Regulation of circulating leptin and its soluble receptor during pubertal development in the male rhesus monkey (Macaca mulatta).

In humans, circulating leptin levels are low in early childhood and rise until puberty, whereas the reverse occurs for the soluble leptin receptor (sOB-R). In women, leptin remains high and sOB-R remains low, but in men leptin declines after adolescence and sOB-R increases. These observations suggest that leptin may regulate the production of sOB-R, and that the increased testosterone in adolescent boys may be responsible for the gender differences in leptin and sOB-R. To test this hypothesis, leptin was administered continuously to agonadal juvenile male monkeys for 16 days. No change in sOB-R was observed. Intact juvenile male monkeys were given pulsatile doses of gonadotropins for a period of 7 weeks to induce precocious puberty and assess the effect on plasma testosterone, leptin, and sOB-R. By 4 weeks testosterone had reached adult levels. No changes were observed in leptin, but by week 4, sOB-R was higher than pretreatment values and remained higher at week 7. These data suggest that leptin may not play a significant role in regulating the production of sOB-R and that gender differences in sOB-R in humans may be driven by the increased production of testosterone at puberty in males.