Behavioral, biochemical and cellular correlates in the protective effect of sertraline against transient global ischemia induced behavioral despair: possible involvement of nitric oxide-cyclic guanosine monophosphate study pathway

Dapoxetine prevents neuronal damage and improves functional outcomes in a model of ischemic stroke through the modulation of inflammation and oxidative stress

Stroke is a medical emergency that is associated with substantial mortality and functional disability in adults. The most popular class of antidepressants, selective serotonin reuptake inhibitors SSRIs, have recently been shown in studies to have positive effects on post-stroke motor and cognitive function. Thus, we hypothesized that dapoxetine (DAP), a short-acting SSRI, would be effective against cerebral ischemia/reperfusion injury. Adult male Wister rats (200-250 g) were subjected to a sham operation or bilateral common carotid artery occlusion (BCCAO) for 30 min followed by 24 h of reperfusion to induce global cerebral ischemia/reperfusion (I/R) injury. Rats were treated with vehicle or DAP (30 or 60 mg/kg, i.p.) 1 h before BCCAO. The neurobehavioral performance of rats was assessed. The infarct volume, histopathological changes, oxidative stress parameters, and apoptotic and inflammatory mediators were determined in the brain tissues of euthanized rats. Our results confirmed that DAP significantly ameliorated cerebral I/R-induced neurobehavioral deficits, reduced cerebral infarct volume, and histopathological damage. Moreover, DAP pretreatment reduced lipid peroxidation, caspase-3, and inflammatory mediators (TNF-α and iNOS) compared to I/R-injured rats. Thus, DAP pretreatment potentially improves neurological function, and cerebral damage in cerebral ischemic rats may be partly related to the reduction in the inflammatory response, preservation of oxidative balance, and suppression of cell apoptosis in brain tissues.

Molecular mechanisms underlying major depressive disorder and post-stroke affective disorders

Two of the most common and incapacitating mental health disorders around the world are major depressive disorder (MDD) and post-stroke depression (PSD). MDD is thought to result from abnormal connectivity between the monoaminergic, glutamatergic, GABAergic, and/or cholinergic pathways. Additional factors include the roles of hormonal, immune, ageing, as well as the influence of cellular, molecular, and epigenetics in the development of mood disorders. This complexity of factors has been anticipated by the Swiss psychiatrists Paul Kielholz and Jules Angst who introduced a multimodal treatment of MDD. Depression is the predominant mood disorder, impacting around one-third of individuals who have experienced a stroke. MDD and PSD share common underlying biological mechanisms related to the disruption of monoaminergic pathways. The major contributor to PSD is the stroke lesion location, which can involve the disruption of the serotoninergic, dopaminergic, glutamatergic, GABAergic, or cholinergic pathways. Additionally, various other disorders such as mania, bipolar disorder, anxiety disorder, and apathy might occur post-stroke, although their prevalence is considerably lower. However, there are differences in the onset of MDD among mood disorders. Some mood disorders develop gradually and can persist for a lifetime, potentially culminating in suicide. In contrast, PSD has a rapid onset because of the severe disruption of neural pathways essential for mood behavior caused by the lesion. However, PSD might also spontaneously resolve several months after a stroke, though it is associated with higher mortality. This review also provides a brief overview of the treatments currently available in medical practice.

Sertraline for Functional Recovery After Acute Ischemic Stroke: A Prospective Observational Study

Background: Neuroprotective and neurorestorative effects have been postulated for selective serotonin-reuptake inhibitors (SSRI). We hypothesized that sertraline, which is characterized by less severe adverse effects and more stable pharmacokinetics than classic SSRI, is associated with improved functional recovery in acute ischemic stroke patients with motor deficits.

Methods: Prospective observational study of consecutive acute ischemic stroke patients who received sertraline for clinically suspected post-stroke depression (PSD) or at high risk for PSD. Eligibility comprised acute motor deficit caused by ischemic stroke (≥2 points on NIHSS motor items) and functional independence pre-stroke (mRS ≤1). Decision to initiate treatment with SSRI during hospital stay was at the discretion of the treating stroke physician. Patients not receiving sertraline served as control group. Favorable functional recovery defined as mRS ≤2 was prospectively assessed at 3 months. Multivariable logistic regression analysis was used to explore the effects of sertraline on 3-months functional recovery. Secondary outcomes were frequency of any and incident PSD (defined by BDI ≥10) at 3 months.

Results: During the study period (03/2017–12/2018), 114 patients were assigned to sertraline (n = 72, 62.6%) or control group (n = 42, 37.4%). At study entry, patients in sertraline group were more severely neurologically affected than patients in the control group (NIHSS: 8 [IQR, 5–11] vs. 5 [IQR, 4–7]; p = 0.002). Also, motor NIHSS scores were more pronounced in sertraline than in control group (4 [IQR 2–7] vs. 2 [IQR 2–4], p = 0.001). After adjusting for age and baseline NIHSS, multivariable regression analysis revealed a significant association between sertraline intake and favorable functional outcome at 3 months (OR 3.10, 95% CI 1.02–9.41; p = 0.045). There was no difference between both groups regarding the frequency of any depression at 3 months (26/53 [49.1%] vs. 14/28 [50.0%] patients, p = 0.643, BDI ≥10). However, fewer incident depressions were observed in sertraline group patients compared to patients in control group (0/53 [0%] vs. 5/28 [17.9%] patients, p = 0.004).

