Citalopram enhances neurovascular regeneration and sensorimotor functional recovery after ischemic stroke in mice

The atypical antidepressant tianeptine confers neuroprotection against oxygen-glucose deprivation

Proregenerative and neuroprotective effects of antidepressants are an important topic of inquiry in neuropsychiatric research. Oxygen-glucose deprivation (OGD) mimics key aspects of ischemic injury in vitro. Here, we studied the effects of 24-h pretreatment with serotonin (5-HT), citalopram (CIT), fluoxetine (FLU), and tianeptine (TIA) on primary mouse cortical neurons subjected to transient OGD. 5-HT (50 μM) significantly enhanced neuron viability as measured by MTT assay and reduced cell death and LDH release. CIT (10 μM) and FLU (1 μM) did not increase the effects of 5-HT and neither antidepressant conferred neuroprotection in the absence of supplemental 5-HT in serum-free cell culture medium. By contrast, pre-treatment with TIA (10 μM) resulted in robust neuroprotection, even in the absence of 5-HT. Furthermore, TIA inhibited mRNA transcription of candidate genes related to cell death and hypoxia and attenuated lipid peroxidation, a hallmark of neuronal injury. Finally, deep RNA sequencing of primary neurons subjected to OGD demonstrated that OGD induces many pathways relating to cell survival, the inflammation-immune response, synaptic dysregulation and apoptosis, and that TIA pretreatment counteracted these effects of OGD. In conclusion, this study highlights the comparative strength of the 5-HT independent neuroprotective effects of TIA and identifies the molecular pathways involved.

Exploring the "gene-metabolite" network of ischemic stroke with blood stasis and toxin syndrome by integrated transcriptomics and metabolomics strategy

A research model combining a disease and syndrome can provide new ideas for the treatment of ischemic stroke. In the field of traditional Chinese medicine, blood stasis and toxin (BST) syndrome is considered an important syndrome seen in patients with ischemic stroke (IS). However, the biological basis of IS-BST syndrome is currently not well understood. Therefore, this study aimed to explore the biological mechanism of IS-BST syndrome. This study is divided into two parts: (1) establishment of an animal model of ischemic stroke disease and an animal model of BST syndrome in ischemic stroke; (2) use of omics methods to identify differentially expressed genes and metabolites in the models. We used middle cerebral artery occlusion (MCAO) surgery to establish the disease model, and utilized carrageenan combined with active dry yeast and MCAO surgery to construct the IS-BST syndrome model. Next, we used transcriptomics and metabolomics methods to explore the differential genes and metabolites in the disease model and IS-BST syndrome model. It is found that the IS-BST syndrome model exhibited more prominent characteristics of IS disease and syndrome features. Both the disease model and the IS-BST syndrome model share some common biological processes, such as thrombus formation, inflammatory response, purine metabolism, sphingolipid metabolism, and so on. Results of the "gene-metabolite" network revealed that the IS-BST syndrome model exhibited more pronounced features of complement-coagulation cascade reactions and amino acid metabolism disorders. Additionally, the "F2 (thrombin)-NMDAR/glutamate" pathway was coupled with the formation process of the blood stasis and toxin syndrome. This study reveals the intricate mechanism of IS-BST syndrome, offering a successful model for investigating the combination of disease and syndrome.

Type II & III inhibitors of tropomyosin receptor kinase (Trk): a 2020-2022 patent update

INTRODUCTION

The Trk family proteins are membrane-bound kinases predominantly expressed in neuronal tissues. Activated by neurotrophins, they regulate critical cellular processes through downstream signaling pathways. Dysregulation of Trk signaling can drive a range of diseases, making the design and study of Trk inhibitors a vital area of research. This review explores recent advances in the development of type II and III Trk inhibitors, with implications for various therapeutic applications.

AREAS COVERED

Patents covering type II and III inhibitors targeting the Trk family are discussed as a complement of the previous review, Type I inhibitors of tropomyosin receptor kinase (Trk): a 2020-2022 patent update. Relevant patents were identified using the Web of Science database, Google, and Google Patents.

EXPERT OPINION

While type II and III Trk inhibitor development has advanced more gradually compared to their type I counterparts, they hold significant promise in overcoming resistance mutations and achieving enhanced subtype selectivity - a critical factor in reducing adverse effects associated with pan-Trk inhibition. Recent interdisciplinary endeavors have marked substantial progress in the design of subtype selective Trk inhibitors, with impressive success heralded by the type III inhibitors. Notably, the emergence of mutant-selective Trk inhibitors introduces an intriguing dimension to the field, offering precise treatment possibilities.

Activation of the Epac/Rap1 signaling pathway alleviates blood-brain barrier disruption and brain damage following cerebral ischemia/reperfusion injury

Blood brain barrier (BBB) destruction plays a key role in ischemia stroke, including promoting BBB leakage and brain edema, and leads to unfavorable patient prognosis. Epac/Rap1 signaling pathway is important in mediating endothelial cell barrier function. This study will investigate the regulatory role of Epac/Rap1 signaling pathway in BBB disruption after cerebral ischemia/reperfusion (CI/R) injury. CI/R model was induced by 90 min of transient middle cerebral artery occlusion (MCAO) in male C57BL/6J mice. Injection of Epac/Rap1 signaling pathway agonist was performed half an hour before the MCAO operation. The results showed that CI/R injured the tight connection of BBB and evoked the suppression of the Epac/Rap1 signaling pathway. Based on Epac activation with a cAMP analogue, 8-CPT could improve BBB disfunction by increasing the expression of tight junction protein and reducing the formation of stress fibers. In addition, 8-CPT could ameliorate neurobehavioral disorders, cerebral edema, and cerebral infarction volume in MCAO mice. Moreover, inhibition of Epac pathway with Rap1 inhibitor GGTI298 and Rac1 inhibitor NSC23766 could aggravate the damage of BBB and cerebral injury accordingly. Our results indicate that, the activation of Epac/Rap1 signaling pathway has neuroprotective effects on CI/R damaged brain, through the recovery of BBB.

