Blockade of Spontaneous Ovulation by Isocarboxazid (MAO-Inhibitor) in Rats

Abstract

SynopsisSpontaneous ovulation was inhibited in female rats with isocarboxazid (IC), MAO-Inhibitor. Administration of HCG to IC-treated females at 3:00p.m. on the day of proestrus induced ovulation. Although the brain serotonin level was still high (1.5 times the control) from 9:00a m. to 6:00p.m. on the next day after IC-injection, ovulation occurred on the second day morning. Female rats, with the increased brain serotonin level by IC-injection, copulated on the afternoon of proestrus, and ovulation occurred in the mated animals on the next morning. These results indicate that the stimulus provided by mating may overcome the inhibitory effects of serotonin in IC-treated females.

Median Raphe Stimulation and Sham Procedures Inhibit the LH Surge

“…Early pharmacological studies have sug gested that a serotonergic mechanism can in hibit ovulatory LH release [3,15,17,29,30,32,34,42,44,54], More recent studies em ploying similar pharmacological procedures, have suggested that a facilitatory serotonergic mechanism also plays a role in regulating the LH surge [9,23,25,26,35,53], Meyer [36], utilizing microinjection of neurotoxin directly into the raphe area, has implicated raphehypothalamic serotonergic projections in this facilitatory effect. On the basis of the results of the present paper, we can conclude that no data yet available convincingly demonstrate an involvement of raphe neurons in the in hibitory mechanism.…”