Reduction of food intake by intestinal macronutrient infusion is not reversed by NMDA receptor blockade.
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 real- and sham-feeding paradigms. MK-801 (100 microg/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 sham-feeding rats. These results indicate that MK-801 does not increase meal size and duration by interfering with signals activated by intestinal macronutrients.
Covasa
M
M
College of Veterinary Medicine, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164, USA. mcovasa@vetmed.wsu.edu
Ritter
R C
RC
Burns
G A
GA
D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D007422:Intestines / Q000187:drug effects*; D007441:Intubation, Gastrointestinal; D008297:Male; D019301:Oleic Acid / Q000008:administration & dosage* / Q000494:pharmacology; D010649:Phenylalanine / Q000008:administration & dosage* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D012996:Solutions; D013395:Sucrose; D014312:Trisaccharides / Q000008:administration & dosage* / Q000494:pharmacology
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D012996:Solutions; D014312:Trisaccharides; D019301:Oleic Acid; D010649:Phenylalanine; D013395:Sucrose; C008317:maltotriose; D016291:Dizocilpine Maleate