SECOR, S.M.*; NAGY, T.R.: Postprandial response of plasma lipds and the hormone leptin in pythons

With each meal, pythons rapidly upregulate gut performance and dramatically increase metabolic rate. We suggest one manner by which pythons fuel these postprandial responses is to mobilize stored energy sources, particularly lipids. To evaluate the mobilization of lipids with feeding we measured plasma levels of triglycerides, free fatty acids, and cholesterol from fasted and fed pythons. Aware that the hormone leptin possibly mediates fat deposition and metabolism, we simultaneously measured plasma levels of leptin from fasted and fed snakes. Following the ingestion of meals equaling 25% of their body mass, pythons significantly increased plasma levels of triglycerides (by 50-fold), free fatty acids (by 50%), and cholesterol (by 80%). Simultaneously, pythons experienced significant increases (by 65%) in plasma concentrations of leptin. Fasted control snakes (sampled at the same time and in the same fashion as fed snakes) exhibited no significant changes in plasma lipid or leptin concentrations. Feeding induces in pythons the mobilization of lipids which conceivably serve as the energy source to fuel the costly upregulation of their guts after feeding. Leptin may function to trigger the release of these lipids from fat bodies and to stimulate the postprandial increase in metabolism.