Delayed citalopram administration reduces brain inflammation and enhances skilled motor function after ischaemic stroke in 'MacGreen' mice

Recent evidence suggests that treatment with antidepressants may promote functional recovery. However, the timeframe in which these pharmacological agents can influence stroke recovery is not well understood. This research investigated whether delayed administration of citalopram, used clinically in the management of post-stroke depression, could improve long-term functional recovery following experimental stroke. MacGreen mice carrying an enhanced green fluorescent protein reporter gene in monocyte and macrophage populations were subjected to 45 min occlusion of the middle cerebral artery. Animals were administered citalopram (10 mg/kg/day, n = 20) or saline (n = 20) starting 3 days after stroke for 28 days. Neurological deficits and skilled motor performance in the staircase task were recorded for 9 weeks post stroke. Grey and white matter structural lesions were quantified at Week 9, and enhanced green fluorescent protein immunohistochemistry was used to evaluate the effect of citalopram on inflammation. Twenty-five animals were included in the final analysis. Citalopram-treated animals (n = 13) showed a significant increase in impaired forepaw use in the staircase task compared with saline-treated animals (n = 12) 2, 3 and 7 weeks post stroke but no difference in neurological score at any time point examined. Citalopram treatment was associated with decreased monocyte/macrophage cell density and increased white matter tract integrity within the ipsilateral cortex. In conclusion, delayed administration of citalopram decreased brain inflammation and produced functional gains in our mouse model of stroke. Beneficial effects on skilled motor functions were long-lasting.

Cannabidiol Confers Neuroprotection in Rats in a Model of Transient Global Cerebral Ischemia: Impact of Hippocampal Synaptic Neuroplasticity

Evidence for the clinical use of neuroprotective drugs for the treatment of cerebral ischemia (CI) is still greatly limited. Spatial/temporal disorientation and cognitive dysfunction are among the most prominent long-term sequelae of CI. Cannabidiol (CBD) is a non-psychotomimetic constituent of Cannabis sativa that exerts neuroprotective effects against experimental CI. The present study investigated possible neuroprotective mechanisms of action of CBD on spatial memory impairments that are caused by transient global cerebral ischemia (TGCI) in rats. Hippocampal synaptic plasticity is a fundamental mechanism of learning and memory. Thus, we also evaluated the impact of CBD on neuroplastic changes in the hippocampus after TGCI. Wistar rats were trained to learn an eight-arm aversive radial maze (AvRM) task and underwent either sham or TGCI surgery. The animals received vehicle or 10 mg/kg CBD (i.p.) 30 min before surgery, 3 h after surgery, and then once daily for 14 days. On days 7 and 14, we performed a retention memory test. Another group of rats that received the same pharmacological treatment was tested in the object location test (OLT). Brains were removed and processed to assess neuronal degeneration, synaptic protein levels, and dendritic remodeling in the hippocampus. Cannabidiol treatment attenuated ischemia-induced memory deficits. In rats that were subjected to TGCI, CBD attenuated hippocampal CA1 neurodegeneration and increased brain-derived neurotrophic factor levels. Additionally, CBD protected neurons against the deleterious effects of TGCI on dendritic spine number and the length of dendritic arborization. These results suggest that the neuroprotective effects of CBD against TGCI-induced memory impairments involve changes in synaptic plasticity in the hippocampus.

Selective serotonin reuptake inhibitors for functional recovery after stroke: similarities with the critical period and the role of experience-dependent plasticity

There has been a growing interest in the potential for plasticity-inducing pharmacological interventions to enhance post-stroke recovery. One group of drugs that continues to garner a great deal of attention in this regard is a class of antidepressants called the selective serotonin reuptake inhibitors. Here we propose a model for the mechanism by which these drugs may enhance plasticity after ischemic brain injury. First, we review the research in animal models demonstrating how selective serotonin reuptake inhibitors reopen the critical period for ocular dominance plasticity in adulthood. We then compare this period of heightened plasticity to the cellular and biochemical milieu of perilesional tissue after an ischemic event in the adult brain. We argue that selective serotonin reuptake inhibitors administered acutely after an ischemic stroke alter excitatory-inhibitory balance in perilesional tissue and reinstate a type of plasticity reminiscent of the critical period in development. Finally, we discuss opportunities for future research in this area in both the preclinical and clinical realms.

Escitalopram improves neural functional prognosis and endothelial dysfunction in patients with acute cerebral infarction

BACKGROUND

Escitalopram is one of the most commonly used SSRIs at present, which has the characteristics of quick onset, less interactions with other drugs, and relative safety.

OBJECTIVE

This study aims to investigate the effects of escitalopram on neural functional prognoses and endothelial dysfunction after acute ischemic stroke.

METHODS

One hundred eligible patients afflicted with acute ischemic stroke were randomized into two groups: control and treatment groups. Patients in the treatment group received escitalopram in addition to the basic therapies in the control group over a period of 90 days. Neurological deficits were quantified using the National Institutes of Health Stroke Scale (NIHSS) score and Barthel index (BI) score, cognitive impairment was determined using the Mini-Mental State Examination (MMSE) score, depressive symptoms were measured using the 17-item Hamilton Depression Rating Scale (HAMD). Furthermore, post-stroke depression (PSD) was defined based on the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition), with a HAMD score ≥17. Flow-mediated vascular dilatation (FMD) of the brachial artery was use as a surrogate indicator for endothelial dysfunction assessment with ultrasound.

RESULTS

The mean NIHSS and HAMD scores on day 90 after treatment were significantly lower in the treatment group than in the control group (2.17±0.36 vs. 4.24±0.85; 5.81±1.35 vs. 10.43±4.91; P < 0.01), while the mean BI score and FMD were significantly higher in the treatment group (93.08±6.23 vs. 79.64±7.56, P < 0.01; 8.71±2.35 vs. 5.83±1.21, P < 0.05) than in the control group. The improvement in MMSE score was not significantly different between the two groups.

CONCLUSIONS

Treatment with escitalopram early after ischemic stroke can improve neural functional prognoses and endothelial dysfunction. Escitalopram had less side effects, which is worthy of clinical prophylactic application.

Citalopram Administration Does Not Promote Function or Histological Recovery after Spinal Cord Injury

Citalopram is a selective serotonin reuptake inhibitor, and although widely used as an antidepressant, this drug has also demonstrated interesting repairing properties leading to motor recovery and pathology amelioration in animal models of stroke and degeneration. Here, we tested the efficacy of both 7-day and 8-week citalopram treatment in a contusive spinal cord injury (SCI) rat model. A combination of behavioral tests, histological and serum cytokine analysis was used to assess overall recovery. Despite promoting a mild reduction of inflammatory cells as well as an early, but transient increase of specific serum cytokines, citalopram administration showed no overall beneficial effects on motor performance or lesion extension. Our results do not support citalopram treatment as a therapeutic strategy for SCI.

