nervus terminalis reveals the potential for an alternative route to brain infection in COVID-19. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.04.11.439398. [PMID: 33880469 PMCID: PMC8057234 DOI: 10.1101/2021.04.11.439398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Previous studies suggested that the SARS-CoV-2 virus may gain access to the brain by using a route along the olfactory nerve. However, there is a general consensus that the obligatory virus entry receptor, angiotensin converting enzyme 2 (ACE2), is not expressed in olfactory receptor neurons, and the timing of arrival of the virus in brain targets is inconsistent with a neuronal transfer along olfactory projections. We determined whether nervus terminalis neurons and their peripheral and central projections should be considered as a potential alternative route from the nose to the brain. Nervus terminalis neurons in postnatal mice were double-labeled with antibodies against ACE2 and two nervus terminalis markers, gonadotropin-releasing hormone (GnRH) and choline acetyltransferase (CHAT). We show that a small fraction of CHAT-labeled nervus terminalis neurons, and the large majority of GnRH-labeled nervus terminalis neurons with cell bodies in the region between the olfactory epithelium and the olfactory bulb express ACE2 and cathepsins B and L. Nervus terminalis neurons therefore may provide a direct route for the virus from the nasal epithelium, possibly via innervation of Bowman's glands, to brain targets, including the telencephalon and diencephalon. This possibility needs to be examined in suitable animal models and in human tissues.
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Affiliation(s)
- Katarzyna Bilinska
- L. Rydygier Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Christopher S. von Bartheld
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV, United States
| | - Rafal Butowt
- L. Rydygier Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
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Abstract
Many of the recent advances in our understanding of human reproductive biology and its genetic basis have arisen directly via the genetic investigation of patients with Kallmann syndrome and their families. The disease is characterised by the association of an isolated defect in the secretion (or, less commonly, action) of gonadotropin-releasing hormone (GnRH) and consequent infertility, with anosmia and potentially other associated non-reproductive features. GnRH-producing neurons are located in the hypothalamic brain region after a peculiar migration during embryonic life. To date, different genes affecting GnRH neuron development/migration have so far been implicated in Kallmann syndrome, but our knowledge of the genetic basis of the syndrome remains incomplete. From a clinical point of view, the disease has suffered from a lack of definitive diagnosis and treatment, and although progress has been made in terms of timely diagnosis and evidence-based treatment of patients, implementation remains inconsistent. These aspects will be discussed in this review, which examines new strategies for arriving at more evidence-based and patient-centred medical practice in Kallmann syndrome.
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Affiliation(s)
- Du Soon Swee
- Department of Endocrinology, Singapore General Hospital, Singapore
| | - Richard Quinton
- Department of Endocrinology, Diabetes & Metabolism, Royal Victoria Infirmary, Newcastle-Upon-Tyne Hospitals, Newcastle-upon-Tyne, UK
- Translational & Clinical Research Institute, University of Newcastle-upon-Tyne, Newcastle-Upon-Tyne, UK
| | - Roberto Maggi
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Milan, MI, Italy
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Abstract
An increase in pulsatile release of gonadotropin releasing hormone (GnRH) initiates puberty in mammalian species. While mutations in KISS1 and TAC3 and their receptors, KISS1R and NK3R, respectively, result in the absence or abnormal timing of puberty, the neurocircuitry and precise role of kisspeptin and neurokinin B (NKB) in regulation of the GnRH neurosecretory system in primate puberty remain elusive. This review discusses how kisspeptin and NKB signaling contributes to the pubertal increase in GnRH release in non-human primates and how remodeling of the NKB and kisspeptin signaling circuitry controlling GnRH neurons takes place during the progress of puberty. Importantly, the pubertal remodeling of kisspeptin and NKB signaling ensures efficient functions of the GnRH neurosecretory system that regulates sex-specific reproduction in primates.
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Affiliation(s)
- Ei Terasawa
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53706, USA.,Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715, USA
| | - James P Garcia
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715, USA
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Jin ZW, Cho KH, Shibata S, Yamamoto M, Murakami G, Rodríguez-Vázquez JF. Nervus terminalis and nerves to the vomeronasal organ: a study using human fetal specimens. Anat Cell Biol 2019; 52:278-285. [PMID: 31598357 PMCID: PMC6773908 DOI: 10.5115/acb.19.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 03/19/2019] [Accepted: 03/19/2019] [Indexed: 02/08/2023] Open
Abstract
The human nervus terminalis (terminal nerve) and the nerves to the vomeronasal organ (VNON) are both associated with the olfactory nerves and are of major interest to embryologists. However, there is still limited knowledge on their topographical anatomy in the nasal septum and on the number and distribution of ganglion cells along and near the cribriform plate of the ethmoid bone. We observed serial or semiserial sections of 30 fetuses at 7-18 weeks (crown rump length [CRL], 25-160 mm). Calretinin and S100 protein staining demonstrated not only the terminal nerve along the anterior edge of the perpendicular lamina of the ethmoid, but also the VNON along the posterior edge of the lamina. The terminal nerve was composed of 1-2 nerve bundles that passed through the anterior end of the cribriform plate, whereas the VNON consisted of 2-3 bundles behind the olfactory nerves. The terminal nerve ran along and crossed the posterior side of the nasal branch of the anterior ethmoidal nerve. Multiple clusters of small ganglion cells were found on the lateral surfaces of the ethmoid's crista galli, which are likely the origin of both the terminal nerve and VNON. The ganglions along the crista galli were ball-like and 15-20 µm in diameter and, ranged from 40-153 in unilateral number according to our counting at 21-µm-interval except for one specimen (480 neurons; CRL, 137 mm). An effect of nerve degeneration with increasing age seemed to be masked by a remarkable individual difference.