Conclusions: In this non-randomized comparison, early treatment with sertraline tended to favor functional recovery in patients with acute ischemic stroke. While exploratory in nature, this hypothesis needs further investigation in a clinical trial.

Anti-mouse CX3CR1 Antibody Alleviates Cognitive Impairment, Neuronal Loss and Myelin Deficits in an Animal Model of Brain Ischemia

White matter lesions are common when global cerebral ischemia (GCI) occurs in the elderly, and cause damage to neurological and psychological functions. Remyelination often fails because of the limited recruitment of oligodendrocyte progenitor cells (OPCs) to the demyelinated site or the inefficient differentiation of OPCs to mature oligodendrocytes (OLs). The activation of microglia, the most important immune cells in the central nervous system, and subsequent inflammation have been implicated in myelination repair disorder. Little is known about the role of the Fractalkine/CX3CR1 signaling pathway, the key regulator of microglia activation, on myelin in microglia. In this study, a GCI animal model was generated through bilateral common carotid artery occlusion to induce ischemic inflammation and white matter damage; then, we downregulated CX3CR1 by intracerebroventricular administration of neutralizing antibody anti-FKR. Downregulation of CX3CR1 significantly reversed the depression-like behavior and cognitive impairment in GCI mice. Activation of microglia was inhibited, and the peripheral inflammatory responses were also ameliorated as revealed by decreased serum levels of IL-1β, IL-6 and TNF-α. CX3CR1 block substantially reversed demyelination in striatum, cortex and hippocampus and promoted differentiation and maturation of OPCs into mature OLs in the hippocampus. No effect was found on myelin in the corpus callosum. Besides, hippocampal neurons were protected by anti-FKR treatment after GCI. Collectively, our data demonstrated that downregulating of the Fractalkine/CX3CR1 signaling pathway had an anti-depressant and cognition-improvement effect by inhibiting microglia activation, promoting OPCs maturation and remyelination.

Selective serotonin reuptake inhibitors for functional independence and depression prevention in early stage of post-stroke: A meta-analysis

BACKGROUND

The efficacy and safety of selective serotonin reuptake inhibitors (SSRIs) for functional independence and depression prevention in early stage of post-stroke (within 1 month after stroke onset) are still unclear.

METHODS

Relevant randomized controlled trials (RCTs) comparing early SSRIs therapy with placebo were sought from PubMed, Cochrane Library, Medline, and Embase. Primary outcomes were functional independence and depression occurrence. Secondary outcomes contained the improvement of Fugl-Meyer motor scale (FMMS) score and adverse events. We used fixed or random effects model to pooled effect estimates. And we chose risk ratio (RR) or mean differences (MDs) with the 95% confidence intervals (CIs) for data analysis.

RESULTS

We included 10 RCTs with total 5370 patients. The outcome of functional independence showed no significant difference between SSRIs and placebo group (RR, 1.28; 95% CI, 0.96-1.72; P = .10; I = 92%). However, depression occurrence differed significantly between these 2 groups, which favored SSRIs group (RR, 0.78; 95% CI, 0.67-0.90; P = .001; I = 23%). In addition, we observed that the side effects of SSRIs were seizure and nausea. Except psychiatric disorders/insanity rate was less in SSRIs group than placebo group (RR, 0.66; 95% CI, 0.48-0.90; P = .009) (I = 0%), other adverse events were revealed non-significant in our meta-analysis.

CONCLUSIONS

Our meta-analysis revealed that early SSRIs therapy were effective to prevent post-stroke depression. However, SSRIs did not improve patient's post-stroke functional independence. In addition to increase the occurrence of seizure and nausea, SSRIs were relatively safe.

The Effect of Sertraline on Hemodynamic Parameters and Nitric Oxide Production in Isolated Rat Hearts Subjected to Ischemia and Reperfusion

Purpose

The aim of the study was to investigate the effect of sertraline on the rat heart during ischemia and reperfusion and to determine its effect on NO production.

Materials and methods

The study was performed on isolated rat hearts. Hearts from three groups were perfused with sertraline at three different concentrations and subjected to global ischemia and reperfusion. Hearts from the other three groups were perfused with the same concentrations of sertraline but without the ischemia/reperfusion process. Two control groups were perfused with the Krebs-Henseleit solution only with and without ischemia/reperfusion process. Coronary flow (CF), heart rate (HR), left ventricular developed pressure (LVDP) and maximum rate of rise of left ventricular pressure (dP/dt max) were measured. Perfusate effluent was collected to determine creatine phosphokinase (CPK) and nitrate plus nitrite (NOx) levels.

Results

In non-ischemic groups, sertraline at the concentration of 10 μmol/L exerts a strong vasodilatory effect on CF, and after a short positive inotropic effect, it exerts a strong inotropic and chronotropic negative effect on isolated rat hearts and causes a direct damage to cardiomyocytes. At the concentration of 1 μmol/L, sertraline exerts an increasing negative inotropic effect. There were no hemodynamic differences between any of groups of hearts subjected to reperfusion. Sertraline had no effect on the nitric oxide concentration in coronary effluent neither in rat hearts subjected to ischemia/reperfusion nor in non-ischemic conditions.

