Combination treatment with progesterone and vitamin D hormone is more effective than monotherapy in ischemic stroke: the role of BDNF/TrkB/Erk1/2 signaling in neuroprotection

Investigating the therapeutic effects of nimodipine on vasogenic cerebral edema and blood-brain barrier impairment in an ischemic stroke rat model

Vasogenic brain edema, a potentially life-threatening consequence following an acute ischemic stroke, is a major clinical problem. This research aims to explore the therapeutic benefits of nimodipine, a calcium channel blocker, in mitigating vasogenic cerebral edema and preserving blood-brain barrier (BBB) function in an ischemic stroke rat model. In this research, animals underwent the induction of ischemic stroke via a 60-min blockage of the middle cerebral artery and treated with a nonhypotensive dose of nimodipine (1 mg/kg/day) for a duration of five days. The wet/dry method was employed to identify cerebral edema, and the Evans blue dye extravasation technique was used to assess the permeability of the BBB. Furthermore, immunofluorescence staining was utilized to assess the protein expression levels of matrix metalloproteinase-9 (MMP-9) and intercellular adhesion molecule-1 (ICAM-1). The study also examined mitochondrial function by evaluating mitochondrial swelling, succinate dehydrogenase (SDH) activity, the collapse of mitochondrial membrane potential (MMP), and the generation of reactive oxygen species (ROS). Post-stroke administration of nimodipine led to a significant decrease in cerebral edema and maintained the integrity of the BBB. The protective effects observed were associated with a reduction in cell apoptosis as well as decreased expression of MMP-9 and ICAM-1. Furthermore, nimodipine was observed to reduce mitochondrial swelling and ROS levels while simultaneously restoring MMP and SDH activity. These results suggest that nimodipine may reduce cerebral edema and BBB breakdown caused by ischemia/reperfusion. This effect is potentially mediated through the reduction of MMP-9 and ICAM-1 levels and the enhancement of mitochondrial function.

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

The mutual effect of progesterone and vitamin D in an animal model of peripheral nerve injury

Background and purpose

Experimental and clinical studies have shown the potential role of progesterone in relieving neural injury. In addition, emerging data on vitamin D, a steroid hormone, have shown its neuroprotective properties. This study was designed to evaluate the mutual effect of vitamin D and progesterone on neuropathic pain (NP) in male rats.

Experimental approach

Chronic constriction injury (CCI) was induced by inserting four ligatures around the sciatic nerve. Hyperalgesia and allodynia (cold and mechanical) were considered positive behavioral scores of NP. After surgery, Sprague Dawley male rats (weighing 200-250 g) were assigned into 7 groups. Vitamin D (250 and 500 units/kg/day, i.p.) and progesterone (4 and 6 mg/kg/day, i.p.) were injected from the 1st day after CCI which continued for 21 days. Moreover, one group received the co-administration of vitamin D (500 units/kg/day, i.p.) and progesterone (6 mg/kg/day, i.p.) from the 1st day until the 21st post-CCI day. Behavioral tests were performed on the 7th, 14th, and 21st days.

Findings/Results

Daily supplementation with vitamin D (250 and 500 units/kg) did not alter nociception. Progesterone (4 and 6 mg/kg/day) was ineffective on thermal hyperalgesia. In the allodynia test, progesterone significantly decreased pain-related behaviors. The co-administration of vitamin D (500 units/kg/day) with progesterone (6 mg/kg/day) significantly relieved thermal hyperalgesia. Finally, the combination significantly decreased cold and mechanical allodynia.

Conclusion and implications

This study showed the mutual effect of progesterone and vitamin D on NP for the first time. Hyperalgesia and allodynia were significantly relieved following co-administration of vitamin D and progesterone.

Relationship between plasma brain-derived neurotrophic factor levels and neurological disorders: An investigation using Mendelian randomisation

Background

Altered brain-derived neurotrophic factor (BDNF) concentrations have been detected in the central nervous system tissues and peripheral blood. These alterations are associated with a series of neurological disorders.

Objective

To investigate the potential causal relationships between genetically determined plasma BDNF levels and various neurological diseases using a two-sample Mendelian randomisation study.

Methods

We selected single nucleotide polymorphisms strongly related to plasma BDNF levels as instrumental variables. Within the Mendelian randomisation framework, we used summary-level statistics for exposure (plasma BDNF levels) and outcomes (neurological disorders).

Results

We observed suggestive evidence of a relation between higher plasma BDNF levels and less risk of nontraumatic intracranial haemorrhage (nITH) (odds ratio [OR] = 0.861, 95 % confidence interval [CI]: 0.774-0.958, P = 0.006, PFDR = 0.078), epilepsy (OR = 0.927, 95 % CI: 0.880-0.976, P = 0.004, PFDR = 0.078), focal epilepsy (OR = 0.928, 95 % CI: 0.874-0.986, P = 0.016, PFDR = 0.139), and non-lesional focal epilepsy (OR = 0.981, 95 % CI: 0.964-0.999, P = 0.041, PFDR = 0.267). Combined with the UK Biobank dataset, the association of plasma BDNF levels with nITH remained significant (OR = 0.88, 95 % CI: 0.81-0.96, P < 0.01). The combined analysis of three consortium datasets demonstrated a considerable impact of plasma BDNF on epilepsy (OR = 0.94, 95 % CI: 0.90-0.98, P < 0.01) and a suggestive impact on focal epilepsy (OR = 0.94, 95 % CI: 0.89-0.99, P = 0.02). However, there was no apparent correlation between plasma BDNF levels and other neurological disorders or related subtypes.

Conclusions

Our study supports a possible causal relationship between elevated plasma BDNF levels and a reduced risk of nITH, epilepsy, and focal epilepsy.

Vitamin D and ischemic stroke - Association, mechanisms, and therapeutics

Confronting the rising tide of ischemic stroke and its associated mortality and morbidity with ageing, prevention and acute management of ischemic stroke is of paramount importance. Mounting observational studies have established a non-linear association of vitamin D status with cardiovascular diseases, including ischemic stroke. Paradoxically, current clinical trials fail to demonstrate the cardiovascular benefits of vitamin D supplementation. We aim to update recent clinical and experimental findings on the role of vitamin D in the disease course of ischemic stroke, from its onset, progression, recovery, to recurrence, and the established and alternative possible pathophysiological mechanisms. This review justifies the necessities to address stroke etiological subtypes and focus on vitamin D-deficient subjects for investigating the potential of vitamin D supplementation as a preventive and therapeutic approach for ischemic stroke. Well-powered clinical trials are warranted to determine the efficacy, safety, timing, target individuals, optimal dosages, and target 25OHD concentrations of vitamin D supplementation in the prevention and treatment of ischemic stroke.

Efficacy and safety of Y-2 sublingual tablet for patients with acute ischaemic stroke: protocol of a phase III randomised double-blind placebo-controlled multicentre trial

BACKGROUND AND PURPOSE

Clinical studies have demonstrated that edaravone dexborneol can improve the functional outcomes in patients with acute ischaemic stroke (AIS). The present clinical trial aimed at testing the efficacy and safety of Y-2 sublingual tablet on 90-day functional outcome in patients with AIS.

METHODS AND DESIGN

This is a randomised, double-blind, placebo-controlled, multicentre, parallel-group trial of Y-2 sublingual tablet on patients with AIS.An estimated 914 patients at age of 18-80 years with AIS within 48 hours after symptom onset from 40 hospitals will be randomly assigned to receive Y-2 sublingual tablet or placebo for 14 days. Patients are at score 6-20 points on National Institutes of Health Stroke Scale (NIHSS) and had a modified Rankin Scale (mRS) ≤1 before this stroke, except mechanical thrombectomy and neuroprotective agents treatment.

STUDY OUTCOMES

The primary outcome is the proportion of patients with mRS ≤1 on day 90 after randomisation. Secondary efficacy outcomes include mRS score on day 90, the proportion of patients with mRS ≤2 on day 90; the change of NIHSS score from baseline to day 14 and the proportion of patients with NIHSS score ≤1 at the days 14, 30 and 90.

DISCUSSION

This trial will provide valuable evidence for the efficacy and safety of Y-2 sublingual table for improving 90 days the functional outcomes in patients with AIS.

