Novel functions of orexigenic hypothalamic peptides: from genes to behavior.

The regulation of energy balance depends on the precise co-ordination of multiple peripheral and central systems. Much recent research has highlighted the importance of behavioral mechanisms is this control and suggested that the regulation of body weight shares central nervous system pathways in common with other complex behaviors, including learning and drug addiction. We present a brief review of some of this work and highlight the novel functions for central orexigenic neuropeptides. We review evidence that organisms engage in critical regulatory behaviors before and after ingestion has occurred. Additional evidence supports the idea that appetitive mechanisms are engaged that are critical for the regulation of intake during the act of ingestion. We briefly discuss the recent work on the potential role for central nervous system reward centers, how those might be critically linked to the central regulation of food intake, and how they may be dysregulated by the abundance of highly palatable, energy-dense foods.