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Neuron. 2011 Nov 17;72(4):616-29. doi: 10.1016/j.neuron.2011.08.027.

Activation of central orexin/hypocretin neurons by dietary amino acids.

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1
Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK.

Abstract

Hypothalamic orexin/hypocretin (orx/hcrt) neurons regulate energy balance, wakefulness, and reward; their loss produces narcolepsy and weight gain. Glucose can lower the activity of orx/hcrt cells, but whether other dietary macronutrients have similar effects is unclear. We show that orx/hcrt cells are stimulated by nutritionally relevant mixtures of amino acids (AAs), both in brain slice patch-clamp experiments, and in c-Fos expression assays following central or peripheral administration of AAs to mice in vivo. Physiological mixtures of AAs electrically excited orx/hcrt cells through a dual mechanism involving inhibition of K(ATP) channels and activation of system-A amino acid transporters. Nonessential AAs were more potent in activating orx/hcrt cells than essential AAs. Moreover, the presence of physiological concentrations of AAs suppressed the glucose responses of orx/hcrt cells. These results suggest a new mechanism of hypothalamic integration of macronutrient signals and imply that orx/hcrt cells sense macronutrient balance, rather than net energy value, in extracellular fluid.

PMID:
22099463
DOI:
10.1016/j.neuron.2011.08.027
[Indexed for MEDLINE]
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