Activation of 5-HT1A postsynaptic receptors by NLX-101 results in functional recovery and an increase in neuroplasticity in mice with brain ischemia

Pharmacological interventions that selectively activate serotonin 5-hydroxytryptramine-1A (5-HT_1A) heteroreceptors may prevent or attenuate the consequences of brain ischemic episodes. The present study investigated whether the preferential 5-HT_1A postsynaptic receptor agonist NLX-101 (a.k.a. F15599) mitigates cognitive and emotional impairments and affects neuroplasticity in mice that are subjected to the bilateral common carotid artery occlusion (BCCAO) model of brain ischemia. The selective serotonin reuptake inhibitor escitalopram (Esc) was used for comparative purposes because it is able to decrease morbidity and improve recovery in stroke patients and ischemic rodents. Sham and BCCAO mice received daily doses of NLX-101 (0.32 mg/kg, i.p) or Esc (20 mg/kg, i.p) for 28 days. During this period, they were evaluated for locomotor activity, anxiety- and despair-related behaviors and hippocampus-dependent cognitive function, using the open field, elevated zero maze, forced swim test and object location test, respectivelly. The mice's brains were processed for biochemical and histological analyses. BCCAO mice exhibited high anxiety and despair-like behaviors and performed worse than controls in the cognitive assessment. BCCAO induced neuronal and dendritic spine loss and decreases in the protein levels of neuronal plasticity markers, including brain-derived neurotrophic factor (BDNF), synaptophysin (SYN), and postsynaptic density protein-95 (PSD-95), in prefrontal cortex (PFC) and hippocampus. NLX-101 and Esc attenuated cognitive impairments and despair-like behaviors in BCCAO mice. Only Esc decreased anxiety-like behaviors due to brain ischemia. Both NLX-101 and Esc blocked the increase in plasma corticosterone levels and, restored BDNF, SYN and PSD-95 protein levels in the hippocampus. Moreover, both compounds impacted positively dentritic remodeling in the hippocampus and PFC of ischemic mice. In the PFC, NLX-101 increased the BDNF protein levels, while Esc in turn, attenuated the decrease in the PSD-95 protein levels induced by BCCAO. The present results suggest that activation of post-synaptic 5-HT_1A receptors is the molecular mechanism for serotonergic protective effects in BCCAO. Moreover, post-synaptic biased agonists such as NLX-101 might constitute promising therapeutics for treatment of functional and neurodegenerative outcomes of brain ischemia.

Are they necessary? Preventive therapies for post-stroke depression: A meta-analysis of RCTs

To explore the necessity and feasibility of early anti-depressive therapies in acute stroke patients, we conducted a meta-analysis of currently available randomized control studies (RCTs). Literature search in six databases was done with keywords of cerebrovascular accident, depression and prevention. Only RCTs that met the inclusion criteria were enrolled for further analysis. Twelve eligible studies were included in this meta-analysis. Prophylactic anti-depressive therapies following acute stroke were shown to reduce the incidence of depression in the patients (RR = =0.33, 95% CI: 0.25 to 0.43, p < 0.001), improve symptoms of depression (WMD: 5.73, 95% CI: 4.18 to 7.29, p < 0.001), improve motor function (WMD: 12.56, 95%CI: 9.07 to 16.04, p < 0.001) and neurological function (WMD: 1.13, 95%CI: 0.57 to 1.69, p < 0.001). However, anti-depressive therapies showed no effects on mortality (RR = 1.63, 95%CI: 0.55 to 4.85, p = 0.377) and adverse events incidence (RR = 0.93, 95%CI: 0.53 to 1.64, p = 0.806). Anti-depressive therapies following acute stroke is effective thus deserves to be advocated.

Regulation of BDNF-TrkB Signaling and Potential Therapeutic Strategies for Parkinson's Disease

Brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase receptor type B (TrkB) are widely distributed in multiple regions of the human brain. Specifically, BDNF/TrkB is highly expressed and activated in the dopaminergic neurons of the substantia nigra and plays a critical role in neurophysiological processes, including neuro-protection and maturation and maintenance of neurons. The activation as well as dysfunction of the BDNF-TrkB pathway are associated with neurodegenerative diseases. The expression of BDNF/TrkB in the substantia nigra is significantly reduced in Parkinson's Disease (PD) patients. This review summarizes recent progress in the understanding of the cellular and molecular roles of BNDF/TrkB signaling and its isoform, TrkB.T1, in Parkinson's disease. We have also discussed the effects of current therapies on BDNF/TrkB signaling in Parkinson's disease patients and the mechanisms underlying the mutation-mediated acquisition of resistance to therapies for Parkinson's disease.

Effects of Paroxetine on Motor and Cognitive Function Recovery in Patients with Non-Depressed Ischemic Stroke: An Open Randomized Controlled Study

Introduction: To investigate the effects of paroxetine (PAR) on motor and cognitive function recovery in patients with non-depressed ischemic stroke (nD-AIS).

Methods: One hundred sixty-seven patients hospitalized for non-depressed acute ischemic stroke were selected and divided into treatment (T) and control (C) groups using a random number table. All patients received conventional secondary ischemic stroke prevention and rehabilitation training; patients in Group T additionally received treatment with PAR (10 mg/day during week 1 and 20 mg/day thereafter) for 3 months. The follow-up observation lasted 6 months. The Fugl–Meyer motor scale (FMMS), Montreal cognitive assessment (MoCA), and Hamilton depression scale (HAMD) were used on D0, D15, D90, and D180 (T0, 1, 2, and 3, respectively; D180 = 90 days after treatment cessation) after study initiation, and scores were compared between the groups.

Results: The FMMS and MoCA scores differed significantly between Groups T and C at T2 and T3 (p < .05); by contrast, these scores did not differ significantly between the groups at T1 (p > .05). Furthermore, the HAMD scores differed significantly between the two groups at T3 (p < .05), but not at T1 and T2 (p > .05).

Conclusions: PAR treatment may improve motor and cognitive function recovery in patients with nD-AIS. Moreover, PAR may reduce the occurrence of depression after stroke.

Neurochemical changes underpinning the development of adjunct therapies in recovery after stroke: A role for GABA?

