Brainstem nutrient sensing in the nucleus of the solitary tract inhibits feeding

Central leucine sensing in the control of energy homeostasis

This article reviews recent studies identifying two key brain regions as two critical nodes in the neural network where central leucine sensing contributes to whole body energy homeostasis: the mediobasal hypothalamus and the dorsal vagal complex of the caudal brainstem. Activation of these leucine sensing sites engages multiple determinants of energy balance, including glucose homeostasis, food intake, and adiposity.

Duodenal lipid sensing activates vagal afferents to regulate non-shivering brown fat thermogenesis in rats

Previous evidence indicates that duodenal lipid sensing engages gut-brain neurocircuits to determine food intake and hepatic glucose production, but a potential role for gut-brain communication in the control of energy expenditure remains to be determined. Here, we tested the hypothesis that duodenal lipid sensing activates a gut-brain-brown adipose tissue neuraxis to regulate thermogenesis. We demonstrate that direct administration of lipids into the duodenum increases brown fat temperature. Co-infusion of the local anesthetic tetracaine with duodenal lipids abolished the lipid-induced increase in brown fat temperature. Systemic administration of the CCKA receptor antagonist devazepide blocked the ability of duodenal lipids to increase brown fat thermogenesis. Parenchymal administration of the N-methyl-d-aspartate receptor blocker MK-801 directly into the caudomedial nucleus of the solitary tract also abolished duodenal lipid-induced activation of brown fat thermogenesis. These findings establish that duodenal lipid sensing activates a gut-brain-brown fat axis to determine brown fat temperature, and thereby reveal a previously unappreciated pathway that regulates thermogenesis.