Effect of Melatonin on 5-HT Active Transport

**133**

**Chapter 8**

**Abstract**

patients.

**1. Introduction**

expectancy [3].

Depression

*and Akira Iwanami*

Studies on Tryptophan Metabolites

Plasma levels of tryptophan metabolites were compared between healthy volunteers and patients of major monopolar depression at various ages and genders. An ultrahigh-speed liquid chromatography/mass spectrometry has been used for analysis. There are significant gender and age differences in TRP metabolites of healthy volunteers. At the upper stream of metabolism, metabolites of young women and old men are higher, but at the lower stream of metabolism, their levels are higher in young men and old women. Such differences disappear in plasma of patients of major monopolar depression except for kynurenine (KYN). Daily variation of blood serotonin (5-HT) levels showed that 5-HT levels were low in the morning and increased toward evening, but blood levels of 5-HT were higher in healthy people than depressive people in the morning and decreased to ward evening. Significant age and gender differences of plasma levels of tryptophan metabolites in healthy volunteers disappear in patients of major monopolar depression. Blood levels of 5-HT were higher in healthy people than depressive

**Keywords:** depression, monopolar depression, bipolar depression, tryptophan, serotonin, 5-hydroxyindoleacetic acid, kynurenine, 3-hydroxykynurenine, kynurenic acid, anthranilic acid, xanthurenic acid, indole-3-acetic acid,

selective serotonin reuptake inhibitor (SSRI), serotonin norepinephrine reuptake

Recently, it has been shown that both the responses to placebo and antidepressant increased [1]. Kirsch has claimed that pharmaceutical companies did not include mildly and moderately depressed patients in trials of efficacy after finding that these patients did not benefit beyond placebo [2]. He consistently insists that antidepressants are not more effective than placebos in moderately depressed patients [3]. Drug-placebo differences are considered to be small in efficacy trials, and most of the response to antidepressants seems due to

inhibitor (SNRI), anxiolytic, antipsychotic, and circadian variation

in Patients of Major Monopolar

*Hiroi Tomioka, Junichi Masuda, Akikazu Takada* 
