Constancy of adult hypothalamic tyrosine hydroxylase after gonadal steroid treatment during development

Tyrosine hydroxylase (TH) was studied in the entire hypothalamus of 60-day-old male and female rats, and its activity was similar in both sexes. Administration of estrogen or androgen to male or female pups soon after birth and during development did not affect the kinetic parameters of TH. It is, thus, suggested that sexual dimorphism in the levels and turnover of catecholamines (CA) and their sensitivity to fluctuations in gonadal steroids during development do not depend on corresponding sex-related or steroid-sensitive differences in the synthesis of hypothalamic CA.