Effect of acute and chronic treatment with tricyclic antidepressants on 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4) contents in various regions of rat brain.

1. Effects of acute and chronic treatment with desipramine (DMI) and amitriptyline (AMI) on 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4) levels in eight brain regions were examined in rats. 2. A single injection of DMI decreased MHPG-SO4 levels in all brain regions except the midbrain, whereas the effect disappeared after the chronic treatment except in the septal area. MHPG-SO4 levels in the hippocampus and thalamus were increased after the chronic treatment with the drug. 3. A single and chronic administration of AMI decreased MHPG-SO4 levels in the thalamus and hippocampus, respectively. 4. These results indicate that the effects of acute and chronic treatment with the tricyclic antidepressants on the central noradrenergic systems differ in different regions of rat brain.