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Both clinical and preclinical studies demonstrate the antidepressant activity of the functional NMDA receptor antagonists. In this study, we assessed the effects of two glycine/NMDA receptor ligands, namely L-701,324 (antagonist) and d-cycloserine (a partial agonist) on the action of antidepressant drugs with different pharmacological profiles in the forced swim test in mice. Swim sessions were conducted by placing mice individually in glass cylinders filled with warmed water for 6 min. The duration of behavioral immobility during the last 4 min of the test was evaluated. The locomotor activity of mice was measured with photoresistor actimeters. L-701,324 and d-cycloserine given with reboxetine (administered in subeffective doses) did not change the behavior of animals in the forced swim test. A potentiating effect was seen when both tested glycine site ligands were given concomitantly with imipramine or fluoxetine in this test. The lesion of noradrenaline nerve terminals produced by DSP-4 neither altered the baseline activity nor influenced the antidepressant-like action of L-701,324 or d-cycloserine. The depletion of serotonin by p-CPA did not alter baseline activity in the forced swim test. However, it completely antagonized the antidepressant-like action produced by L-701,324 and d-cycloserine. Moreover, the antidepressant-like effects of imipramine, fluoxetine and reboxetine were abolished by d-serine, a full agonist of glycine/NMDA receptors. The present study demonstrates that glycine/NMDA receptor functional antagonists enhance the antidepressant-like action of serotonin, but not noradrenaline-based antidepressants and such their activity seems to depend on serotonin rather than noradrenaline pathway.

Caffeine is the most widely used behaviorally active drug in the world which exerts its activity on central nervous system through adenosine receptors. Worrying data indicate that excessive caffeine intake applies to patients suffering from mental disorders, including depression. The main goal of the present study was to evaluate the influence of caffeine on animals’ behavior in forced swim test (FST) as well as the effect of caffeine (5 mg/kg) on the activity of six typical antidepressants, such as imipramine (15 mg/kg), desipramine (10 mg/kg), fluoxetine (5 mg/kg), paroxetine (0.5 mg/kg), escitalopram (2 mg/kg), and reboxetine (2.5 mg/kg). Locomotor activity was estimated to verify and exclude false-positive/negative results. In order to assess the influence of caffeine on the levels of antidepressant drugs studied, their concentrations were determined in murine serum and brains using high-performance liquid chromatography. The results showed that caffeine at a dose of 10, 20, and 50 mg/kg exhibited antidepressant activity in the FST, and it was not related to changes in locomotor activity in the animals. Caffeine at a dose of 5 mg/kg potentiated the activity of all antidepressants, and the observed effects were not due to the increase in locomotor activity in the animals. The interactions between caffeine and desipramine, fluoxetine, escitalopram, and reboxetine were exclusively of pharmacodynamic character, because caffeine did not cause any changes in the concentrations of these drugs neither in blood serum nor in brain tissue. As a result of joint administration of caffeine and paroxetine, an increase in the antidepressant drug concentrations in serum was observed. No such change was noticed in the brain tissue. A decrease in the antidepressant drug concentrations in brain was observed in the case of imipramine administered together with caffeine. Therefore, it can be assumed that the interactions caffeine-paroxetine and caffeine-imipramine occur at least in part in the pharmacokinetic phase.

Introduction and hypothesisEpidemiological studies demonstrated that patients suffering from overactive bladder often present with different mental problems, amongst which depression is the most frequently observed. The main goal of our study was to check if the repeated administration of corticosterone (CORT) is able to evoke the depressive-like behaviour and detrusor overactivity (DO) symptoms in rats. Moreover, we investigated whether the acute administration of common antidepressants (imipramine, 30 mg/kg, and fluoxetine, 15 mg/kg), antimuscarinic (oxybutynin chloride, 0.5 mg/kg) or CRF1 (SN 003, 1 mg/kg) antagonists has an impact on the cystometric parameters, behaviour in the Porsolt test, and overall locomotor activity of animals exposed to CORT.MethodsThe experiments were carried out on female Wistar rats. All applied surgical and histopathology procedures, cystometric investigations, locomotor activity and forced swim measurements have been fully described in the published literature.ResultsFourteen-day administration of CORT may induce both depressive and DO symptoms in rats, which are reversed by the inhibition of CRF1 receptors.ConclusionsIt seems that the CRF1 receptor could be an interesting target for overactive bladder pharmacotherapy, particularly in patients with co-existing depression.

Chronic environmental stress is associated with reactive oxygen species (ROS) overproduction and the pathogenesis of depression. The purpose of this study was to evaluate biochemical and molecular changes associated with ROS generation in the brains of rats submitted to chronic variable stress. Male Wistar rats (50–55 days old, weighing 200–250 g) were divided in two groups (n = 10): control and stressed. Rats in the stressed group were exposed to stress conditions for 40 days. The animals were decapitated and the brain samples were collected. In prefrontal cortex, we measured the following biochemical parameters: lipid peroxidation and concentration of glutathione—GSH, GSSG, GSH/GSSG ratio, glutathione peroxidase, and glutathione reductase activities. In the hippocampus marker of DNA, oxidative damage and expression of DNA-repairing genes (Ogg1, MsrA) and gene-encoding antioxidative transcriptional factor (Nrf2) were determined. The results demonstrate indirect evidence of ROS overproduction and presence of oxidative stress. They also reveal disruption of oxidative defense systems (decreased GR activity, diminished GSH/GSSG ratio, and decreased Nrf2 expression) and activation of the oxidative DNA repair system (increased Ogg1 and MsrA expression). Together, the presented data suggest that independent activation of oxidative stress response genes occurs in chronic variable stress conditions.

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