No effect of neonatal estrogenic stimulation or hypophysectomy on spontaneous activity in female rats.

Ovariectomized 33 Sprague-Dawley rats on the day of birth and administered 0, 50, 100, 200, or 400 mg of estradiol benzoate (EB) on Days 2 and 4. In adulthood, estrogenic stimulation (15 and 250 mg/day of EB) significantly increased activity as measured in revolving drums. The adult activities of Ss given 0-200 mg of EB neonatally were equivalent; Ss given 400 mg of EB were the least reactive, suggesting neonatal desensitization The activity increase produced by 250 mg of EB was greater than that produced by 15 mg. Exp II examined the effects of EB in 10 hypophysectomized and ovariectomized Ss: Estrogen increased running in Ss demonstrating that the effects of estradiol on activity are not mediated by the pituitary. Similarities between the influence of perinatal steroids on spontaneous activity and mating behavior are noted. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)