Tyrosine Hydroxylase Immunoreactivity in the Locus Coeruleus is Reduced in Depressed Non-Suicidal Patients but Normal in Depressed Suicide Patients

This postmortem study determined numbers of noradrenergic neurons by immunostaining the synthesizing enzyme tyrosine hydroxylase in the locus coeruleus of 12 non-elderly depressed patients with a mood disorder as compared to 12 matched normal controls. 6 patients died by suicide, 6 from natural causes. Non-suicidal patients had fewer neurons immunoreactive for tyrosine hydroxylase than suicide victims or controls. No difference appeared between the number of tyrosine hydroxylase neurons in suicide patients & controls. Results suggest a presynaptic noradrenergic deficit of the locus coeruleus in depressed non-suicidal patients. (51 refs.) JA