Effects of opioid receptor ligands in rats trained to discriminate 22 from 2 hours of food deprivation suggest a lack of opioid involvement in eating for hunger.

Effects of opioid receptor ligands in rats trained to discriminate 22 from 2 hours of food deprivation suggest a lack of opioid involvement in eating for hunger. Behav Brain Res. 2019 Nov 16;:112369 Authors: Jewett DC, Klockars A, Smith TR, Brunton C, Head MA, Tham RL, Kwilasz AJ, Hahn TW, Wiebelhaus JM, Ewan EE, Carroll RM, Grace MK, Levine AS, Olszewski PK Abstract It is well accepted that opioids promote feeding for reward. Some studies suggest a potential involvement in hunger-driven intake, but they suffer from the scarcity of methodologies differentiating between factors that intersect eating for pleasure versus energy. Here, we used a unique food deprivation discrimination paradigm to test a hypothesis that, since opioids appear to control feeding reward, injection of opioid agonists would not produce effects akin to 22 h of food deprivation. We trained rats to discriminate between 22- and 2-h food deprivation in a two-lever, operant discrimination procedure. We tested whether opioid agonists at orexigenic doses produce discriminative stimulus effects similar to 22-h deprivation. We injected DAMGO, DSLET, or orphanin FQ in the paraventricular hypothalamic nucleus (PVN), a site regulating hunger/satiety, and butorphanol subcutaneously (to produce maximum consumption). We assessed the ability of the opioid antagonist, naltrexone, to reduce the discriminative stimulus effects of 22-h deprivation and of the 22-h deprivation-like...
Source: Behavioural Brain Research - Category: Neurology Authors: Tags: Behav Brain Res Source Type: research