Effects of L-5HTP with and without carbidopa on plasma beta-endorphin and pain perception: possible implications in migraine prophylaxis.
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. To measure also an objective indicator of pain, the nociceptive flexion reflex threshold was studied. L-5HTP treatment with and without carbidopa administration increased beta-EP levels significantly (p less than 0.05). 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.
D000328:Adult; D002230:Carbidopa / Q000008:administration & dosage / Q000494:pharmacology*; D004359:Drug Therapy, Combination; D004723:Endorphins / Q000097:blood*; D006801:Humans; D008881:Migraine Disorders / Q000517:prevention & control*; D010146:Pain / Q000503:physiopathology*; D012684:Sensory Thresholds / Q000187:drug effects; D014364:Tryptophan / Q000008:administration & dosage / Q000494:pharmacology*; D001615:beta-Endorphin
D004723:Endorphins; D001615:beta-Endorphin; D014364:Tryptophan; D002230:Carbidopa