Stroke is a leading cause of long-term disability, with around three-quarters of stroke survivors experiencing motor problems. Intensive physiotherapy is currently the most effective treatment for post-stroke motor deficits, but much recent research has been targeted at increasing the effects of the intervention by pairing it with a wide variety of adjunct therapies, all of which aim to increase cortical plasticity, and thereby hope to maximize functional outcome. Here, we review the literature describing neurochemical changes underlying plasticity induction following stroke. We discuss methods of assessing neurochemicals in humans, and how these measurements change post-stroke. Motor learning in healthy individuals has been suggested as a model for stroke plasticity, and we discuss the support for this model, and what evidence it provides for neurochemical changes. One converging hypothesis from animal, healthy and stroke studies is the importance of the regulation of the inhibitory neurotransmitter GABA for the induction of cortical plasticity. We discuss the evidence supporting this hypothesis, before finally summarizing the literature surrounding the use of adjunct therapies such as non-invasive brain stimulation and SSRIs in post-stroke motor recovery, both of which have been show to influence the GABAergic system.

Pyruvate Kinase M2 Increases Angiogenesis, Neurogenesis, and Functional Recovery Mediated by Upregulation of STAT3 and Focal Adhesion Kinase Activities After Ischemic Stroke in Adult Mice

Ischemic stroke remains a serious threat to human life. Generation of neuronal and vascular cells is an endogenous regenerative mechanism in the adult brain, which may contribute to tissue repair after stroke. However, the regenerative activity is typically insufficient for significant therapeutic effects after brain injuries. Pyruvate kinase isoform M2 (PKM2) is a key regulator for energy metabolism. PKM2 also has nonmetabolic roles involving regulations of gene expression, cell proliferation, and migration in cancer cells as well as noncancerous cells. In a focal ischemic stroke mouse model, recombinant PKM2 (rPKM2) administration (160 ng/kg, intranasal delivery) at 1 h after stroke showed the significant effect of a reduced infarct volume of more the 60%. Delayed treatment of rPKM2, however, lost the acute neuroprotective effect. We then tested a novel hypothesis that delayed treatment of PKM2 might show proregenerative effects for long-term functional recovery and this chronic action could be mediated by its downstream STAT3 signaling. rPKM2 (160 ng/kg) was delivered to the brain using noninvasive intranasal administration 24 h after the stroke and repeated every other day. Western blot analysis revealed that, 7 days after the stroke, the levels of PKM2 and phosphorylated STAT3 and the expression of angiogenic factors VEGF, Ang-1, and Tie-2 in the peri-infarct region were significantly increased in the rPKM2 treatment group compared with those of the stroke vehicle group. To label proliferating cells, 5-bromo-2'-deoxyuridine (BrdU, 50 mg/kg, i.p.) was injected every day starting 3 days after stroke. At 14 days after stroke, immunohistochemistry showed that rPKM2 increased cell homing of doublecortin (DCX)-positive neuroblasts to the ischemic cortex. In neural progenitor cell (NPC) cultures, rPKM2 (0.4-4 nM) increased the expression of integrin β1 and the activation/phosphorylation of focal adhesion kinase (FAK). A mediator role of FAK in PKM2-promoted cell migration was verified in FAK-knockout fibroblast cultures. In the peri-infarct region of the brain, increased numbers of Glut-1/BrdU and NeuN/BrdU double-positive cells indicated enhanced angiogenesis and neurogenesis, respectively, compared to stroke vehicle mice. Using Laser Doppler imaging, we observed better recovery of the local blood flow in the peri-infarct region of rPKM2-treated mice 14 days after stroke. Meanwhile, rPKM2 improved the sensorimotor functional recovery measured by the adhesive removal test. Inhibiting the STAT3 phosphorylation/activation by the STAT3 inhibitor, BP-1-102 (3 mg/kg/day, o.g.), abolished all beneficial effects of rPKM2 in the stroke mice. Taken together, this investigation provides the first evidence demonstrating that early treatment of rPKM2 shows an acute neuroprotective effect against ischemic brain damage, whereas delayed rPKM2 treatment promotes regenerative activities in the poststroke brain leading to better functional recovery. The underlying mechanism involves activation of the STAT3 and FAK signals in the poststroke brain.

Neuroplasticity and behavioral effects of fluoxetine after experimental stroke

The brain can undergo self-repair and has the ability to compensate for functions lost after a stroke. The plasticity of the ischemic brain is influenced by several factors including aging and pharmacotherapy. Fluoxetine is an antidepressant which enhances serotonergic neurotransmission through selective inhibition of neuronal reuptake of serotonin. In clinical practice, fluoxetine alleviates the symptoms of post-stroke depression (PSD), helps motor recovery in stroke patients. In animal experiments, chronic administration of fluoxetine induces increased excitability of mature granule cells (GCs), enhancing axonal and dendritic reorganization, as well as promoting neurogenesis or angiogenesis in the dentate gurus (DG), but the effect of fluoxetine in the subventricular zone (SVZ) remains controversial. Meanwhile, chronic treatment with fluoxetine did not reverse age-dependent suppression of proliferation cells in the DG. Interestingly, although fluoxetine has been found to enhance neurogenesis in the DG in stroke rats, this property is not consistent with the behavioral recovery. More studies into this issue will be required to reveal how to translate enhanced neuronal plasticity into behavioral benefits. This review provides an update of the current knowledge about the neurogenesis and the fate of the newly generated cells after the use of fluoxetine, as well as its ability to promote a behavioral recovery after stroke in clinical and experimental results and attempts to define the therapeutic properties of fluoxetine in regenerative neuroscience.

Autocrine and paracrine regulatory functions of platelet serotonin

Platelets serotonin (5-hydroxytrytamine, 5-HT) uptake and storage in dense granules is tightly regulated by the serotonergic transport system in the blood. Several 5-HT transporters (5-HTTs) have been identified in the vasculature and blood cells, beyond them 5-HTT is the major 5-HT transporter in platelets. Abnormal 5-HT concentrations in the blood plasma or increased platelet 5-HT uptake or abnormal release contribute to the development of various diseases in the vasculature. Consequently, several clinical trials suggested the positive therapeutic effects of 5-HTT blockade in the circulation. Inhibition of 5-HT strongly attenuates autocrine and paracrine functions of platelets, influencing platelet aggregation, vascular contraction, permeability, tissue repair, wound healing, immunity and cancer. Here, we highlight the current state of basic biological research regarding the hemostatic and non-hemostatic functions of platelet-derived 5-HT in normal and disease conditions. We also describe the physiological consequences of targeting platelet 5-HT functions in thrombosis, stroke, inflammation and cancer to overcome common health problems.

