PubMed · 7580037
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C St Dennis, G Synoground. 1995. Imipramine.. https://pubmed.ncbi.nlm.nih.gov/7580037/
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Alterations in catecholamine levels and neurotransmission have been shown in depressive disorders. However, the exact sites of alterations and the relation between these alterations to the etiology of the disease and the effectiveness of antidepressant therapy are poorly understood. In this study, catecholamine levels and metabolism were measured in specific brain regions of a genetic rat model of depression [Flinders Sensitive Line (FSL) rats], and compared to normal Sprague-Dawley rats. Norepinephrine levels were found to be two to threefold higher in the nucleus accumbens, prefrontal cortex, hippocampus and median raphe nucleus of FSL rats as compared with control Sprague-Dawley rats. Dopamine levels were sixfold higher in the nucleus accumbens and twofold higher in the striatum, hippocampus and hypothalamus of FSL rats as compared with control Sprague-Dawley rats. After chronic treatment with the antidepressant desipramine, the immobility score in a swim test, as a measure of a behavioral deficit, as well as catecholamine levels of the FSL rats became normalized, but these parameters in the control rats did not change. The results indicate that the behavioral deficits expressed in the FSL model for depression correlate with increased catecholamine levels in specific brain sites, and further suggest the FSL rats as a model for elucidation of the molecular mechanism of clinically used antidepressant drugs.
Chronic electroshock treatment (once daily for 12 days) increases extracellular norepinephrine in the frontal cortex and hippocampus as measured by microdialysis. This chronic treatment produced an elevation of basal norepinephrine overflow into extracellular space while both the first and the twelfth treatments produced a transient increase in norepinephrine overflow of about 40 min. Acutely, desmethylimipramine (10 mg/kg) treatment significantly increased extracellular norepinephrine. While chronic desmethylimipramine (once daily for 10 days) increased basal overflow of norepinephrine in the frontal cortex and hippocampus, the tenth daily administration of desmethylimipramine did not produce a statistically significant increase in extracellular norepinephrine. Both daily electroshock and daily desmethylimipramine produced down regulation of beta-adrenoceptors in the hippocampus and the frontal cortex. Chronic electroshock caused up regulation of alpha-adrenoceptors in the frontal cortex but not in the hippocampus while chronic desmethylimipramine administration did not alter alpha-adrenoceptors in either structure. Depletion of norepinephrine with reserpine or with 6-hydroxydopamine prevented the down regulation of beta-adrenoceptors while depletion of this neurotransmitter did not prevent the electroshock-induced up regulation of alpha-adrenoceptors in the frontal cortex. These data suggest that down regulation of beta-adrenoceptors is mediated through increases in extracellular norepinephrine. In contrast, up regulation of alpha-adrenoceptors appears to be independent of norepinephrine release and does not require the presence of noradrenergic neurons in order to be induced by electroshock.
CONTEXT: Elderly patients with major depression are at high risk for recurrence, increased mortality, and chronic disability. OBJECTIVE: To determine the efficacy of maintenance nortriptyline hydrochloride and interpersonal psychotherapy (IPT) in preventing recurrence of major depressive episodes in patients older than 59 years. DESIGN: A 2 x 2 randomized, double-blind, placebo-controlled clinical trial, stratified by therapist. SETTING: University-based psychiatric research clinic. PATIENTS: Of a total of 187 patients with recurrent nonpsychotic unipolar major depression (average age, 67 years; one third aged > or =70 years) recruited through clinical referral and media announcements, 107 were fully recovered after open acute and treatment continuation with nortriptyline and IPT. These patients were randomly assigned to 1 of 4 maintenance therapy conditions. INTERVENTIONS: Monthly medication clinic with nortriptyline hydrochloride (80-120 ng/mL steady-state levels) (n = 24); medication clinic with placebo (n = 29); monthly maintenance IPT with placebo (n = 21); and monthly maintenance IPT with nortriptyline (n = 22). MAIN OUTCOME MEASURE: Recurrence of major depressive episode. RESULTS: The time to recurrence of a major depressive episode for all 3 active treatments was significantly better than for placebo. Recurrence rates over 3 years were as follows: nortriptyline and IPT, 20% (95% confidence interval [CI], 4%-36%); nortriptyline and medication clinic visits, 43 % (95% CI, 25%-61%); IPT and placebo, 64% (95% CI, 45%-83%); and placebo and medication clinic visits, 90% (95% CI, 79%-100%). Combined treatment with nortriptyline and IPT was superior to IPT and placebo and showed a trend to superior efficacy over nortriptyline monotherapy (Wald chi2 = 3.56; P = .06). Subjects aged 70 years and older had a higher and more rapid rate of recurrence than those aged 60 to 69 years. CONCLUSION: In geriatric patients with recurrent major depression, maintenance treatment with nortriptyline or IPT is superior to placebo in preventing or delaying recurrence. Combined treatment using both appears to be the optimal clinical strategy in preserving recovery.