Naltrexone fails to suppress spontaneous locomotor activity in hamsters.
The increased spontaneous locomotor activity (SLMA) of rats exposed to a novel environment is decreased by opiate antagonists. In the present study, naltrexone (1.0-40 mg/kg) failed to reduce the SLMA of hamsters exposed to the novel environment of activity cages. The SLMA of another group of untreated hamsters declined following 4 consecutive exposures to the activity cages. Thus, the novelty-induced increase in hamster SLMA is not sensitive to opiate antagonism. The differential sensitivity of rats and hamsters to opiate effects on activity and feeding may be due to the presence of an opiate-sensitive hibernation system in hamsters.
D000818:Animals; D006224:Cricetinae; D004777:Environment; D005106:Exploratory Behavior / Q000187:drug effects; D008297:Male; D008647:Mesocricetus; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D009270:Naloxone / Q000031:analogs & derivatives*; D009271:Naltrexone / Q000494:pharmacology*; D051381:Rats; D013045:Species Specificity; D013997:Time Factors
D009270:Naloxone; D009271:Naltrexone