Evidence for a dopaminergic component in the series of neural events that lead to the pro-oestrous surge of LH.

The possible participation of dopamine in the neural events that lead to the pro-oestrous surge of luteinizing hormone (LH) was investigated utilizing a dopaminergic ergoline derivative (lergotrile mesylate). Administration of reserpine (2.0 mg/kg, ip) to rats on the day of pro-oestrus depleted brain dopamine and norepinephrine and prevented the LH surge and ovulation. Administration of legotrile mesylate prior to or at the same time as reserpine prevented the inhibitory effects of reserpine on LH release and on ovulation in about half of the animals. When lergotrile mesylate was given on the morning of pro-oestrus, the LH surge was advanced. The results indicate that there is a dopaminergic component in the series of neural events that precede the surge of LH on pro-oestrus, and that the dopaminergic stimulus precedes the LH surge by about 4--5 h.