Post-mortem studies of brain phosphatidylinositol hydrolysis in depression and the effect of antidepressant treatment.

Basal, neurotransmitter and G protein-mediated [3H]PI hydrolysis was measured in the frontal cortex, temporal cortex, hippocampus and thalamus from suicides, with a firm retrospective diagnosis of depression, and individually matched controls. Suicides were divided into those who had been free of antidepressant drugs for at least 3 months and those in whom prescription of antidepressants was clearly documented. There were no significant differences in basal, GTP?S-, 5-HT- or ACPD-stimulated [3H]PI hydrolysis in either antidepressant- free or antidepressant-treated suicides and their respective controls in the four brain regions studied. This was also the case when suicides were divided into those dying by violent or non-violent means. The two main conclusions from this study are: (i) neurotransmitter- (5-HT and ACPD) stimulated [3H]PI hydrolysis was unaltered in depression, and (ii) antidepressant treatment did not modify PI-mediated signal transduction.