Central infusion of leptin does not increase AMPK signaling in skeletal muscle of sheep

In sheep, central leptin infusion reduces food intake and increases energy expenditure in adipose tissue and skeletal muscle. The mechanism(s) for these peripheral effects of central leptin in sheep are not known but, based on rodent studies, may involve AMP-activated protein kinase (AMPK). In mice, central leptin acutely increases both skeletal muscle AMPK activation and glucose uptake. Thus, to investigate if these effects exist in higher order mammals, ovariectomized Corriedale ewes (N=4 per group) received a continuous lateral ventricular infusion (60mul/h) of either leptin (50mug/h) or artificial cerebrospinal fluid (aCSF, CON) for 8 days. Tritiated glucose (3-(3)H-glucose) was infused intravenously for calculation of whole body glucose turnover during both acute (6 h) and chronic (7-8 days) leptin/aCSF infusion. Muscle biopsies were also obtained. Leptin infusion reduced (P