Technique for study of hypothalamus (-) pituitary (-) testis function in vitro

An in vitro system consisting of the rat hypothalamic tissue, the collagenase-digested isolated anterior pituitary cells and the Leydig cells, has been employed, where the testosterone production of the incubated Leydig cells was measured as the end point. The method appeared to be highly sensitive and specific in studying the functional interrelations of hypothalamus-pituitary-testis system. The sensitivity of the Leydig cells to hCG was 0.1--1.0 mU per 10(6) cells, and that of the anterior pituitary cells to LHRH responding with LH release was in the range of 0.1--1.0 ng per 10(6) cells. Two hypothalamic blocks can release a sufficient amount of LHRH to produce LH secretion in the pituitary cell preparation. The described technique seems to be a suitable in vitro approach for measuring the functional activity of the system studied and for evaluation of the sites of response to various external agents.