Ovariectomized-hysterectomized (OH) CD rats given sequential treatments with 2 μg of estradiol benzoate (EB) and. 5 mg of progesterone (P) showed significantly higher lordosis quotients than ovariectomized (OV) Ss in 2 tests, 1 and 2 wks after surgery. To test whether the effects of hysterectomy persist, 3 groups of OV and OH Ss received weekly injections of EB, EB+ P, or sesame oil for 4 wks, were given 2 μg of EB followed 24 hrs later by. 5 mg of P, and tested for receptivity. Only the OH Ss that had received hormones for 4 wks showed a significantly higher lordosis score than OV Ss. The effects of hysterectomy on food intake, weight gain, and running wheel activity were also tested. After 1 wk of 2 μg/day EB, OH Ss lost significantly more weight and consumed less food than OV Ss, but by 2 wks the effects of hysterectomy were no longer evident. Treatment with. 5 μg/day EB resulted in a significant loss in weight and food intake in OH Ss throughout the experiment. OH Ss implanted with Silastic capsules containing EB were significantly more active in running wheels than OV Ss over the 1st 9 days, but by Day 23 the activity of both groups was similar. 24 hrs following a single injection of EB, hypothalamic-preoptic area cell nuclear estrogen receptors and cytoplasmic progestin receptors were significantly higher in OH than in OV Ss. Possible mechanisms by which hysterectomy might act to enhance hormone-dependent behaviors are discussed.(20 ref)(PsycINFO Database Record (c) 2016 APA, all rights reserved)