Effects of leptin on secretion of LH and FSN from primary cultured female rat pituitary cells

Background: Leptin, which is the product of the obese gene, is believed to play important roles in pubertal development and reproductive function in f emales. In a study using adult male rats, it was found that leptin stimulat ed secretion of gonadotropin from the pituitary in a dose-related manner. H owever, there has been no such study in female rats. Objective: To investigate the effects of leptin on the production of LH and FSH from the pituitary in female rats, using primary cultured pituitary ce lls. Methods: In this study, we determined body weight. serum leptin concentrati on and serum estradiol (E-2) concentration in female Wistar rats at 3, 5, 6 , 7, 9 and 11 weeks of age, and cultured pituitary cells from 6-week-old fe male Wistar rats with leptin (0-10(-7) mol/l) and GnRH (0 or 10(-8) mol/l). Then basal and GnRH-stimulated extra- and intracellular LH and FSH were as sayed by RIA. Results: Serum leptin concentration increased with increases in body weight and E-2 concentration. The pubertal serum leptin concentration was about 1 0(-10) mol/l. At a lower or moderate concentration, leptin produced dose-re lated increases in both basal and GnRH-stimulated extra- and intracellular LH and FSH in pituitary cells. At a concentration of 10(-10) mol/l, leptin significantly (P < 0.05) stimulated both basal and GnRH-stimulated extra- a nd intracellular LH and FSH. However, at greater concentrations, these effe cts diminished. Conclusions: These results indicated that leptin induced pituitary cells to produce and secrete both LH and FSH, with or without GnRH. The concentrati on of leptin that induced the greatest production of gonadotropins by pitui tary cells was 10(-10) mol/l, which was the same as the physiological puber tal concentration. Leptin may be involved in the onset of puberty. It is al so conceivable that leptin may be a cause of ovulatory failure, not only in weight loss but also in weight gain.