Prevention of the anovulatory syndrome and testosterone-induced rise in catecholamine level in the hypothalamus of newborn rats with steroid aromatase inhibitors.

Testosterone propionate administration in a dose of 50 micrograms on the 5th day of the postnatal life did not change hypothalamic noradrenaline and dopamine levels in female rats on the 7th, 8th, 12th days of life but increased it significantly in 10-day-old animals. This rise was completely prevented by steroid aromatase inhibitors (4-androstene-3,16,17-trione, 0.5 mg or 1,4,6-androstatriene-3,17-dione, 1 mg per animal) on the 5th or 7th days of life. Aromatase inhibitors reduced the anovulatory syndrome occurrence in neonatally androgenized rats from 93% to 15-17%. The data obtained prove the importance of testosterone conversion into estrogen for sexual brain differentiation. They support authors' hypothesis that testosterone-induced rise of hypothalamic catecholamine content in newborn female rats is evoked by the estrogen metabolites of testosterone.