TRIAL REGISTRATION NUMBER

NCT04950920.

Neuroprotectant Activity of Novel Water-Soluble Synthetic Neurosteroids on Organophosphate Intoxication and Status Epilepticus-Induced Long-Term Neurological Dysfunction, Neurodegeneration, and Neuroinflammation

Organophosphates (OPs) and nerve agents are potent neurotoxic compounds that cause seizures, status epilepticus (SE), brain injury, or death. There are persistent long-term neurologic and neurodegenerative effects that manifest months to years after the initial exposure. Current antidotes are ineffective in preventing these long-term neurobehavioral and neuropathological changes. Additionally, there are few effective neuroprotectants for mitigating the long-term effects of acute OP intoxication. We have pioneered neurosteroids as novel anticonvulsants and neuroprotectants for OP intoxication and seizures. In this study, we evaluated the efficacy of two novel synthetic, water-soluble neurosteroids, valaxanolone (VX) and lysaxanolone (LX), in combating the long-term behavioral and neuropathological impairments caused by acute OP intoxication and SE. Animals were exposed to the OP nerve agent surrogate diisopropylfluorophosphate (DFP) and were treated with VX or LX in addition to midazolam at 40 minutes postexposure. The extent of neurodegeneration, along with various behavioral and memory deficits, were assessed at 3 months postexposure. VX significantly reduced deficits of aggressive behavior, anxiety, memory, and depressive-like traits in control (DFP-exposed, midazolam-treated) animals; VX also significantly prevented the DFP-induced chronic loss of NeuN(+) principal neurons and PV(+) inhibitory neurons in the hippocampus and other regions. Additionally, VX-treated animals exhibited a reduced inflammatory response with decreased GFAP(+) astrogliosis and IBA1(+) microgliosis in the hippocampus, amygdala, and other regions. Similarly, LX showed significant improvement in behavioral and memory deficits, and reduced neurodegeneration and cellular neuroinflammation. Together, these results demonstrate the neuroprotectant effects of the novel synthetic neurosteroids in mitigating the long-term neurologic dysfunction and neurodegeneration associated with OP exposure. SIGNIFICANCE STATEMENT: Survivors of nerve agents and organophosphate (OP) exposures suffer from long-term neurological deficits. Currently, there is no specific drug therapy for mitigating the impact of OP exposure. However, novel synthetic neurosteroids that activate tonic inhibition provide a viable option for treating OP intoxication. The data from this study indicates the neuroprotective effects of synthetic, water-soluble neurosteroids for attenuation of long-term neurological deficits after OP intoxication. These findings establish valaxanolone and lysaxanolone as potent and efficacious neuroprotectants suitable for injectable dosing.

Homer1 ameliorates ischemic stroke by inhibiting necroptosis-induced neuronal damage and neuroinflammation

OBJECTIVE

Proinflammatory necroptosis is the main pathological mechanism of ischemic stroke. Homer scaffolding protein 1 (Homer1) is a postsynaptic scaffolding protein that exerts anti-inflammatory effects in most central nervous system diseases. However, the relationship between Homer1 and proinflammatory necroptosis in ischemic stroke remains unclear.

AIM

This study aimed to investigate the role of Homer1 in ischemia-induced necroptosis.

METHODS

C57BL/6 mice were used to establish a model of permanent middle cerebral artery occlusion model (pMCAO). Homer1 knockdown mice were generated using adeno-associated virus (AAV) infection to explore the role of Homer1 and its impact on necroptosis in pMCAO. Finally, Homer1 protein was stereotaxically injected into the ischemic cortex of Homer1flox/flox/Nestin-Cre +/- mice, and the efficacy of Homer1 was investigated using behavioral assays and molecular biological assays to explore potential mechanisms.

RESULTS

Homer1 expression peaked at 8 h in the ischemic penumbral cortex after pMCAO and colocalized with neurons. Homer1 knockdown promoted neuronal death by enhancing necroptotic signaling pathways and aggravating ischemic brain damage in mice. Furthermore, the knockdown of Homer1 enhanced the expression of proinflammatory cytokines. Moreover, injection of Homer1 protein reduced necroptosis-induced brain injury inhibited the expression of proinflammatory factors, and ameliorated the outcomes in the Homer1flox/flox/Nestin-Cre+/- mice after pMCAO.

CONCLUSIONS

Homer1 ameliorates ischemic stroke by inhibiting necroptosis-induced neuronal damage and neuroinflammation. These data suggested that Homer1 is a novel regulator of neuronal death and neuroinflammation.

Microglia/macrophages require vitamin D signaling to restrain neuroinflammation and brain injury in a murine ischemic stroke model

Vitamin D deficiency is associated with worse clinical outcomes after ischemic stroke; nevertheless, the pathophysiological mechanisms remain largely unexplored. In this study, we characterized the molecular mechanisms of how vitamin D signaling modulated stroke progression in male mouse ischemia-reperfusion stroke models. We found that vitamin D receptor (VDR) exhibited a predominant upregulation in peri-infarct microglia/macrophages following cerebral ischemia. Conditional Vdr inactivation in microglia/macrophages markedly augmented infarct volumes and neurological deficits. VDR-deficient microglia/macrophages exhibited a more primed proinflammatory phenotype with substantial secretion of TNF-α and IFN-γ. These inflammatory cytokines further enhanced CXCL10 release from endothelial cells and blood-brain barrier disruption, and ultimately infiltration of peripheral T lymphocytes. Notably, blocking TNF-α and IFN-γ significantly ameliorated stroke phenotypes in Vdr conditional knockout mice. Collectively, VDR signaling in microglia/macrophages plays a crucial role in restraining ischemia-elicited neuroinflammation and stroke progression. Our findings delineate a novel mechanism underlying the association between vitamin D deficiency and poor stroke outcomes, and underline the significance of maintaining a functional vitamin D signaling in the management of acute ischemic stroke.

Calcitriol modulate post-ischemic TLR signaling pathway in ischemic stroke patients

BACKGROUND

Neuroinflammation is a significant contributor to post-ischemic neuronal death after stroke, and Toll-Like Receptors (TLRs) are one of the essential mediators in many inflammatory pathways. TLRs activate the nuclear factor kappa β (NF-kβ), which promotes the expression of various pro-inflammatory genes such as interleukin (IL-1β) and IL-6. 1,25(OH)2D3, also known as calcitriol, is an active form of vitamin D3 that acts as a neurosteroid compound with anti-inflammatory properties. This study aimed to determine the modulatory effects of calcitriol hormone on post-ischemic immunity response.

METHODS

Neurological tests and conventional blood factors were evaluated in patients with stroke symptoms upon arrival (n = 38) to confirm the stroke. A blood sample was taken from each stroke patient immediately upon admission and again after 24 h. The experimental group was given 10 μg calcitriol orally. The gene expression levels of TLR4, TLR2, NF-kβ, IL-1β, and IL-6 pro-inflammatory factors were measured using real-time PCR. The protein expression of TLR4 and NF-kβ markers was assessed using the flow cytometry technique.

RESULTS

TLR4, NF-kβ, and pro-inflammatory factors IL-1β and IL-6 expression increased significantly after an ischemic stroke, and calcitriol could modulate the TLR4/NF-kβ signaling pathway 24 h after ischemia.

CONCLUSIONS

Calcitriol may be considered a protective reagent after ischemia by reducing the TLR4/NF-kB activation cascade and probably plays a beneficial role in reducing and improving ischemic stroke patients' symptoms.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials identifier: IRCT2017012532174N1.

