THE EFFECT OF CHANGING GONADOTROPIN-RELEASING-HORMONE PULSE FREQUENCYON PUBERTY

We have examined the effect of using different pulse frequencies of ex ogenous GnRH to induce puberty and the time relationship among LH, FSH , sex steroids, and GH in these individuals. Five girls and three boys with delayed puberty received exogenous GnRH at either 3-h frequency (slow) or every 45 min (fast). Treatment was initially given overnight and increased to 24 h when breast stage 3 in girls or testicular volu me of 10 mt in boys was attained. Twentyfour-hour gonadotropin profile s were performed after 5 days, 1 month, 3 months, 6 months, and 1 yr o f treatment. Temporal relationships among LH, FSH, and estradiol; LH a nd testosterone; GH and estradiol; and GH and testosterone were examin ed by cross-correlation. There was no difference in the rate of pubert al progress between the groups. Mean serum gonadotropin and sex steroi d levels did not differ. LH was correlated with estradiol for both gro ups at 240 min (slow group, r = 0.54; fast group, r = 0.50). Estradiol correlated with LH at 300 min in the slow group (r = -0.41) and 200 m in in the fast group (r = -0.37). FSH correlated with estradiol at 140 min in the slow group (r = 0.62) and 160 min in the fast group (r = 0 .50). A rise in estradiol occurred 140-160 min after a rise in FSH and 240 min afterrise in LH. A rise in estradiol was followed 200-300 min later by a fall in LH. LH was correlated with testosterone at 60 min in the slow group (r = 0.73) and at 40 min in the fast group (r = 0.55 ). Testosterone correlated with LH at 420 min in the slow (r = -0.67) and 460 min in the fast group (r = -0.40). A rise in LH was followed 4 0-60 min later by a rise in testosterone. A rise in testosterone was f ollowed by fall in LH 420-460 min later. GH correlated with estradiol at 320 min in the slow group (r = 0.37) and 380 min in the fast group (r = 0.38). A rise in GH was followed, after 320-380 min, by a rise in estradiol. There was a correlation between GH and testosterone in the slow group after 280 min (r = 0.44). A rise in GH was followed by a r ise in testosterone after 280 min. The pituitary-gonadal axis is suffi ciently robust to allow puberty to progress with different fixed pulse frequencies. There is a temporal relationship among LH, FSH, and estr adiol secretion and between LH and testosterone secretion. We have dem onstrated the feedback effect of sex steroids at the level of the pitu itary and the time course of the effect of GH on gonadal function.