The effect of eliprodil on the evolution of a focal cerebral ischaemia in vivo

A Preclinical Systematic Review and Meta-Analysis of Behavior Testing in Mice Models of Ischemic Stroke

Stroke remains one of the most important causes of death and disability. Preclinical research is a powerful tool for understanding the molecular and cellular response to stroke. However, a lack of standardization in animal evaluation does not always ensure reproducible results. In the present study, we wanted to identify the best strategy for evaluating animal behavior post-experimental stroke. As such, a meta-analysis was made, evaluating behavioral tests done on male C57BL/6 mice subjected to stroke or sham surgery. Overall, fifty-six studies were included. Our results suggest that different types of tests should be used depending on the post-stroke period one needs to analyze. In the hyper-acute, post-stroke period, the best quantifier will be animal examination scoring, as it is a fast and inexpensive way to identify differences between groups. When evaluating stoke mice in the acute phase, a mix of animal examination and motor tests that focus on movement asymmetry (foot-fault and cylinder testing) seem to have the best chance of picking up differences between groups. Complex tasks (the rotarod test and Morris water maze) should be used within the chronic phase to evaluate differences between the late-subacute and chronic phases.

Pre-clinical to Clinical Translational Failures and Current Status of Clinical Trials in Stroke Therapy: A Brief Review

In stroke (cerebral ischemia), despite continuous efforts both at the experimental and clinical level, the only approved pharmacological treatment has been restricted to tissue plasminogen activator (tPA). Stroke is the leading cause of functional disability and mortality throughout worldwide. Its pathophysiology starts with energy pump failure, followed by complex signaling cascade that ultimately ends in neuronal cell death. Ischemic cascade involves excessive glutamate release followed by raised intracellular sodium and calcium influx along with free radicals' generation, activation of inflammatory cytokines, NO synthases, lipases, endonucleases and other apoptotic pathways leading to cell edema and death. At the pre-clinical stage, several agents have been tried and proven as an effective neuroprotectant in animal models of ischemia. However, these agents failed to show convincing results in terms of efficacy and safety when the trials were conducted in humans following stroke. This article highlights the various agents which have been tried in the past but failed to translate into stroke therapy along with key points that are responsible for the lagging of experimental success to translational failure in stroke treatment.

Small molecule inhibitors in the treatment of cerebral ischemia

INTRODUCTION

Stroke is the world's second leading cause of death. Although recombinant tissue plasminogen activator is an effective treatment for cerebral ischemia, its limitations and ischemic stroke's complex pathophysiology dictate an increased need for the development of new therapeutic interventions. Small molecule inhibitors (SMIs) have the potential to be used as novel therapeutic modalities for stroke, since many preclinical and clinical trials have established their neuroprotective capabilities.

AREAS COVERED

This paper provides a summary of the pathophysiology of stroke as well as clinical and preclinical evaluations of SMIs as therapeutic interventions for cerebral ischemia. Cerebral ischemia is broken down into four mechanisms in this article: thrombosis, ischemic insult, mitochondrial injury and immune response. Insight is provided into preclinical and current clinical assessments of SMIs targeting each mechanism as well as a summary of reported results.

EXPERT OPINION

Many studies demonstrated that pre- or post-treatment with certain SMIs significantly ameliorated adverse effects from stroke. Although some of these promising SMIs moved on to clinical trials, they generally failed, possibly due to the poor translation of preclinical to clinical experiments. Yet, there are many steps being taken to improve the quality of experimental research and translation to clinical trials.

NMDA receptor antagonists and glycine site NMDA antagonists

Extracellular concentrations of excitatory amino acids increase substantially within cerebral tissue beds exposed to ischaemic conditions. This leads to excessive stimulation of N-methyl-D-aspartate (NMDA) receptors, a major cerebral excitatory neurotransmitter receptor that likely plays a critical role in the propagation of ischaemic injury in neurons. Pharmacological blockade of these receptors has proven to be an effective neuroprotective therapy by a number of animal models of central nervous system ischaemia. Clinical trials of these drugs were begun with high expectations for successful therapy of human stroke. These putative neuroprotective drugs included competitive or non-competitive inhibitors of the NMDA receptor itself, as well as inhibitors of a co-modulatory glycine site. Thus far, all clinical trials of NMDA antagonists have been unsuccessful in establishing benefit for human stroke.

Nuclear factor-kappa B activation in permanent intraluminal focal cerebral ischemia in the rat

Nuclear factor-kappa B (NF-kappa B) is an oxidative stress responsive transcription factor known to be activated in response to transient middle cerebral artery intraluminal occlusion. Since oxidative stress activation may largely occur during reperfusion, the aim of this study was to determine if permanent middle cerebral artery intraluminal occlusion without reperfusion induces NF-kappa B activation and the relationship of NF-kappa B activation to HSP70 expression and neuronal cell death. Our results suggest that permanent intraluminal occlusion is sufficient to induce NF-kappa B activation 7 h after the onset of occlusion. Interestingly, this activation seems to occur specifically in dying neurons of the penumbra area devoid of any HSP70 neuronal immunoreactivity. These findings are consistent with the suggested protective role of HSP70 expression and suggest that NF-kappa B activation observed in the penumbra area has a role in neuronal cell death after permanent intraluminal cerebral ischemia.