Dose dependence of the thyrotropin (TSH) receptor damaging effect of gonadotropin in the newborn rats

A single gonadotropin treatment of newborn rats influenced the thyrotropin (TSH) provoked thyroxine (T4) production of 2 months old animals. On pretreatment with 10, 20, 50, 100 and 200 I.U. of gonadotropin, the T4 blood level of animals given 10 and 200 I.U. differed scarcely from the controls treated only by TSH, while intermediary doses had a damaging effect as the T4 values were well below the control values measured in animals treated by TSH in adulthood.