Effects of ergot alkaloids on stress-induced analgesia.
Repeated, thirty minute anticipation of unavoidable painful stimulation causes endorphin-induced analgesia in rats. This type of stress-induced analgesia (SIA) develops rapidly during the first minutes of the exposure to anticipation stress. SIA can be demonstrated during the whole period of anticipation stress. Ergot drugs (DH--ergotoxine, lisuride, trans-9,10 dihydrolisuride) administered 30 min before the onset of anticipation stress, blocked completely this form of SIA. On the other hand, no effect of ergot alkaloids in the tail-flick latency, as measured under resting conditions, was observed. Possible interactions of ergot alkaloids with opiate receptors as an important mechanism by which ergot drugs affect SIA are discussed.
D000818:Animals; D004088:Dihydroergotoxine; D004723:Endorphins / Q000502:physiology*; D004876:Ergot Alkaloids / Q000494:pharmacology; D008090:Lisuride / Q000031:analogs & derivatives; D008297:Male; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects; D013312:Stress, Physiological / Q000503:physiopathology*
D004723:Endorphins; D004876:Ergot Alkaloids; D011957:Receptors, Opioid; D004088:Dihydroergotoxine; C006208:dironyl; D008090:Lisuride