Advances in stroke pharmacology

Stroke occurs when a cerebral blood vessel is blocked or ruptured, and it is the major cause of death and adult disability worldwide. Various pharmacological agents have been developed for the treatment of stroke either through interrupting the molecular pathways leading to neuronal death or enhancing neuronal survival and regeneration. Except for rtPA, few of these agents have succeeded in clinical trials. Recently, with the understanding of the pathophysiological process of stroke, there is a resurrection of research on developing neuroprotective agents for stroke treatment, and novel molecular targets for neuroprotection and neurorestoration have been discovered to predict or offer clinical benefits. Here we review the latest major progress of pharmacological studies in stroke, especially in ischemic stroke; summarize emerging potential therapeutic mechanisms; and highlight recent clinical trials. The aim of this review is to provide a panorama of pharmacological interventions for stroke and bridge basic and translational research to guide the clinical management of stroke therapy.

Differential effects of neonatal SSRI treatments on hypoxia-induced behavioral changes in male and female offspring

Prenatal hypoxia induced by transient intrauterine ischemia is a serious clinical problem, and at present, effective treatments are lacking. Currently, it is unknown how prenatal hypoxia affects behaviors in adulthood. Therefore, we developed a mouse model that mimics prenatal hypoxia in humans using uterine artery occlusion in late gestation. We examined whether prenatal hypoxia induces behavioral changes in adult male and female offspring by conducting a series of behavioral tests. In adulthood, longer immobility was observed in the forced swim test in males, whereas females showed decreased inhibition in the prepulse inhibition test. We then investigated the effects of two different selective serotonin reuptake inhibitors (SSRIs), fluoxetine (FLX) and escitalopram (ESC), on these behavioral changes. These drugs affect the neurodevelopmental process and have long-term neurological consequences. FLX treatment from postnatal day 3 (P3) to P21 ameliorated the behavioral changes in both male and female mice. In comparison, ESC treatment ameliorated the behavioral changes only in female mice. Neurochemical analysis revealed that dopamine was increased in the female hippocampus, but not in males. Thus, neonatal SSRI treatment decreases dopamine levels in the hippocampus in females selectively. Our findings suggest that prenatal hypoxia is a risk factor for behavioral abnormalities in adulthood, and that neonatal SSRI treatment might have clinical potential for alleviating these long-term behavioral deficits.

Molecular structure, FT IR, NMR, UV, NBO and HOMO-LUMO of 1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile by DFT/B3LYP and PBEPBE methods with LanL2DZ and 6-311++G(d,2p) basis sets

Structural and molecular properties of antidepressants 1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile were examined using quantum mechanics of Density Functional Theory (DFT)/B3LYP and PBEPBE methods with 6-311++G(d,2p) and LanL2DZ basis sets to study the therapeutic properties of the drug. For this, the structure of desired material was optimized by the computer calculation method and with the use of powerful Gaussian 09 software. Then the lowest energy value and the bond length, bond angle and dihedral angle between its constituent atoms in the crystal structure of the desired material were measured from the optimized values. Then the amount of positive and negative charges, polarizability and dipole moment of its atoms using Mulliken charge and Natural atomic charges, DFT/B3LYP and PBEPBE methods with 6-311++G(d,2p) and LanL2DZ basis sets were determined and the results were compared with each other for individual atoms and by mentioned methods. Also the type of stretching vibrations and bending vibrations between the constituent atoms of the molecule were specified using mentioned computational methods and FT IR vibrational spectra. The experimental spectrum of this material was taken to determine the functional groups and the computational and experimental values were compared to each other and Nuclear Magnetic Resonance (NMR) was used to specify the isomer shift between the carbons and protons in the presence of polar and nonpolar solvents. Also Natural Bond Orbital (NBO) was used to determine the type of electron transfers in σ→σ∗ and π→π∗ and LP(1)→σ∗ and LP(2)→σ∗ and the amount of hardness and softness in molecule was determined using the difference between ionization energy and electron affinity energy in constituent atoms of that molecule in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and in the presence of solvents H₂O, CH₃CN and C₆H₁₂. UV-Vis spectrum of the drug was taken using DFT/B3LYP and PBEPBE methods with 6-311++G(d,2p) and LanL2DZ basis sets as well as solvents H₂O, CH₃CN and C₆H₁₂ and the associated transmissions were examined.

Activation of the sigma-1 receptor by haloperidol metabolites facilitates brain-derived neurotrophic factor secretion from human astroglia

Glial cells play a critical role in neuronal support which includes the production and release of the neurotrophin brain-derived neurotrophic factor (BDNF). Activation of the sigma-1 receptor (S1R) has been shown to attenuate inflammatory stress-mediated brain injuries, and there is emerging evidence that this may involve a BDNF-dependent mechanism. In this report we studied S1R-mediated BDNF release from human astrocytic glial cells. Astrocytes express the S1R, which mediates BDNF release when stimulated with the prototypical S1R agonists 4-PPBP and (+)-SKF10047. This effect could be antagonized by a selective concentration of the S1R antagonist BD1063. Haloperidol is known to have high affinity interactions with the S1R, yet it was unable to facilitate BDNF release. Remarkably, however, two metabolites of haloperidol, haloperidol I and haloperidol II (reduced haloperidol), were discovered to facilitate BDNF secretion and this effect was antagonized by BD1063. Neither 4-PPBP, nor either of the haloperidol metabolites affected the level of BDNF mRNA as assessed by qPCR. These results demonstrate for the first time that haloperidol metabolites I and II facilitate the secretion of BDNF from astrocytes by acting as functionally selective S1R agonists.

Efficacy of Citalopram on Acute Ischemic Stroke Outcome: A Randomized Clinical Trial

BACKGROUND AND PURPOSE

Ischemic stroke (IS) is one of the main causes of death and disability in the adult population, and recovery from it is a major health concern worldwide. The aim of the present study was to evaluate the effectiveness of citalopram on 3-mounth outcome of nondepressed acute IS patients.

METHODS

In a randomized, placebo-controlled clinical trial, 144 patients with acute IS were studied for 3 months. In one group, the patients received oral citalopram 20 mg (once daily), and in the other group, they received placebo. All patients received standard care, including physiotherapy. Patients with depression were excluded throughout the study. The primary outcome of the study was set to a 50% reduction in the 3-month National Institutes of Health Stroke Scale compared with the baseline scores (Clinical Trial Registration URL: http://www.irct.ir ; Unique identifier: IRCT201203192150N2).

RESULTS

The mean age of patients was 66.4 years. Of 144 eligible patients, 15 patients died (4 in the citalopram and 11 in the placebo group), and 21 patients did not complete the study follow-up period (10 in the citalopram and 11 in the placebo group). The primary outcome of the study was achieved in 57 patients (79%) in the citalopram and 39 patients (54%) in the placebo group ( P < .001), with risk ratio and number needed to treat of 2 (CI = 1.2-3) and 4 (CI = 2.5-8.6), respectively. No major adverse events were found in either group.

