Nocturnal secretory dynamics of inhibin B and testosterone in pre- and peripubertal boys.
To investigate the secretory dynamics of testosterone and inhibin B, we collected samples every 20 min from 2000 h to 0800 h in 20 boys. Boys in group 1 (n = 5) were aged less than 8 yr, group 2 (n = 5) were aged more than 8 yr but 1.5 yr or more before pubertal onset, group 3 (n = 5) were studied 1.0 yr or less before pubertal onset, and group 4 (n = 5) were in early puberty. Testosterone increased after midnight in peripubertal boys, coinciding with the onset of LH pulsatility, and showed a pulsatile pattern in 6 of 10 of these boys. Cross-correlation analysis indicated significant temporal coupling between LH and testosterone. Inhibin B was higher in groups 3 and 4, compared with groups 1 and 2 (P < 0.01) and showed a downward trend overnight with no evidence of pulsatility and no evidence of short-term interactions with LH, FSH, or testosterone. Inhibin B and LH nocturnal means were both inversely correlated with time before pubertal onset (r(s) > or = -0.85, P < 0.01). Only LH nocturnal mean and amplitude, respectively, contributed independently to prediction of testosterone and inhibin B nocturnal means, explaining 71 and 65% of their variability. We conclude that both testosterone and inhibin B are related to nocturnal LH release in peripubertal boys but over different time scales.
Crofton
P M
PM
Department of Pediatric Biochemistry, Royal Hospital for Sick Children, Edinburgh EH9 1LF, United Kingdom. patricia.crofton@luht.scot.nhs.uk
Evans
A E M
AE
Wallace
A M
AM
Groome
N P
NP
Kelnar
C J H
CJ
D000293:Adolescent; D002648:Child; D002940:Circadian Rhythm; D043373:Follicle Stimulating Hormone, Human / Q000378:metabolism; D006801:Humans; D007265:Inhibins / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D011627:Puberty / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism*; D013997:Time Factors
D043373:Follicle Stimulating Hormone, Human; C422364:inhibin B; D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone