Intraportal mercaptoacetate infusion increases afferent activity in the common hepatic vagus branch of the rat.

Because dissection of the common hepatic vagus branch attenuated the feeding response to intraperitoneal injection of mercaptoacetate (MA), an inhibitor of fatty acid oxidation, in rats fed a fat-enriched diet (18% fat), the effect of MA on the discharge rate in afferents of the common hepatic vagus branch was investigated. Intraportal infusion of the Na salt of MA (200, 400, and 800 mumol/kg) in rats adapted to the 18% fat diet dose dependently increased the discharge rate in afferents of the common hepatic vagus branch, whereas NaCl and the Na salt of the structurally related compound 2-mercaptopropionate had no effect. The lowest dose of MA yielding a significant increase in the discharge rate was 400 mumol/kg. This agrees with the dose dependence of the feeding response to MA. These findings are consistent with the notion that hepatic fatty acid oxidation controls food intake by modulating the discharge rate of vagal afferents.