CONCLUSIONS

Citalopram is a safe and tolerable medication in patients with acute IS, which could improve the outcome in these patients.

Update on Inflammatory Biomarkers and Treatments in Ischemic Stroke

After an acute ischemic stroke (AIS), inflammatory processes are able to concomitantly induce both beneficial and detrimental effects. In this narrative review, we updated evidence on the inflammatory pathways and mediators that are investigated as promising therapeutic targets. We searched for papers on PubMed and MEDLINE up to August 2016. The terms searched alone or in combination were: ischemic stroke, inflammation, oxidative stress, ischemia reperfusion, innate immunity, adaptive immunity, autoimmunity. Inflammation in AIS is characterized by a storm of cytokines, chemokines, and Damage-Associated Molecular Patterns (DAMPs) released by several cells contributing to exacerbate the tissue injury both in the acute and reparative phases. Interestingly, many biomarkers have been studied, but none of these reflected the complexity of systemic immune response. Reperfusion therapies showed a good efficacy in the recovery after an AIS. New therapies appear promising both in pre-clinical and clinical studies, but still need more detailed studies to be translated in the ordinary clinical practice. In spite of clinical progresses, no beneficial long-term interventions targeting inflammation are currently available. Our knowledge about cells, biomarkers, and inflammatory markers is growing and is hoped to better evaluate the impact of new treatments, such as monoclonal antibodies and cell-based therapies.

Improvement in Compensation for Chronic Poststroke Homonymous Hemianopsia After Initiation of a Selective Serotonin Reuptake Inhibitor: A Case Report

Homonymous hemianopsia (HH) is a common adverse outcome after stroke. Spontaneous improvement more than 6 months poststroke is thought to be unlikely, and traditional visual rehabilitation techniques lack clear evidence of efficacy. The case presented is of a 22-year-old woman who demonstrated improved compensation of her stroke-induced HH after the initiation of a selective serotonin reuptake inhibitor (SSRI). There is evidence supporting the use of SSRIs to improve poststroke cognitive impairment, motor impairment, and depression. This is the first case, however, demonstrating the potential novel use SSRIs to improve HH compensation after stroke, to our knowledge.

LEVEL OF EVIDENCE

V.

Neuroimmunological interactions in stroke

INTRODUCTION

Stroke is one of the leading causes of death in the world; its incidence is increasing due to increased life expectancy. However, treatment options for these patients are limited since no clinically effective drugs have been developed to date.

DEVELOPMENT

According to clinical evidence, a number of neurochemical changes take place after stroke, including energy depletion, increased free radical synthesis, calcium accumulation, neurotransmitter imbalance, excitotoxicity, and, at a later stage, immune system activation leading to inflammation. Immune response has been shown to be a major factor in disease progression. The release of proinflammatory cytokines such as TNF increase brain damage secondary to excitotoxicity and calcium accumulation, and promote free radical synthesis and cell death through various mechanisms. On the other hand, certain anti-inflammatory cytokines, such as IL-10 and IL-4, have been shown to have a neuroprotective effect and even promote neurogenesis and synapse remodeling, which makes immune modulation a promising treatment approach.

CONCLUSIONS

Understanding the relationship between the immune system and the nervous system not only deepens our knowledge of stroke but also provides new diagnostic, prognostic, and therapeutic strategies that may increase the quality of life of stroke patients.

Induced cortical neurogenesis after focal cerebral ischemia--Three active components from Huang-Lian-Jie-Du Decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-Lian-Jie-Du-Decoction (HLJDD) is a Traditional Chinese Medicine (TCM) clinical prescription noted for its neuroprotective effects. The total alkaloids, flavonoids, and iridoids are the main active components of HLJDD. In the present study we explored the possible effects of the total alkaloids, flavonoids, and iridoids from HLJDD on behavioral recovery and cortical neurogenesis after stroke.

METHODS

The stroke model was induced by permanent middle cerebral artery occlusion (pMACO). The total alkaloids (44 mg/kg), flavonoids (50 mg/kg), and iridoids (80 mg/kg) from HLJDD were orally administered for 2h after stroke and daily thereafter. Neurological function was assessed and then rats were sacrificed 7 days after pMACO. Following repeated intraperitoneal injections of the cell proliferation - specific marker 5-bromodeoxyuridine (BrdU) after stroke induction, precursor cell proliferation and differentiation was monitored by immunofluorescent staining. The levels of relevant proteins were determined by western blotting and the mRNA expressions were assessed by quantitative real time-polymerase chain reaction (qRT-PCR).

RESULTS

Total alkaloids, flavonoids and iridoids from HLJDD showed improved functional outcome after brain ischemia. The total alkaloids and iridoids increased number of BrdU-positive cells and enhanced neuronal differentiation in the cortex. Alkaloids-enhanced neurogenesis might be associated with increased VEGF, Ang-1, and Ang-2 protein expression. And the neuroproliferative effect of alkaloids was partially correlated with increased phosphorylation of AKT, and GSK-3β. Flavonoids treatment was found to promote differentiation of cortical precursor cells into neuronal but not glial cells, which may be at least attributable to the regulation of AKT, GSK-3β mRNA and Ang-1 protein levels.

CONCLUSIONS

Total alkaloids, iridoids and flavonoids from HLJDD promoted functional recovery likely via enhancing cortical neurogenesis and thus have potential as a treatment for ischemic brain injury.

Partially Defective Store Operated Calcium Entry and Hem(ITAM) Signaling in Platelets of Serotonin Transporter Deficient Mice

BACKGROUND

Serotonin (5-hydroxytryptamin, 5-HT) is an indolamine platelet agonist, biochemically derived from tryptophan. 5-HT is secreted from the enterochromaffin cells into the gastrointestinal tract and blood. Blood 5-HT has been proposed to regulate hemostasis by acting as a vasoconstrictor and by triggering platelet signaling through 5-HT receptor 2A (5HTR2A). Although platelets do not synthetize 5-HT, they take 5-HT up from the blood and store it in their dense granules which are secreted upon platelet activation.

OBJECTIVE

To identify the molecular composite of the 5-HT uptake system in platelets and elucidate the role of platelet released 5-HT in thrombosis and ischemic stroke.

METHODS

5-HT transporter knockout mice (5Htt-/-) were analyzed in different in vitro and in vivo assays and in a model of ischemic stroke.