Conclusion

Sertraline at dose 10 μmol/L exerts a strong vasodilatory effect on coronary flow, and after a short positive inotropic effect, it exerts a strong negative effect on isolated rat hearts, causing a direct damage to cardiomyocytes. Sertraline had no effect on the nitric oxide concentration in coronary effluent.

Psychotropic and neurological medication effects on mitochondrial complex I and IV in rodent models

Mitochondrial complex I (NADH-dehydrogenase) and complex IV (cytochrome-c-oxidase) are reported to be affected by drugs used to treat psychiatric or neurodegenerative diseases, including antidepressants, antipsychotics, anxiolytics, mood stabilizers, stimulants, antidementia, and antiparkinsonian drugs. We conducted meta-analyses examining the effects of each drug category on complex I and IV. The electronic databases Pubmed, EMBASE, CENTRAL, and Google Scholar were searched for studies published between 1970 and 2018. Of 3105 screened studies, 68 articles covering 53 drugs were included in the meta-analyses. All studies assessed complex I and IV in rodent brain at the level of enzyme activity. Results revealed that selected antidepressants increase or decrease complex I and IV, antipsychotics and stimulants decrease complex I but increase complex IV, whereas anxiolytics, mood stabilizers, antidementia, and antiparkinsonian drugs preserve or even enhance both complex I and IV. Potential contributions to the drug effects were found to be related to the drugs' neurotransmitter receptor profiles with adrenergic (α1B), dopaminergic (D1/2), glutaminergic (NMDA1,3), histaminergic (H1), muscarinic (M1,3), opioid (OP1-3), serotonergic (5-HT_2A, 5-HT_2C, 5-HT_3A) and sigma (σ1) receptors having the greatest effects. The findings are discussed in relation to pharmacological mechanisms of action that might have relevance for clinical and research applications.

Combining Fluoxetine and rTMS in Poststroke Motor Recovery: A Placebo-Controlled Double-Blind Randomized Phase 2 Clinical Trial

Background. Although recent evidence has shown a new role of fluoxetine in motor rehabilitation, results are mixed. We conducted a randomized clinical trial to evaluate whether combining repetitive transcranial magnetic stimulation (rTMS) with fluoxetine increases upper limb motor function in stroke. Methods. Twenty-seven hemiparetic patients within 2 years of ischemic stroke were randomized into 3 groups: Combined (active rTMS + fluoxetine), Fluoxetine (sham rTMS + fluoxetine), or Placebo (sham rTMS + placebo fluoxetine). Participants received 18 sessions of 1-Hz rTMS in the unaffected primary motor cortex and 90 days of fluoxetine (20 mg/d). Motor function was assessed using Jebsen-Taylor Hand Function (JTHF) and Fugl-Meyer Assessment (FMA) scales. Corticospinal excitability was assessed with TMS. Results. After adjusting for time since stroke, there was significantly greater improvement in JTHF in the combined rTMS + fluoxetine group (mean improvement: -214.33 seconds) than in the placebo (-177.98 seconds, P = 0.005) and fluoxetine (-50.16 seconds, P < 0.001) groups. The fluoxetine group had less improvement than placebo on both scales (respectively, JTHF: -50.16 vs -117.98 seconds, P = 0.038; and FMA: 6.72 vs 15.55 points, P = 0.039), suggesting that fluoxetine possibly had detrimental effects. The unaffected hemisphere showed decreased intracortical inhibition in the combined and fluoxetine groups, and increased intracortical facilitation in the fluoxetine group. This facilitation was negatively correlated with motor function improvement (FMA, r² = -0.398, P = 0.0395). Conclusion. Combined fluoxetine and rTMS treatment leads to better motor function in stroke than fluoxetine alone and placebo. Moreover, fluoxetine leads to smaller improvements than placebo, and fluoxetine's effects on intracortical facilitation suggest a potential diffuse mechanism that may hinder beneficial plasticity on motor recovery.

Effects of Fluoxetine on Poststroke Dysphagia: A Clinical Retrospective Study

BACKGROUND

To investigate whether fluoxetine improves poststroke dysphagia and to detect the potential relationship between serum brain-derived neurotrophic factor (BDNF) levels and fluoxetine effects.

METHODS

In this retrospective study, 159 stroke patients who met our study criteria were included. In total, 110 patients were placed in the control group, and 49 patients were placed in the fluoxetine group. Demographic and clinical characteristics of the patients were collected for the baseline assessment. Functional independence measure scores and American speech-language-hearing association/functional communication measures scores for swallowing were collected to evaluate the patients' swallowing function. Patients' serums were collected at weeks 1 and 3 after admission, and serum BDNF levels were measured by enzyme-linked immunosorbent assay. T test, chi-squared test, and general linear model analysis were performed to determine the differences between the two groups.

