Articles: pain.
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When rats were tested more than two weeks following surgery, lesions of the medial basal hypothalamus centered on the arcuate nucleus enhanced a form of foot-shock stress-induced analgesia (SIA) that was not blocked by injections of the opiate receptor blocker, naltrexone (6 mg/kg;). These arcuate nucleus lesions reduced the SIA produced by the same stressor when similar rats were tested 3-4 days following surgery. ⋯ We suggest that arcuate nucleus lesions disrupt a system important for the elaboration of opiate-mediated SIA (Expt. 4), perhaps by damaging the brain's beta-endorphin system. In response to damage to this opioid analgesic system, we hypothesize that the damaged brain initiates time-dependent compensatory changes in an undamaged non-opioid analgesic system, resulting in enhanced non-opiate-mediated SIA.
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L-Tryptophan (L-TP) has been used in migraine and other pain conditions. The mechanism underlying the analgesic effect is still partly undefined. In this study the effects of subchronic administration of L-5-hydroxytryptophan (L-5HTP) (with and without carbidopa) on plasma beta-endorphin (beta-EP) levels and subjective pain threshold and tolerance were investigated in seven healthy volunteers. ⋯ L-5HTP plus carbidopa induced an increase in beta-EP significantly (p less than 0.05) greater than that induced by L-5HTP alone. Neither the subjective pain threshold and tolerance nor the RIII threshold was modified by either treatment. Our data seem to point to the existence of a complex linkage between plasma opioid levels and pain perception.
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Comparative Study Clinical Trial Controlled Clinical Trial
Comparison of intramuscular ketorolac tromethamine and morphine sulfate for analgesia of pain after major surgery.
Ketorolac tromethamine is a new injectable nonnarcotic analgesic. In a parallel, double-blind study, the analgesic efficacies of single intramuscular doses of ketorolac 10, 30 and 90 mg were compared with those of morphine sulfate 6 and 12 mg. Two hundred forty-one patients were categorized according to type of surgical procedure and severity of pain. ⋯ Patients receiving ketorolac 10, 30 or 90 mg or morphine (MS) 12 mg all had significantly better pain relief in almost all measurements performed than those receiving MS 6 mg (p less than 0.05). Ketorolac 10 and 30 mg were as effective as morphine 12 mg during the entire 6-hour observation period, and ketorolac 90 mg was more effective than morphine 12 mg during the entire 6 hours. Patients with pain related to major surgery (e.g., cholecystectomy and abdominal hysterectomy) were better able to distinguish analgesic potency of morphine than those having less traumatic procedures (e.g., tendon and ligament repairs).