THE ROLE OF THE UTERUS AND CERVIX IN SYSTEMIC OXYTOCIN-PGE(2) FACILITATED LORDOSIS BEHAVIOR

The effect of ovariectomy, hysterectomy, and cerviectomy on systemic o xytocin-PGE(2) induced facilitation of lordosis behavior was examined in estrogen and progesterone treated rats. Females were injected with 0.25 mu g estradiol benzoate for 3 days, followed by 500 mu g progeste rone on day 4, 4 hr prior to behavioral testing. Ten minutes before be havioral testing with a male, females were injected systemically with either oxytocin (2.1, 4.2, or 8.4 mu g); PGE(2) (0.05, 0.10, or 0.20 m u g); concomitant administration of both oxytocin and PGE(2); or physi ological saline. Oxytocin (2.1 mu g) or PGE(2) (0.05 mu g) significant ly increased lordosis behavior in ovariectomized females; however, nei ther had any facilitatory effect in hysterectomized animals. Facilitat ed lordosis behavior was only reinstated in hysterectomized females th at received concomitant administration of 2.1 mu g oxytocin plus 0.05 mu g PGE(2). This latter dose also resulted in a further potentiation of lordosis behavior in ovariectomized animals, compared to 2.1 mu g o xytocin or 0.05 mu g PGE(2) alone. Concomitant administration of oxyto cin and PGE(2) at all doses had no facilitatory effect on lordosis beh avior in cerviectomized animals. These results suggest that the uterus and the cervix may be important components of a peripheral mechanism by which systemic oxytocin and/or PGE, induce facilitated lordosis beh avior in female rats. (C) 1995 Academic Press, Inc.