Serotonin involvement in the inhibition of luteinizing hormone (LH) release induced by prostaglandin D 2 (PGD 2) in castrated male rats

Abstract

p-Chlorophenylalanine (PCPA, 320 mg/kg i.p.), an inhibitor of serotonin (5-HT) synthesis, and 5,6-dihydroxy-tryptamine (5,6-DHT, 50 μg i.c.v.), a drug toxic to the indoleaminergic system were used to test the involvement of 5-HT in the mediation of the inhibitory effect of prostaglandin D 2 (PGD 2) on luteinizing hormone (LH) release in castrated male rats. The i.c.v. administration of PGD 2 suppressed the episodic LH release characteristic of castrated rats and decreased mean plasma LH levels and mean LH pulse amplitude significantly. Pretreatment with PCPA or 5,6-DHT apparently eliminated the inhibitory effect of PGD 2 on LH secretion. These results suggest the possible involvement of a serotonergic mechanism in the mediation of the suppression of LH secretion induced by PGD 2 in castrated male rats.