Hormonal activation of the striatum and the nucleus accumbens modulates paced mating behavior in the female rat.

Sexual behavior in the female rat has both sensorimotor and motivational components, which can be distinguished when the female rat is able to pace the rate of copulation. The experiments reported were conducted to determine whether estrogen application to the striatum and/or nucleus accumbens affects pacing behavior. In order to induce sexual receptivity, ovariectomized rats received sequential bilateral implants of 17beta-estradiol followed by progesterone into the ventromedial nucleus of the hypothalamus. Then, bilateral implants of 17beta-estradiol or cholesterol were administered into either the dorsolateral striatum or the nucleus accumbens. Pacing behavior was tested 4 hr later. It was found that intrastriatal application of estradiol significantly facilitated the percent exits exhibited after copulatory contact, whereas application of estradiol in the nucleus accumbens affected the return latency. To determine whether estrogen in the striatum or nucleus accumbens normally plays a role in pacing behavior, intrastriatal or intra-accumbens implants containing the steroidal antiestrogen ICI 182,780 or vehicle were given to ovariectomized female rats treated systemically with estrogen and progesterone. The antiestrogen treatment decreased the percent exits when delivered to the striatum and affected return latency when delivered to the nucleus accumbens. The results indicate that estrogen acts directly in the striatum and in the nucleus accumbens to differentially modulate specific components of pacing behavior. Copyright 1997 Academic Press.