Regulation of energy balance and body weight by the brain: A distributed system prone to disruption

摘要

Energy balance refers to the physiologic mechanisms that are reciprocally linked to ensure that adequate energy is available for cellular processes required for survival and reproduction. As the term implies, there are two arms of this balance, each equally important in maintaining energy homeostasis: energy intake (ie, food intake) and energy expenditure (eg, physical activity, metabolism, and core body temperature regulation). Any internal or external perturbations to the physiologic mechanisms governing either energy intake or expenditure will almost undoubtedly affect the other arm of the system and result in disruption to the energy balance system as a whole. The coordinated regulation of energy balance is therefore ultimately controlled by the central nervous system (CNS). Given the reciprocal link between energy intake and expenditure, and the fundamental requirement to maintain adequate energy for survival and reproduction, the CNS control of energy balance is one that is multidetermined. Multiple internal signals, neural receptors, and regions of the brain operate with a degree of redundancy to ensure that enough energy exists to sustain life. This article discusses some of the classic internal signals, physiologic mechanisms, the distinct nuclei within the brain, as well as the brain's response to environmental stimuli, that together play an essential role in energy balance regulation.