Central administration of Orphanin FQ inhibits GnRH secretion by ORL1 receptor in the median eminence of freely moving ovariectomized rats.
OBJECTIVE
This study aimed to investigate the possible role of Orphanin FQ (OFQ) in the regulation of hypo-thalamic gonadotropin-releasing hormone (GnRH) secretion.


METHODS
The method of push-pull perfusion and radioimmuno-assay (RIA) were adopted to examine the secretory profile of GnRH in the median eminence (ME) in freely moving ovari-ectomized (OVX) rats after intracerebroventricular (icv) injection of OFQ and/or [Nphe(1)]NC(1-13)NH(2) (NC13), a competitive antagonists of the opioid receptor-like 1 receptor (ORL1 receptor).


RESULTS
GnRH release from ME significantly decreased from 40 min to 80 min after the administration of 20 and 200 nmol OFQ in OVX rats (P < 0.05). This inhibitory effect of 20 nmol OFQ could be abolished by pretreatment with equal dose of NC13. More interestingly, GnRH secretion from ME was increased markedly 60 min after icv injection of 100 and 200 nmol NC13 (P < 0.05).


CONCLUSIONS
Our results suggested central administration of OFQ could inhibit the release of GnRH in the ME of hypothalamus through ORL1 receptor, providing further in vivo evidence supporting the role of OFQ in the control of GnRH secretion.
An
Xiao-Fei
XF
Department of Endocrinology, Jiangsu Province Hospital of Traditional Chinese Med, Nanjing 210029, China. anxiaofei2000@163.com
He
Ming
M
Feng
Yi
Y
Feng
Hao
H
Yu
Jiang-Yi
JY
D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D008473:Median Eminence / Q000378:metabolism*; D009292:Narcotic Antagonists; D018847:Opioid Peptides / Q000494:pharmacology*; D010052:Ovariectomy / Q000379:methods; D010446:Peptide Fragments / Q000494:pharmacology; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000378:metabolism*; D055571:Secretory Pathway / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*; D014851:Wakefulness / Q000502:physiology*; D000094942:Nociceptin Receptor; D000097629:Nociceptin
D007987:Gonadotropin-Releasing Hormone; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D010446:Peptide Fragments; D011957:Receptors, Opioid; D014665:Vasodilator Agents; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C403776:nociceptin-(1-13)-NH2, NPhe(1)-; C000722285:Oprl1 protein, rat