Changes in bar-press duration accompanying the estrous cycle.

Abstract

12 intact female rats showed regular 4-5 day cyclic changes in bar-press duration (BPD) when tested daily in a light-contingent bar-pressing situation. Peak duration was associated with (1) presence of well developed nucleated epithelial cells and a smaller amount of cornified epithelial cells in vaginal smears, and (2) high sexual receptivity. Cyclic variations in BPD were absent in males and in females during pseudopregnancy, during prolonged states of vaginal estrus, and after ovariectomy. 9 ovariectomized females when treated with estrogen and progesterone, in the proper sequence and interval, showed increased BPD and readiness to copulate. The BPD appears to covary with the estrous cycle and sexual receptivity in the female rat. (PsycINFO Database Record (c) 2006 APA, all rights reserved)