Synergistic effect of uncompetitive NMDA receptor antagonists and antidepressant drugs in the forced swimming test in rats.
ABSTRACT In spite of intensive research, the problem of treating antidepressant-resistant depressive patients has not yet been solved. The authors previously reported that combined administration of imipramine and the uncompetitive NMDA receptor antagonist amantadine reduced immobility time in the forced swimming test in rats to a much greater extent than either treatment alone. The present paper investigates the possibility of synergistic interactions between three antidepressants (imipramine, venlafaxine, fluoxetine) with three uncompetitive NMDA receptor antagonists (amantadine, memantine and neramexane). Most combinations resulted in synergistic (hyperadditive) antidepressive-like effects in the forced swim test. Most interesting was the observation that fluoxetine, which was inactive when given alone, showed a positive effect when combined with amantadine (10 and 20 mg/kg), memantine (2.5 and 5 mg/kg) or neramexane (2.5 and 5 mg/kg). The specificity of these observations is supported by control open field studies, which demonstrated no significant increase, or even a decrease in general locomotion after coadministration of the compounds. The present results suggest that the combination of traditional antidepressant drugs and NMDA receptor antagonists may produce enhanced antidepressive effects, and this is of particular relevance for antidepressant-resistant patients.
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ABSTRACT: Memantine, a noncompetitive N-methyl-D-aspartate receptor antagonist with a mood-stabilizing effect, and an association between bipolar disorder and proinflammatory cytokine levels have been reported. Whether adding-on memantine would reduce cytokine levels and is more effective than valproic acid (VPA) alone in bipolar II disorder was investigated. A randomized, double-blind, controlled, 12-week study was conducted. Patients undergoing regular VPA treatments were randomly assigned to a group: VPA + memantine (5 mg/d) (n = 106) or VPA + placebo (n = 108). The Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) were used to evaluate clinical response. Symptom severity, plasma tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), IL-8, and IL-1 levels were examined during weeks 0, 1, 2, 4, 8, and 12. To adjust within-subject dependence over repeated assessments, multiple linear regressions with generalized estimating equation methods were used to examine the therapeutic effect. Tumor necrosis factor α levels were significantly lower in the VPA + memantine group than in the VPA + placebo group (P = 0.013). Posttreatment HDRS and YMRS scores decreased significantly in both groups, but not significant, nor was the other between-group cytokine level difference pretreatment and posttreatment. The HDRS score changes were significantly associated with IL-6 (P = 0.012) and IL-1 (P = 0.005) level changes and changes in YMRS score changes with TNF-α (P = 0.005) level changes. Treating bipolar II depression with VPA + memantine may improve the plasma TNF-α level. However, adding-on memantine may not improve clinical symptoms or cytokine levels other than TNF-α. Clinical symptoms may be correlated with certain cytokines.Journal of clinical psychopharmacology 04/2014; · 5.09 Impact Factor
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ABSTRACT: A number of studies demonstrated a rapid onset of an antidepressant effect of non-competitive N-methyl-d-aspartic acid receptor (NMDAR) antagonists. Nonetheless, its therapeutic potential is rather limited, due to a high coincidence of negative side-effects. Therefore, the challenge seems to be in the development of NMDAR antagonists displaying antidepressant properties, and at the same time maintaining regular physiological function of the NMDAR. Previous results demonstrated that naturally occurring neurosteroid 3α5β-pregnanolone sulfate shows pronounced inhibitory action by a use-dependent mechanism on the tonically active NMDAR. The aim of the present experiments is to find out whether the treatment with pregnanolone 3αC derivatives affects behavioral response to chronic and acute stress in an animal model of depression. Adult male mice were used throughout the study. Repeated social defeat and forced swimming tests were used as animal models of depression. The effect of the drugs on the locomotor/exploratory activity in the open-field test was also tested together with an effect on anxiety in the elevated plus maze. Results showed that pregnanolone glutamate (PG) did not induce hyperlocomotion, whereas both dizocilpine and ketamine significantly increased spontaneous locomotor activity in the open field. In the elevated plus maze, PG displayed anxiolytic-like properties. In forced swimming, PG prolonged time to the first floating. Acute treatment of PG disinhibited suppressed locomotor activity in the repeatedly defeated group-housed mice. Aggressive behavior of isolated mice was reduced after the chronic 30-day administration of PG. PG showed antidepressant-like and anxiolytic-like properties in the used tests, with minimal side-effects. Since PG combines GABAA receptor potentiation and use-dependent NMDAR inhibition, synthetic derivatives of neuroactive steroids present a promising strategy for the treatment of mood disorders. Highlights: -3α5β-pregnanolone glutamate (PG) is a use-dependent antagonist of NMDA receptors.-We demonstrated that PG did not induce significant hyperlocomotion.-We showed that PG displayed anxiolytic-like and antidepressant-like properties.Frontiers in Behavioral Neuroscience 01/2014; 8:130. · 4.76 Impact Factor
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ABSTRACT: Background According to reports in the literature, more than 30% of depressive patients fail to achieve remission. Therapy with the conventional antidepressant drugs may induce the serious adverse reactions. Moreover, its benefits may be seen at least 2–4 weeks after the first dose. Therefore, the alternative strategies for prevention and treatment of depression are sought. The main aim of our study was to assess the effects of ifenprodil given at a non-active dose (10 mg/kg) on the activity of antidepressant agents from diverse pharmacological groups. Methods The antidepressant-like effect was assessed by the forced swim test in mice. Results Ifenprodil potentiated the antidepressant-like effect of imipramine (15 mg/kg) and fluoxetine (5 mg/kg) while did not reduce the immobility time of animals which simultaneously received reboxetine (2.5 mg/kg) or tianeptine (15 mg/kg). Conclusion The concomitant administration of certain commonly prescribed antidepressant drugs that affect the serotonergic neurotransmission (i.e., typical tricyclic antidepressants and selective serotonin reuptake inhibitors) with a negative modulator selectively binding to the GluN1/N2B subunits of the NMDA receptor complex (i.e., ifenprodil) may induce a more pronounced antidepressant-like effect than monotherapy. However, these findings still need to be confirmed in further experiments.Pharmacological reports: PR 12/2014; 66(6):1031–1036. · 1.97 Impact Factor