Effect of leptin on in vitro development of ovine preantral ovarian follicles

The influence of human or ovine leptin on in vitro culture of preantral follicles (PFs) isolated from sheep ovaries was investigated. Among the 12 different concentrations (0-1000 ng/mL) of human leptin tested, proportion of PFs exhibiting growth, mean increase in diameter, antrum formation, and maturation of the oocytes to MII stage were the best in 10 ng/mL. Culture of sheep ovarian PFs in TCM 199 supplemented with 10 ng/mL of human or ovine leptin FSH (2.5 μg/mL), thyroxine (1 μg/mL), insulinlike growth factor I (10 ng/mL), and GH (1 mIU/mL) resulted in significantly (P ≤ 0.05) greater average increase in diameter (11 and 9 vs. 6 μm), better proportions of PFs exhibiting growth (66% and 58% vs. 48%), antrum formation (51% and 51% vs. 34%), and maturation of oocytes to MII stage (24% and 22% vs. 7%) than the control medium. It is concluded that (1) the optimum dose of leptin for the growth of sheep PFs in vitro was 10 ng/mL, (2) human or ovine leptin supported similar development in vitro of PFs in sheep, (3) inclusion of leptin along with FSH, thyroxine, insulinlike growth factor I, and GH resulted in only a marginal further improvements in in vitro development of sheep PFs'.