Chemical lesion of visceral afferents causes transient overconsumption of unfamiliar high-fat diets in rats.
Because it is commonly assumed that the major role of visceral afferents in food intake control is to terminate meals by carrying negative-feedback signals to the brain, we hypothesized that overconsumption should occur in rats with chemically lesioned visceral afferents if they were presented with an unfamiliar diet. Adult male Sprague-Dawley (SD) rats were treated with multiple doses of capsaicin or vehicle as a control. Five weeks later, a series of 3-h feeding tests after 24-h deprivation was carried out, first with chow and then with either a solid (vegetable shortening) or liquid (Ensure) unfamiliar high-fat diet. Both groups consumed similar amounts of their powdered chow maintenance diet, but capsaicin-treated rats consumed at least 50% more of either high-fat diet than vehicle controls (P < 0.01) at the beginning of the first trial. During second and third trials with the now-familiar high-fat diet, intake was no longer significantly different between the two groups, suggesting rapid engagement of redundant control mechanisms. These results support a role of capsaicin-sensitive visceral afferents in providing negative feedback for early meal termination during the ingestion of unfamiliar diets.
Chavez
M
M
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge 70808, USA.
Kelly
L
L
York
D A
DA
Berthoud
H R
HR
D000344:Afferent Pathways; D000818:Animals; D001835:Body Weight; D002211:Capsaicin / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology; D003213:Conditioning, Psychological / Q000502:physiology; D004041:Dietary Fats / Q000378:metabolism*; D004064:Digestive System / Q000294:innervation; D004068:Digestive System Physiological Phenomena; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D005727:Ganglia, Spinal / Q000187:drug effects; D008297:Male; D009620:Nodose Ganglion / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012527:Satiation / Q000502:physiology; D013864:Thioglycolates / Q000494:pharmacology; D014630:Vagus Nerve / Q000502:physiology
D004041:Dietary Fats; D013864:Thioglycolates; C017487:2-mercaptoacetate; D002766:Cholecystokinin; D002211:Capsaicin