Neuroanatomical Organization of the Brain Gonadotropin-Inhibitory Hormone and Gonadotropin-Releasing Hormone Systems in the Frog Pelophylax esculentus

2014 ◽  
Vol 85 (1) ◽  
pp. 15-28 ◽  
Author(s):  
Claudia Pinelli ◽  
Arun G. Jadhao ◽  
Saikat P. Biswas ◽  
Kazuyoshi Tsutsui ◽  
Biagio D''Aniello
Keyword(s):  
Preoptic Area ◽  
Anterior Commissure ◽  
Medial Septum ◽  
Gonadotropin Releasing Hormone ◽  
Gonadotropin Secretion ◽  
Releasing Hormone ◽  
Gnrh Release ◽  
Medial Septal Area ◽  
Gonadotropin Inhibitory Hormone ◽  
The Brain

Growing evidence suggests that gonadotropin-inhibitory hormone (GnIH) may play a key role in mediating vertebrate reproduction. GnIH inhibits gonadotropin synthesis and release by decreasing the activity of gonadotropin-releasing hormone (GnRH) neurons as well as by directly regulating gonadotropin secretion from the pituitary. Whereas the presence of GnIH has been widely investigated in various classes of vertebrates, there are very few immunohistochemical reports focusing on GnIH in amphibians. The aim of this study was to assess the presence and neuroanatomical distribution of GnIH-like immunoreactivity in the brain of the anuran amphibian Pelophylax (Rana) esculentus (esculenta) and to explore any potential anatomical relationship with mammalian GnRH-immunoreactive (mGnRH-ir) elements. The GnIH-like immunoreactive (GnIH-ir) system constitutes two distinct subpopulations in the telencephalon and diencephalon, with the highest number of immunoreactive cells located in the preoptic and suprachiasmatic areas. GnIH-ir neurons were also observed in the medial septum, the anterior commissure, the dorsal hypothalamus, the periventricular nucleus of the hypothalamus, and the posterior tuberculum. Scattered GnIH-ir fibers were present in all major subdivisions of the brain but only occasionally in the median eminence. mGnRH-ir neurons were distributed in the mediobasal telencephalon, the medial septal area, and the anterior preoptic area. Double-label immunohistochemistry revealed that the GnRH and GnIH systems coexist and have overlapping distributions at the level of the anterior preoptic area. Some GnIH-ir fibers were in close proximity to mGnRH-ir cell bodies. Our results suggest that both the neuroanatomy and the functional regulation of GnRH release are conserved properties of the hypothalamic GnIH-ir system among vertebrate species.

N-methyl-D,L-aspartate (NMDA) stimulates gonadotropin secretion in the ovine fetus through gonadotropin-releasing hormone (GnRH) release

1988 ◽  
Vol 117 (4_Suppl) ◽  
pp. S93-S94
Author(s):  
M. BETTENDORF ◽  
F. DE ZEGHER ◽  
N. ALBERS ◽  
S. L. KAPLAN ◽  
M. M. GRUMBACH
Keyword(s):  
Gonadotropin Releasing Hormone ◽  
Gonadotropin Secretion ◽  
Releasing Hormone ◽  
Gnrh Release ◽  
Ovine Fetus

Distribution of lamprey gonadotropin-releasing hormone in the brain and pituitary gland of larval, metamorphic, and adult sea lampreys, Petromyzon marinus

1994 ◽  
Vol 72 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Glenda M. Wright ◽  
Kim M. McBurney ◽  
John H. Youson ◽  
Stacia A. Sower
Keyword(s):  
Pituitary Gland ◽  
Preoptic Area ◽  
Petromyzon Marinus ◽  
Gonadotropin Releasing Hormone ◽  
Immunoperoxidase Technique ◽  
Dorsal Region ◽  
Releasing Hormone ◽  
Sea Lampreys ◽  
The Brain

