Body weight regulation in female rats following neonatal testosterone.

Neonatal testosterone treatment of female rats led to an increase in body weight and skeletal growth and produced evidence of altered ovarian function over a 76 day period following treatment. Bilateral ovariectomy performed eleven weeks after neonatal treatment increased the rate of body weight gain of both testosterone propionate- and oil-treated groups, but no differences in the increased rates of weight gain were evident between groups over a five week post-ovex observation period. Subsequently, long-term oestrogen replacement therapy, via subcutaneous Silastic implants, produced equal reductions in the rates of body weight gain and somatic growth of both early testosterone- and oil-treated ovariectomized groups. In spite of the marked effects of these manipulations on body weight and skeletal growth, no significant differences were noted in the Lee Index of obesity between androgenized and the appropriate non-androgenized control rats at any interval of the experimental period. These results indicate that neither ovarian hormones nor an altered sensitivity to oestrogen of body weight regulatory mechanisms are important in the increased body weight that follows perinatal testosterone treatment. Additionally, the present data add support to previous work which has suggested that a general increase of somatic growth rather than "obesity" provides the major contribution to the elevated body weights of androgenized female rats.