title: The aging Leydig cell: VI. Response of testosterone precursors to gonadotrophin in men.
abstract: The effects of a single im injection of human chorionic gonadotrophin (hCG) on circulating testosterone precursor levels at 0, 1-6, 24, 48 and 72 h were examined in normal young adult (mean age 34 years) and normal aged men (mean age 74 years) Basal 08.30- 09.00 h concentrations of androstenedione and dehydroepiandrosterone were lower in aged men while progesterone levels were not significantly different from young men. A significant biphasic increase of circulating progesterone was observed in young men, characterized by an early peak at 2 h (33% above basal) and a secondary peak at 24 h (49% above basal). In old men there were no increases in circulating progesterone levels following hCG treatment during the early (1-6 h) or late (24-72 h) periods. There were not discernable increases in circulating dehydroepiandrosterone levels following hCG administration in both groups of men. Androstenedione levels in young men. Androstenedione levels in young men did not change during the first 6 h following hCG but increased significantly at 48 and 72 h, while in old men there was a small peak at 4 h (which was not statistically significant) and a secondary significant rise at 48 and 72 h. However, early and late stimulated absolute levels for androstenedione were lower in the aged population. Thus, there are differences in precursor concentrations in the basal state and in response to hCG in aged men.
mesh_terms: D000367:Age Factors; D000368:Aged; D000735:Androstenedione / Q000097:blood*; D002470:Cell Survival; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D002845:Chromatography; D003687:Dehydroepiandrosterone / Q000097:blood*; D006801:Humans; D007985:Leydig Cells / Q000502:physiology*; D008297:Male; D011374:Progesterone / Q000097:blood*; D011863:Radioimmunoassay; D013739:Testosterone / Q000097:blood*
chemical_list: D006063:Chorionic Gonadotropin; D013739:Testosterone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D011374:Progesterone