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Affiliation(s)
- Zhe Wu Jin
- Department of Anatomy, Wuxi School of Medicine, Jiangnan University, Wuxi, China
| | - Kwang Ho Cho
- Department of Neurology, Wonkwang University School of Medicine and Hospital, Institute of Wonkwang Medical Science, Iksan, Korea
| | - Shunichi Shibata
- Department of Maxillofacial Anatomy, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan
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Casoni F, Malone SA, Belle M, Luzzati F, Collier F, Allet C, Hrabovszky E, Rasika S, Prevot V, Chédotal A, Giacobini P. Development of the neurons controlling fertility in humans: new insights from 3D imaging and transparent fetal brains. Development 2016; 143:3969-3981. [DOI: 10.1242/dev.139444] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 09/05/2016] [Indexed: 12/12/2022]
Abstract
Fertility in mammals is controlled by hypothalamic neurons that secrete gonadotropin-releasing hormone (GnRH). These neurons differentiate in the olfactory placodes during embryogenesis and migrate from the nose to the hypothalamus before birth. Information regarding this process in humans is sparse. Here, we adapted new tissue-clearing and whole-mount immunohistochemical techniques to entire human embryos/fetuses to meticulously study this system during the first trimester of gestation in the largest series of human fetuses examined to date. Combining these cutting-edge techniques with conventional immunohistochemistry, we provide the first chronological and quantitative analysis of GnRH neuron origins, differentiation and migration, as well as a 3D atlas of their distribution in the fetal brain. We reveal not only that the number of GnRH-immunoreactive neurons in humans is significantly higher than previously thought, but that GnRH cells migrate into several extrahypothalamic brain regions in addition to the hypothalamus. Their presence in these areas raises the possibility that GnRH has non-reproductive roles, creating new avenues for research on GnRH functions in cognitive, behavioral and physiological processes.
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Affiliation(s)
- Filippo Casoni
- University of Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille 59000, France
- Inserm, UMR-S 1172, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille 59000, France
| | - Samuel A. Malone
- University of Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille 59000, France
- Inserm, UMR-S 1172, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille 59000, France
| | - Morgane Belle
- Sorbonne Université, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | - Federico Luzzati
- Department of Life Sciences and Systems Biology (DBIOS), University of Turin, Turin 10123, Italy
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano 10043, Italy
| | - Francis Collier
- FHU 1,000 Days for Health, University of Lille, School of Medicine, Lille 5900, France
- CHU Lille, Gynaecology Service - Hospital Jeanne de Flandre, Lille 59000, France
| | - Cecile Allet
- University of Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille 59000, France
- Inserm, UMR-S 1172, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille 59000, France
| | - Erik Hrabovszky
- Institute of Experimental Medicine, Laboratory of Endocrine Neurobiology, Budapest 1083, Hungary
| | | | - Vincent Prevot
- University of Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille 59000, France
- Inserm, UMR-S 1172, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille 59000, France
- FHU 1,000 Days for Health, University of Lille, School of Medicine, Lille 5900, France
| | - Alain Chédotal
- Sorbonne Université, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision, Paris 75012, France
| | - Paolo Giacobini
- University of Lille, UMR-S 1172 - JPArc - Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille 59000, France
- Inserm, UMR-S 1172, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille 59000, France
- FHU 1,000 Days for Health, University of Lille, School of Medicine, Lille 5900, France
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Lund C, Pulli K, Yellapragada V, Giacobini P, Lundin K, Vuoristo S, Tuuri T, Noisa P, Raivio T. Development of Gonadotropin-Releasing Hormone-Secreting Neurons from Human Pluripotent Stem Cells. Stem Cell Reports 2016; 7:149-57. [PMID: 27426041 PMCID: PMC4982984 DOI: 10.1016/j.stemcr.2016.06.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 06/13/2016] [Accepted: 06/15/2016] [Indexed: 12/18/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons regulate human puberty and reproduction. Modeling their development and function in vitro would be of interest for both basic research and clinical translation. Here, we report a three-step protocol to differentiate human pluripotent stem cells (hPSCs) into GnRH-secreting neurons. Firstly, hPSCs were differentiated to FOXG1, EMX2, and PAX6 expressing anterior neural progenitor cells (NPCs) by dual SMAD inhibition. Secondly, NPCs were treated for 10 days with FGF8, which is a key ligand implicated in GnRH neuron ontogeny, and finally, the cells were matured with Notch inhibitor to bipolar TUJ1-positive neurons that robustly expressed GNRH1 and secreted GnRH decapeptide into the culture medium. The protocol was reproducible both in human embryonic stem cells and induced pluripotent stem cells, and thus provides a translational tool for investigating the mechanisms of human puberty and its disorders. GnRH neurons regulate puberty and reproduction We generated GnRH-expressing and secreting neurons from hPSCs These neurons can be used to study diseases affecting the reproductive system
