Androgens in testicular venous blood in the rat, with special reference to puberal change in the secretory pattern.

A puberal change in the secretory pattern of androgen was investigated in the rat. Using immature and adult rats which received an acute human chorionic gonadotrophin(HCG) stimulation, androstenedione and testosterone were measured both in the testicular venous blood(TVB) and in the testis by means of gaschromatography after preliminary separation by paperchromatography. In contrast to the adult pattern of testosterone-dominance, an androstenedione-dominant pattern was found in the immature rat. The change from immature to the adult pattern was assumed to take place at around day 40, being coincident with the onset of puberty in this species. The adult pattern of androgen secretion, however, could not be induced precociously even in the immature rat pretreated with HCG for 2 weeks, up to 34 days of age. The ratio of testosterone to androstenedione in TVB or in the testis of the intact adult animal was significantly increased by an acute stimulation of HCG. This finding is discussed in connection with the locus(ci) in the pathway of testosterone-biogenesis which HCG accelerates.