[Insulin potentiating and antidepressant effects of 3-oxypyridine and succinic acid derivatives].

The dependence of the antidepressant action of 3-oxypyridine and succinic acid derivatives (emoxipine, reamberin, and mexidol) on the insulin potentiating activity of these therapeutic agents has been studied in experiments on rats. Alpha-lipoic acid was used as a reference drug. It was established that single administration of emoxipine, reamberin, mexidol and alpha-lipoic acid in optimal doses, corresponding to the therapeutic range in humans, increased the sensitivity of animals to insulin according to the criterion of insulin coma development. Triple administration of the therapeutic agents studied in the same single dose produced an antidepressant effect according to the criterion of "desperate behavior" in Porsolt forced swimming test. Standardization of obtained data by average difference from the control and further correlation analysis demonstrated that the extent of antidepressant action of emoxipine, reamberin, mexidol and alpha-lipoic acid considerably depends on their insulin potentiating activity (r = 0.762, p = 0.004).

Involvement of NMDA and AMPA receptors in the antidepressant-like activity of antidepressant drugs in the forced swim test.

BACKGROUND: The involvement of glutamate system (particularly the NMDA and AMPA receptors) in the mechanism of antidepressant activity was demonstrated in preclinical and clinical studies. METHODS: In the present study, we investigated the effect of NMDA and AMPA receptors' ligands (agonists and antagonists) on the antidepressant-like activity of escitalopram, milnacipran, imipramine and reboxetine in the forced swim test in mice. RESULTS: Antidepressant activity (reduction in immobility time) of escitalopram and milnacipran but not of imipramine and reboxetine was antagonized by N-methyl-D-aspartate acid. CGP37849 (antagonist of the NMDA receptor) enhanced the antidepressant activity of all examined antidepressants. On the other hand, CX614 (a potentiator/positive allosteric modulator of the AMPA receptor) enhanced the antidepressant activity of imipramine and reboxetine but not of escitalopram and milnacipran in this test. NBQX (the AMPA receptor antagonist) did not influence the antidepressant activity of all tested agents. CONCLUSIONS: The data indicate the complex interactions following the activation or blockade of the NMDA and AMPA receptors with antidepressant drugs. The general phenomenon is the enhancing effect of the NMDA receptor antagonism on the antidepressant activity. Moreover, is can be concluded that the activity of antidepressants with a serotonergic mechanism of action can be inhibited by NMDA activation, while antidepressants with a noradrenergic mechanism of action are dependent on AMPA receptor transmission.

Captodiamine, a putative antidepressant, enhances hypothalamic BDNF expression in vivo by synergistic 5-HT2c receptor antagonism and sigma-1 receptor agonism.

The putative antidepressant captodiamine is a 5-HT2c receptor antagonist and agonist at sigma-1 and D3 dopamine receptors, exerts an anti-immobility action in the forced swim paradigm, and enhances dopamine turnover in the frontal cortex. Captodiamine has also been found to ameliorate stress-induced anhedonia, reduce the associated elevations of hypothalamic corticotrophin-releasing factor (CRF) and restore the reductions in hypothalamic BDNF expression. Here we demonstrate chronic administration of captodiamine to have no significant effect on hypothalamic CRF expression through sigma-1 receptor agonism; however, both sigma-1 receptor agonism or 5-HT2c receptor antagonism were necessary to enhance BDNF expression. Regulation of BDNF expression by captodiamine was associated with increased phosphorylation of transcription factor CREB and mediated through sigma-1 receptor agonism but blocked by 5-HT2c receptor antagonism. The existence of two separate signalling pathways was confirmed by immunolocalisation of each receptor to distinct cell populations in the paraventricular nucleus of the hypothalamus. Increased BDNF induced by captodiamine was also associated with enhanced expression of synapsin, but not PSD-95, suggesting induction of long-term structural plasticity between hypothalamic synapses. These unique features of captodiamine may contribute to its ability to ameliorate stress-induced anhedonia as the hypothalamus plays a prominent role in regulating HPA axis activity.

[Pineal hormone melatonin in low doses potentiates psychotropic and chronotropic activity of tofisopam in rats].

Combination with a low dose of pineal hormone melatonin increased the anxiolytic effect of tofisopam (subthreshold dose) in open-field and cross-maze tests, as well as its chronotropic activity in time-course of forced swimming test in rats.