Effect of perinatal thyroxine treatment on some endocrine functions of male and female rats.

Sprague-Dawley rats were treated with 10 microgram/g b.w. thyroxine on days 8, 9 and 10 of life. This treatment had no effect on the development of the female diurnal pattern of plasma corticosterone or on the time of vaginal opening. Treated females cycled normally and they showed compensatory hypertrophy (CH) of ovaries comparable to that of vehicle-treated controls. Treated males responded to a combined ether-hemorrhage stress, as did controls, and they exhibited normal adrenal CH. Both treated males and females had lower body weights and reduced endocrine organ weights on day 49 of life.