Chronic lithium treatment decreases [3H]-imipramine binding in rat brain

The effect of a chronic lithium treatment on the [3H]-imipramine binding in rat brain regions was investigated. In the striatum, an oral administration of lithium for 30 days induced a decrease in the [3H]-imipramine binding at the concentration of [3H]-imipramine, 1.0 nM, compared to the control. Lithium did not affect the [3H]-imipramine binding in the cerebral cortex and hypothalamus. A Scatchard analysis in the striatum revealed a decrease in the number of [3H]-imipramine binding sites with no changes in the binding affinity. These results suggest that the chronic lithium treatment may produce subsensitivity of the [3H]-imipramine binding in man and that this effect of the ion may be closely related to the established effect of lithium in the treatment of affective disorders.