Orexigenic Hypothalamic Peptides Behavior and Feeding

Abstract

Orexigenic hypothalamic peptides have been studied extensively for their ability to regulate feeding behavior. The traditional contention regarding orexigenic peptide function ascribed that peptides produced within the Arc & LH exerted their effects on feeding through acting within local hypothalamic centers, with a major emphasis on the LH. However, reports over the last decade indicate that orexigenic peptides not only act within hypothalamic centers to regulate food intake but are also capable of affecting feeding through their actions at extra-hypothalamic centers, namely, within the brain’s endogenous reward circuitry. This observation expands the complexity of feeding behavior and indicates that feeding behavior can be manifested through reward processing. Moreover, studies from the field of addiction biology now indicate that orexigenic peptides are also capable of modulating drug taking behavior. Here, we consider, individually, four separate orexigenic hypothalamic peptide systems, their functional–anatomical location as well as the ability of each system to activate mesolimbic reward circuitry. As some have even suggested that a disruption within a hypothalamic neuropeptide system might underlie pathological overfeeding and addictive behaviors, this chapter also describes literature detailing the ability of orexigenic peptides to modulate addictive behavior with special emphasis given to relapse and reinstatement of psychostimulant use. Collectively, these ideas suggest that orexigenic peptides regulate reward processing, food reinforced behavior, and addictive behavior.