Neurotrophic factor-based pharmacological approaches in neurological disorders

Aging is a physiological event dependent on multiple pathways that are linked to lifespan and processes leading to cognitive decline. This process represents the major risk factor for aging-related diseases such as Alzheimer's disease, Parkinson's disease, and ischemic stroke. The incidence of all these pathologies increases exponentially with age. Research on aging biology has currently focused on elucidating molecular mechanisms leading to the development of those pathologies. Cognitive deficit and neurodegeneration, common features of aging-related pathologies, are related to the alteration of the activity and levels of neurotrophic factors, such as brain-derived neurotrophic factor, nerve growth factor, and glial cell-derived neurotrophic factor. For this reason, treatments that modulate neurotrophin levels have acquired a great deal of interest in preventing neurodegeneration and promoting neural regeneration in several neurological diseases. Those treatments include both the direct administration of neurotrophic factors and the induced expression with viral vectors, neurotrophins' binding with biomaterials or other molecules to increase their bioavailability but also cell-based therapies. Considering neurotrophins' crucial role in aging pathologies, here we discuss the involvement of several neurotrophic factors in the most common brain aging-related diseases and the most recent therapeutic approaches that provide direct and sustained neurotrophic support.

Molecular Basis Underlying the Therapeutic Potential of Vitamin D for the Treatment of Depression and Anxiety

Major depressive disorder and anxiety disorders are common and disabling conditions that affect millions of people worldwide. Despite being different disorders, symptoms of depression and anxiety frequently overlap in individuals, making them difficult to diagnose and treat adequately. Therefore, compounds capable of exerting beneficial effects against both disorders are of special interest. Noteworthily, vitamin D deficiency has been associated with an increased risk of developing depression and anxiety, and individuals with these psychiatric conditions have low serum levels of this vitamin. Indeed, in the last few years, vitamin D has gained attention for its many functions that go beyond its effects on calcium–phosphorus metabolism. Particularly, antioxidant, anti-inflammatory, pro-neurogenic, and neuromodulatory properties seem to contribute to its antidepressant and anxiolytic effects. Therefore, in this review, we highlight the main mechanisms that may underlie the potential antidepressant and anxiolytic effects of vitamin D. In addition, we discuss preclinical and clinical studies that support the therapeutic potential of this vitamin for the management of these disorders.

Possible Engagement of Nicotinic Acetylcholine Receptors in Pathophysiology of Brain Ischemia-Induced Cognitive Impairment

Post-stroke disabilities like cognitive impairment impose are complex conditions with great economic burdens on health care systems. For these comorbidities, no effective therapies have been identified yet. Nicotinic acetylcholine receptors (nAChRs) are multifunctional receptors participating in various behavioral and neurobiological functions. During brain ischemia, the increased glutamate accumulation leads to neuronal excitotoxicity as well as mitochondrial dysfunction. These abnormalities then cause the increased levels of oxidants, which play key roles in neuronal death and apoptosis in the infarct zone. Additionally, recall of cytokines and inflammatory factors play a prominent role in the exacerbation of ischemic injury. As well, neurotrophic factors' insufficiency results in synaptic dysfunction and cognitive impairments in ischemic brain. Of note, nAChRs through various signaling pathways can participate in therapeutic approaches such as cholinergic system's stimulation, and reduction of excitotoxicity, inflammation, apoptosis, oxidative stress, mitochondrial dysfunction, and autophagy. Moreover, the possible roles of nAChRs in neurogenesis, synaptogenesis, and stimulation of neurotrophic factors expression have been reported previously. On the other hand, the majority of the above-mentioned mechanisms were found to be common in both brain ischemia pathogenesis and cognitive function tuning. Therefore, it seems that nAChRs might be known as key regulators in the control of ischemia pathology, and their modulation could be considered as a new avenue in the multi-target treatment of post-stroke cognitive impairment.

Artemether confers neuroprotection on cerebral ischemic injury through stimulation of the Erk1/2-P90rsk-CREB signaling pathway

Ischemic stroke is one of the leading causes of death and disability among adults. Despite the economic burden of the disease, available treatment options are still very limited. With the exception of anti-thrombolytics and hypothermia, current therapies fail to reduce neuronal injury, neurological deficits and mortality rates, suggesting that the development of novel and more effective therapies against ischemic stroke is urgent. In the present study, we found that artemether, which has been used in the clinic as an anti-malarial drug, was able to improve the neurological deficits, attenuate the infarction volume and the brain water content in a middle cerebral artery occlusion (MCAO) animal model. Furthermore, artemether treatment significantly suppressed cell apoptosis, stimulated cell proliferation and promoted the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), P90^rsk and cAMP responsive element-binding protein (CREB). Artemether protective effect was attenuated by PD98059, an ERK1/2 inhibitor, administration. Similarly, in oxygen-glucose deprivation/reperfusion (OGD/RP) cell models, artemether pre-treatment induced the suppression of the intracellular ROS, the down-regulation of LDH activity, the reduction of caspase 3 activity and of the apoptosis cell rate and reversed the decrease of mitochondrial membrane potential. As with MCAO animal model, artemether promoted the activation of Erk1/2-P90^rsk-CREB signaling pathway. This effect was blocked by the inhibition or knock-down of ERK1/2. The present study provides evidences of the neuroprotective effect of artemether unravelling its potential as a new therapeutic candidate for the prevention and treatment of stroke.

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Artemether conferred neuroprotection in a middle cerebral artery occlusion (MCAO) animal model.

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Artemether conferred neuroprotection on oxygen-glucose deprivation/reperfusion-induced cell injury model.

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Artemether promoted the activation of Erk1/2-P90^rsk-CREB signaling pathway in vitro and in vivo.

Toll-Like Receptor Signaling Pathways: Novel Therapeutic Targets for Cerebrovascular Disorders

Toll-like receptors (TLRs), a class of pattern recognition proteins, play an integral role in the modulation of systemic inflammatory responses. Cerebrovascular diseases (CVDs) are a group of pathological conditions that temporarily or permanently affect the brain tissue mostly via the decrease of oxygen and glucose supply. TLRs have a critical role in the activation of inflammatory cascades following hypoxic-ischemic events and subsequently contribute to neuroprotective or detrimental effects of CVD-induced neuroinflammation. The TLR signaling pathway and downstream cascades trigger immune responses via the production and release of various inflammatory mediators. The present review describes the modulatory role of the TLR signaling pathway in the inflammatory responses developed following various CVDs and discusses the potential benefits of the modulation of different TLRs in the improvement of functional outcomes after brain ischemia.

Stroke-Induced Peripheral Immune Dysfunction in Vitamin D-Deficient Conditions: Modulation by Progesterone and Vitamin D

Vitamin D deficiency (Ddef) alters morphology and outcomes after a stroke. We investigated the interaction of Ddef following post-stroke systemic inflammation and evaluated whether administration of progesterone (P) or vitamin D (D) will improve outcomes. Ddef rats underwent stroke with lipopolysaccharide (LPS)-induced systemic inflammation. Rats were randomly divided into 9 groups and treated with P, D, or vehicle for 4 days. At day 4, rats were tested on different behavioral parameters. Markers of neuronal inflammation, endoplasmic reticulum stress, oxidative stress, white matter integrity, and apoptosis were measured along with immune cell populations from the spleen, thymus, and blood. Severely altered outcomes were observed in the Ddef group compared to the D-sufficient (Dsuf) group. Stroke caused peripheral immune dysfunction in the Dsuf group which was worse in the Ddef group. Systemic inflammation exacerbated injury outcomes in the Dsuf group and these were worse in the Ddef group. Monotherapy with P/D showed beneficial functional effects but the combined treatment showed better outcomes than either alone. Ddef as a comorbid condition with stroke worsens stroke outcomes and can delay functional recovery. Combination treatment with P and D might be promising for future stroke therapeutics in Ddef.

Post-ischemic stroke systemic inflammation: Immunomodulation by progesterone and vitamin D hormone

Post-stroke systemic inflammation, due to the injury itself and exacerbated by in-hospital infections, can increase morbidity and mortality in stroke patients. In this study, we examined the immunomodulatory effects of progesterone (P4) alone and in combination with vitamin D hormone (VDH) on acute phase post-stroke peripheral immune dysfunction and functional/behavioral deficits. Adult rats underwent transient middle cerebral artery occlusion/reperfusion (tMCAO) and delayed systemic inflammation was induced by injections of lipopolysaccharide (LPS) beginning 24 h post-stroke. Animals were tested for behavioral outcomes and immune function at day 4 post-stroke. We also measured infarction volume and markers of neuronal inflammation (GFAP, IL-6) and apoptosis (cleaved caspase-3) in brain post-stroke. We observed the worst stroke outcomes in the stroke + systemic inflammation group compared to the stroke-alone group. Flow cytometric analysis of different subsets of immune cells in blood, spleen and thymus revealed peripheral immune dysfunction which was restored by both P4 and VDH monotherapy. P4 monotherapy reduced infarction volume, behavioral/functional deficits, peripheral immune dysfunction, neuronal inflammation, and apoptosis induced by post-stroke systemic inflammation. Combination treatment with P4+VDH improved outcomes better than monotherapy. Our findings can be taken to suggest that the current standard of care for stroke and post-stroke infection can be substantially improved by P4 and VDH combination therapy.

