Neurotransmitter metabolites and endocrine responses in depression

Urinary 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG), 3-4-dihydroxyphenylethyleneglycol (DHPG), 5-hydroxyindoleacetic acid (5-HIAA), plasma thyroid stimulating hormone (TSH), prolactin (PRL) and growth hormone (GH) were measured before and after the injection of thyrotropin releasing hormone (TRH) in healthy subjects and depressed patients with primary affective disorder. The TSH response to TRH did not differ in depressed compared with control subjects. A trend (.05 less than p less than .10) toward a lower PRL response appeared in male depressed compared with male control subjects. GH levels did not consistently change after TRH. In all subjects the TSH response correlated positively with pre- and post-TRH urinary MHPG. The PRL response correlated negatively with pre-TRH urinary 5-HIAA. Pre-TRH daytime urinary 5-HIAA levels were elevated in depressed subjects.