Context-specific sensitization to naloxone-precipitated withdrawal in hamsters: effect of pimozide.
Three experiments were conducted to investigate the development of context-specific sensitization to naloxone-precipitated withdrawal in hamsters. In Experiment 1, animals in group M/S were given morphine (15 mg/kg) injections in a distinctive environment and saline in the home cage. Animals in group S/M were given saline in the distinctive environment and morphine in the home cage, and animals in group S/S were given saline in both environments. All groups were challenged subsequently with naloxone (0.4 mg/kg) in the distinctive environment and then observed for signs of opiate withdrawal. The results showed that group M/S gave more naloxone-precipitated withdrawal signs than each of the other groups, which did not differ from one another. Experiment 2 was designed to test the effect of pimozide on context-specific sensitization to naloxone-precipitated withdrawal. The design was similar to that of Experiment 1 but group P/M/S, which received an injection of pimozide (0.5 mg/kg) 4 h prior to morphine, was added. The results indicated that context-specific sensitization developed as in Experiment 1, except among animals treated with pimozide. Experiment 3 was designed to determine whether pimozide interferes with the development or the expression of context-specific sensitization. Six groups, differing in the frequency and timing of the pimozide injection, were employed. The results indicated that pimozide interfered with context-specific sensitization, whenever it was given. It is concluded that pimozide interferes with the expression of context-specific sensitization, although a separate effect on the development of sensitization is not ruled out.
Schnur
P
P
University of Southern Colorado.
Espinoza
M
M
Flores
R
R
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D006224:Cricetinae; D003463:Cues; D004777:Environment; D005260:Female; D008297:Male; D008647:Mesocricetus; D009021:Morphine Dependence / Q000523:psychology; D009270:Naloxone / Q000494:pharmacology*; D010868:Pimozide / Q000494:pharmacology*; D013375:Substance Withdrawal Syndrome / Q000523:psychology*
D010868:Pimozide; D009270:Naloxone