The present study was designed to assess the participation of
estrogen receptors alpha (ERα) and beta (ERβ) in the short-term facilitation of
lordosis behavior in ovariectomized (ovx),
estradiol (E2) primed rats. In experiment 1, dose response curves for PPT and
DPN (ERα and ERβ agonists, respectively) facilitation of
lordosis behavior (
lordosis quotient and
lordosis score) were established by infusing these agonists into the right lateral ventricle (icv) in female rats injected 40h previously with 5μg of E2
benzoate. PPT doses of 0.08 and 0.4ng produced high
lordosis quotients starting at 30min and continuing at 120 and 240min post-injection.
DPN induced high levels of
lordosis behavior at all times tested. However, the intensity of
lordosis induced by both agonists was weak. In experiment 2, we tested the involvement of each ER in facilitation of
lordosis by icv infusion of MPP (ERα-selective antagonist) or PHTPP (ERβ-selective antagonist) prior to infusion of 2ng of free E2. Icv infusion of either MPP or PHTPP 30min before free E2 significantly depressed E2 facilitation of
lordosis. The results suggest that both forms of ER are involved in the short-latency facilitation of
lordosis behavior in E2-primed rats.