EFFECTS OF THYROID STATUS ON THE CHARACTERISTICS OF ALPHA1-IMIPRAMINE, ALPHA2-IMIPRAMINE, BETA-IMIPRAMINE IMIPRAMINE AND GABA RECEPTORS IN THE RAT-BRAIN
The effects of a chronic treatment with L-triiodothyronine (T3; 100 mg/rat/day s.c. for 7 days) or with propylthiouracil (PTU; 50 mg/rat/day for 35 days by stomach tube) on the characteristics of alpha1, alpha2, beta, imipramine and GABA binding sites in different brain areas of the adult rat have been studied. T3-treatment caused an increase in the number of [H-3]dihydroalprenolol and a decrease in the number of [H-3]muscimol binding sites in the cerebral cortex. PTU-treatment caused a decrease in the number of [H-3]prazosin, [H-3]yohimbine and [H-3]dihydroalprenolol binding sites in the cerebra cortex, while the number of [H-3]imipramine binding sites was reduced in the cerebral cortex and hypothalamus, and increased in the hippocampus. Affinity constants were never modified. Concurrent experiments showed that the in vitro addition of T3 and PTU did not influence the binding of any of the ligands employed to control rat brain membranes. The present data further support the view that neurotransmission in the CNS is influenced by the thyroid status