Neuroprotective effect of paricalcitol in a rat model of transient global cerebral ischemia

Background

Paricalcitol is known to attenuate ischemic-reperfusion injury of various organs. However, it is not known whether paricalcitol prevents neuronal injury after global cerebral ischemia. The purpose of this study is to investigate the neuroprotective effect of paricalcitol in a rat model of transient global cerebral ischemia.

Methods

This is a prospective, randomized experimental study. Male Sprague-Dawley rats that survived 10 min of four-vessel occlusion were randomly assigned to two treatment groups: one group was treated with paricalcitol 1 μg/kg IP, and the other was given an equivalent volume of normal saline IP. Drugs were administered at 5 min, 1 day, 2 days, and 3 days after ischemia. Neurologic function was assessed at 2 h, 1 day, 2 days, 3 days, and 4 days after ischemia. We tested motor function 3 days after ischemia using the rotarod test. Also, we tested memory function 4 days after ischemia using the passive avoidance test. We assessed neuronal degeneration in the hippocampus of surviving rats 4 days after ischemia.

Results

Eight rats were allocated to each group. No significant differences were found between the groups in terms of survival rate, motor coordination, or memory function. The neurological function score 2-h post-ischemia was significantly higher in the paricalcitol group (p = 0.04). Neuronal degeneration was significantly less in the paricalcitol group compared with the control group (p = 0.01).

Conclusions

Paricalcitol significantly attenuated neuronal injury in the hippocampus. Although motor coordination, memory function, and survival rate were not significantly improved by paricalcitol treatment in this study, paricalcitol remains a potential neuroprotective drug after global cerebral ischemia.

Brain-Derived Neurotrophic Factor and Its Potential Therapeutic Role in Stroke Comorbidities

With the rise in the aging global population, stroke comorbidities have become a serious health threat and a tremendous economic burden on human society. Current therapeutic strategies mainly focus on protecting neurons from cytotoxic damage at the acute phase upon stroke onset, which not only is a difficult way to ameliorate stroke symptoms but also presents a challenge for the patients to receive effective treatment in time. The brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the adult brain, which possesses a remarkable capability to repair brain damage. Recent promising preclinical outcomes have made BDNF a popular late-stage target in the development of novel stroke treatments. In this review, we aim to summarize the latest progress in the understanding of the cellular/molecular mechanisms underlying stroke pathogenesis, current strategies and difficulties in drug development, the mechanism of BDNF action in poststroke neurorehabilitation and neuroplasticity, and recent updates in novel therapeutic methods.

Effects of vitamin D on drugs: Response and disposal

Vitamin D supplementation and vitamin D deficiency are common in clinical experience and in daily life. Vitamin D not only promotes calcium absorption and immune regulation, but also changes drug effects (pharmacodynamics and adverse reactions) and drug disposal in vivo when combined with various commonly used clinical drugs. The extensive physiological effects of vitamin D may cause synergism effects or alleviation of adverse reactions, and vitamin D's affect on drugs in vivo disposal through drug transporters or metabolic enzymes may also lead to changes in drug effects. Herein, the effects of vitamin D combined with commonly used drugs were reviewed from the perspective of drug efficacy and adverse reactions. The effects of vitamin D on drug transport and metabolism were summarized and analyzed. Hopefully, more attention will be paid to vitamin D supplementation and deficiency in clinical treatment and drug research and development.

Neurosteroids as regulators of neuroinflammation

Neuroinflammation is a physiological protective response in the context of infection and injury. However, neuroinflammation, especially if chronic, may also drive neurodegeneration. Neurodegenerative diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD) and traumatic brain injury (TBI), display inflammatory activation of microglia and astrocytes. Intriguingly, the central nervous system (CNS) is a highly steroidogenic environment synthesizing steroids de novo, as well as metabolizing steroids deriving from the circulation. Neurosteroid synthesis can be substantially affected by neuroinflammation, while, in turn, several steroids, such as 17β-estradiol, dehydroepiandrosterone (DHEA) and allopregnanolone, can regulate neuroinflammatory responses. Here, we review the role of neurosteroids in neuroinflammation in the context of MS, AD, PD and TBI and describe underlying molecular mechanisms. Moreover, we introduce the concept that synthetic neurosteroid analogues could be potentially utilized for the treatment of neurodegenerative diseases in the future.

Calcitriol alleviates global cerebral ischemia-induced cognitive impairment by reducing apoptosis regulated by VDR/ERK signaling pathway in rat hippocampus

BACKGROUND

Vitamin D (VD) has important neuroprotective functions in the central nervous system. However, further exploration is still needed in the neuroprotective effects of VD monomer therapy on global cerebral ischemia (GCI) and its potential molecular mechanism.

OBJECTIVE

To investigate whether calcitriol, a biologically active metabolite of VD, could alleviate cognitive impairment induced by GCI via reducing cell apoptosis and activating the extracellular signal-regulated kinase (ERK) signaling pathway.

METHODS

A total of 145 adult male Sprague Dawley rats were randomly divided into five groups: Sham group (n = 45), GCI group (n = 45), calcitriol treatment group (GCI + calcitriol, n = 45), PD98059 treatment group (n = 5) and vehicle group (n = 5). Morris water maze test was used for evaluating spatial learning and memory functions. Neurological Severity Score and wet-dry weight method were applied to detect neurological deficits and brain water content, respectively. Hematoxylin and eosin staining, transmission electron microscopy, and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end-labeling staining were performed for evaluating the changes of hippocampal CA1 neurons. Immunocytochemistry, immunofluorescence chemistry, and western blot analysis were performed for evaluating the changes of related proteins.

RESULTS

Calcitriol significantly ameliorated the spatial learning and memory impairments, improved neurological function, attenuated brain edema, and improved the morphological defects in the CA1 area of the hippocampus. Besides, calcitriol reduced GCI-induced cell apoptosis and reversed the up-regulation of pro-apoptotic proteins (Caspase-3 and Bax) and the down-regulation of anti-apoptotic protein (Bcl-2). Furthermore, calcitriol also increased the expression of VD receptors (VDR) and activated the ERK signaling pathway. Moreover, the p-ERK1/2 inhibitor PD98059 reversed the effect of calcitriol on the expression of apoptosis-related proteins.

CONCLUSIONS

Calcitriol may have a protective effect against GCI-induced cognitive impairments via inhibition of apoptotic cascade by activating the VDR/ERK signaling pathway.

Magnesium sulfate protects blood-brain barrier integrity and reduces brain edema after acute ischemic stroke in rats

Brain edema is a fatal complication of acute ischemic stroke and associated with worse outcomes in patients. This study was designed to evaluate the effects of magnesium sulfate on vasogenic brain edema formation and blood-brain barrier (BBB) disruption caused by ischemia-reperfusion (IR) in a rat model of ischemic stroke. A total of 72 male Sprague-Dawley rats were categorized into the following three primary groups: sham, control ischemic, magnesium-sulfate-treated (300 mg/kg loading dose, followed by an additional 100 mg/kg) ischemic (n = 24 in each group). Transient focal cerebral ischemia was induced by 60-min-long occlusion of the left middle cerebral artery, followed by 24-h-long reperfusion. Sensorimotor deficits, infarct volume, and brain edema were evaluated at the end of the reperfusion period. The BBB permeability was assessed by Evans Blue extravasation technique. Lipid peroxidation levels were assessed by measuring the malondialdehyde content in the brain tissue homogenate, and the activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase were detected according to the technical manual of the assay kits. Induction of cerebral ischemia in the control group produced considerable BBB damage in conjunction with severe brain edema formation. Treatment with magnesium sulfate significantly attenuated brain edema and protected BBB integrity in the ischemic lesioned hemisphere. In addition, magnesium sulfate reduced lipid peroxidation and increased antioxidant protection of brain tissue by upregulating the activities of antioxidant enzymes. Treatment with magnesium sulfate protected BBB integrity against IR-induced damage and reduced vasogenic edema formation partly via antioxidant mechanisms in a rat model of acute ischemic stroke.

