High-affinity binding of 3H-imipramine in brain and platelets and its relevance to the biochemistry of affective disorders

Abstract

Specific high-affinity binding of 3 H-imipramine has been demonstrated in the brain of various species including man. These binding sites have many of the characteristics to be expected for a pharmacological receptor and appear to be associated with the neuronal uptake mechanism for serotonin. Different antidepressant treatments like chronic administration of tricyclic antidepressants, chronic electroshock or sleep-deprivation result in decreases in the density of 3 H-imipramine binding sites in normal animals. 3 H-imipramine binding sites have also been found in blood platelets from different species including man. These sites are identical to those described in the brain. Clinical studies have shown that untreated severely depressed patients have a lower density of 3 H-imipramine binding sites in their platelets when compared with control volunteers of the same age and sex. Longitudinal studies indicate that the low density of 3 H-imipramine binding sites does not change during treatment with tricyclic antidepressant drugs and the subsequent clinical recovery from depression. 3 H-imipramine binding in brain and platelets is proposed as a useful research tool in biochemical and clinical studies in affective disorders.