RESULTS

A significantly higher improvement of swallowing function was observed in the fluoxetine group compared with that of the control group (P = .023). In addition, a general linear model analysis showed that the treatment of fluoxetine has a statistically significant effect on swallowing improvement after adjustment of swallowing score on admission, stroke types, and interval between the onset of stroke and admission (P = .022, R² = .46, adjusted R² = .446). There is no significant difference in the change of serum BDNF levels in the two groups (P = .269).

CONCLUSIONS

This study suggests that treatment with fluoxetine in stroke patients with dysphagia may improve swallowing function. A placebo-controlled, randomized clinical trial is warranted to confirm this finding.

Early Selective Serotonin Reuptake Inhibitors for Recovery after Stroke: A Meta-Analysis and Trial Sequential Analysis

BACKGROUND

Potential benefits and risks of early (≤30 days from stroke onset) selective serotonin reuptake inhibitors (SSRIs) treatment for neurologic functional recovery after stroke are not fully understood.

METHODS

We searched PubMed, Embase, and the Cochrane Library to identify randomized controlled trials that assessed SSRI medications during the initial ictus after stroke versus placebo. Primary outcome was decrease in National Institutes of Health Stroke Scale (NIHSS) score. Secondary outcomes included the improvement of Barthel index, functional independence (modified Rankin Scale score 0-2 at the end of follow-up), the incidence of depression, and adverse events including diarrhea, insomnia, hepatic enzyme disorders, seizure, and intracranial hemorrhage. We used fixed effects models or random effects models to estimate weighted mean differences (WMDs) and relative risks (RRs) with 95% confidence intervals (CIs) according to heterogeneity.

RESULTS

Eight trials were included, with 1549 patients. Compared with placebo, decrease in NIHSS was greater in SSRI-treated patients (WMD, 0.82; 95% CI, 0.31-1.33; P = .002). Trial sequential analysis showed that the cumulative z curve crossed the trial sequential monitoring boundary for benefit, establishing sufficient and conclusive evidence. Early SSRI treatment also promoted Barthel index (WMD, 5.32; 95% CI, 1.65-8.99; P = .005) and functional independence (RR, 2.54; 95% CI, 1.82-3.55; P < .0001). There was no difference in the incidence of depression and adverse events between groups. No evidence of publication bias was detected.

CONCLUSIONS

The early SSRIs treatment reduces the defective neurologic function in patients undergoing rehabilitation after stroke.

Phosphodiesterase 5 inhibition as a therapeutic target for ischemic stroke: A systematic review of preclinical studies

Phosphodiesterase 5 inhibitors (PDE5i), such as sildenafil (Viagra®) are widely used for erectile dysfunction and pulmonary hypertension. Preclinical studies suggest that PDE5i may improve functional outcome following ischemic stroke. In this systematic review we aimed to evaluate the effects of selective PDE5i in animal models of brain ischaemia. A systematic search in Medline, Embase, and The Cochrane Library was performed including studies in English assessing the effects of selective PDE5i. 32 publications were included describing outcome in 3646 animals. Neuroprotective effects of PDE5i were dependent on the NO-cGMP-PKG-pathway. These included reduced neuronal apoptosis (n=3 studies), oxidative stress (n=5), and neuroinflammation (n=2). PDE5i increased angiogenesis and elevated regional cerebral blood flow in the ischemic penumbra, and improved functional recovery. Some studies found that PDE5i treatment reduced lesion volume (n=9), others found no effect (n=9). Treatment was effective when administered within 24h post-ischemia, though treatment delayed to seven days improved outcome in one study. This review demonstrates both neuroprotective and neurorestorative effects of PDE5i in animal models of stroke, though the specific underlying signaling pathways relating to PDE5 inhibition and cGMP may remain serendipitous in some studies. There is currently limited evidence on the effects of selective PDE5i in human stroke patients, hence translation of preclinical results into clinical trials may be warranted.

Effect of using fluoxetine at different time windows on neurological functional prognosis after ischemic stroke

PURPOSE

To evaluate the effect of using fluoxetine at different time intervals after ischemic stroke on neurological functional prognosis in China.

METHODS

The patients enrolled were randomly allocated to three groups. Group A received fluoxetine 20 mg/day immediately; group B received fluoxetine 20 mg/day 7 days after enrollment; and group C did not receive fluoxetine. The therapeutic duration of fluoxetine was 90 days and the follow-up period was 180 days.

RESULTS

The mean NIHSS score at day 90 was significantly lower in group A than group C (P = 0.005), while at day 180, the mean score in group A was significantly lower than groups B and C (P = 0.035, P = 0.000), respectively. The mean BI score at day 90 was significantly higher in group A than group C (P = 0.001), while at day 180, the mean score in group A was significantly higher than groups B and C (P = 0.036, P = 0.000), respectively. Regression analysis indicated that lower NIHSS score and higher BI score at day 180 were attributed to the early administration of fluoxetine.

CONCLUSIONS

In patients with ischemic stroke, early administration of fluoxetine may improve the neurological functional prognosis.

