Brain reward circuitry and the regulation of energy balance.

Reward signals contribute to the regulation of energy balance by influencing switching between feeding and competing behaviors. Properties of natural rewards are mimicked by electrical stimulation of certain brain regions. The rewarding effect produced by stimulating the perifornical region of the hypothalamus is modulated by body weight and is attenuated both by leptin and insulin. Research is reviewed concerning the dependence of the rewarding effect of perifornical stimulation on long-term energy stores and the effects of two neuropeptides implicated in the regulation of energy balance, neuropeptide Y and corticotropin-releasing hormone. It is proposed that the potentiating effect of weight loss on perifornical self-stimulation is not tied to an increased propensity to eat or to an enhancement of food reward per se, but resembles the influence of long-term energy stores on non-ingestive behaviors that defend body weight, such as hoarding.