Gonadotropin-releasing hormone neurons in the preoptic-hypothalamic region of the rat contain lamprey gonadotropin-releasing hormone III, mammalian luteinizing hormone-releasing hormone, or both peptides.
This study utilized a newly developed antiserum, specific for lamprey gonadotropin-releasing hormone III (l-GnRH-III), to determine the following: in which regions of the rat hypothalamus the neuronal perikarya producing l-GnRH-III are localized; and whether this peptide, known to selectively induce follicle-stimulating hormone release, is coexpressed in neurons containing mammalian luteinizing hormone-releasing hormone (m-LHRH). Double-label immunocytochemistry was performed by using an l-GnRH-III polyclonal antiserum and an LHRH monoclonal antiserum. Immunopositive neurons for l-GnRH-III, m-LHRH, or neurons coexpressing both peptides were detected within the organum vasculosum lamina terminalis (OVLT) region of the preoptic area (POA). Caudal to the OVLT, l-GnRH-III-positive neurons were also observed dorso-medially, above the third ventricle in the medial POA. The m-LHRH neurons were not observed in this area. The lateral POA region contained neurons positive for both peptides along with single-labeled neurons for each peptide. Importantly, neurons that expressed l-GnRH-III, m-LHRH, or both peptides were also detected in the ventral regions of the rostral hypothalamus, dorsolateral to the borders of the supraoptic nuclei. In both of these latter areas, neurons containing l-GnRH-III were slightly dorsal to neurons containing only m-LHRH. The l-GnRH-III perikarya and fibers were eliminated by absorption of the primary antiserum with l-GnRH-III, but not by l-GnRH-I, chicken-GnRH-II, or m-LHRH. These results indicate that, unlike other isoforms of GnRH found in the mammalian brain, l-GnRH-III neurons not only are observed in regions that control follicle-stimulating hormone release but also are colocalized with m-LHRH neurons in areas primarily controlling LH release. These findings suggest an interrelationship between these two peptides in the control of gonadotropin secretion.
Hiney
J K
JK
Department of Veterinary Anatomy and Public Health, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4458, USA. jhiney@cvm.tamu.edu
Sower
S A
SA
Yu
W H
WH
McCann
S M
SM
Dees
W L
WL
D000818:Animals; D001931:Brain Mapping; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis* / Q000737:chemistry; D006062:Gonadotropins / Q000378:metabolism; D006728:Hormones / Q000096:biosynthesis* / Q000737:chemistry; D007031:Hypothalamus / Q000378:metabolism* / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D008953:Models, Anatomic; D009474:Neurons / Q000378:metabolism*; D009842:Oligopeptides / Q000096:biosynthesis* / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011301:Preoptic Area / Q000378:metabolism* / Q000502:physiology; D020033:Protein Isoforms; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D051381:Rats; D017207:Rats, Sprague-Dawley
D006062:Gonadotropins; D006728:Hormones; D009842:Oligopeptides; D010455:Peptides; D020033:Protein Isoforms; C448022:gonadotropin-releasing hormone-III; D007987:Gonadotropin-Releasing Hormone; D011761:Pyrrolidonecarboxylic Acid