Circadian rhythms in plasma levels of cortisol, dehydroepiandrosterone, Δ4-androstenedione, testosterone and dihydrotestosterone of healthy young men

Abstract

Three healthy males (18, 22 and 30 yr of age; 85 kg/177 m, 82 kg/181 cm and 75 kg/168 cm, respectively), synchronized with a diurnal activity (0600 to 2300 h) and nocturnal rest, volunteered for this study. Blood was sampled (venous catheter) hourly during a 24 h span. A radiocompetition method was used for cortisol determinations. Other steroids were first extracted (ethyl-ether) from each plasma sample, then chromatographed on a celite column to isolate 3 fractions: .DELTA.4-androstenedione (.DELTA.-4); dihydrotestosterone (DHT) and dehydroepiandrosterone (DHA); testosterone. A radioimmunological assay was used thereafter for the determination of androgenic steroids. Statistically significant (both conventional and cosinor methods) circadian rhythms were detected (P < 0.005). Acrophases (peak times) occurred in the following order: cortisol (0728), DHA (0843), .DELTA.-4 (0954), T (1115) and DJT (1637). The respective circadian amplitudes of DHA and .DELTA.-4 were smaller than those of cortisol while the amplitudes T and DHT did not show differences statistically significant from each other.