Control of Energy Expenditure by AgRP Neurons of the Arcuate Nucleus: Neurocircuitry, Signaling Pathways, and Angiotensin

Purpose of Review Here, we review the current understanding of the functional neuroanatomy of neurons expressing Agoutirelated peptide (AgRP) and the angiotensin 1A receptor (AT(1A)) within the arcuate nucleus (ARC) in the control of energy balance. Recent Findings The development and maintenance of obesity involves suppression of resting metabolic rate (RMR). RMR control is integrated via AgRP and proopiomelanocortin neurons within the ARC. Their projections to other hypothalamic and extrahypothalamic nuclei contribute to RMR control, though relatively little is known about the contributions of individual projections and the neurotransmitters involved. Recent studies highlight a role for AT(1A), localized to AgRP neurons, but the specific function of AT(1A) within these cells remains unclear. Summary AT(1A) functions within AgRP neurons to control RMR, but additional work is required to clarify its role within subpopulations of AgRP neurons projecting to distinct second-order nuclei, and the molecular mediators of its signaling within these cells.