Efficacy of Simultaneous Administration of Nimodipine, Progesterone, and Magnesium Sulfate in Patients with Severe Traumatic Brain Injury: A Randomized Controlled Trial

OBJECTIVE

To investigate the safety and efficacy of simultaneous administration of nimodipine, progesterone, magnesium sulfate in patients suffering from severe traumatic brain injury (TBI).

METHODS

Overall, 90 patients with blunt head trauma who were admitted to the Besat hospital, Hamadan University of Medical Sciences, Iran through the Emergency Department in 2017 to 2018 were randomly assigned to the study or control groups each containing 45 patients. In the study group, intravenous nimodipine 60 mg every 12 hours for 5 days, intramuscular progesterone 1 mg/kg daily for 5 days, and magnesium sulfate 5 grams stat followed by 2.5 grams every 4 hours for 21 days were administered. Daily GCS and jugular venous oxygen saturation (SjvO2) of the patients were measured on admission day (day 0) through hospitalization day 4 at the intensive care unit. Then, all patients were visited at three months after discharge.

RESULTS

The mean age of the patients was 31.4 ± 12.8 years including 59 (65.6%) men with no significant difference between the groups. The baseline GCS and SjvO2 of the patients were comparable in both groups, however, GCS of the patients in the study group were significantly higher in the next 4 hospitalization days compared to the controls. Whereas, the SjvO2 of the patients were not significantly different between the groups during these days. Three-month mortality rate of the patients in the study group was significantly lower than the three-month mortality rate of the patients in the control groups (22.2% vs. 42.2%, p=0.042).

CONCLUSION

Administration of combined protocol of magnesium sulfide, progesterone and nimodipine may be safe and effective in patients suffering from severe TBI.

CLINICAL TRIAL REGISTRY

IRCT201210229534N2.

Is a combination of progesterone and chloroquine more effective than either alone in the treatment of cerebral ischemic injury?

BACKGROUND

In this proof-of-concept paper, we investigated whether combination treatment with progesterone (P4) and chloroquine (CQ) would reduce ischemic injury more effectively than either agent alone in a transient middle cerebral artery occlusion (tMCAO) model in male rats.

METHODS

P4 (8 mg/kg) and CQ (25 mg/kg) were given alone or in combination beginning at different times during surgery and for 3 days post-occlusion. Locomotor activity and grip strength were evaluated as measures of impairment and recovery. Infarct size was assessed by TTC staining. Markers of autophagy (LC3 and SQSTM1/p62) and apoptosis (Bcl-2 and Bax) were evaluated with western blotting.

RESULTS

At the doses we employed, the combination was not more effective than either drug given separately on measures of grip strength or locomotor activity. However, combination therapy substantially reduced infarct size, and significantly increased Bcl-2 protein levels and suppressed Bax expression. Progesterone decreased the expression of LC3-II 24 h and SQSTM1/p62 after ischemia.

CONCLUSIONS

Our findings suggest that combination therapy with P4 and CQ is not detrimental and has a small-to-moderate additive neuroprotective effect on ischemic injury in rats without substantively affecting behavioral outcomes. CQ and P4 may help to regulate the expression of both autophagy-related and apoptosis-related proteins.

The regulatory role of Toll-like receptors after ischemic stroke: neurosteroids as TLR modulators with the focus on TLR2/4

Ischemic stroke is the most common cerebrovascular disease and considered as a worldwide leading cause of death. After cerebral ischemia, different pathophysiological processes including neuroinflammation, invasion and aggregation of inflammatory cells and up-regulation of cytokines occur simultaneously. In this respect, Toll-like receptors (TLRs) are the first identified important mediators for the activation of the innate immune system and are widely expressed in glial cells and neurons following brain trauma. TLRs are also able to interact with endogenous and exogenous molecules released during ischemia and can increase tissue damage. Particularly, TLR2 and TLR4 activate different downstream inflammatory signaling pathways. In addition, TLR signaling can alternatively play a role for endogenous neuroprotection. In this review, the gene and protein structures, common genetic polymorphisms of TLR2 and TLR4, TLR-related molecular pathways and their putative role after ischemic stroke are delineated. Furthermore, the relationship between neurosteroids and TLRs as neuroprotective mechanism is highlighted in the context of brain ischemia.

High-fructose diet during adolescent development increases neuroinflammation and depressive-like behavior without exacerbating outcomes after stroke

Diseases, disorders, and insults of aging are frequently studied in otherwise healthy animal models despite rampant co-morbidities and exposures among the human population. Stressor exposures can increase neuroinflammation and augment the inflammatory response following a challenge. The impact of dietary exposure on baseline neural function and behavior has gained attention; in particular, a diet high in fructose can increase activation of the hypothalamic-pituitary-adrenal axis and alter behavior. The current study considers the implications of a diet high in fructose for neuroinflammation and outcomes following the cerebrovascular challenge of stroke. Ischemic injury may come as a "second hit" to pre-existing metabolic pathology, exacerbating inflammatory and behavioral sequelae. This study assesses the neuroinflammatory consequences of a peri-adolescent high-fructose diet model and assesses the impact of diet-induced metabolic dysfunction on behavioral and neuropathological outcomes after middle cerebral artery occlusion. We demonstrate that consumption of a high-fructose diet initiated during adolescent development increases brain complement expression, elevates plasma TNFα and serum corticosterone, and promotes depressive-like behavior. Despite these adverse effects of diet exposure, peri-adolescent fructose consumption did not exacerbate neurological behaviors or lesion volume after middle cerebral artery occlusion.

Let-7i inhibition enhances progesterone-induced functional recovery in a mouse model of ischemia

Progesterone (P4) is a potent neuroprotectant and a promising therapeutic for stroke treatment. However, the underlying mechanism(s) remain unclear. Our laboratory recently reported that brain-derived neurotrophic factor (BDNF) is a critical mediator of P4's protective actions and that P4-induced BDNF release from cortical astrocytes is mediated by a membrane-associated progesterone receptor, Pgrmc1. Here, we report that the microRNA (miRNA) let-7i is a negative regulator of Pgrmc1 and BDNF in glia and that let-7i disrupts P4-induced BDNF release and P4's beneficial effects on cell viability and markers of synaptogenesis. Using an in vivo model of ischemia, we demonstrate that inhibiting let-7i enhances P4-induced neuroprotection and facilitates functional recovery following stroke. The discovery of such factors that regulate the cytoprotective effects of P4 may lead to the development of biomarkers to differentiate/predict those likely to respond favorably to P4 versus those that do not.

Glibenclamide Enhances the Therapeutic Benefits of Early Hypothermia after Severe Stroke in Rats

Glibenclamide (GBC) is an antidiabetic drug that is in a class of medications known as sulfonylureas, which play critical roles in attenuating brain edema and reducing mortality in ischemic stroke patients. Therapeutic hypothermia (TH) is another robust neuroprotectant that prevents brain swelling and improves the neurological outcomes of stroke patients. However, whether the combination of GBC and TH can be used as a reliable neuroprotectant in ischemic stroke remains largely unknown. We used the middle cerebral artery occlusion (MCAO) rat model as well as oxygen and glucose deprivation-reoxygenation (OGD/R) endothelial cells as ischemic stroke models to investigate the efficacy and mechanisms of treating ischemic stroke with the combination of GBC and TH. The serum glucose, mortality rate, neurobehavioral functions, tight junctions, endothelial cells and inflammatory cytokines were evaluated in the stroke models after treatment with GBC, TH or the combination of them. After 5-hour occlusion and subsequent reperfusion, rats exhibited a large volume of hemispheric swelling and a high mortality rate. Stroke rats treated with the combined therapy did not exhibit hypoglycemia. The combination of GBC and TH exhibited synergistic neuroprotective effects in stroke rats that were associated with greater reductions in edema volume, better improvement in neurobehavioral functions, prevention of tight junction loss, and reduction of expression of the inflammatory cytokines COX-2 and iNOS. In OGD/R endothelia cells, the combination reduced endothelial cell death. This study demonstrated that both GBC and TH are neuroprotective after the severe stroke; however, combined therapy with GBC and TH enhanced the efficiency and efficacy of the effects of TH and GBC in the treatment of ischemia. This combined therapy may facilitate the clinical translation of TH management for severe stroke. The combination of GBC and TH seems to be a feasible and promising clinical strategy to alleviate cerebral injury following severe stroke.

