Facilitation of lordosis behavior in ovariectomized estrogen-primed rats by medial preoptic implantation of 5 beta, 3 beta, pregnanolone: a ring A reduced progesterone metabolite.

The effect on lordosis behavior of progesterone (P) and some of its ring A reduced metabolites (5 beta pregnane 3 alpha ol 20 one, 5 beta pregnane 3 beta ol 20 one and 5 alpha pregnanes 3 beta ol 20 one) was studied in estrogen primed overiectomized rats by unilaterally implanting them in two brain areas related to the control of lordosis behavior: the ventromedial hypothalamic nucleus (VMH) and the medial preoptic area (mPOA). Of the four pregnanes studied only 5 beta 3 beta pregnanolone consistently induced lordosis behavior when implanted into the mPOA. The present results show that some 5 beta reduced P metabolites can facilitate with a short latency the display of lordosis behavior, probably by depressing the activity of telencephalic neurons inhibitory to sexual behavior.