EVIDENCE FOR A DOPAMINERGIC COMPONENT IN THE SERIES OF NEURAL EVENTS THAT LEAD TO THE PRO-OESTROUS SURGE OF LH

Abstract

The possible participation of dopamine in the neural events that lead to the proestrous surge of luteinizing hormone (LH) was investigated utilizing a dopaminergic ergoline derivative (lergotrile mesylate). Administration of reserpine (2.0 mg/kg, i.p.) to rats on proestrus depleted brain dopamine and norepinephrine and prevented the LH surge and ovulation. Administration of lergotrile mesylate prior to or at the same time as reserpine prevented the inhibitory effects of reserpine on LH release and on ovulation in about 1/2 of the animals. When lergotrile mesylate was given on the morning of proestrus, the LH surge was advanced. There is probably a dopaminergic component in the series of neural events that precede the surge of LH on proestrus, and the dopaminergic stimulus probably precedes the LH surge by about 4-5 h.