Effect of hypothalamic extracts of rats of various age on pituitary adenylate cyclase in vitro.

Adenylate cyclase activity in rat pituitary gland in vitro after the addition of hypothalamic extracts from rats of different age was investigated. Hypothalamic extracts from fetuses, 20 day-old and adult rats significantly increased the adenylate cyclase activity in pituitary of the adult rat incubated in vitro. However, any similar stimulatory effect was not found after the addition of extracts from 1 or 5 day-old rats. These results show possibly age dependent differences in the content of substances which stimulate the adenylate cyclase activity in the hypothalamus.