ERK 1/2 Activation Mediates the Neuroprotective Effect of BpV(pic) in Focal Cerebral Ischemia-Reperfusion Injury

Bisperoxovanadium (pyridine-2-carboxyl) [bpV(pic)] is a commercially available PTEN inhibitor. Previous studies from us and others have shown that bpV(pic) confers neuroprotection in cerebral ischemia injury. We set up to determine whether ERK 1/2 activation plays a role in bpV(pic)-induced neuroprotective effect in cerebral ischemia injury. We found that the phosphorylation levels of Akt (p-AKT) and ERK1/2 (p-ERK 1/2) were down-regulated after cerebral ischemia–reperfusion injury. The injection of bpV(pic) after injury not only increased the level of p-AKT but also the level of p-ERK 1/2. While the inhibition of PTEN mediated the up-regulatation of p-AKT and p-ERK 1/2 by bpV(pic). Interestingly, the ERK 1/2 activation induced by bpV(pic) was also independent of the inhibition of PTEN. Our results indicate that bpV(pic) protects against OGD-induced neuronal death and promotes the functional recovery of stroke animals through PTEN inhibition and ERK 1/2 activation, respectively. This study suggests that the effect of bpV(pic) on ERK 1/2 signaling should be considered while using bpV(pic) as a PTEN inhibitor.

Swimming improves cognitive reserve in ovariectomized rats and enhances neuroprotection after global cerebral ischemia

Cognitive reserve has been proposed to account for different responses to brain damage or pathology. Factors implicated to influence cognitive reserve include cognitive engagement, physical activity, leisure activities, stress levels, and diet. Furthermore, long-term ovariectomy (OVX), such as occurs in women that have underwent surgical menopause, has been reported to increase the risk of cognitive impairment. In the current study, we examined whether swimming improves cognitive function in long-term OVX-rats. We also examined the neuroprotective effect of swimming after global cerebral ischemia (GCI) and explored the effect of swimming preconditioning on activation of the MAPK cascade signaling pathway, synaptic proteins and brain-derived growth factor (BDNF) - all factors implicated in regulating synaptic plasticity and neuroprotection in the brain. Adult Sprague-Dawley OVX-rats were randomly assigned into four groups: Sham (Sh), Sham + Swimming (Sh + Sw), Ischemia/Reperfusion (IR) and IR + Sw. Our results revealed that (1) Morris water maze and shuttle box test analysis revealed that swimming improved cognitive function in OVX-rats, (2) The levels of PSD95 and synaptophysin, as well as the protein expression of p-ERK, p-CREB and BDNF were all increased in the hippocampus after swimming with or without GCI, and (3) Swimming also increased the number of surviving neurons and IL4 protein expression, while decreasing the Iba1 (a microglia marker) level in the hippocampus. In conclusion, our study demonstrates that swimming improves memory in OVX-rats, and that swimming preconditioning enhances the neuroprotective ERK1/2/CREB/BDNF pathway signaling and ameliorates brain damage after GCI in OVX-rats, which may be closely related to induction of an IL4-mediated anti-inflammatory mechanism.

Lipoic Acid and Progesterone Alone or in Combination Ameliorate Retinal Degeneration in an Experimental Model of Hereditary Retinal Degeneration

Retinitis pigmentosa (RP) is a group of inherited retinopathies characterized by photoreceptors death. Our group has shown the positive progesterone (P4) actions on cell death progression in an experimental model of RP. In an effort to enhance the beneficial effects of P4, the aim of this study was to combine P4 treatment with an antioxidant [lipoic acid (LA)] in the rd1 mice. rd1 and control mice were treated with 100 mg/kg body weight of P4, LA, or a combination of both on postnatal day 7 (PN7), 9, and 11, and were sacrificed at PN11. The administration of LA and/or P4 diminishes cell death in rd1 retinas. The effect obtained after the combined administration of LA and P4 is higher than the one obtained with LA or P4 alone. The three treatments decreased GFAP staining, however, in the far peripheral retina, and the two treatments that offered better results were LA and LA plus P4. LA or LA plus P4 increased retinal glutathione (GSH) concentration in the rd1 mice. Although LA and P4 are able to protect photoreceptors from death in rd1 mice retinas, a better effectiveness is achieved when administering LA and P4 at the same time.

Repurposing and repositioning neurosteroids in the treatment of traumatic brain injury: A report from the trenches

The field of neuroprotection after brain injuries has been littered with failed clinical trials. Finding a safe and effective treatment for acute traumatic brain injury remains a serious unmet medical need. Repurposing drugs that have been in use for other disorders is receiving increasing attention as a strategy to move candidate drugs more quickly to trial while reducing the very high cost of new drug development. This paper describes our own serendipitous discovery of progesterone's neuroprotective potential, and the strategies we are using in repurposing and developing this hormone for use in brain injuries-applications very different from its classical uses in treating disorders of the reproductive system. We have been screening and testing a novel analog that maintains progesterone's therapeutic properties while overcoming its physiochemical challenges, and testing progesterone in combination treatment with another pleiotropic hormone, vitamin D. Finally, our paper, in the context of the problems and pitfalls we have encountered, surveys some of the factors we found to be critical in the clinical translation of repurposed drugs. This article is part of the Special Issue entitled 'Drug Repurposing: old molecules, new ways to fast track drug discovery and development for CNS disorders'.

Combination Therapy for Multi-Target Manipulation of Secondary Brain Injury Mechanisms

Traumatic brain injury (TBI) is a major healthcare problem that affects millions of people worldwide. Despite advances in understanding and developing preventative and treatment strategies using preclinical animal models, clinical trials to date have failed, and a 'magic bullet' for effectively treating TBI-induced damage does not exist. Thus, novel pharmacological strategies to effectively manipulate the complex and heterogeneous pathophysiology of secondary injury mechanisms are needed. Given that goal, this paper discusses the relevance and advantages of combination therapies (COMTs) for 'multi-target manipulation' of the secondary injury cascade by administering multiple drugs to achieve an optimal therapeutic window of opportunity (e.g., temporally broad window) and compares these regimens to monotherapies that manipulate a single target with a single drug at a given time. Furthermore, we posit that integrated mechanistic multiscale models that combine primary injury biomechanics, secondary injury mechanobiology/neurobiology, physiology, pharmacology and mathematical programming techniques could account for vast differences in the biological space and time scales and help to accelerate drug development, to optimize pharmacological COMT protocols and to improve treatment outcomes.

Progesterone improves neurocognitive outcomes following therapeutic cranial irradiation in mice

Despite improved therapeutic methods, CNS toxicity resulting from cancer treatment remains a major cause of post-treatment morbidity. More than half of adult patients with cranial irradiation for brain cancer develop neurobehavioral/cognitive deficits that severely impact quality of life. We examined the neuroprotective effects of the neurosteroid progesterone (PROG) against ionizing radiation (IR)-induced neurobehavioral/cognitive deficits in mice. Male C57/BL mice were exposed to one of two fractionated dose regimens of IR (3Gy×3 or 3Gy×5). PROG (16mg/kg; 0.16mg/g) was given as a pre-, concurrent or post-IR treatment for 14days. Mice were tested for short- and long-term effects of IR and PROG on neurobehavioral/cognitive function on days 10 and 30 after IR treatment. We evaluated both hippocampus-dependent and -independent memory functions. Locomotor activity, elevated plus maze, novel object recognition and Morris water maze tests revealed behavioral deficits following IR. PROG treatment produced improvement in behavioral performance at both time points in the mice given IR. Western blot analysis of hippocampal and cortical tissue showed that IR at both doses induced astrocytic activation (glial fibrillary acidic protein), reactive macrophages/microglia (CD68) and apoptosis (cleaved caspase-3) and PROG treatment inhibited these markers of brain injury. There was no significant difference in the degree of deficit in any test between the two dose regimens of IR at either time point. These findings could be important in the context of patients with brain tumors who may undergo radiotherapy and eventually develop cognitive deficits.

