Effects of starvation on plasma GH activity, pituitary GH and GH-RF levels in the rat.

Abstract

The effects of complete food removal for 7 days were measured on plasma GH activity, hypothalamic content of growth hormone releasing factor (GH-RF) and pituitary concentration of growth hormone (GH) in male rats. Control male rats were fed ad lib. for 7 days. In another experiment, the starved rats received replacement doses of L-Na-thyroxine (2.5 μg/ 100 g body weight/day) beginning on day 2 starvation. On day 8 all rats were weighed, anesthetized with ether and bled from the abdominal aorta. The pituitaries were removed and individually weighed; the hypothalami were placed in ice cold O.lN HC1 (0.1 ml/hypothalamus). Hypothalamic GH-RF was assayed by an in vitro incubation method. Lyophilized plasma, anterior pituitaries and incubation medium were assayed for GH by the standard tibia test, using a 4-point assay procedure. Statistical analysis of the data showed a significantly lower plasma GH content in starved or thyroxine-treated starved rats (p<0.01). Pituitary GH content and hypothalamic content of ...