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
| Autor: | Chloe Brunton, Regina M. Carroll, Andrew J. Kwilasz, Mitchell A. Head, Pawel K. Olszewski, Thomas W. Hahn, David C. Jewett, Anica Klockars, Allen S. Levine, Jason M. Wiebelhaus, Martha K. Grace, Rachel L. Tham, Travis R. Smith, Eric E. Ewan |
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| Rok vydání: | 2019 |
| Předmět: |
Male
medicine.medical_specialty medicine.drug_class Hunger Narcotic Antagonists Neuropeptide Satiation Naltrexone Discrimination Learning Rats Sprague-Dawley 03 medical and health sciences Behavioral Neuroscience chemistry.chemical_compound 0302 clinical medicine Reward Opioid receptor Orexigenic Internal medicine medicine Animals Neuropeptide Y 030304 developmental biology 0303 health sciences Behavior Animal business.industry digestive oral and skin physiology Feeding Behavior Rats Analgesics Opioid DAMGO Endocrinology chemistry Opioid Time Perception Conditioning Operant Stimulus control business Food Deprivation 030217 neurology & neurosurgery Opioid antagonist medicine.drug |
| Zdroj: | Behavioural brain research. 380 |
| ISSN: | 1872-7549 |
| Popis: | 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 h 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 discriminative stimulus effects of PVN-injected hunger mediator, neuropeptide Y (NPY). In contrast to PVN NPY, centrally or peripherally injected opioid agonists failed to induce discriminative stimuli similar to those of 22 h deprivation. In line with that, naltrexone did not reduce the hunger discriminative stimuli induced by either 22 h deprivation or NPY administration in 2 h food-restricted subjects, even though doses used therein were sufficient to decrease deprivation-induced feeding in a non-operant setting in animals familiar with consequences of 2 h and 22 h deprivation. We conclude that opioids promote feeding for reward rather than in order to replenish lacking energy. |
| Databáze: | OpenAIRE |
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