Alterations in the corticotropin-releasing hormone (CRH) neurocircuitry: Insights into post stroke functional impairments

Although it is well accepted that changes in the regulation of the hypothalamic-pituitary adrenal (HPA) axis may increase susceptibility to affective disorders in the general population, this link has been less examined in stroke patients. Yet, the bidirectional association between depression and cardiovascular disease is strong, and stress increases vulnerability to stroke. Corticotropin-releasing hormone (CRH) is the central stress hormone of the HPA axis pathway and acts by binding to CRH receptors (CRHR) 1 and 2, which are located in several stress-related brain regions. Evidence from clinical and animal studies suggests a role for CRH in the neurobiological basis of depression and ischemic brain injury. Given its importance in the regulation of the neuroendocrine, autonomic, and behavioral correlates of adaptation and maladaptation to stress, CRH is likely associated in the pathophysiology of post stroke emotional impairments. The goals of this review article are to examine the clinical and experimental data describing (1) that CRH regulates the molecular signaling brain circuit underlying anxiety- and depression-like behaviors, (2) the influence of CRH and other stress markers in the pathophysiology of post stroke emotional and cognitive impairments, and (3) context and site specific interactions of CRH and BDNF as a basis for the development of novel therapeutic targets. This review addresses how the production and release of the neuropeptide CRH within the various regions of the mesocorticolimbic system influences emotional and cognitive behaviors with a look into its role in psychiatric disorders post stroke.

On the effect of minocycline on the depressive-like behavior of mice repeatedly exposed to malathion: interaction between nitric oxide and cholinergic system

This study was performed to investigate the antidepressant-like effect of minocycline in mice exposed to organophosphate pesticide malathion and possible involvement of nitric oxide/cGMP pathway in this paradigm. Mice were administered specific doses of malathion once daily for 7 consecutive days. After induction of depression, different doses of minocycline were daily injected alone or combined with non-specific NOS inhibitor, L-NAME, specific inducible NOS inhibitor, AG, NO precursor, L-arginine, and PDE5I, sildenafil. After locomotion assessment in open-field test, immobility times were recorded in the FST and TST. Moreover, hippocampal nitrite concentrations and acetylcholinesterase activity were measured. The results showed that repeated exposure to malathion induces depressive-like behavior at dose of 250 mg/kg. Minocycline (160 mg/kg) significantly reduced immobility times in FST and TST (P < 0.001). Combination of sub-effective doses of minocycline (80 mg/kg) with either L-NAME (3 mg/kg) or AG (25 mg/kg) significantly exerted a robust antidepressant-like effect in FST and TST (P < 0.001). Furthermore, minocycline at the same dose which has antidepressant-like effect, significantly reduced hippocampal nitrite concentration. The investigation indicates the essential role for NO/cGMP pathway in malathion-induced depressive-like behavior and antidepressant-like effect of minocycline. Moreover, the interaction between nitrergic and cholinergic systems are suggested to be involved in malathion-induced depression.

A review on animal models of stroke: An update

Stroke is one of the major healthcare challenges prevailing across the globe due to its significant rate of mortality and morbidity. Stroke is multifactorial in nature and involves several cellular and molecular signaling cascades that make the pathogenesis complex and treatment difficult. For a deeper understanding of the diverse pathological mechanisms and molecular & cellular cascades during stroke, animal modeling serves as a reliable and an effective tool. This also helps to develop and critically analyse various neuroprotective strategies for the mitigation of this devastating disease. Animal modeling for stroke has been revolutionized with the development of newer and more relevant models or approaches that mimic the clinical setting of stroke to a greater extent. This review analyses experimental models of stroke (ischemic and hemorrhagic) and their reliability in stroke situation. Besides this, the review also stresses upon the use of various preclinical models to understand the pathophysiological mechanisms that operate during stroke and to elucidate new, safe and effective neuroprotective agents to combat this life threatening healthcare concern.

Combined use of spatial restraint stress and middle cerebral artery occlusion is a novel model of post-stroke depression in mice

Post stroke depression (PSD) is one of the most common complications of ischemic stroke. At present, the underlying mechanisms are unclear, largely because there are no reliable, valid and reproducible animal models of PSD. Here we report a novel animal model of PSD that displays consistent and reliable clinical features of hemiplegic stroke. The animal model encompasses a combination of the middle cerebral artery occlusion (MCAO) and spatial restraint stress. We found that a 60-minute MCAO followed by spatial restraint stress for 2 h daily for 2 to 4 weeks from the fourth day after MCAO induced PSD-like depressive phenotypes in mice. Importantly, the mice showed exacerbated deficits of neurological functions and decreased body weights, which were accompanied with reduced levels of brain derived neurotrophic factor and neurotransmitters including serotonin and dopamine. In addition, we identified increased levels of serum cortisol in our PSD mice. Finally, we found that mice with PSD were responsive to the tri-cyclic antidepressant imipramine as evidenced by their attenuated depressive behaviors, increased body weights, recovered brain serotonin levels, and decreased serum cortisol levels. This mouse model replicates multiple features of human post-stroke depression and thus provides a new model for the investigation of PSD.

