[3H]Leu-enkephalin binding following chronic swim-stress in mice.
Warm water swimming produces in mice an opiate-like antinociceptive response. Chronic swimming produces tolerance to the antinociceptive response and, depending on the schedule, cross-tolerance with morphine and naloxone intensified withdrawal signs. Low affinity [3H]Leu-enkephalin binding to brain homogenates at low temperature was significantly reduced in acutely swum mice and chronically swum mice whether or not they were swum. Preincubation at 37 degrees C abolished all between-group differences. Results following chronic swimming were similar whether or not the schedule produced morphine cross-tolerance. These results were discussed in terms of the interpretation that reduced binding reflects increase in vivo occupation of opioid binding sites.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D003080:Cold Temperature; D004743:Enkephalin, Leucine / Q000378:metabolism*; D005260:Female; D009115:Muridae; D009619:Nociceptors / Q000378:metabolism; D013312:Stress, Physiological / Q000378:metabolism*; D013550:Swimming
D004743:Enkephalin, Leucine