Monoamine Interaction ―Effects of Long-Term Treatments with L-tryptophan and Setiptiline Maleate on Rat Brain a2- and β-adrenergic Receptor―
The role of serotonin precursor L-tryptophan and the new tetracyclic antidepressant Setiptiline Maleate in the regulation of β-and α2-adrenergic receptor was examined by Radio Receptor Assay method. Treatment with either L-tryptophan (300 mg/kg, twice, daily) or Setiptiline Maleate (3 mg/kg, twice, daily) for 14 days caused a significant decrease in the number of β-adrenergic receptors (Bmax) measured 12 hours after the last dose. Treatment with co-administration of both L-tryptophan and Setiptiline caused no significant difference from that of either L-tryptophan or Setiptiline alone. Treatment with Setiptiline caused a significant decrease in the number of α2-adrenergic receptor (Bmax), but treatment with L-tryptophan caused no change in it. Treatment with co-administration of both Setiptiline and L-tryptophan potentiated the decrease in the number of α2-adrenergic receptors compared with single administration of Setiptiline alone.