Phosphodiesterase inhibitors as therapeutics for traumatic brain injury

Developing therapeutics for traumatic brain injury remains a challenge for all stages of recovery. The pathological features of traumatic brain injury are diverse, and it remains an obstacle to be able to target the wide range of pathologies that vary between traumatic brain injured patients and that evolve during recovery. One promising therapeutic avenue is to target the second messengers cAMP and cGMP with phosphodiesterase inhibitors due to their broad effects within the nervous system. Phosphodiesterase inhibitors have the capability to target different injury mechanisms throughout the time course of recovery after brain injury. Inflammation and neuronal death are early targets of phosphodiesterase inhibitors, and synaptic dysfunction and circuitry remodeling are late potential targets of phosphodiesterase inhibitors. This review will discuss how signaling through cyclic nucleotides contributes to the pathology of traumatic brain injury in the acute and chronic stages of recovery. We will review our current knowledge of the successes and challenges of using phosphodiesterase inhibitors for the treatment of traumatic brain injury and conclude with important considerations in developing phosphodiesterase inhibitors as therapeutics for brain trauma.

Capsaicin induces "brite" phenotype in differentiating 3T3-L1 preadipocytes

Objective

Targeting the energy storing white adipose tissue (WAT) by pharmacological and dietary means in order to promote its conversion to energy expending “brite” cell type holds promise as an anti-obesity approach. Present study was designed to investigate/revisit the effect of capsaicin on adipogenic differentiation with special reference to induction of “brite” phenotype during differentiation of 3T3-L1 preadipocytes.

Methods

Multiple techniques such as Ca²⁺ influx assay, Oil Red-O staining, nutrigenomic analysis in preadipocytes and matured adipocytes have been employed to understand the effect of capsaicin at different doses. In addition to in-vitro experiments, in-vivo studies were carried out in high-fat diet (HFD) fed rats treated with resiniferatoxin (RTX) (a TRPV1 agonist) and in mice administered capsaicin.

Results

TRPV1 channels are expressed in preadipocytes but not in adipocytes. In preadipocytes, both capsaicin and RTX stimulate Ca²⁺ influx in dose-dependent manner. This stimulation may be prevented by capsazepine, a TRPV1 antagonist. At lower doses, capsaicin inhibits lipid accumulation and stimulates TRPV1 gene expression, while at higher doses it enhances accumulation of lipids and suppresses expression of its receptor. In doses of 0.1–100 µM, capsaicin promotes expression of major pro-adipogenic factor PPARγ and some of its downstream targets. In concentrations of 1 µM, capsaicin up-regulates anti-adipogenic genes. Low-dose capsaicin treatment of 3T3-L1 preadipocytes differentiating into adipocytes results in increased expression of brown fat cell marker genes. In white adipose of mice, capsaicin administration leads to increase in browning-specific genes. Global TRPV1 ablation (i.p. by RTX administration) leads to increase in locomotor activity with no change in body weight.

Conclusion

Our findings suggest the dual modulatory role of capsaicin in adipogenesis. Capsaicin inhibits adipogenesis in 3T3-L1 via TRPV1 activation and induces brown-like phenotype whereas higher doses.

Possible nitric oxide mechanism in the protective effect of hesperidin against pentylenetetrazole (PTZ)-induced kindling and associated cognitive dysfunction in mice

Epilepsy is a complex neurological disorder manifested by recurrent episodes of convulsive seizures, loss of consciousness, and sensory disturbances. Pentylenetetrazole (PTZ)-induced kindling primarily represents a model of generalized epilepsy. The present study has been undertaken to evaluate the neuroprotective potential of hesperidin and its interaction with nitric oxide modulators against PTZ-induced kindling and associated cognitive dysfunction in mice. The experimental protocol comprised of eleven groups (n=6), where a subconvulsive dose of PTZ (40 mg/kg, i.p.) had been administered every other day for a period of 12 days, and seizure episodes were noted after each PTZ injection over a period of 30 min. The memory performance tests were carried out on days 13 and 14 followed by the estimation of biochemical and mitochondrial parameters. Chronic administration of a subconvulsive dose of PTZ resulted in an increase in convulsive activity culminating in generalized clonic-tonic seizures, as revealed by a progressive increase in seizure score as well as alteration in antioxidant enzyme levels (lipid peroxidation, nitrite, glutathione, super oxide dismutase, and catalase) and mitochondrial complex (I, II, and IV) activities, whereas chronic treatment with hesperidin (200 mg/kg) significantly attenuated these behavioral, biochemical, and mitochondrial alterations. Further, treatment with l-arginine (100 mg/kg) or l-NAME (10 mg/kg) in combination with hesperidin significantly modulated the protective effect of hesperidin which was significant as compared to their effects per se in PTZ-treated animals. Thus, the present study suggests a possible involvement of the NO-cGMP pathway in the neuroprotective effect of hesperidin in PTZ-kindled mice.

