Prolonged intermittent footshock stress decreases Met and Leu enkephalin levels in brain with concomitant decreases in pain threshold.
The influence of a 21 day intermittent footshock regimen upon enkephalin levels in brain and adrenals was examined in the rat. Changes in pain sensitivity as well as analgesic and hyperthermic responsiveness to morphine (7.5 mg/kg) were also monitored. Following the stress regimen, Met and Leu enkephalin levels were decreased by 40 to 50% in brain, but were unchanged in adrenals. Post-stress pain thresholds were markedly decreased in stressed animals while the analgesic properties of morphine were enhanced. Core body temperature of stressed animals was significantly raised, but the hyperthermic response to morphine was unchanged.
D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D004597:Electroshock; D004743:Enkephalin, Leucine / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000378:metabolism*; D005528:Foot; D007837:Latency Period, Psychological; D008297:Male; D009020:Morphine / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000503:physiopathology*
D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D009020:Morphine