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Affiliation(s)
- Carina Lund
- Faculty of Medicine, Department of Physiology, University of Helsinki, Helsinki 00014, Finland
| | - Kristiina Pulli
- Faculty of Medicine, Department of Physiology, University of Helsinki, Helsinki 00014, Finland
| | - Venkatram Yellapragada
- Faculty of Medicine, Department of Physiology, University of Helsinki, Helsinki 00014, Finland
| | - Paolo Giacobini
- Inserm, Jean-Pierre Aubert Research Center, Development and Plasticity of the Neuroendocrine Brain, Unité 1172, 59045 Lille Cedex, France; School of Medicine, University of Lille, Lille 59000, France
| | - Karolina Lundin
- Department of Obstetrics and Gynecology, HUCH, Helsinki 00029, Finland
| | - Sanna Vuoristo
- Faculty of Medicine, Department of Physiology, University of Helsinki, Helsinki 00014, Finland
| | - Timo Tuuri
- Department of Obstetrics and Gynecology, HUCH, Helsinki 00029, Finland
| | - Parinya Noisa
- School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; Faculty of Medicine/Physiology, University of Helsinki, Biomedicum Helsinki, PO Box 63 (Haartmaninkatu 8), Helsinki 00014, Finland
| | - Taneli Raivio
- Faculty of Medicine, Department of Physiology, University of Helsinki, Helsinki 00014, Finland; Children's Hospital, Pediatric Research Center, Helsinki University Central Hospital (HUCH), Helsinki 00029, Finland; Faculty of Medicine/Physiology, University of Helsinki, Biomedicum Helsinki, PO Box 63 (Haartmaninkatu 8), Helsinki 00014, Finland.
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Maggi R, Cariboni AM, Marelli MM, Moretti RM, Andrè V, Marzagalli M, Limonta P. GnRH and GnRH receptors in the pathophysiology of the human female reproductive system. Hum Reprod Update 2015; 22:358-81. [PMID: 26715597 DOI: 10.1093/humupd/dmv059] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 12/03/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Human reproduction depends on an intact hypothalamic-pituitary-gonadal (HPG) axis. Hypothalamic gonadotrophin-releasing hormone (GnRH) has been recognized, since its identification in 1971, as the central regulator of the production and release of the pituitary gonadotrophins that, in turn, regulate the gonadal functions and the production of sex steroids. The characteristic peculiar development, distribution and episodic activity of GnRH-producing neurons have solicited an interdisciplinary interest on the etiopathogenesis of several reproductive diseases. The more recent identification of a GnRH/GnRH receptor (GnRHR) system in both the human endometrium and ovary has widened the spectrum of action of the peptide and of its analogues beyond its hypothalamic function. METHODS An analysis of research and review articles published in international journals until June 2015 has been carried out to comprehensively summarize both the well established and the most recent knowledge on the physiopathology of the GnRH system in the central and peripheral control of female reproductive functions and diseases. RESULTS This review focuses on the role of GnRH neurons in the control of the reproductive axis. New knowledge is accumulating on the genetic programme that drives GnRH neuron development to ameliorate the diagnosis and treatment of GnRH deficiency and consequent delayed or absent puberty. Moreover, a better understanding of the mechanisms controlling the episodic release of GnRH during the onset of puberty and the ovulatory cycle has enabled the pharmacological use of GnRH itself or its synthetic analogues (agonists and antagonists) to either stimulate or to block the gonadotrophin secretion and modulate the functions of the reproductive axis in several reproductive diseases and in assisted reproduction technology. Several inputs from other neuronal populations, as well as metabolic, somatic and age-related signals, may greatly affect the functions of the GnRH pulse generator during the female lifespan; their modulation may offer new possible strategies for diagnostic and therapeutic interventions. A GnRH/GnRHR system is also expressed in female reproductive tissues (e.g. endometrium and ovary), both in normal and pathological conditions. The expression of this system in the human endometrium and ovary supports its physiological regulatory role in the processes of trophoblast invasion of the maternal endometrium and embryo implantation as well as of follicular development and corpus luteum functions. The GnRH/GnRHR system that is expressed in diseased tissues of the female reproductive tract (both benign and malignant) is at present considered an effective molecular target for the development of novel therapeutic approaches for these pathologies. GnRH agonists are also considered as a promising therapeutic approach to counteract ovarian failure in young female patients undergoing chemotherapy. CONCLUSIONS Increasing knowledge about the regulation of GnRH pulsatile release, as well as the therapeutic use of its analogues, offers interesting new perspectives in the diagnosis, treatment and outcome of female reproductive disorders, including tumoral and iatrogenic diseases.
