Gut-brain circuits for fat preference.

The perception of fat evokes strong appetitive and consummatory responses. Here we show that fat stimuli can induce behavioural attraction even in the absence of a functional taste system. We demonstrate that fat acts after ingestion via the gut-brain axis to drive preference for fat. Using single-cell data, we identified the vagal neurons responding to intestinal delivery of fat, and showed that genetic silencing of this gut-to-brain circuit abolished the development of fat preference. Next, we compared the gut-to-brain pathways driving preference for fat versus sugar, and uncovered two parallel systems, one functioning as a general sensor of essential nutrients, responding to intestinal stimulation with sugar, fat and amino acids, whereas the other is activated only by fat stimuli. Finally, we engineered mice lacking candidate receptors to detect the presence of intestinal fat, and validated their role as the mediators of gut-to-brain fat-evoked responses. Together, these findings reveal distinct cells and receptors that use the gut-brain axis as a fundamental conduit for the development of fat preference.