The findings summarized in this paper show that norepinephrine turnover in brain is decreased after acute administration of imipramine or desmethylimipramine but tends to increase during chronic administration of these tricyclic antidepressants. Similarly, it appears that there also may be important differences between the effects of acute and chronic administration of lithium salts on norepinephrine turnover in the central nervous system. Such changes in norepinephrine turnover that develop gradually over the course of long-term drug administration may help to explain the need for chronic administration of tricyclic antidepressants or lithium salts in the treatment of patients with affective disorders.
Indirect evidence has linked opioid reinforcement with changes in noradrenergic metabolism secondary to drug administration. Methodological precedents for biobehavioral correlations in depressive illness have suggested an important association between changes in mood and biogenic amine excretion patterns in the urines of patients during depression and recovery. This paper presents preliminary data on the possible relationship between changes in catecholamine excretion that were observed and the changes in behavior, mood, psychiatric status, and cardiorespiratory physiology secondary to heroin administration and methadone-assisted withdrawal. This study focuses on the urinary excretion of MHPG, since an appreciable fraction of this metabolite is probably derived from norepinephrine originating in the brain. The subjective changes in mood associated with heroin use, the decrease in respiratory rate, and the behavioral and mental status effects associated with opiate intoxication were observed only in the individuals whose MHPG excretion increased during the period of opiate administration.
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