title: Characteristics of analgesias induced by brief or prolonged stress.
abstract: Some characteristics of the effects of brief and prolonged stress on tail-flick latency are described. The pharmacological profiles of the latency responses to 30 sec and 30 min footshock are strikingly different. Thus, the increase of tail-flick latency after 30 sec shock is unaffected by naloxone and enhanced by drugs which decrease 5HT or DA-dependent transmission, while the increase after 30 min shock is blocked by naloxone and also by the above drugs. The increased tail-flick latency after 30 sec shock only occurs if tail-flick latency is also determined before shock. This finding, together with the attenuation or enhancement of the post-shock response by drugs that similarly affect conditioned avoidance behavior, suggests that the increased latency after brief shock occurs through a mechanism that is related to passive avoidance learning. Finally, a new approach to the investigation of stress-induced analgesia is described in which neurochemical changes during prolonged immobilization stress are repeatedly monitored using cisternal CSF samples taken in parallel with tail-flick latency measurements.
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000698:Analgesia; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D001522:Behavior, Animal; D004597:Electroshock; D008297:Male; D010830:Physostigmine / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012149:Restraint, Physical; D012701:Serotonin / Q000378:metabolism; D013312:Stress, Physiological / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D011759:Pyrrolidines; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; C038438:pramiracetam; D010830:Physostigmine