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

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 microg luteinizing hormone-releasing hormone (LHRH), 100 microg 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 proceptive 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.