Lamprey gonadotropin-releasing hormone was demonstrated in the brains of larval, metamorphic, and adult sea lampreys, Petromyzon marinus, using an immunoperoxidase technique. Gonadotropin-releasing hormone was observed in the neurohypophysis and preoptic area of the brain of larval, metamorphic, juvenile, and prespawning adults. The occurrence of immunoreactive cells and the intensity of the immunostaining was lowest in larvae, but by stage 5 of metamorphosis there was a marked increase in the prevalence and staining of these cells, which continued into adults. In larvae and lampreys in metamorphic stages 1–4, most immunoreactive fibres were confined to the dorsal region of the neurohypophysis. During stage 5 there was an expansion of immunopositive fibres into the ventral portion of the neurohypophysis. Prominent immunoreactivity was observed throughout the neurohypophysis from stage 5 onward through the adult stages. Changes in immunoreactivity of these cells and fibres in the brain and neurohypophysis correlate well with increased concentrations of hormone in the brain during development and with the timing of presumed changes in activity of cells in the adenohypophysis during metamorphosis.

Two Subgroups of Gonadotropin Releasing Hormone Neurons Control Gonadotropin Secretion in Rats

Physiology ◽  
1998 ◽  
Vol 13 (5) ◽  
pp. 225-231
Author(s):  
Fukuko Kimura ◽  
Toshiya Funabashi
Keyword(s):  
Preoptic Area ◽  
Pulse Generator ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
The Other ◽  
Aminobutyric Acid ◽  
Mediobasal Hypothalamus ◽  
Luteinizing Hormone Secretion ◽  
Gonadotropin Secretion ◽  
Releasing Hormone

Two distinct subgroups of gonadotropin-releasing hormone (GnRH) neurons are involved in the control of luteinizing hormone secretion, at least in rats: one subgroup located in the mediobasal hypothalamus constitutes the GnRH pulse generator associated with opioid neurons, and the other located in the preoptic area constitutes the GnRH surge generator associated with γ-aminobutyric acid neurons.

scholarly journals Distinct Mechanisms Involving Diverse Histone Deacetylases Repress Expression of the Two Gonadotropin β-Subunit Genes in Immature Gonadotropes, and Their Actions Are Overcome by Gonadotropin-Releasing Hormone

2007 ◽  
Vol 27 (11) ◽  
pp. 4105-4120 ◽  
Author(s):  
Stefan Lim ◽  
Min Luo ◽  
Mingshi Koh ◽  
Meng Yang ◽  
Mohammed Nizam bin Abdul Kadir ◽  
...  
Keyword(s):  
Histone Deacetylases ◽  
Reproductive Function ◽  
Gonadotropin Releasing Hormone ◽  
Β Subunit ◽  
Releasing Hormone ◽  
Calcium Calmodulin Dependent ◽  
Gnrh Release ◽  
Dependent Protein ◽  
Reproductive Cycles ◽  
Class Iia Hdacs

ABSTRACT The gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are produced in the embryonic pituitary in response to delivery of the hypothalamic gonadotropin releasing hormone (GnRH). GnRH has a pivotal role in reestablishing gonadotropin levels at puberty in primates, and for many species with extended reproductive cycles, these are reinitiated in response to central nervous system-induced GnRH release. Thus, a clear role is evident for GnRH in overcoming repression of these genes. Although the mechanisms through which GnRH actively stimulates LH and FSH β-subunit (FSHβ) gene transcription have been described in some detail, there is currently no information on how GnRH overcomes repression in order to terminate reproductively inactive stages. We show here that GnRH overcomes histone deacetylase (HDAC)-mediated repression of the gonadotropin β-subunit genes in immature gonadotropes. The repressive factors associated with each of these genes comprise distinct sets of HDACs and corepressors which allow for differentially regulated derepression of these two genes, produced in the same cell by the same regulatory hormone. We find that GnRH activation of calcium/calmodulin-dependent protein kinase I (CaMKI) plays a crucial role in the derepression of the FSHβ gene involving phosphorylation of several class IIa HDACs associated with both the FSHβ and Nur77 genes, and we propose a model for the mechanisms involved. In contrast, derepression of the LH β-subunit gene is not CaMK dependent. This demonstration of HDAC-mediated repression of these genes could explain the temporal shut-down of reproductive function at certain periods of the life cycle, which can easily be reversed by the actions of the hypothalamic regulatory hormone.

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