[An increase in hypothalamic sensitivity to the inhibiting effects of estrogens caused by use of L-DOPA, diphenine, epithalamin and phenformin in old rats].

Daily treatment of hemicastrated young rats with 0.57 mug of stilbestrol inhibited compensatory ovarian hypertrophy (COH) by 48% in the 3-month animals and by 3% only in the 18-month animals. Administration of L-DOPA, dilantin, epithalamin or phenoformin with the same dose of estrogen to old rats suppressed the COH by 65-98%. L-DOPA and epithalamin were effective when administered into the 3rd cerebral ventricle. A functional nature of the age changes in the hypothalamic sensitivity to the estrogen action is suggested.