SUPPRESSIVE EFFECT OF PROSTAGLANDIN (PG)D2ON PULSATILE LUTEINIZING HORMONE RELEASE IN CONSCIOUS CASTRATED RATS

Abstract

The effect of intraventricular administration of prostaglandin (PG)D₂ on pulsatile LH release was studied in castrated conscious rats. The administration of 5 μg of PGD₂ into the lateral ventricle inhibited pulsatile discharge of LH secretion, in contrast to the stimulatory effect of PGE₂. Intraventricular administration of 13,14-dihydro-15-keto-PGD₂, a metabolite of PGD₂, had no significant effect. Intravenous administration of 100 /ig of PGD₂ caused only a slight decrease in LH secretion. Intravenous administration of naloxone, a specific opiate antagonist, blocked the suppressive effect of PGD₂ on LH release. These results suggest that PGD₂ plays an inhibitory role in pulsatile LH secretion in castrated male rats and that opiate receptors are involved in the PGD_2-nduced inhibition of LH secretion.