RESULTS

In 5Htt-/- platelets, 5-HT uptake from the blood was completely abolished and agonist-induced Ca2+ influx through store operated Ca2+ entry (SOCE), integrin activation, degranulation and aggregation responses to glycoprotein VI (GPVI) and C-type lectin-like receptor 2 (CLEC-2) were reduced. These observed in vitro defects in 5Htt-/- platelets could be normalized by the addition of exogenous 5-HT. Moreover, reduced 5-HT levels in the plasma, an increased bleeding time and the formation of unstable thrombi were observed ex vivo under flow and in vivo in the abdominal aorta and carotid artery of 5Htt-/- mice. Surprisingly, in the transient middle cerebral artery occlusion (tMCAO) model of ischemic stroke 5Htt-/- mice showed nearly normal infarct volume and the neurological outcome was comparable to control mice.

CONCLUSION

Although secreted platelet 5-HT does not appear to play a crucial role in the development of reperfusion injury after stroke, it is essential to amplify the second phase of platelet activation through SOCE and plays an important role in thrombus stabilization.

Neurotrophic Factors and Their Potential Applications in Tissue Regeneration

Neurotrophic factors are growth factors that can nourish neurons and promote neuron survival and regeneration. They have been studied as potential drug candidates for treating neurodegenerative diseases. Since their identification, there are more and more evidences to indicate that neurotrophic factors are also expressed in non-neuronal tissues and regulate the survival, anti-inflammation, proliferation and differentiation in these tissues. This mini review summarizes the characteristics of the neurotrophic factors and their potential clinical applications in the regeneration of neuronal and non-neuronal tissues.

Fluoxetine enhanced neurogenesis is not translated to functional outcome in stroke rats

Fluoxetine is widely used in clinical practice. It regulates hippocampal neurogenesis, however, the effect of fluoxetine on neurogenesis in the subventricular zone (SVZ) remains controversial. We aimed to study the effect of fluoxetine on neurogenesis in the SVZ and subgranular zone (SGZ) of dentate gyrus (DG) in relation to behavioral recovery after stroke in rats. Adult male Wistar rats were randomly assigned to four groups: sham-operated rats, sham-operated rats treated with fluoxetine, rats subjected to cerebral ischemia, and rats with ischemia treated with fluoxetine. Fluoxetine was orally administrated starting 1 week after ischemia, with a dose of 16mg/kg/day for 3 weeks. Focal cerebral ischemia was induced by intracranial injection of vasoconstrictive peptide endothelin-1(ET-1). Behavioral recovery was evaluated on post-stroke days 29-31 after which the survival rate and fate of proliferating cells in the SVZ and DG were measured by immunohistochemistry. The production of neuroblasts in both the SVZ and DG was significantly increased after stroke. Chronic post-stroke fluoxetine treatment increased the dendritic complexity of newborn dentate granule cells. However, fluoxetine treatment did not influence the survival or differentiation of newly generated cells. Neither fluoxetine treatment improved sensorimotor recovery following focal cerebral ischemia.

A novel snake venom-derived GPIb antagonist, anfibatide, protects mice from acute experimental ischaemic stroke and reperfusion injury

BACKGROUND AND PURPOSE

Ischaemic stroke is a serious disease with limited therapy options. Glycoprotein (GP)Ib binding to von Willebrand factor (vWF) exposed at vascular injury initiates platelet adhesion and contributes to platelet aggregation. GPIb has been suggested as an effective target for antithrombotic therapy in stroke. Anfibatide is a GPIb antagonist derived from snake venom and we investigated its protective effect on experimental brain ischaemia in mice.

EXPERIMENTAL APPROACH

Focal cerebral ischaemia was induced by 90 min of transient middle cerebral artery occlusion (MCAO). These mice were then treated with anfibatide (4, 2, 1 μg·kg(-1) ), injected i.v., after 90 min of MCAO, followed by 1 h of reperfusion. Tirofiban, a GPIIb/IIIα antagonist, was used as a positive control.

KEY RESULTS

Twenty-four hours after MCAO, anfibatide-treated mice showed significantly improved ischaemic lesions in a dose-dependent manner. The mice had smaller infarct volumes, less severe neurological deficits and histopathology of cerebrum tissues compared with the untreated MCAO mice. Moreover, anfibatide decreased the amount of GPIbα, vWF and accumulation of fibrin(ogen) in the vasculature of the ischaemic hemisphere. Tirofiban had similar effects on infarct size and fibrin(ogen) deposition compared with the MCAO group. Importantly, the anfibatide-treated mice showed a lower incidence of intracerebral haemorrhage and shorter tail bleeding time compared with the tirofiban-treated mice.

CONCLUSIONS AND IMPLICATIONS

Our data indicate anfibatide is a safe GPIb antagonist that exerts a protective effect on cerebral ischaemia and reperfusion injury. Anfibatide is a promising candidate that could be beneficial for the treatment of ischaemic stroke.

Phase II anti-inflammatory and immune-modulating drugs for acute ischaemic stroke

INTRODUCTION

Stroke is the second leading cause of death worldwide and the leading cause of adult neurological disability. Despite advances in stroke unit care, and increasing use of thrombolysis, there remains an urgent need for safe and effective treatments for acute ischaemic stroke. However, this is against a backdrop of multiple failures in translational drug development. Cerebral ischaemia initiates a complex cascade of immune and inflammatory pathways in the brain microvasculature and periphery, which contribute to the evolution of cerebral injury, resolution and repair. Targeting specific inflammatory or immune pathways, therefore, represents an attractive treatment strategy in acute ischaemic stroke. Although anti-inflammatory drugs have already failed in clinical trial development, several are currently at the Phase II developmental stage.

AREAS COVERED

The authors highlight several candidate drugs, which modulate a range of inflammatory and immune pathways, and have been investigated in pre-clinical and Phase II studies to date.

EXPERT OPINION

Drugs targeting inflammatory and immune pathways offer theoretical advantages including potentially longer therapeutic time windows and effects complementary to thrombolysis (ameliorating reperfusion injury). Fundamental changes in the approach to pre-clinical and clinical drug development are required to facilitate successful translation of promising candidate drugs into clinical practice.