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Affiliation(s)
- Roberto Maggi
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via G. Balzaretti, 9, 20133 Milano, Italy
| | - Anna Maria Cariboni
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via G. Balzaretti, 9, 20133 Milano, Italy
| | - Marina Montagnani Marelli
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via G. Balzaretti, 9, 20133 Milano, Italy
| | - Roberta Manuela Moretti
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via G. Balzaretti, 9, 20133 Milano, Italy
| | - Valentina Andrè
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via G. Balzaretti, 9, 20133 Milano, Italy
| | - Monica Marzagalli
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via G. Balzaretti, 9, 20133 Milano, Italy
| | - Patrizia Limonta
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via G. Balzaretti, 9, 20133 Milano, Italy
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Wolfe A, Divall S, Wu S. The regulation of reproductive neuroendocrine function by insulin and insulin-like growth factor-1 (IGF-1). Front Neuroendocrinol 2014; 35:558-72. [PMID: 24929098 PMCID: PMC4175134 DOI: 10.1016/j.yfrne.2014.05.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 04/01/2014] [Accepted: 05/27/2014] [Indexed: 12/27/2022]
Abstract
The mammalian reproductive hormone axis regulates gonadal steroid hormone levels and gonadal function essential for reproduction. The neuroendocrine control of the axis integrates signals from a wide array of inputs. The regulatory pathways important for mediating these inputs have been the subject of numerous studies. One class of proteins that have been shown to mediate metabolic and growth signals to the CNS includes Insulin and IGF-1. These proteins are structurally related and can exert endocrine and growth factor like action via related receptor tyrosine kinases. The role that insulin and IGF-1 play in controlling the hypothalamus and pituitary and their role in regulating puberty and nutritional control of reproduction has been studied extensively. This review summarizes the in vitro and in vivo models that have been used to study these neuroendocrine structures and the influence of these growth factors on neuroendocrine control of reproduction.
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Affiliation(s)
- Andrew Wolfe
- Johns Hopkins University School of Medicine, Department of Pediatrics, Division of Endocrinology, Baltimore, MD 21287, United States.
| | - Sara Divall
- Johns Hopkins University School of Medicine, Department of Pediatrics, Division of Endocrinology, Baltimore, MD 21287, United States
| | - Sheng Wu
- Johns Hopkins University School of Medicine, Department of Pediatrics, Division of Endocrinology, Baltimore, MD 21287, United States
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Zempo B, Kanda S, Okubo K, Akazome Y, Oka Y. Anatomical distribution of sex steroid hormone receptors in the brain of female medaka. J Comp Neurol 2013; 521:1760-80. [PMID: 23124931 DOI: 10.1002/cne.23255] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 01/27/2012] [Accepted: 10/25/2012] [Indexed: 12/19/2022]
Abstract
Estrogen and androgen play crucial roles in coordinating reproductive functions through estrogen receptors (ERs) and androgen receptors (ARs), respectively. These receptors are considered important for regulation of the hypothalamo-pituitary-gonadal (HPG) axis. Despite their biological importance, the distribution of sex steroid receptors has not been fully analyzed anatomically in the teleost brain. The teleosts have many characteristic features, which allow unique approaches toward an understanding of the regulatory mechanisms of reproductive functions. Medaka serves as a good model system for studying the mechanisms by which steroid receptor-mediated systems are regulated, because (1) their breeding conditions can be easily manipulated; (2) we can take advantage of the genome database; and 3) molecular genetic tools, such as transgenic techniques, are applicable. We analyzed the distribution of ERα, ERβ1, ERβ2, ARα, and ARβ mRNA by in situ hybridization in the brain of female medaka. We found that all subtypes of ERs and ARs were expressed in the following nuclei: the dorsal part of the ventral telencephalic area (Vd), supracommissural part of the ventral telencephalic area (Vs), postcommissural part of the ventral telencephalic area (Vp), preoptic area (POA), and nucleus ventralis tuberis (NVT). These regions are known to be involved in the regulation of sexual behavior (Vd, Vs, Vp, POA) or the HPG axis (NVT). These ER- and/or AR-expressing neurons may regulate sexual behavior or the HPG axis according to their axonal projections. Future analysis should be targeted to the neurons described in the present study to extend our understanding of the central regulatory mechanisms of reproduction.
