Metabolic effects of neuropeptide Y injected into the sulcal prefrontal cortex

The metabolic effects of 10, 39 and 156 pmol doses of neuropeptide Y (NPY) injected into the sulcal prefrontal cortex (SPC) were investigated in an open-circuit calorimeter. The 39 pmol dose produced a large and long lasting increase in respiratory quotient indicating both increased utilization of carbohydrate as an energy substrate and the synthesis of fat from carbohydrate. The 10 and 39 pmol doses produced an inhibition of energy expenditure that was still evident 24 hours following the 10, but not the 39 pmol, dose. These energy expenditure effects appeared to reflect an inhibition of thermogenesis as they were not systematically related to changes in locomotor activity. In separate tests, 39 pmol NPY reliably enhanced food intake. This combination of effects, namely increased carbohydrate utilization, fat synthesis and food intake with reduced energy expenditure, shows NPY to be a potent anabolic force. In addition, these results indicate both the functional significance of NPY at a cortical level and the important role of the SPC in the control of energy balance.