Effects of neonatal antithyroid treatment on brain [3H]-imipramine binding sites.

The action of the antithyroid, sulphydryl reagent methimazole (MMI) on the specific binding of [3H]-imipramine in the cerebral cortex and corpus striatum of immature and mature rats has been examined. Chronic administration of MMI through the first 30 days of life decreased the number of imipramine binding sites in cortical but not striatal membranes, as assessed 48 h after the last injection of goitrogen. A similar treatment did not affect the binding profile of [3H]-imipramine in mature rats. Acute administration of MMI to 30 day-old rats increased the number of imipramine binding sites shortly after the injection, an effect no longer evident 48 h later. MMI in vitro increased the binding of [3H]-imipramine. It is concluded that maturational impairment of the hypothyroid cortex, rather than any alteration of membrane bound thiol groups, was a major cause for the diminished binding of [3H]-imipramine in MMI-treated, immature rats.