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Affiliation(s)
- Buntaro Zempo
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
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Kawai T, Abe H, Oka Y. Burst generation mediated by cholinergic input in terminal nerve-gonadotrophin releasing hormone neurones of the goldfish. J Physiol 2013; 591:5509-23. [PMID: 23959678 DOI: 10.1113/jphysiol.2013.258343] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Peptidergic neurones play a pivotal role in the neuromodulation of widespread areas in the nervous system. Generally, it has been accepted that the peptide release from these neurones is regulated by their firing activities. The terminal nerve (TN)-gonadotrophin releasing hormone (GnRH) neurones, which are one of the well-studied peptidergic neurones in vertebrate brains, are characterised by their spontaneous regular pacemaker activities, and GnRH has been suggested to modulate the sensory responsiveness of animals. Although many peptidergic neurones are known to exhibit burst firing activities when they release the peptides, TN-GnRH neurones show spontaneous burst firing activities only infrequently. Thus, it remains to be elucidated whether the TN-GnRH neurones show burst activities and, if so, how the mode switching between the regular pacemaking and bursting modes is regulated in these neurones. In this study, we found that only a single pulse electrical stimulation of the neuropil surrounding the TN-GnRH neurones reproducibly induces transient burst activities in TN-GnRH neurones. Our combined physiological and morphological data suggest that this phenomenon occurs following slow inhibitory postsynaptic potentials mediated by cholinergic terminals surrounding the TN-GnRH neurones. We also found that the activation of muscarinic acetylcholine receptors induces persistent opening of potassium channels, resulting in a long-lasting hyperpolarisation. This long hyperpolarisation induces sustained rebound depolarisation that has been suggested to be generated by a combination of persistent voltage-gated Na(+) channels and low-voltage-activated Ca(2+) channels. These new findings suggest a novel type of cholinergic regulation of burst activities in peptidergic neurones, which should contribute to the release of neuropeptides.
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Affiliation(s)
- Takafumi Kawai
- Y. Oka: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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15
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Moeller JF, Meredith M. Differential co-localization with choline acetyltransferase in nervus terminalis suggests functional differences for GnRH isoforms in bonnethead sharks (Sphyrna tiburo). Brain Res 2010; 1366:44-53. [PMID: 20950589 PMCID: PMC2993777 DOI: 10.1016/j.brainres.2010.10.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 10/05/2010] [Accepted: 10/06/2010] [Indexed: 11/22/2022]
Abstract
The nervus terminalis (NT) is a vertebrate cranial nerve whose function in adults is unknown. In bonnethead sharks, the nerve is anatomically independent of the olfactory system, with two major cell populations within one or more ganglia along its exposed length. Most cells are immunoreactive for either gonadotropin-releasing hormone (GnRH) or RF-amide-like peptides. To define further the cell populations and connectivity, we used double-label immunocytochemistry with antisera to different isoforms of GnRH and to choline acetyltransferase (ChAT). The labeling patterns of two GnRH antisera revealed different populations of GnRH-immunoreactive (ir) cell profiles in the NT ganglion. One antiserum labeled a large group of cells and fibers, which likely contain mammalian GnRH (GnRH-I) as described in previous studies and which were ChAT immunoreactive. The other antiserum labeled large club-like structures, which were anuclear, and a sparse number of fibers, but with no clear labeling of cell bodies in the ganglion. These club structures were choline acetyltrasferase (ChAT)-negative, and preabsorption control tests suggest they may contain chicken-GnRH-II (GnRH-II) or dogfish GnRH. The second major NT ganglion cell-type was immunoreactive for RF-amides, which regulate GnRH release in other vertebrates, and may provide an intraganglionic influence on GnRH release. The immunocytochemical and anatomical differences between the two GnRH-immunoreactive profile types indicate possible functional differences for these isoforms in the NT. The club-like structures may be sites of GnRH release into the general circulation since these structures were observed near blood vessels and resembled structures seen in the median eminence of rats.
