AREGU February 47/2

Covasa, M., R. C. Ritter, and G. A. Burns. Reduction of food intake by intestinal macronutrient infusion is not reversed by NMDA receptor blockade. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 278: R345–R351, 2000.—Rats increase their intake of food, but not water, after intraperitoneal injection of MK-801, a noncompetitive antagonist of N-methyl-D-aspartate-activated ion channels. We hypothesized that MK-801 might enhance intake by interfering with intestinal chemosensory signals. To test this hypothesis, we examined the effect of the antagonist on 15% sucrose intake after an intraduodenal infusion of maltotriose, oleic acid, or phenylalanine in both realand sham-feeding paradigms. MK-801 (100 μg/kg) significantly increased sucrose intake regardless of the composition of the infusate during real feeding. Furthermore, MK-801 had no effect on reduction of sucrose intake by intestinal nutrient infusions in shamfeeding rats. These results indicate that MK-801 does not increase meal size and duration by interfering with signals activated by intestinal macronutrients.