Oxytocin augmentation of gonadotropin-releasing hormone-stimulated luteinizing hormone release is modulated by cyclic AMP.
Oxytocin has been previously shown to augment GnRH-stimulated LH release. However it is currently unknown which intracellular mediators participate in the process. In this study, after preincubation with oxytocin for 3 hours, quartered pituitaries were stimulated for 15 minutes with GnRH. The effects of diBucAMP, a cell permeable analog of cAMP, and DDA, an adenyl cyclase inhibitor, on the augmentation by oxytocin were investigated. Although addition of diBucAMP increased GnRH-stimulated LH release, it inhibited the augmentation by oxytocin of the response to GnRH. On the other hand addition of DDA induced an increased augmentation by oxytocin. These results indicate that intracellular cAMP inhibits the augmentory activity of oxytocin, and suggest that oxytocin modulation of GnRH action in vivo would be optimal when the hormonal milieu results in reduced levels of cAMP.
Hurd
S J
SJ
Department of Obstetrics and Gynaecology, Christchurch School of Medicine, New Zealand.
Evans
J J
JJ
Mason
D R
DR
D000704:Analysis of Variance; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D016048:Dideoxyadenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D066298:In Vitro Techniques; D007536:Isomerism; D007700:Kinetics; D010121:Oxytocin / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011359:Proestrus; D051381:Rats; D017208:Rats, Wistar
D007987:Gonadotropin-Releasing Hormone; D016048:Dideoxyadenosine; D010121:Oxytocin; D003994:Bucladesine; C021008:2',5'-dideoxyadenosine