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Affiliation(s)
- John F. Moeller
- Program in Neuroscience, Department of Biological Sciences, Florida State University, Tallahassee, FL 32306
| | - Michael Meredith
- Program in Neuroscience, Department of Biological Sciences, Florida State University, Tallahassee, FL 32306
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16
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Kawai T, Abe H, Akazome Y, Oka Y. Neuromodulatory Effect of GnRH on the Synaptic Transmission of the Olfactory Bulbar Neural Circuit in Goldfish, Carassius auratus. J Neurophysiol 2010; 104:3540-50. [DOI: 10.1152/jn.00639.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) is well known as a hypophysiotropic hormone that is produced in the hypothalamus and facilitates the release of gonadotropins from the pituitary gonadotropes. On the other hand, the functions of extrahypothalamic GnRH systems still remain elusive. Here we examined whether the activity of the olfactory bulbar neural circuits is modulated by GnRH that originates mainly from the terminal nerve (TN) GnRH system in goldfish ( Carassius auratus). As the morphological basis, we first observed that goldfish TNs mainly express salmon GnRH (sGnRH) mRNA and that sGnRH-immunoreactive fibers are distributed in both the mitral and the granule cell layers. We then examined by extracellular recordings the effect of GnRH on the electrically evoked in vitro field potentials that arise from synaptic activities from mitral to granule cells. We found that GnRH enhances the amplitude of the field potentials. Furthermore, these effects were observed in both cases when the field potentials were evoked by stimulating either the lateral or the medial olfactory tract, conveying functionally different sensory information, separately, and suggesting that GnRH may modulate the responsiveness to wide categories of odorants in the olfactory bulb. Because GnRH also changed the paired-pulse ratio, it is suggested that the increased amplitude of the field potential results from changes in the presynaptic glutamate release of mitral cells rather than the increase in the glutamate receptor sensitivity of granule cells. These results suggest that TN regulates the olfactory responsiveness of animals appropriately by releasing sGnRH peptides in the olfactory bulbar neural circuits.
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Affiliation(s)
- Takafumi Kawai
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Hideki Abe
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Yasuhisa Akazome
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Yoshitaka Oka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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Kawai T, Oka Y, Eisthen H. The role of the terminal nerve and GnRH in olfactory system neuromodulation. Zoolog Sci 2010; 26:669-80. [PMID: 19832678 DOI: 10.2108/zsj.26.669] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Animals must regulate their sensory responsiveness appropriately with respect to their internal and external environments, which is accomplished in part via centrifugal modulatory pathways. In the olfactory sensory system, responsiveness is regulated by neuromodulators released from centrifugal fibers into the olfactory epithelium and bulb. Among the modulators known to modulate neural activity of the olfactory system, one of the best understood is gonadotropin-releasing hormone (GnRH). This is because GnRH derives mainly from the terminal nerve (TN), and the TN-GnRH system has been suggested to function as a neuromodulator in wide areas of the brain, including the olfactory bulb. In the present article we examine the modulatory roles of the TN and GnRH in the olfactory epithelium and bulb as a model for understanding the ways in which olfactory responses can be tuned to the internal and external environments.
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Affiliation(s)
- Takafumi Kawai
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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18
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Abraham E, Palevitch O, Gothilf Y, Zohar Y. Targeted gonadotropin-releasing hormone-3 neuron ablation in zebrafish: effects on neurogenesis, neuronal migration, and reproduction. Endocrinology 2010; 151:332-40. [PMID: 19861502 DOI: 10.1210/en.2009-0548] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hypophysiotropic GnRH neurons are located in the preoptic area and ventral hypothalamus of sexually mature vertebrates. In several species, the embryonic origin of hypophysiotropic GnRH neurons remains unclear. Using the Tg(GnRH3:EGFP) zebrafish line, in which GnRH3 neurons express EGFP, GnRH3 neurons in the olfactory region were specifically and individually ablated during early development using laser pulses. After ablation, the olfactory region maintained the capacity to regenerate GnRH3 neurons. However, this capacity was time-limited. When ablation of GnRH3 cells was conducted at 2 d after fertilization, high regeneration rates were observed, but regeneration capacity significantly decreased when ablation was performed at 4 or 6 d after fertilization. Unilateral GnRH3 neuron ablation results in unilateral soma presence. These unilateral somata are capable of projecting fiber extensions bilaterally. Successful bilateral GnRH3 soma ablation during development resulted in complete lack of olfactory, terminal nerve, preoptic area, and hypothalamic GnRH3 neurons and fibers in 12-wk-old animals. Mature animals lacking GnRH3 neurons exhibited arrested oocyte development and reduced average oocyte diameter. Animals in which GnRH3 neurons were partially ablated exhibited normal oocyte development; however, their fecundity was significantly reduced. These findings demonstrate that the hypophysiotropic GnRH3 populations in zebrafish consist of neurons that originate in the olfactory region during early development. The presence of GnRH3 neurons of olfactory region origin in reproductively mature zebrafish is a prerequisite for normal oocyte development and reproduction.