Stress primes microglial polarization after global ischemia: Therapeutic potential of progesterone

Despite the fact that stress is associated with increased risk of stroke and worsened outcome, most preclinical studies have ignored this comorbid factor, especially in the context of testing neuroprotective treatments. Preclinical research suggests that stress primes microglia, resulting in an enhanced reactivity to a subsequent insult and potentially increasing vulnerability to stroke. Ischemia-induced activated microglia can be polarized into a harmful phenotype, M1, which produces pro-inflammatory cytokines, or a protective phenotype, M2, which releases anti-inflammatory cytokines and neurotrophic factors. Selective modulation of microglial polarization by inhibiting M1 or stimulating M2 may be a potential therapeutic strategy for treating cerebral ischemia. Our laboratory and others have shown progesterone to be neuroprotective against ischemic stroke in rodents, but it is not known whether it will be as effective under a comorbid condition of chronic stress. Here we evaluated the neuroprotective effect of progesterone on the inflammatory response in the hippocampus after exposure to stress followed by global ischemia. We focused on the effects of microglial M1/M2 polarization and pro- and anti-inflammatory mediators in stressed ischemic animals. Male Sprague-Dawley rats were exposed to 8 consecutive days of social defeat stress and then subjected to global ischemia or sham surgery. The rats received intraperitoneal injections of progesterone (8mg/kg) or vehicle at 2h post-ischemia followed by subcutaneous injections at 6h and once every 24h post-injury for 7days. The animals were killed at 7 and 14days post-ischemia, and brains were removed and processed to assess outcome measures using histological, immunohistochemical and molecular biology techniques. Pre-ischemic stress (1) exacerbated neuronal loss and neurodegeneration as well as microglial activation in the selectively vulnerable CA1 hippocampal region, (2) dysregulated microglial polarization, leading to upregulation of both M1 and M2 phenotype markers, (3) increased pro-inflammatory cytokine expression, and (4) reduced anti-inflammatory cytokine and neurotrophic factor expression in the ischemic hippocampus. Treatment with progesterone significantly attenuated stress-induced microglia priming by modulating polarized microglia and the inflammatory environment in the hippocampus, the area most vulnerable to ischemic injury. Our findings can be taken to suggest that progesterone holds potential as a candidate for clinical testing in ischemic stroke where high stress may be a contributing factor.

Early oxygen therapy does not protect the brain from vasogenic edema following acute ischemic stroke in adult male rats

Brain edema aggravates primary brain injury and increases its mortality rate after ischemic stroke. It is believed that normobaric oxygen therapy (NBO) may produce neuroprotective effects against ischemic stroke; however, reports have been controversial, and its effects on vasogenic brain edema as a major complication of brain ischemia have not been clarified. The present study investigates the effects of NBO on cerebral edema and blood – brain barrier integrity using rat model of ischemic stroke. Transient focal cerebral ischemia was induced in adult male Sprague-Dawley rats by left middle cerebral artery occlusion (MCAO) for 90 min followed by 24 h reperfusion. Early NBO supplementation was started 15 min after MCAO and continued for 90 min. The results of the present study show that early oxygen therapy following acute ischemic stroke does not reduce vasogenic brain edema, nor does it protect against oxidative stress-induced BBB destruction. Additionally, cerebral edema formation occurs in conjunction with an increased mortality rate, serious brain injury, and impairment of brain antioxidant power. These findings suggest that further experimental studies should be carried out to clarify the beneficial effects and potential side effects of early oxygen therapy in acute ischemic stroke before its clinical use.

Bisperoxovandium (pyridin-2-squaramide) targets both PTEN and ERK1/2 to confer neuroprotection

BACKGROUND AND PURPOSE

We and others have shown that inhibiting phosphatase and tensin homolog deleted on chromosome 10 (PTEN) or activating ERK1/2 confer neuroprotection. As bisperoxovanadium compounds are well-established inhibitors of PTEN, we designed bisperoxovandium (pyridin-2-squaramide) [bpV(pis)] and determined whether and how bpV(pis) exerts a neuroprotective effect in cerebral ischaemia-reperfusion injury.

EXPERIMENTAL APPROACH

Malachite green-based phosphatase assay was used to measure PTEN activity. A western blot assay was used to measure the phosphorylation level of Akt and ERK1/2 (p-Akt and p-ERK1/2). Oxygen-glucose deprivation (OGD) was used to injure cultured cortical neurons. Cell death and viability were assessed by LDH and MTT assays. To verify the effects of bpV(pis) in vivo, Sprague-Dawley rats were subjected to middle cerebral artery occlusion, and brain infarct volume was measured and neurological function tests performed.

KEY RESULTS

bpV(pis) inhibited PTEN activity and increased p-Akt in SH-SY5Y cells but not in PTEN-deleted U251 cells. bpV(pis) also elevated p-ERK1/2 in both SH-SY5Y and U251 cells. These data indicate that bpV(pis) enhances Akt activation through PTEN inhibition but increases ERK1/2 activation independently of PTEN signalling. bpV(pis) prevented OGD-induced neuronal death in vitro and reduced brain infarct volume and promoted functional recovery in stroke animals. This neuroprotective effect of bpV(pis) was blocked by inhibiting Akt and/or ERK1/2.

CONCLUSIONS AND IMPLICATIONS

bpV(pis) confers neuroprotection in OGD-induced injury in vitro and in cerebral ischaemia in vivo by suppressing PTEN and activating ERK1/2. Thus, bpV(pis) is a bi-target neuroprotectant that may be developed as a drug candidate for stroke treatment.

Treatment Perspectives Based on Our Current Understanding of Concussion

Sports-related concussion also referred to in the literature as mild traumatic brain injury remains a popular area of study for physicians, neurologists, neuropsychologists, neuroimaging, athletic trainers, and researchers across the other areas of brain sciences. Treatment for concussion is an emerging area of focus with investigators seeking to improve outcomes and protect patients from the deleterious short-term and long-term consequences which have been extensively studied and identified. Broadly, current treatment strategies for athletes recovering from concussion have remained largely unchanged since early 2000s. Knowledge of the complex pathophysiology surrounding injury should improve or advance our ability to identify processes which may serve as targets for therapeutic intervention. Clinicians working with athletes recovering from sports-related concussion should have an advanced understanding of the injury cascade and also be aware of the current efforts within the research to treat concussion. In addition, how clinicians use the word "treatment" should be carefully defined and promoted so the patient is aware of the level of intervention and what stage of recovery or healing is being affected by a specific intervention. The purpose of this review is to bring together efforts across disciplines of brain science into 1 platform where clinicians can assimilate this information before making best practices decisions regarding the treatment of patients and athletes under their care.

Neuroprotection by progesterone after transient cerebral ischemia in stroke-prone spontaneously hypertensive rats

We investigated the neuroprotective effects of progesterone (P4) treatment in stroke-prone spontaneously hypertensive rats (SHRSPs) given 60-min transient middle cerebral artery occlusion (tMCAO). The treatment groups were: (1) Wistar-Kyoto (normotensive sham), (2) SHRSP (hypertensive sham), (3) tMCAO SHRSPs (SHRSP+tMCAO), and (4) SHRSP+tMCAO+P4. P4 (8mg/kg) was administered 1h after occlusion and then daily for 14days. We measured cerebral infarction volume, blood pressure and body weight. Behavioral outcomes were analyzed at post-stroke days 3, 9, and 14. To assess morphological protection we measured activation of microglia and astrocytes, oxidative stress, apoptosis, expression of vascular endothelial growth factor (VEGF), an angiogenic marker, and IL-1β, a marker of inflammation, on day 14 post-stroke. There was no effect of P4 on body weight or systolic blood pressure compared to the SHRSP+tMCAO group. However, grip strength and sensory neglect measures in the P4 group were improved compared to SHRSP+tMCAO. In addition, significantly larger infarct volumes were seen in the SHRSP+tMCAO group compared to SHRSP+tMCAO+P4. Increased markers of the injury cascade such as macrophages, activated astrocytes, superoxide anion and apoptotic cells observed in the SHRSP+tMCAO group were significantly decreased by P4. We conclude that, despite hypertensive comorbidity, P4 improves functional outcomes and attenuates stroke infarct in hypertensive rats by reducing superoxide anion expression and by decreasing inflammation and neuronal apoptosis.

