Intracerebroventricular injection of arginine-vasopressin V1 receptor antagonist attenuates the surge of luteinizing hormone and prolactin secretion in proestrous rats.

In the present study, we examined the effect of arginine-vasopressin (AVP) V1 receptor antagonist ([Deamino-Pen1, Tyr(Me)2, Arg8]-vasopressin) injection (1 microg/2 microl saline) into the third ventricle in the proestrous rat on serum concentrations of luteinizing hormone (LH) and prolactin (PRL) which were determined between 1100 and 2100 h at 1-h intervals. Control rats were injected with 2 microl saline. The injection of AVP receptor antagonist at 1300 h resulted in significant decreases in both LH and PRL secretion compared to saline-injected rats. The present study provides evidence supporting our hypothesis that endogenous AVP plays a role in the induction of the surge of LH and PRL secretion as a stimulatory factor.