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Affiliation(s)
- Eytan Abraham
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA
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Witt M, Hummel T. Vomeronasal versus olfactory epithelium: is there a cellular basis for human vomeronasal perception? INTERNATIONAL REVIEW OF CYTOLOGY 2006; 248:209-59. [PMID: 16487792 DOI: 10.1016/s0074-7696(06)48004-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The vomeronasal organ (VNO) constitutes an accessory olfactory organ that receives chemical stimuli, pheromones, which elicit behavioral, reproductive, or neuroendocrine responses among individuals of the same species. In many macrosmatic animals, the morphological substrate constitutes a separate organ system consisting of a vomeronasal duct (ductus vomeronasalis, VND), equipped with chemosensory cells, and a vomeronasal nerve (nervus vomeronasalis, VNN) conducting information into the accessory olfactory bulb (AOB) in the central nervous system (CNS). Recent data require that the long-accepted dual functionality of a main olfactory system and the VNO be reexamined, since all species without a VNO are nevertheless sexually active, and species possessing a VNO also can sense other than "vomeronasal" stimuli via the vomeronasal epithelium (VNE). The human case constitutes a borderline situation, as its embryonic VNO anlage exerts a developmental track common to most macrosmatics, but later typical structures such as the VNN, AOB, and probably most of the chemoreceptor cells within the still existent VND are lost. This review also presents recent information on the VND including immunohistochemical expression of neuronal markers, intermediate filaments, lectins, integrins, caveolin, CD44, and aquaporins. Further, we will address the issue of human pheromone candidates.
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Affiliation(s)
- Martin Witt
- Department of Anatomy, University of Technology Dresden, Dresden, Germany
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Romanelli RG, Barni T, Maggi M, Luconi M, Failli P, Pezzatini A, Pelo E, Torricelli F, Crescioli C, Ferruzzi P, Salerno R, Marini M, Rotella CM, Vannelli GB. Expression and function of gonadotropin-releasing hormone (GnRH) receptor in human olfactory GnRH-secreting neurons: an autocrine GnRH loop underlies neuronal migration. J Biol Chem 2003; 279:117-26. [PMID: 14565958 DOI: 10.1074/jbc.m307955200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Olfactory neurons and gonadotropin-releasing hormone (GnRH) neurons share a common origin during organogenesis. Kallmann's syndrome, clinically characterized by anosmia and hypogonadotropic hypogonadism, is due to an abnormality in the migration of olfactory and GnRH neurons. We recently characterized the human FNC-B4 cell line, which retains properties present in vivo in both olfactory and GnRH neurons. In this study, we found that FNC-B4 neurons expressed GnRH receptor and responded to GnRH with time- and dose-dependent increases in GnRH gene expression and protein release (up to 5-fold). In addition, GnRH and its analogs stimulated cAMP production and calcium mobilization, although at different biological thresholds (nanomolar for cAMP and micromolar concentrations for calcium). We also observed that GnRH triggered axon growth, actin cytoskeleton remodeling, and a dose-dependent increase in migration (up to 3-4-fold), whereas it down-regulated nestin expression. All these effects were blocked by a specific GnRH receptor antagonist, cetrorelix. We suggest that GnRH, secreted by olfactory neuroblasts, acts in an autocrine pattern to promote differentiation and migration of those cells that diverge from the olfactory sensory lineage and are committed to becoming GnRH neurons.
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Affiliation(s)
- Roberto Giulio Romanelli
- Department of Internal Medicine, University of Florence, School of Medicine, Florence I-50134, Italy
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Cunto FD, Imarisio S, Camera P, Boitani C, Altruda F, Silengo L. Essential role of citron kinase in cytokinesis of spermatogenic precursors. J Cell Sci 2002; 115:4819-26. [PMID: 12432070 DOI: 10.1242/jcs.00163] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During spermatogenesis, the first morphological indication of spermatogonia differentiation is incomplete cytokinesis, followed by the assembly of stable intercellular cytoplasmic communications. This distinctive feature of differentiating male germ cells has been highly conserved during evolution, suggesting that regulation of the cytokinesis endgame is a crucial aspect of spermatogenesis. However, the molecular mechanisms underlying testis-specific regulation of cytokinesis are still largely unknown. Citron kinase is a myotonin-related protein acting downstream of the GTPase Rho in cytokinesis control. We previously reported that Citron kinase knockout mice are affected by a complex neurological syndrome caused by cytokinesis block and apoptosis of specific neuronal precursors. In this report we show that, in addition, these mice display a dramatic testicular impairment, with embryonic and postnatal loss of undifferentiated germ cells and complete absence of mature spermatocytes. By contrast, the ovaries of mutant females appear essentially normal. Developmental analysis revealed that the cellular depletion observed in mutant testes is caused by increased apoptosis of undifferentiated and differentiating precursors. The same cells display a severe cytokinesis defect, resulting in the production of multinucleated cells and apoptosis. Our data indicate that Citron kinase is specifically required for cytokinesis of the male germ line.
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Affiliation(s)
- Ferdinando Di Cunto
- Department of Genetics, Biology and Biochemistry, Via Santena 5 bis, Torino, Italy.
