STIMULATORY EFFECTS OF 1-5-HYDROXYTRYPTOPHAN ON POSTDEXAMETHASONE BETA-ENDORPHIN LEVELS IN MAJOR DEPRESSION

Recently it has been shown that acute administration of 200 mg L-5-hyd roxytryptophan (L-5-HTP) PO may increase post-dexamethasone (DST) adre nocorticotropic hormone (ACTH) and cortisol levels in major, but not m inor, depressed subjects. This study aimed to examine the effects of 2 00 mg L-5-HTP PO on post-DST beta-endorphin levels in the same depress ed subjects. It was found that in major, but not minor, depressed subj ects, L-5-HTP significantly increased post-DST beta-endorphin concentr ations as compared to placebo. The L-5-HTP-induced post-DST beta-endor phin responses were significantly higher in major than in minor depres sed subjects. There was a significant and positive relationship betwee n L-5-HTP-induced post-DST beta-endorphin and ACTH or cortisol respons es. There was a significant and positive relationship between L-5-HTP- induced post-DST beta-endorphin values and the Hamilton Depression Rat ing Scale (HDRS) score. The results show that the acute administration of L-5-HTP may increase the escape of beta-endorphin secretion from s uppression by dexamethasome in major, but not minor, depression.