The role of the uterus in sequential inhibition of sexual behavior and on heat duration in rats

The Role of The Uterus in Sequential Inhibition of Sexual Behavior and on Heat Duration in Rats (September, 1984) Harry B. Ahdieh, B.A., University of Bridgeport M.S. and Ph.D., University of Massachusetts Directed by: Professor George N. Wade These studies examined the role of the uterus in sequential inhibition of lordosis by progesterone (P) and on the duration of estrus in estrous-cycling rats. One mg of P significantly reduced lordosis quotients in response to subsequent P treatment in estradiol benzoate (EB)-primed ovariectomized (OV) animals, whereas 2 mg of P was required to suppress lordosis in ovar iectomized-hysterectomized (OH) rats. Treatment with 1.0 ug of EB permitted, and 6.0 ug of EB prevented, sequential inhibition of lordosis by P in both groups. The concentration of hypothalamic progestin receptors was significantly lower in EB-primed OV animals given 1.0 or 2.0 mg of P than oil-treated controls, but only the 2.0 mg dose of P reduced the concentration of receptors in OH animals. Hysterectomy did not affect the onset of estrus but prolonged the duration of sexual receptivity in estrouscycling rats. Hysterectomized (H) animals given .5 mg of P within 2 hr, or 4.0 mg of P 24 hr following the termination