Opiate antagonists and long-term analgesic reaction induced by inescapable shock in rats.

Authors:
  • SMSteven F. Maier
    Steven F. Maier
  • SDSusan Davies
    Susan Davies
  • JGJames W. Grau
    James W. Grau
  • RJRaymond L. Jackson
    Raymond L. Jackson
  • DMDaniel H. Morrison
    Daniel H. Morrison
  • TMThomas Moye
    Thomas Moye
  • JMJohn Madden
    John Madden
  • JBJack D. Barchas
    Jack D. Barchas
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Abstract
Five experiments examined the influence of opiate antagonists on both the short-term analgesic reaction resulting 30 min after exposure to inescapable shock and the long-term analgesic reaction resulting after reexposure to shock 24 hr after inescapable shock exposure. Experiment 1 showed that the long-term analgesic reaction could be reduced by administration of naltrexone prior to exposure to inescapable tail shock. Experiment 2 showed that the reduction in the long-term analgesic reaction produced by naltrexone was dose-dependent. Experiment 3 showed that the long-term analgesic reaction could also be reduced by administration of naltrexone prior to reexposure to shock. Experiment 4 showed that the long-term analgesic reaction could be reduced by administration of large dose of naloxone prior to reexposure to shock. Experiment 5 showed that the short-term analgesic reaction was reduced by naltrexone administered prior to inescapable shock. Some implications of these results for the biochemical substrates of both learned helplessness and stress-induced analgesia are discussed.