title: A study of the short-time variation and interrelationship of plasma hormone levels reflecting pituitary, adrenocortical and testicular function in fertile men.
abstract: Using radioimmunoassay method, we have estimated the levels of cortisol (C), pregnenolone (delta 5P), 17-hydroxypregnenolone (17-OH-delta 5P), dehydroepiandrosterone (DHEA), 17-hydroxyprogesterone (17-OH-P), androstenedione (A), testosterone (T) and dihydrotestosterone (DHT) in peripheral plasma samples collected at short-time (15 min) intervals from 10 fertile men, during two 4-h periods (06.00 to 10.00 and 18.00 to 22.00). In addition, the levels of biologically active luteinizing hormone (LH) were measured by an in vitro bioassay method in 9 of the subjects. The levels of all steroids studied exhibited diurnal variation with higher levels during the morning and lower levels during the evening period. The cortisol and the delta 5-steroid levels also exhibited individual short-term episodic spikes during the 2 periods. No short-term variation was observed in the levels of 17-OH-P, A, T and DHT. Statistically significant correlations were found between the levels of C and those of the delta 5-steroids and A in most of the subjects. No correlation was found between the above steroid levels and those of 17-OH-P, T and DHT. Also the LH levels exhibited episodic spikes of 60 to 90 min duration, but no diurnal variation. When the LH levels were related to those of T found in the same samples or in samples withdrawn 15 to 810 min afterwards, a significant positive correlation was found on repeated occasions in 5 of the 9 subjects. No systematic negative correlation was found when the T levels were related to those of LH in the same sequential fashion. Whereas the positive correlations found between LH and T levels in some of the subjects might suggest that physiological changes in peripheral LH levels are instrumental in regulating T-secretion, the rather consistent lack of significant negative correlation between T and LH levels seems to favour the view that the release of LH is not modulated by peripheral testosterone levels alone.
mesh_terms: D000305:Adrenal Cortex Hormones / Q000097:blood*; D000328:Adult; D000728:Androgens / Q000097:blood*; D002940:Circadian Rhythm; D005298:Fertility; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D010907:Pituitary Hormones / Q000097:blood*; D011284:Pregnenolone / Q000097:blood; D013737:Testis / Q000502:physiology*
chemical_list: D000305:Adrenal Cortex Hormones; D000728:Androgens; D010907:Pituitary Hormones; D011284:Pregnenolone; D007986:Luteinizing Hormone; D006854:Hydrocortisone