Post-stroke depression: mechanisms, translation and therapy

The interaction between depression and stroke is highly complex. Post-stroke depression (PSD) is among the most frequent neuropsychiatric consequences of stroke. Depression also negatively impacts stroke outcome with increased morbidity, mortality and poorer functional recovery. Antidepressants such as the commonly prescribed selective serotonin reuptake inhibitors improve stroke outcome, an effect that may extend far beyond depression, e.g., to motor recovery. The main biological theory of PSD is the amine hypothesis. Conceivably, ischaemic lesions interrupt the projections ascending from midbrain and brainstem, leading to a decreased bioavailability of the biogenic amines – serotonin (5HT), dopamine (DA) and norepinephrine (NE). Acetylcholine would also be involved. So far, preclinical and translational research on PSD is largely lacking. The implementation and characterization of suitable animal models is clearly a major prerequisite for deeper insights into the biological basis of post-stroke mood disturbances. Equally importantly, experimental models may also pave the way for the discovery of novel therapeutic targets. If we cannot prevent stroke, we shall try to limit its long-term consequences. This review therefore presents animal models of PSD and summarizes potential underlying mechanisms including genomic signatures, neurotransmitter and neurotrophin signalling, hippocampal neurogenesis, cellular plasticity in the ischaemic lesion, secondary degenerative changes, activation of the hypothalamo-pituitary-adrenal (HPA) axis and neuroinflammation. As stroke is a disease of the elderly, great clinical benefit may especially accrue from deciphering and targeting basic mechanisms underlying PSD in aged animals.

Neuroprotective potentials of candesartan, atorvastatin and their combination against stroke induced motor dysfunction

Cerebral ischaemia is a leading cause of death and disability. The objective of the present investigation was to explore the neuroprotective potentials of candesartan and atorvastatin alone and their combination against the cerebral ischaemia induced behavioral, biochemical, and mitochondrial dysfunction. Male Wistar rats (200-220 g) were subjected to bilateral common carotid artery occlusion for 30 min followed by 24 h reperfusion. Candesartan (0.1 and 0.3 mg/kg) and atorvastatin (10 and 20 mg/kg) were pretreated for 7 days before animals were subjected to ischaemia reperfusion injury. Various behavioral tests (locomotor activity and rotarod performance), biochemical parameters (Malondialdehyde levels, nitrite concentration, superoxide dismutase and catalase activity, redox ratio, and GST) and mitochondrial enzyme (Complex I, II, III, and IV) dysfunctions were measured in cerebral cortex, striatum and hippocampus of the ischaemic brain. Seven days candesartan (0.1 and 0.3 mg/kg) or atorvastatin (10 and 20 mg/kg) pretreatment significantly attenuated neurobehavioral alterations, oxidative damage and restored mitochondrial enzyme dysfunction as compared to control (I/R) group. Further, combined treatment of candesartan (0.1 mg/kg) and atorvastatin (10 mg/kg) significantly potentiated their protective effect which was significant as compared to their effect alone. Present study suggests the protective effect of candesartan and atorvastatin and their combination against ischaemia reperfusion induced behavioral and biochemical alterations in rats.

Nitric oxide modulation in protective role of antidepressants against chronic fatigue syndrome in mice

Background and Objective:

The present study was designed to elucidate the possible nitric oxide (NO) mechanism in the protective effect of antidepressants using mice model of chronic fatigue syndrome (CFS).

Materials and Methods:

Male albino laca mice were forced to swim for each 6 min session for 7 days and immobility period was measured on every alternate day (1^st, 3^rd, 5^th, 7^th). After 7 days various behavioral tests (locomotor, mirror chamber, and plus maze tests for anxiety) were performed and biochemical estimations (lipid peroxidation, nitrite levels, GSH (reduced glutathione), and catalase activity) in mice brain were performed. Animals were pretreated with citalopram (5 and 10 mg/kg) and imipramine (10 and 20 mg/kg) daily for 7 days.

Results:

The present study showed that continued forced swimming for 7 days caused chronic fatigue-induced anxiety-like behavior as assessed in mirror chamber, plus maze tests, and impairment in locomotor activity followed by oxidative damage (as evidenced by increased lipid peroxidation, nitrite levels, depleted reduced glutathione, and catalase activity) in animals. Seven days pretreatment with citalopram (5 and 10 mg/kg) and imipramine (10 and 20 mg/kg) significantly improved behavioral and biochemical alterations. Further, L-nitro-arginine methyl ester (L-NAME,5 mg/kg) and methylene blue (MB, 10 mg/kg) pretreatment with citalopram (5 mg/kg) or imipramine (10 mg/kg) potentiated their protective effect. However, l-arginine (100 mg/kg) pretreatment with citalopram (5 mg/kg) or imipramine (10 mg/kg) reversed their protective effect as compared with their effect per se (P < 0.05).

Conclusion:

The present study suggests that protective effect of citalopram and imipramine might be due to its NO modulation against chronic fatigue induced behavioral and biochemical alterations.

Experimental depression induces renal oxidative stress in rats

Depression has been associated to inflammatory and oxidative events. Previous report has shown renal oxidative stress in patients with depression. In order to analyze if depressive status is related to renal oxidative and inflammatory events, Sprague Dawley rats were submitted to forced swimming test (FST) and the renal oxidative metabolism, monocyte-macrophage infiltration and Angiotensin II (Ang II) expression were determined. Rats were submitted to FST daily (30 min) for 15 days. Motor activity was analyzed before FST. Kidney sections were homogenized to measure nitric oxide (NO), malondialdehyde (MDA), reduced glutathione (GSH) and catalase activity by enzymatic and biochemical methods. Renal frozen sections were studied for superoxide anion (O2-), monocyte/macrophage infiltration and Ang II expression by histochemical and immunofluorescence methods. In addition, three groups of FST rats were treated with losartan, sertraline or water for 18 days with further renal O2-analysis. In the FST group, struggle time, motor activity, food intake and body weight gain were found decreased. Increased number of glomerular, interstitial and tubular O2-positive cells was observed in FST rats. High renal content of nitrite/nitrate (NO), MDA and decreased amount of GSH were found in FST rats. Values of renal ED-1 or Ang II positive cells in FST rats remained similar to controls; however, AT1 receptor blocking (losartan) and sertraline reduced both depressive-like behavior and renal O2-expression. These data suggests that depression-like behavior in rats is involved in kidney oxidative stress probably mediated by AT1 receptors.

