The effect of opioid antagonism on food intake behavior and body weight in a biobehavioral model of obese binge eating.
The obese Zucker rat (OZR) exhibits a hyperphagic eating pattern similar to the obese binge eater. Dynorphin, an endogenous agonist of the kappa receptor, is associated with regulation offood intake. Lessened sensitivity to opioid antagonists and/or increased central dynorphin levels may contribute to the hyperphagic eating pattern observed in the OZR. This study examined the temporal effect of a single intracerebroventricular (ICV) dose of nor-binaltorphimine (NBNI), a specific and long-lasting kappa opioid antagonist, on food intake, body weight, and satiety measures (meal size and the shape of the cumulative food intake curve [CFIC]) in adult male OZRs. Analysis of individual subjects revealed a differential response to opioid antagonism with respect to weight loss, reduction in food intake, and change in the slope of the CFIC, with some responding and others responding poorly. Repeated-measures analysis of variance showed a significant decrease in body weight (P = 0.001) and food intake (P = 0.03) in responders compared to poor responders and controls. Satiation was influenced to a greater extent in responders, who showed a significant reduction in meal size and a greater change in the CFICfor the largest meal of the day toward a pattern of satiation. These data suggest that a differential response to chronic opioid antagonism may exist in the OZR.
Jarosz
Patricia A
PA
College of Nursing at Wayne State University, Detroit, Michigan 48202, USA. pjarosz@wayne.edu
Metzger
Bonnie L
BL
D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D001921:Brain / Q000187:drug effects*; D002032:Bulimia / Q000150:complications / Q000188:drug therapy; D002149:Energy Intake / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects*; D006963:Hyperphagia / Q000150:complications / Q000188:drug therapy; D007276:Injections, Intraventricular; D023421:Models, Animal; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D009765:Obesity / Q000188:drug therapy / Q000209:etiology*; D051381:Rats; D011924:Rats, Zucker; D012527:Satiation / Q000187:drug effects
D009292:Narcotic Antagonists; C051844:norbinaltorphimine; D009271:Naltrexone