The role of PACAP in gonadotropic hormone secretion at hypothalamic and pituitary levels.
The presence of pituitary adenylate cyclase-activating polypeptide (PACAP) and its mRNAin the three levels of the hypothalamo-hypophyseal-ovarian axis was previously demonstrated using immunohistochemistry, in situ hybridization, and reverse transcriptase polymerase chain reaction (RT-PCR). In the hypothalamus, PACAP is present in neuroendocrine effector cells and in the median eminence. In the anterior pituitary and ovary, PACAP is transiently present during the proestrous stage of the estrous cycle. In the pituitary, PACAP was observed in gonadotropes. In the ovary, PACAP was demonstrated in the granulosa cells of the preovulatory ovarian follicles. The effect of PACAP on luteinizing hormone (LH) secretion was demonstrated in in vivo and in vitro models. In our work we have studied the role of PACAP in gonadotropic hormone secretion at hypothalamic and pituitary levels. At the hypothalamic level, PACAP, administered intracerebroventricularly to female rats before the critical period of the proestrus stage, can inhibit LH release and ovulation. Its inhibiting effect is mediated through corticotropin-releasing factor (CRF) and endogenous opioids. PACAP administered to neonatal female rats delayed the onset of puberty by influencing the luteinizing hormone-releasing hormone (LHRH) neuronal system. In the pituitary gland, the release of PACAP depended on the stage of the estrous cycle and on the time of day the animals were sacrificed. On the day of proestrus, the number of PACAP-releasing cells showed a diurnal change with two peaks (in the morning and in the evening). The peak was much higher in the evening at the end of the LH surge than in the morning.
Köves
Katalin
K
Department of Human Morphology and Developmental Biology, Faculty of Medicine, Semmelweis University, Budapest, Hungary. koves@ana2.sote.hu
Kántor
Orsolya
O
Molnár
Judith
J
Heinzlmann
Andrea
A
Szabó
Enikö
E
Szabó
Flóra
F
Nemeskéri
Agnes
A
Horváth
Judit
J
Arimura
Akira
A
D000818:Animals; D000831:Animals, Newborn; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D030762:Estrous Cycle / Q000187:drug effects / Q000502:physiology*; D005260:Female; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D006062:Gonadotropins / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D007276:Injections, Intraventricular; D007986:Luteinizing Hormone / Q000378:metabolism; D009292:Narcotic Antagonists / Q000494:pharmacology; D009479:Neuropeptides / Q000378:metabolism* / Q000494:pharmacology; D010060:Ovulation / Q000187:drug effects / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011359:Proestrus / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000494:pharmacology
C495403:Adcyap1 protein, rat; D018755:GABA Agonists; D018756:GABA Antagonists; D006062:Gonadotropins; D009292:Narcotic Antagonists; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D007987:Gonadotropin-Releasing Hormone; D013004:Somatostatin; D007986:Luteinizing Hormone; D003346:Corticotropin-Releasing Hormone