title: The opioid/nonopioid nature of stress-induced analgesia and learned helplessness.
abstract: Exposure to a variety of stressors produces a subsequent analgesic reaction. This stress-induced analgesia (SIA) is sometimes opioid in nature (reversed by opiate antagonists and cross-tolerant with morphine) and sometimes nonopioid. Both 30 min of intermittent footshock and 60-80 five-sec tailshocks have been shown to produce opioid SIA, whereas 3 min of continuous footshock and 5-40 tailshocks produce nonopioid SIA. We report that both of the opioid SIA procedures produce a learned helplessness effect as assessed by shuttlebox escape acquisition and an analgesia that is reinstatable 24 hr. later. The nonopioid procedures produce neither a learned helplessness effect nor a reinstatable analgesia. It is argued that these data implicate the learning of uncontrollability in the activation of opioid systems.
mesh_terms: D000698:Analgesia; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D004597:Electroshock; D004723:Endorphins / Q000502:physiology; D004924:Escape Reaction; D005528:Foot; D006380:Helplessness, Learned; D006801:Humans; D008297:Male; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D011930:Reaction Time; D013312:Stress, Physiological / Q000503:physiopathology; D013623:Tail
chemical_list: D004723:Endorphins; D009292:Narcotic Antagonists