Systemic hyperthermia masks the neuroprotective effects of MK-801, but not rosiglitazone in brain ischaemia

Targeting Caveolin-1 and Claudin-5 with AY9944, Improve Blood-Brain Barrier Permeability; Computational Simulation and Experimental Study

The current study aimed to determine the protective effect of AY9944 related to Caveolin-1 and Claudin-5 role in lipid raft, which can rescue the blood-brain barrier from enhanced permeability. Therefore, in vivo analyses were performed following ischemia in normal, ischemic, and AY9944-treated animal groups. The results revealed that AY9944 reduced the infarct size, edema, and brain water content. The extravasation of Alb-Alexa 594 and biocytin-TMR was minimum in the AY9944-treated animals. The results showed a significant decrease in the expression level of Caveolin-1 over 8 h and 48 h and a remarkable increase in the level of Claudin-5 over 48 h following ischemia in AY9944-treated animals. Molecular docking simulation demonstrated that AY9944 exerts a possible protective role via attenuating the interaction of the Caveolin-1 and cholesterol in lipid raft. These findings point out that AY9944 plays a protective role in stroke by means of blood-brain barrier preservation. Proper neural function essentially needs a constant homeostatic brain environment which is provided by the blood-brain barrier. Rescuing blood-brain barrier from enhanced permeability via inducing the protective effect of AY9944 related to caveolin-1 and claudin-5 role in lipid raft was the aim of the current study.

MK-801 attenuates lesion expansion following acute brain injury in rats: a meta-analysis

OBJECTIVE:

To evaluate the efficacy and safety of MK-801 and its effect on lesion volume in rat models of acute brain injury.

DATA SOURCES:

Key terms were “stroke”, “brain diseases”, “brain injuries”, “brain hemorrhage, traumatic”, “acute brain injury”, “dizocilpine maleate”, “dizocilpine”, “MK-801”, “MK801”, “rat”, “rats”, “rattus” and “murine”. PubMed, Cochrane library, EMBASE, the China National Knowledge Infrastructure, WanFang database, the VIP Journal Integration Platform (VJIP) and SinoMed databases were searched from their inception dates to March 2018.

DATA SELECTION:

Studies were selected if they reported the effects of MK-801 in experimental acute brain injury. Two investigators independently conducted literature screening, data extraction, and methodological quality assessments.

OUTCOME MEASURES:

The primary outcomes included lesion volume and brain edema. The secondary outcomes included behavioral assessments with the Bederson neurological grading system and the water maze test 24 hours after brain injury.

RESULTS:

A total of 52 studies with 2530 samples were included in the systematic review. Seventeen of these studies had a high methodological quality. Overall, the lesion volume (34 studies, n = 966, MD = −58.31, 95% CI: −66.55 to −50.07; P < 0.00001) and degree of cerebral edema (5 studies, n = 75, MD = −1.21, 95% CI: −1.50 to −0.91; P < 0.00001) were significantly decreased in the MK-801 group compared with the control group. MK-801 improved spatial cognition assessed with the water maze test (2 studies, n = 60, MD = −10.88, 95% CI: −20.75 to −1.00; P = 0.03) and neurological function 24 hours after brain injury (11 studies, n = 335, MD = −1.04, 95% CI: −1.47 to −0.60; P < 0.00001). Subgroup analysis suggested an association of reduction in lesion volume with various injury models (34 studies, n = 966, MD = −58.31, 95% CI: −66.55 to −50.07; P = 0.004). Further network analysis showed that 0–1 mg/kg MK-801 may be the optimal dose for treatment in the middle cerebral artery occlusion animal model.

CONCLUSION:

MK-801 effectively reduces brain lesion volume and the degree of cerebral edema in rat models of experimental acute brain injury, providing a good neuroprotective effect. Additionally, MK-801 has a good safety profile, and its mechanism of action is well known. Thus, MK-801 may be suitable for future clinical trials and applications.

Fever worsens outcomes in animal models of ischaemic stroke: A systematic review and meta-analysis

Background

Subfebrile temperatures and fever in the first days after stroke are associated with a greater risk of a poor outcome. If this relation is causal, prevention of hyperthermia may improve outcome. Causality can be tested in animal models. We therefore assessed the effects of hyperthermia on outcomes in animal models of ischaemic stroke and explored under which conditions prevention of hyperthermia could be most effective.

Methods

We performed a systematic review and meta-analysis of data from animal experiments testing the effect of spontaneous or induced hyperthermia on outcome after focal cerebral ischaemia. Our primary outcome measure was infarct size. Normalised mean differences were combined using the random effects model and stratified meta-analysis was used to explore the impact of study characteristics.

Results

We included 19 publications, reporting on 49 comparisons involving 603 animals. Overall, hyperthermia increased infarct size by 43.4% (95% confidence interval, 29.8-56.9%) and worsened neurobehavioral outcomes by 48.5% (17.2-79.8%). The increase in infarct size was larger with higher temperatures. Hyperthermia was most harmful if present for more than 2 h and when started at the time of artery occlusion rather than later.

Conclusion

Hyperthermia substantially increased infarct size in animal models of ischaemic stroke, suggesting that the relation between fever and poor outcome observed in patients is at least in part causal. These data provide support to trials testing the effect of the prevention of fever with antipyretic drugs in patients with acute stroke.

