Differential effects of antidepressant drugs on [3H]dihydroalprenolol and [3H]imipramine ligand recognition sites in olfactory bulbectomized and sham-lesioned rats.

In the olfactory bulbectomy rat model of major depression, the binding of [3H]imipramine is increased by 60% in the midbrain, reduced by 30% in the pons and by 20% in the hippocampus, and unchanged in the hypothalamus 6 weeks after the bulbectomy. Binding of [3H]dihydroalprenolol is unchanged in the midbrain but is increased by 30% in the pons and 15% in the hippocampus. The i.p. administration of the antidepressants amitriptyline, mianserin, tranylcypromine (all at a dose of 10 mg/kg) or iprindole (25 mg/kg) for 28 days followed by a 5-day drug washout period, alters brain part [3H]imipramine and [3H]dihydroalprenolol binding in a manner that is a function of the particular drug, brain part and lesion effect. Only in the hippocampus did the lesion increase beta-binding that was reduced by all four antidepressant drugs.