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22
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Abstract
"Intellectual excellence lies in having faith in the observation of apparently nontranscendental and unimportant facts. To observe an anatomic element calmly, with an open, analytical spirit, and with spiritual freedom, can lead to an explosive vortex of new knowledge."-Miguel Orticochea, M.D.(1) Traditional descriptive embryology based upon the interaction of frontonasal, lateral nasal, and medial nasal prominences is incapable of explaining the three-dimensional development of the facial midline. The internal structure of the nose and that of the oronasal midline can best be explained by the presence of paired A fields originating from the prechordal mesendoderm, associated with the nasal and optic placodes, supplied by the internal carotid artery, and sharing a common genetic coding with the prosomeres of the forebrain. Mesial drift of these fields leads to fusion of their medial walls; this in turn provides bilateral functional matrics within which form the orbits ethmoids, lacrimals, turbinates, premaxillae, vomerine bones, and the cartilages of the nose. This two-part paper reports six lines of evidence supporting the field theory model of facial development: (1) An apparent watershed exists in the midline of the base between the territories of the internal and external carotid systems. Isolation of the ICA in injected fetal specimens confirmed that the demarcation was distinct and restricted to the embryonic nasal capsule. (2) Field theory explains the developmental anatomy of the contents of the nasal capsule. (3) The neuromeric model of CNS development provides a genetic basis for the anatomy and behavior of fields. (4) Mutants for the Dlx5 gene demonstrate A field deletion patterns. These experiments relate the nasal placode to the structures of the A fields. (5) Separate regions of the original nasal placodes give rise to neurons, which are dedicated to separate sensory and endocrine systems. The A fields constitute the pathways by which these neurons reach the brain. (6) Non-cleft lip-related cleft palate, holoprosencephaly, and the Kallmann syndrome are clinical models that demonstrate the effects of anatomic disturbances within the A fields.
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Abstract
Gonadotropin-releasing hormone (GnRH) regulates the hypothalamo-pituitary-gonadal (HPG) axis in all vertebrates studied. GnRH neurons that regulate the HPG axis are primarily derived from progenitor cells in the nasal compartment (NC) and migrate along olfactory system derived fibers across the cribriform plate to destinations in the forebrain. Across their long and uncommon migratory route many factors are likely important for their successful development. Several classes of molecules are being studied for their potential influences on migration, including those related to cell surface interactions (membrane receptors, adhesion molecules, extracellular matrix (ECM) molecules, etc.) and those related to communication across distances (neurotransmitters, peptides, chemoattractant or repellent molecules). Of the classes of molecules associated with cell surface interactions, glycoconjugates with terminal galactose, are temporally and spatially expressed on olfactory fibers that guide GnRH neurons and may play role(s) in migration. Of the molecules associated with communication across distances, the neurotransmitter gamma-aminobutyric acid (GABA) is associated with the GnRH migration pathway and influences the position and organization of GnRH neurons in vitro and in vivo. Furthermore, galactose-containing glycoconjugates and GABA are associated with GnRH neurons in species ranging from humans to lamprey. In mice and rats, GABA is found transiently within a subpopulation of GnRH neurons as they migrate through the NC. One of the key elements in considering regulators of GnRH neuron migration is the diversity of GnRH synthesizing cells. For example, only subpopulations of GnRH neurons also contain GABA, specific GABA receptors, or select glycoconjugates. Similarly, treatments that influence GnRH neuronal migration may only affect specific subsets and not the entire population. It is likely that we will not be able to characterize the migration of all GnRH neurons by a single factor. By combining molecular inquiries with genetic models, single cell analyses, and an in vitro migration model, we are beginning to decipher one of the most critical events in the establishment of the reproductive axis.
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Affiliation(s)
- S A Tobet
- Program in Neuroscience, The Shriver Center, School of Medicine, The University of Massachusetts, 200 Trapelo Road, Waltham, MA 02452, USA.
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Donahue JE, Stopa EG, Chorsky RL, King JC, Schipper HM, Tobet SA, Blaustein JD, Reichlin S. Cells containing immunoreactive estrogen receptor-alpha in the human basal forebrain. Brain Res 2000; 856:142-51. [PMID: 10677621 DOI: 10.1016/s0006-8993(99)02413-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The distribution of estrogen receptor protein-alpha (ER-alpha)-containing cells in the human hypothalamus and adjacent regions was studied using a monoclonal antibody (H222) raised against ER-alpha derived from MCF-7 human breast cancer cells. Reaction product was found in restricted populations of neurons and astrocyte-like cells. Neurons immunoreactive for ER-alpha were diffusely distributed within the basal forebrain and preoptic area, infundibular region, central hypothalamus, basal ganglia and amygdala. Immunoreactive astrocyte-like cells were noted within specific brain regions, including the lamina terminalis and subependymal peri-third-ventricular region. These data are consistent with the location of estrogen receptors in the basal forebrain of other species and the known effects of estrogens on the cellular functions of both neurons and supporting elements within the human hypothalamus and basal forebrain.
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Affiliation(s)
- J E Donahue
- Department of Pathology, Neuropathology Division, Rhode Island Hospital, Brown University School of Medicine, APC 12th Floor, 593 Eddy St., Providence, RI, USA
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