Pre- and post-treatments with escitalopram protect against experimental ischemic neuronal damage via regulation of BDNF expression and oxidative stress

Selective serotonin re-uptake inhibitors (SSRI) have been widely used in treatment of major depression because of their efficacy, safety, and tolerability. Escitalopram, an SSRI, is known to decrease oxidative stress in chronic stress animal models. In the present study, we examined the neuroprotective effects of pre- and post-treatments with 20 mg/kg and 30 mg/kg escitalopram in the gerbil hippocampal CA1 region (CA1) after transient cerebral ischemia. Pre-treatment with escitalopram protected against ischemia-induced neuronal death in the CA1 after ischemia/reperfusion (I/R). Post-treatment with 30 mg/kg, not 20 mg/kg, escitalopram had a neuroprotective effect against ischemic damage. In addition, 20 mg/kg pre- and 30 mg/kg post-treatments with escitalopram increased brain-derived neurotrophic factor (BDNF) protein levels in the ischemic CA1 compared to vehicle-treated ischemia animals. In addition, 20 mg/kg pre- and 30 mg/kg post-treatments with escitalopram reduced microglia activation and decreased 4-hydroxy-2-nonenal and Cu,Zn-superoxide dismutase immunoreactivity and their levels in the ischemic CA1 compared to vehicle-treated ischemia animals after transient cerebral ischemia. In conclusion, these results indicated that pre- and post-treatments with escitalopram can protect against ischemia-induced neuronal death in the CA1 induced by transient cerebral ischemic damage by increase of BDNF as well as decrease of microglia activation and oxidative stress.

Glibenclamide ameliorates ischemia-reperfusion injury via modulating oxidative stress and inflammatory mediators in the rat hippocampus

Stroke remains a debilitating disease with high incidence of morbidity and mortality, where many reports provide promising venues for prevention/treatment of such ailment. Glibenclamide, a selective blocker of KATP channels, was reported to protect against ischemia and ischemia-reperfusion (IR) injury in several experimental models. Hence, the present study aimed to investigate the possible involvement of free radicals as well as inflammatory and anti-inflammatory mediators in the hippocampus of rats exposed to IR. To this end, male Wistar rats were divided into 3 groups: group I served as sham operated controls; group II was subjected to 15 min ischemia by occlusion of both common carotid arteries, followed by 60 min reperfusion; group III was injected with glibenclamide (1mg/kg, i.p.) 10 min before ischemic-reperfusion injury. IR increased lipid peroxides, myeloperoxidase activity, TNF-α and PGE(2), while decreasing glutathione, total antioxidant capacity, nitric oxide and IL-10 levels in the hippocampus. Glibenclamide reversed all the former alterations, thus highlighting a potential therapeutic utility for this sulphonyl urea in IR brain injury via modulating oxidative stress and inflammatory mediators.

Protective effect of desipramine, venlafaxine and trazodone against experimental animal model of transient global ischemia: possible involvement of NO-cGMP pathway

The present study has been designed to explore the nitric oxide mechanism in the protective effect of desipramine, venlafaxine and trazodone against I/R induced oxidative stress and mitochondrial dysfunction in mice. Vitamin E was taken as standard antioxidant. Laca mice (25-30 g) were subjected to twice BCCAO occlusion (5 min) at the interval of 10 min, followed by 96 h reperfusion. The drug treatments were started from the day of surgery and continued for the next four days. After 96 h the animals were sacrificed for biochemical (malondialdehyde, nitrite concentration, superoxidedismutase, catalase, redox ratio and GST) and mitochondrial enzyme complex (NADH dehydrogenase, succinate dehydrogenase, MTT assay and cytochrome c oxidase) estimations. Ischemia caused significant oxidative damage and mitochondrial enzyme dysfunction after 96 h of reperfusion as compared to sham operated animals. Antidepressant (desipramine, venlafaxine and trazodone) treatment significantly attenuated oxidative damage and restored mitochondrial enzyme complex activities as compared to control (I/R) group. Further, protective effects of desipramine (15 mg/kg) and/or venlafaxine (5 mg/kg) were attenuated by l-arginine (100 mg/kg) or sildenafil (5 mg/kg) pretreatment. Further, L-NAME (10 mg/kg) or 7-NI (10 mg/kg) pretreatment with desipramine (15 mg/kg) and/or venlafaxine (5 mg/kg) significantly potentiated their protective effect which was significant as compared to their effect alone. The present study highlights the involvement of nitric oxide mechanism in the protective effects of desipramine and venlafaxine against I/R induced oxidative stress and mitochondrial dysfunction in mice.