Targeting caspase-6 and caspase-8 to promote neuronal survival following ischemic stroke

Previous studies show that caspase-6 and caspase-8 are involved in neuronal apoptosis and regenerative failure after trauma of the adult central nervous system (CNS). In this study, we evaluated whether caspase-6 or -8 inhibitors can reduce cerebral or retinal injury after ischemia. Cerebral infarct volume, relative to appropriate controls, was significantly reduced in groups treated with caspase-6 or -8 inhibitors. Concomitantly, these treatments also reduced neurological deficits, reduced edema, increased cell proliferation, and increased neurofilament levels in the injured cerebrum. Caspase-6 and -8 inhibitors, or siRNAs, also increased retinal ganglion cell survival at 14 days after ischemic injury. Caspase-6 or -8 inhibition also decreased caspase-3, -6, and caspase-8 cleavage when assayed by western blot and reduced caspase-3 and -6 activities in colorimetric assays. We have shown that caspase-6 or caspase-8 inhibition decreases the neuropathological consequences of cerebral or retinal infarction, thereby emphasizing their importance in ischemic neuronal degeneration. As such, caspase-6 and -8 are potential targets for future therapies aimed at attenuating the devastating functional losses that result from retinal or cerebral stroke.

Rosiglitazone attenuates early brain injury after experimental subarachnoid hemorrhage in rats

Early brain injury (EBI) plays a crucial role in the pathological progress of subarachnoid hemorrhage (SAH). This study was designed to determine whether rosiglitazone protects the brain against EBI in rats, and discuss the role of the anti-apoptotic mechanism mediated by Bcl-2 family proteins in this neuroprotection. 86 male Sprague-Dawley rats were divided into the sham group, the SAH+ vehicle group and the SAH+ rosiglitazone group. SAH was induced via an endovascular perforation technique and rosiglitazone (3mg/kg) or vehicle was administered. Mortality, neurological scores, brain water content, Evans blue dye assay, TUNEL stain assay, Gelatin zymography, and western blot analysis were performed. Rosiglitazone significantly improved mortality, neurological scores, brain water content, blood brain barrier (BBB) and apoptosis compared with the vehicle group within 24h after SAH. The TUNEL staining assay demonstrated that apoptosis was ameliorated. Cleaved Caspase-3 and MMP-9 expression was reduced, whereas Bcl-2 and p-Bad was markedly preserved by rosiglitazone. A significant elevation of p-Akt was detected after rosiglitazone treatment. Our study demonstrated that rosiglitazone plays a neuroprotective role in EBI after SAH via attenuation of BBB disruption, brain edema and apoptosis.

Uncoupling Neogenin association with lipid rafts promotes neuronal survival and functional recovery after stroke

The dependence receptor Neogenin and its ligand, the repulsive guidance molecule a (RGMa), regulate apoptosis and axonal growth in the developing and the adult central nervous system (CNS). Here, we show that this pathway has also a critical role in neuronal death following stroke, and that providing RGMa to neurons blocks Neogenin-induced death. Interestingly, the Neogenin pro-death function following ischemic insult depends on Neogenin association with lipid rafts. Thus, a peptide that prevents Neogenin association with lipid rafts increased neuronal survival in several in vitro stroke models. In rats, a pro-survival effect was also observed in a model of ocular ischemia, as well as after middle cerebral artery occlusion (MCAO). Treatments that prevented Neogenin association with lipid rafts improved neuronal survival and the complexity of the neuronal network following occlusion of the middle artery. Toward the development of a treatment for stroke, we developed a human anti-RGMa antibody that also prevents Neogenin association with lipid rafts. We show that this antibody also protected CNS tissue from ischemic damage and that its application resulted in a significant functional improvement even when administrated 6 h after artery occlusion. Thus, our results draw attention to the role of Neogenin and lipid rafts as potential targets following stroke.

Method parameters' impact on mortality and variability in rat stroke experiments: a meta-analysis

Background

Even though more than 600 stroke treatments have been shown effective in preclinical studies, clinically proven treatment alternatives for cerebral infarction remain scarce. Amongst the reasons for the discrepancy may be methodological shortcomings, such as high mortality and outcome variability, in the preclinical studies. A common approach in animal stroke experiments is that A) focal cerebral ischemia is inflicted, B) some type of treatment is administered and C) the infarct sizes are assessed. However, within this paradigm, the researcher has to make numerous methodological decisions, including choosing rat strain and type of surgical procedure. Even though a few studies have attempted to address the questions experimentally, a lack of consensus regarding the optimal methodology remains.

Methods

We therefore meta-analyzed data from 502 control groups described in 346 articles to find out how rat strain, procedure for causing focal cerebral ischemia and the type of filament coating affected mortality and infarct size variability.

Results

The Wistar strain and intraluminal filament procedure using a silicone coated filament was found optimal in lowering infarct size variability. The direct and endothelin methods rendered lower mortality rate, whereas the embolus method increased it compared to the filament method.

Conclusions

The current article provides means for researchers to adjust their middle cerebral artery occlusion (MCAo) protocols to minimize infarct size variability and mortality.

Administration of thiazolidinediones for neuroprotection in ischemic stroke: a pre-clinical systematic review

Thiazolidinediones (TZDs) may prevent or attenuate CNS injury arising from an ischemic event. We performed meta-analysis of experimental studies in which a TZD (either rosiglitazone or pioglitazone) was administered in a rodent model of focal or global cerebral ischemia. Infarct volume was the primary endpoint for analysis of drug efficacy, and neurological outcome was also assessed. We identified 31 studies through the use of PubMed and Embase, 22 of which met our pre-specified inclusion criteria and were analyzed with the Cochrane Review Manager software. Treatment with TZDs decreased infarct volume and improved neurological outcome regardless of study quality, dose timing, or ischemia model (transient or permanent). Rosiglitazone and pioglitazone were similarly effective in reducing infarct volume and protecting neurologic function. Importantly, the collective data suggest that pre-treatment with a TZD is not required for neuroprotection, although additional studies are clearly needed to define the breadth of the therapeutic window. The data warrant further studies into the potential acute use of TZDs for ischemic stroke therapy in the general population.