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-hydroxy-tryptophan (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 for 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) higher than that after L-5HTP alone. Neither subjective pain threshold and tolerance nor 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.
D006916:5-Hydroxytryptophan / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D002230:Carbidopa / Q000008:administration & dosage / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D004723:Endorphins / Q000097:blood*; D006801:Humans; D008881:Migraine Disorders / Q000097:blood / Q000503:physiopathology / Q000517:prevention & control*; D010146:Pain / Q000503:physiopathology / Q000517:prevention & control*; D012684:Sensory Thresholds / Q000187:drug effects; D001615:beta-Endorphin
D004723:Endorphins; D001615:beta-Endorphin; D006916:5-Hydroxytryptophan; D002230:Carbidopa