Effect of leptin and insulin on chick embryonic muscle cells and hepatocytes

In the present study we used the primary cultures of chick embryonic muscle and liver cells as a model for potential mutual combination effects of lep tin and insulin, respectively. The influence of both hormones on the prolif eration and protein synthesis was dose-dependent and related to the age of embryos from which the cells were isolated. Leptin (10 and 100 ng/well) inc reased the proliferation (estimated by DNA content and incorporation of lab eled thymidine into DNA) and protein synthesis (determined by incorporation of labeled leucine into proteins) of muscle cells. The effect of leptin an d insulin in muscle cells was similar. In younger embryo (11-day-old) the l ower dose of leptin was more effective than the higher one compared to the insulin effect. Mutual effects of leptin and insulin were neither additive nor synergistic and were equivalent to the effects of individual hormones. In hepatocytes the influence of leptin was dependent on the age at which th e cells were isolated (11- and 19-day-old embryos). The presence of insulin neither potentiated nor inhibited the effect of leptin.