Abstract
Serotonin, a preferred monoamine oxidase (MAO) A substrate, may be deficient centrally in suicide victims. In postmortem samples of frontal cortex from suicide victims, receptor changes in the serotonergic system supportive of this hypothesis were demonstrated. These changes were not accompanied in this series of brain samples by alterations in either MAO A or B enzyme kinetics. Thus brain MAO A is not a useful indicator of altered serotonergic function in suicide victims. An age-related increase in cortical MAO B but not MAO A enzyme concentrations in both controls and suicide victims were confirmed.