Effects of leptin administration on the endocrine pancreas and liver in the lizard Podarcis sicula

In this study, we investigated the presence of leptin receptor in pancreatic isletsand the effect of exogenous leptin administration in Podarcis sicula on glucose metabolism. Our datashow the presence of leptin receptor immunoreactivity in the endocrine pancreas suggesting thatleptin may act at a peripheral level as previously postulated in mammals. The effects of short- andlong-term and dose–response treatment with supraphysiological concentrations of leptin oncirculating levels of insulin, glucagon and glucose in the blood have been evaluated. Taken together,our results indicate that leptin treatment was followed by an increase in insulin, glucagon andglucose in the blood, depending on the dose of leptin. Moreover, leptin treatment brought abouta decrease of glycogen and the appearance of tyrosine-phosphorylated proteins in the liver. Thisstudy shows that in the lizard P. sicula leptin is involved in glucose metabolism.