Progesterone receptor participates in the stimulatory effect of LHRH, prostaglandin E2, and cyclic AMP on lordosis and proceptive behaviours in rats

Abstract

We explored the effect of the antiprogestin RU486 on the estrous behaviour (lordosis and proceptivity) induced in sexually experienced ovariectomized oestrogen primed rats by: 5 mu g luteinizing hormone-releasing hormone (LHRH), 100 mu g prostaglandin E2 (PGE2), or 2 mg dibutyryl cyclic AMP (db cAMP). Pretreatment with 5 mg RU 486 (but not with vehicle) 60 min before the injection of the above-mentioned agents significantly decreased both lordosis and preceptive behaviours normally induced by such agents. Results suggest that the estrus-inducing action of LHRH, PGE2 and db cAMP occurs through the activation of the progesterone receptor.