Different gonadotropin pulsatile fashions in anovulatory cycles of young girls indicate different maturational pathways in adolescence.

Abstract

To characterize the spectrum of pulsatile gonadotropin secretion during the postmenarchal period, we studied 24 adolescents whose gynecological age was 1-4 yr. Six women with ovulatory cycles formed a control group. Eighteen women with anovulatory cycles were grouped on the basis of mean plasma LH values: group 1 (n = 8) with high LH values and group 2 (n = 10) with normal LH values. In all women, plasma gonadotropin concentrations were measured at 10-min intervals for 8 h on day 4 of the cycle. Pulsatile gonadotropin secretion was also studied a second time in 7 women from group 1 and 7 from group 2 after 5 days of progesterone (P) in oil treatment to assess the role of P in regulating gonadotropin secretion in the postmenarchal period. Group 1 had more frequent and greater LH pulses than the other two groups (which were very similar) and had the highest plasma 17 beta-estradiol, testosterone (T), androstenedione (A), and 17-hydroxyprogesterone concentrations. In all anovulatory women, basal LH values were correlated with the LH interpulse interval (r = -0.65; P less than 0.01) and pulse amplitude (r = 0.86; P less than 0.001). LH pulse amplitude was correlated with basal 17 beta-estradiol values (r = 0.74; P less than 0.001), and LH interpulse interval with basal T (r = -0.83; P less than 0.001), A (r = -0.51; P less than 0.05), and 17-hydroxyprogesterone (r = -0.79; P less than 0.001) values. P administration decreased LH pulse frequency and increased LH pulse amplitude more in group 2 than in group 1 with high LH values; a clear reduction was also found in A, T, and 5 alpha-dihydrotestosterone values. These results indicate that 1) anovulatory young women with high plasma LH values have an alternative maturational pathway, different from that of anovulatory women with normal plasma LH values, who are similar to ovulatory adolescents; 2) the pulsatile pattern of gonadotropin secretion has specific roles linked separately to amplitude and frequency in controlling ovarian steroidogenesis, which accounts for the endocrine differences between groups; and 3) in the postmenarchal period, by modulating LH and FSH pulsatility and thus reducing androgen levels and their atretic action on follicles, P may be a basic regulatory factor in enhancing functional cyclicity.