Blood and Serum Parameters.

Animals were lightly anesthetized, and blood from the retro-orbital plexus was collected into serum tubes. Serum leptin, adiponectin, insulin, and glucagon were determined by commercially available ELISA kits from Merck Millipore (leptin and adiponectin), from Crystal Chem (insulin), and from R&D systems (glucagon) according to the manufacturer’s instructions. Serum total cholesterol and triglyceride levels were determined by a photometric method according to the manufacturer’s instructions (dri-chem clinical chemistry analyzer FUJI FDC 3500i; Sysmex). Serum HDL-cholesterol and LDL-cholesterol were measured by the central laboratory of the University Hospital of Tübingen according to routine clinical chemistry methods (Siemens). The blood glucose concentration was determined in a drop of tail blood by a glucometer (Accu-Chek Performa, Roche).