Effects of gonadal steroids on hypothalamic and pituitary RNA and protein synthesis in rats

The sexual differences and the effect of castration and of a single i. p. injection of oestradiol-17 beta or testosterone on RNA and protein synthesis have been studied in the anterior pituitary, hypothalamus and cortex from rats. It was found that: 1. Sex-, castration- and tissue dependent differences were found in RNA content and in in vitro synthesis of nucleic acids and proteins. 2. Oestradiol showed a general facilitatory effect on RNA and protein synthesis in every tissue examined in 4-8th and 8-16th day after treatment respectively. This facilitation was followed by a suppression of RNA synthesis in the pituitary from castrated males and females and by that of protein synthesis in the hypothalamus from ovariectomized and in the pituitary from orchidectomized rats. 3. The first significant change in the above measures appeared simultaneously in the pituitary and hypothalamus or - under some experimental conditions - the pituitary anticipated the hypothalamus in its response to steroid treatment.