European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology
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Eur Neuropsychopharmacol · Mar 2008
DHEAS repeated treatment improves cognitive and behavioral deficits after mild traumatic brain injury.
Mild traumatic brain injury (mTBI) is characterized by diffused symptoms, which when combined are called "post-concussion syndrome". Dehydroepiandrosterone sulfate (DHEAS) is a neuroactive neurosteroid. Previously, we have reported that closed head mTBI causes long lasting cognitive deficits and depressive-like behavior. ⋯ Following the induction of mTBI, mice were treated once a week with DHEAS (s.c. 20 mg/kg) and their performance in the passive avoidance test and the forced swimming test (FST) were evaluated 7, 30, 60 and 90 days post-injury. The most important interactions were between injury and injection (passive avoidance; p<0.001 and FST; p=0.001), meaning that DHEAS has beneficial effects only when given to injured animals. Our results demonstrate that the long-term cognitive and behavioral effects induced by mTBI may be improved by a repeated weekly treatment with DHEAS.
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Eur Neuropsychopharmacol · Feb 2008
Neuroprotection by Imipramine against lipopolysaccharide-induced apoptosis in hippocampus-derived neural stem cells mediated by activation of BDNF and the MAPK pathway.
Depression is accompanied by the activation of the inflammatory-response system, and increased production of proinflammatory cytokines may play a role in the pathophysiology of depressive disorders. Imipramine (IM), a tricyclic antidepressant drug, has recently been shown to promote neurogenesis and improve the survival rate of neurons in the hippocampus. However, whether IM elicits a neuroprotective or anti-inflammatory effect, or promotes the differentiation of neural stem cells (NSCs) remains to be elucidated. ⋯ In addition, the percentages of serotonin and MAP-2-positive neuronal cells in the Day 7 culture of IM-treated NSCs were significantly increased. By using microdialysis with high performance liquid chromatography-electrochemical detection, the functional release of serotonin in the process of serotoninergic differentiation of IM-treated NSCs was concomitantly increasing and mediated by the activation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades. In sum, the study results indicate that IM can increase the neuroprotective effects, suppress the LPS-induced inflammatory process, and promote serotoninergic differentiation in NSCs via the modulation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades.
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Eur Neuropsychopharmacol · Dec 2006
ReviewFaulty regulation of tau phosphorylation by the reelin signal transduction pathway is a potential mechanism of pathogenesis and therapeutic target in Alzheimer's disease.
Hyperphosphorylated tau protein is the basic structural component of the neurofibrillary tangle, a histopathological hallmark of Alzheimer's disease. The formation of hyperphosphorylated tau protein may impair learning and the synaptic plasticity of neurons. Tau is a protein that is associated with and stabilizes microtubules; hyperphosphorylated tau protein is unable to perform this stabilization function. ⋯ An important downstream target of reelin signal transduction appears to be inhibition of an enzyme involved in the regulation of tau phosphorylation. The faulty transduction of the reelin signal may be a pathological mechanism leading to hyperphosphorylation of tau protein. Ultimately, inhibition of tau phosphorylation may be an important therapeutic target in Alzheimer's disease and other neuropsychiatric disorders.
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Pregabalin, a compound with a novel mechanism of action (MOA), has demonstrated efficacy as an adjunctive treatment for epilepsy and in several neuropathic pain models. Multiple generalized anxiety disorder (GAD) clinical trials have shown that pregabalin has efficacy similar to the benzodiazepines and venlafaxine. Onset of anxiolytic effect was observed as early as Week 1 of treatment, and efficacy was seen in treating both psychic and somatic anxiety symptoms. ⋯ Pregabalin only modulates the release of excitatory neurotransmitters in "hyper-excited" neurons, restoring them to normal physiological state. This newly defined MOA is believed to confer on pregabalin its anxiolytic, analgesic, and anticonvulsant properties. Thus, pregabalin may offer physicians an effective and well-tolerated therapy for GAD, which differs from existing treatments.
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Eur Neuropsychopharmacol · Apr 2006
The effect of tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs) and newer antidepressant drugs on the activity and level of rat CYP3A.
The aim of the present study was to investigate the influence of tricyclic antidepressants (TADs: imipramine, amitriptyline, clomipramine, and desipramine), selective serotonin reuptake inhibitors (SSRIs: fluoxetine and sertraline) and novel antidepressant drugs (mirtazapine and nefazodone) on the activity of CYP3A measured as a rate of testosterone 2beta- and 6beta-hydroxylation. The reaction was studied in control liver microsomes in the presence of the antidepressants, as well as in microsomes of rats treated intraperitoneally (i.p.) for 1 day or 2 weeks with pharmacological doses of the drugs (imipramine, amitriptyline, clomipramine, nefazodone 10 mg kg(-1) i.p.; desipramine, fluoxetine, sertraline 5 mg kg(-1) i.p.; mirtazapine 3 mg kg(-1) i.p.), in the absence of the antidepressants in vitro. The investigated antidepressants added to control liver microsomes produced some inhibitory effects on CYP3A activity, which were very weak (most of TADs, K(i)=145-212 microM), modest (clomipramine and sertraline, K(i)=67.5 and 62 microM, respectively) or moderate (nefazodone and fluoxetine, K(i)=42 and 43 microM, respectively). ⋯ On the other hand, sertraline increased the activity of the enzyme after its prolonged administration and its effect correlated positively with the observed elevation in CYP3A protein level. Fluoxetine, mirtazapine and nefazodone did not change the activity of CYP3A in liver microsomes after their administration to rats. Three different mechanisms of the antidepressants-CYP3A interaction are postulated: 1) a direct inhibition of CYP3A by nefazodone, SSRIs and clomipramine, shown in vitro, with the inhibitory effect of nefazodone being the strongest, but weaker than the effects of this drug on human CYP3A4; 2) in vivo inhibition of CYP3A produced by 1 day and maintained during chronic treatment with TADs, which suggests inactivation of the enzyme by reactive metabolites; 3) in vivo induction by sertraline of CYP3A produced only by chronic treatment with the antidepressant, which suggests its influence on the enzyme regulation.