Progesterone neuroprotection: The background of clinical trial failure

Since the first pioneering studies in the 1990s, a large number of experimental animal studies have demonstrated the neuroprotective efficacy of progesterone for brain disorders, including traumatic brain injury (TBI). In addition, this steroid has major assets: it easily crosses the blood-brain-barrier, rapidly diffuses throughout the brain and exerts multiple beneficial effects by acting on many molecular and cellular targets. Moreover, progesterone therapies are well tolerated. Notably, increased brain levels of progesterone are part of endogenous neuroprotective responses to injury. The hormone thus emerged as a particularly promising protective candidate for TBI and stroke patients. The positive outcomes of small Phase 2 trials aimed at testing the safety and potential protective efficacy of progesterone in TBI patients then provided support and guidance for two large, multicenter, randomized and placebo-controlled Phase 3 trials, with more than 2000 TBI patients enrolled. The negative outcomes of both trials, named ProTECT III and SyNAPSE, came as a big disappointment. If these trials were successful, progesterone would have become the first efficient neuroprotective drug for brain-injured patients. Thus, progesterone has joined the numerous neuroprotective candidates that have failed in clinical trials. The aim of this review is a reappraisal of the preclinical animal studies, which provided the proof of concept for the clinical trials, and we critically examine the design of the clinical studies. We made efforts to present a balanced view of the strengths and limitations of the translational studies and of some serious issues with the clinical trials. We place particular emphasis on the translational value of animal studies and the relevance of TBI biomarkers. The probability of failure of ProTECT III and SyNAPSE was very high, and we present them within the broader context of other unsuccessful trials.

Vitamins and nutrients as primary treatments in experimental brain injury: Clinical implications for nutraceutical therapies

With the numerous failures of pharmaceuticals to treat traumatic brain injury in humans, more researchers have become interested in combination therapies. This is largely due to the multimodal nature of damage from injury, which causes excitotoxicity, oxidative stress, edema, neuroinflammation and cell death. Polydrug treatments have the potential to target multiple aspects of the secondary injury cascade, while many previous therapies focused on one particular aspect. Of specific note are vitamins, minerals and nutrients that can be utilized to supplement other therapies. Many of these have low toxicity, are already FDA approved and have minimal interactions with other drugs, making them attractive targets for therapeutics. Over the past 20 years, interest in supplementation and supraphysiologic dosing of nutrients for brain injury has increased and indeed many vitamins and nutrients now have a considerable body of the literature backing their use. Here, we review several of the prominent therapies in the category of nutraceutical treatment for brain injury in experimental models, including vitamins (B2, B3, B6, B9, C, D, E), herbs and traditional medicines (ginseng, Gingko biloba), flavonoids, and other nutrients (magnesium, zinc, carnitine, omega-3 fatty acids). While there is still much work to be done, several of these have strong potential for clinical therapies, particularly with regard to polydrug regimens. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Growth factor therapy sequesters inflammation in affording neuroprotection in cerebrovascular diseases

INTRODUCTION

In recent years, accumulating evidence has demonstrated the key role of inflammation in the progression of cerebrovascular diseases. Inflammation can persist over prolonged period of time after the initial insult providing a wider therapeutic window. Despite the acute endogenous upregulation of many growth factors after the injury, it is not sufficient to protect against inflammation and to regenerate the brain. Therapeutic approaches targeting both dampening inflammation and enhancing growth factors are likely to provide beneficial outcomes in cerebrovascular disease.

AREAS COVERED

In this mini review, we discuss major growth factors and their beneficial properties to combat the inflammation in cerebrovascular diseases. Emerging biotechnologies which facilitate the therapeutic effects of growth factors are also presented in an effort to provide insights into the future combination therapies incorporating both central and peripheral abrogation of inflammation. Expert commentary: Many studies discussed in this review have demonstrated the therapeutic effects of growth factors in treating cerebrovascular diseases. It is unlikely that one growth factor can be used to treat these complex diseases. Combination of growth factors and anti-inflammatory modulators may clinically improve outcomes for patients. In particular, transplantation of stem cells may be able to achieve both goals of modulating inflammation and upregulating growth factors. Large preclinical studies and multiple laboratory collaborations are needed to advance these findings from bench to bedside.

Pgrmc1/BDNF Signaling Plays a Critical Role in Mediating Glia-Neuron Cross Talk

Progesterone (P4) exerts robust cytoprotection in brain slice cultures (containing both neurons and glia), yet such protection is not as evident in neuron-enriched cultures, suggesting that glia may play an indispensable role in P4's neuroprotection. We previously reported that a membrane-associated P4 receptor, P4 receptor membrane component 1, mediates P4-induced brain-derived neurotrophic factor (BDNF) release from glia. Here, we sought to determine whether glia are required for P4's neuroprotection and whether glia's roles are mediated, at least partially, via releasing soluble factors to act on neighboring neurons. Our data demonstrate that P4 increased the level of mature BDNF (neuroprotective) while decreasing pro-BDNF (potentially neurotoxic) in the conditioned media (CMs) of cultured C6 astrocytes. We examined the effects of CMs derived from P4-treated astrocytes (P4-CMs) on 2 neuronal models: 1) all-trans retinoid acid-differentiated SH-SY5Y cells and 2) mouse primary hippocampal neurons. P4-CM increased synaptic marker expression and promoted neuronal survival against H2O2. These effects were attenuated by Y1036 (an inhibitor of neurotrophin receptor [tropomysin-related kinase] signaling), as well as tropomysin-related kinase B-IgG (a more specific inhibitor to block BDNF signaling), which pointed to BDNF as the key protective component within P4-CM. These findings suggest that P4 may exert its maximal protection by triggering a glia-neuron cross talk, in which P4 promotes mature BDNF release from glia to enhance synaptogenesis as well as survival of neurons. This recognition of the importance of glia in mediating P4's neuroprotection may also inform the design of effective therapeutic methods for treating diseases wherein neuronal death and/or synaptic deficits are noted.

Progesterone in the treatment of neonatal arterial ischemic stroke and acute seizures: Role of BDNF/TrkB signaling

Neonatal stroke is among the top ten causes of childhood death and permanent disability in survivors, but no safe and effective acute treatments exist. To advance understanding of its neuroprotective mechanisms, we examined the effects of progesterone (PROG) on local and systemic inflammation (IL-1β, IL-6, TNFα), brain derived neurotrophic factor/Tropomyosin receptor kinase B (BDNF/TrkB) signaling, vascular damage (vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9)), acute behavioral seizures and brain infarction size following neonatal arterial ischemic stroke in mice. CD1 mouse pups (postnatal day 12, mixed gender) received permanent unilateral right common carotid ligation (pUCCL) or sham surgery. Pups showing seizure activity during the first hour post-pUCCL were randomly assigned to receive PROG (8 mg/kg) or vehicle injections. PROG treatment significantly (p < 0.05) reduced seizure occurrence by ∼44% compared to vehicle and attenuated the expression of pro-inflammatory cytokines in serum and brain at different time-points. PROG differentially regulated the expression of BDNF and TrkB and the activity of VEGF and MMP-9 over the 7d period. Permanent UCCL resulted in severe hemispheric damage measured at 7 days post-pUCCL but PROG treatment produced a significant (p < 0.05) reduction in infarct volume (∼70%) compared to vehicle. A gender-based comparison of data revealed significantly greater seizure activity in males compared to females. However, we did not observe significant sex differences on any other markers of the injury at this early stage of development. PROG treatment is neuroprotective through a number of signaling pathways and can be beneficial in treating neonatal arterial ischemic stroke in CD1 mice.