Abstract
Naloxone's effects on initiation, maintenance, and maximal response effort to acquire food were examined in rats maintained under different levels of food deprivation. In Experiment 1, naloxone was administered SC to rats responding under an FR 80 (first pellet) FR 3 (subsequent pellets) reinforcement schedule. Naloxone did not increase time to acquire the first pellet. Naloxone's suppression of subsequent intake and lowest effective dose were inversely related to level of deprivation. In Experiment 2, rats responded for food under a Progressive Ratio 2 reinforcement schedule. Breakpoint was lowered only when rats were maintained with free access to food. Decreases in response and running rate were inversely related to deprivation level. Results are consistent with the hypothesis that opioids are involved in the maintenance but not the initiation of feeding.
Original language | English (US) |
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Pages (from-to) | 377-383 |
Number of pages | 7 |
Journal | Pharmacology, Biochemistry and Behavior |
Volume | 49 |
Issue number | 2 |
DOIs | |
State | Published - Oct 1994 |
Bibliographical note
Funding Information:This work was supported by the Department of Veterans Affairs, National Institute of Drug Abuse DA 03999, and National Institute of Aging AG00198.
Keywords
- Feeding
- Naloxone
- Operant reinforcement
- Opiates