THE PUBESCENT GROWTH DELAY OF THE TESTIS AND THE ACCESSORY SEXUAL ORGANS IN EARLY ANDROGENIZED MALE RAT

I. Studies of Early Androgenized Male Rat

Abstract

It was well known that testosterone propionate-treated neonatal female rats showed persistent oesterous condition after their puberty, due to the masculinization of the sexual center and the loss of the regularity. However, few examination have been done on the male rats treated in the same way.
In our experiment, the male rats were injected subcutaneouslyy with 0.5mg testosterone propionate once at 2 days of age and 1mg for 3 days. We examined its effect on the sexual center according to the finding of the germinal epithelium and the change of the accessory sexual organ weight.
In normal male rats the secretion of gonadotropin has been reported to start with pubescent growth of the sexual center. It takes 40 days to nearly complete the growth of the accessory sexual organ and the spermatogenesis.
Nevertheless, in the group androgen-treated immediately after birth, the remarkable delay of the pubescent growth was recognized in both accessory sexual organ and the spermatogenesis at 40 days of age. But at 60 days the pubescent delay of the accessory sexual organ growth overtook the normal maturation level and the spermatogenesis almost came to maturity.
From these findings, we assumed that the administration of testosterone propionate in high doses in the critical period of the sexual center differentiation in the hypothalamus induced some suppressive changes in the sexual center and a delay of pubescent growth occurred. But the suppressive change of the sexual center overtook the normal growth about 40 days later than the time the normal puberty started.
From these results, we may conclude that the administration of androgen in high doses to neonatal male rats causes “Experimental Retarded Puberty”.