24-HOUR CONCENTRATION PROFILES OF GONADOTROPIN AND ESTRADIOL (E(2)) IN PREPUBERTAL AND EARLY PUBERTAL GIRLS - THE DIURNAL RISE OF E(2) IS OPPOSITE THE NOCTURNAL RISE OF GONADOTROPIN

To investigate the detailed pattern of circulating gonadotropin and estradiol (E(2)) concentrations around the onset of puberty, plasma gonadotropin and E(2) were measured at 20-min intervals for 24 h in seven prepubertal and six early pubertal normal short girls. The hormone concentrations obtained were analyzed by Cluster pulse detection algorithm, cosinor analysis, and cross-correlation analysis. All subjects showed spontaneous LH and FSH pulses, and six early pubertal girls showed spontaneous E(2) pulses. Cosinor analysis revealed 24-h LH rhythms in ah subjects except two early pubertal girls and 24-h FSH rhythms in all subjects except one early pubertal girl. The acrophases (clocktime for maximal value) in the 24-h rhythm of LH and FSH were both found in the late hours of sleep. All subjects except three prepubertal girls showed significant 24-h E(2) rhythms. In contrast to the 24-h LH and FSH rhythms, the acrophase of the 24-h E(2) rhythm was found in the daytime waking period. Cross-correlation analysis demonstrated significant positive cross-correlations between LH and E(2) that were maximum at an E(2) lag of 5.7-9.3 h in three of the six early pubertal girls. In conclusion, the E(2) concentration profiles in girls around the onset of puberty show marked 24-h rhythm, with acrophase during the daytime waking period. There exists a 5.7- to 9.3-h time lag between LH and E(2) time series, and this long time lag might correspond to the time required for aromatization for E(2) synthesis.