High matrix metalloproteinase-9 expression induces angiogenesis and basement membrane degradation in stroke-prone spontaneously hypertensive rats after cerebral infarction

Basement membrane degradation and blood-brain barrier damage appear after cerebral infarction, severely impacting neuronal and brain functioning; however, the underlying pathogenetic mechanisms remain poorly understood. In this study, we induced cerebral infarction in stroke-prone spontaneously hypertensive rats by intragastric administration of high-sodium water (1.3% NaCl) for 7 consecutive weeks. Immunohistochemical and immunofluorescence assays demonstrated that, compared with the non-infarcted contralateral hemisphere, stroke-prone spontaneously hypertensive rats on normal sodium intake and Wistar-Kyoto rats, matrix metalloproteinase-9 expression, the number of blood vessels with discontinuous collagen IV expression and microvessel density were significantly higher, and the number of continuous collagen IV-positive blood vessels was lower in the infarct border zones of stroke-prone spontaneously hypertensive rats given high-sodium water. Linear correlation analysis showed matrix metalloproteinase-9 expression was positively correlated with the number of discontinuously collagen IV-labeled blood vessels and microvessel density in cerebral infarcts of stroke-prone spontaneously hypertensive rats. These results suggest that matrix metalloproteinase-9 upregulation is associated with increased regional angiogenesis and degradation of collagen IV, the major component of the basal lamina, in stroke-prone spontaneously hypertensive rats with high-sodium water-induced focal cerebral infarction.

Of mice and men: modelling post-stroke depression experimentally

At least one-third of stroke survivors suffer from depression. The development of comorbid depression after stroke is clinically highly significant because post-stroke depression is associated with increased mortality, slows recovery and leads to worse functional outcomes. Here, we review the evidence that post-stroke depression can be effectively modelled in experimental rodents via a variety of approaches. This opens an exciting new window onto the neurobiology of depression and permits probing potential underlying mechanisms such as disturbed cellular plasticity, neuroendocrine dysregulation, neuroinflammation, and neurodegeneration in a novel context. From the point of view of translational stroke research, extending the scope of experimental investigations beyond the study of short-term end points and, in particular, acute lesion size, may help improve the relevance of preclinical results to human disease. Furthermore, accumulating evidence from both clinical and experimental studies offers the tantalizing prospect of 5-hydroxytryptaminergic antidepressants as the first pharmacological therapy for stroke that would be available during the subacute and chronic phases of recovery. Interdisciplinary neuropsychiatric research will be called on to dissect the mechanisms underpinning the beneficial effects of antidepressants on stroke recovery.

The interaction between training and plasticity in the poststroke brain

PURPOSE OF REVIEW

Recovery after stroke can occur either via reductions in impairment or through compensation. Studies in humans and nonhuman animal models show that most recovery from impairment occurs in the first 1-3 months after stroke as a result of both spontaneous reorganization and increased responsiveness to enriched environments and training. Improvement from impairment is attributable to a short-lived sensitive period of postischemic plasticity defined by unique genetic, molecular, physiological, and structural events. In contrast, compensation can occur at any time after stroke. Here, we address both the biology of the brain's postischemic sensitive period and the difficult question of what kind of training (task-specific vs. a stimulating environment for self-initiated exploration of various natural behaviors) best exploits this period.

RECENT FINDINGS

Data suggest that three important variables determine the degree of motor recovery from impairment: the timing, intensity, and approach to training with respect to stroke onset; the unique postischemic plasticity milieu; and the extent of cortical reorganization.

SUMMARY

Future work will need to further characterize the unique interaction between types of training and postischemic plasticity, and find ways to augment and prolong the sensitive period using pharmacological agents or noninvasive brain stimulation.

Vascular cognitive impairment and post-stroke cognitive deficits

Vascular cognitive impairment (VCI) and focal post-stroke cognitive deficits are an unfortunately common occurrence. Despite this, our understanding of risk factors for development of VCI and treatment thereof is embarrassingly limited. While no FDA approved treatments exist for VCI, recent and ongoing research sheds some light on the problem, showing some efficacy of cholinesterase inhibitors and antidepressants, treatment of vascular risk factors, and other investigational drugs. Treatments for focal cognitive impairments such as aphasia and neglect are also limited, primarily by the size of studies that have been done. With the more widespread acceptance of the AHA-ASA diagnostic criteria for VCI and its subtypes, perhaps we will start to see more in the way of compelling treatment trials.

Cerebral neovascularization in diabetes: implications for stroke recovery and beyond

Neovascularization is an innate physiologic response by which tissues respond to various stimuli through collateral remodeling (arteriogenesis) and new vessel formation from existing vessels (angiogenesis) or from endothelial progenitor cells (vasculogenesis). Diabetes has a major impact on the neovascularization process but the response varies between different organ systems. While excessive angiogenesis complicates diabetic retinopathy, impaired neovascularization contributes to coronary and peripheral complications of diabetes. How diabetes influences cerebral neovascularization remained unresolved until recently. Diabetes is also a major risk factor for stroke and poor recovery after stroke. In this review, we discuss the impact of diabetes, stroke, and diabetic stroke on cerebral neovascularization, explore potential mechanisms involved in diabetes-mediated neovascularization as well as the effects of the diabetic milieu on poststroke neovascularization and recovery, and finally discuss the clinical implications of these effects.

Mobilization of endogenous bone marrow derived endothelial progenitor cells and therapeutic potential of parathyroid hormone after ischemic stroke in mice

Stroke is a major neurovascular disorder threatening human life and health. Very limited clinical treatments are currently available for stroke patients. Stem cell transplantation has shown promising potential as a regenerative treatment after ischemic stroke. The present investigation explores a new concept of mobilizing endogenous stem cells/progenitor cells from the bone marrow using a parathyroid hormone (PTH) therapy after ischemic stroke in adult mice. PTH 1-34 (80 µg/kg, i.p.) was administered 1 hour after focal ischemia and then daily for 6 consecutive days. After 6 days of PTH treatment, there was a significant increase in bone marrow derived CD-34/Fetal liver kinase-1 (Flk-1) positive endothelial progenitor cells (EPCs) in the peripheral blood. PTH treatment significantly increased the expression of trophic/regenerative factors including VEGF, SDF-1, BDNF and Tie-1 in the brain peri-infarct region. Angiogenesis, assessed by co-labeled Glut-1 and BrdU vessels, was significantly increased in PTH-treated ischemic brain compared to vehicle controls. PTH treatment also promoted neuroblast migration from the subventricular zone (SVZ) and increased the number of newly formed neurons in the peri-infarct cortex. PTH-treated mice showed significantly better sensorimotor functional recovery compared to stroke controls. Our data suggests that PTH therapy improves endogenous repair mechanisms after ischemic stroke with functional benefits. Mobilizing endogenous bone marrow-derived stem cells/progenitor cells using PTH and other mobilizers appears an effective and feasible regenerative treatment after ischemic stroke.