Norepinephrine Metabolism and Psychoactive Drugs in the Endogenous Depressions

After intraventricular injection of norepinephrine-H3, the concentration of norepinephrine, of normetanephrine and of the deaminated catechols in rat brains was determined, following action of imipramine, desmethylimipramine, chlorpromazine, lithium chloride or cocaine. Following administration of imipramine, desmethylimipramine, and chlorpromazine, norepinephrine concentration decreased significantly at first, had distinctly increased 4.5 hours after imipramine and desmethylimipramine but was normal once again after chlorpromazine. Normetanephrine concentration increased after imipramine and desmethylimipramine but was unchanged after chlorpromazine. Under the effect of these drugs, the deaminated catechols showed no changes compared with control values. Cocaine resembled the antidepressants, but the amount of deaminated compounds was reduced. Lithium chloride, on the other hand, increased the concentration of deaminated catechols under certain conditions, reduced normetanephrine concentration but did not influence norepinephrine concentration. In addition to the animal experiments, the following data of six patients with an "endogenous" depression were recorded over a period of several weeks: the clinical findings by means of the Hamilton Depression Rating Scale, and the excretion of normetanephrine and of vanillylmandelic acid (VMA) in the urine before, during and after treatment with imipramine. The therapy led to a significant reduction of VMA; however, this reduction cannot be correlated with an improvement in the clinical findings. On the other hand, excretion of normetanephrine is apparently not dependent on the administration of imipramine but seems to reflect the clinical state, since improvement of the depression was regularly combined with an increased excretion of normetanephrine.