Reinforcement of wheel running in BALB/c mice: role of motor activity and endogenous opioids.
The authors investigated the effect of the opioid antagonist naloxone on wheel-running behavior in Balb/c mice. Naloxone delayed the acquisition of wheel-running behavior, but did not reduce the expression of this behavior once acquired. Delayed acquisition was not likely a result of reduced locomotor activity, as naloxone-treated mice did not exhibit reduced wheel running after the behavior was acquired, and they performed normally on the rotarod test. However, naloxone-blocked conditioned place preference for a novel compartment paired previously with wheel running, suggesting that naloxone may delay wheel-running acquisition by blocking the rewarding or reinforcing effects of the behavior. These results suggest that the endogenous opioid system mediates the initial reinforcing effects of wheel running that are important in acquisition of the behavior.
Vargas-Pérez
Héctor
H
Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México. vargashector@yahoo.com
Sellings
Laurie H L
LH
Paredes
Raúl G
RG
Prado-Alcalá
Roberto A
RA
Díaz
José-Luis
JL
D000704:Analysis of Variance; D000818:Animals; D008124:Locomotion / Q000187:drug effects; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D018847:Opioid Peptides / Q000037:antagonists & inhibitors / Q000502:physiology*; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D012054:Reinforcement, Psychology; D045442:Rotarod Performance Test; D012420:Running / Q000502:physiology*
D009292:Narcotic Antagonists; D018847:Opioid Peptides; D011957:Receptors, Opioid; D009270:Naloxone