Acute Ethanol Effects on Focal Cerebral Ischemia in Nonfasted Rats

Hyperglycaemia and infarct size in animal models of middle cerebral artery occlusion: systematic review and meta-analysis

Poststroke hyperglycaemia (PSH) is common, has an unclear pathophysiology, and is associated with poor outcomes. Animal studies report conflicting findings. We systematically reviewed the effects of hyperglycaemia on infarct volume in middle cerebral artery occlusion (MCAO) models, generating weighted mean differences between groups using random effects models summarised as effect size (normalised to control group infarct volume as 100%) and 95% confidence interval. Of 72 relevant papers, 23 reported infarct volume. Studies involved 664 animals and 35 distinct comparisons. Hyperglycaemia was induced by either streptozotocin (STZ, 17 comparisons, n=303) or dextrose (18 comparisons, n=356). Hyperglycaemic animals had infarcts that were 94% larger, but STZ was associated with significantly greater increase in infarct volumes than dextrose infusion (140% larger versus 48% larger). In seven studies, insulin did not significantly reduce infarct size and results were heterogeneous. Although hyperglycaemia exacerbates infarct volume in MCAO models, studies are heterogeneous, and do not address the common clinical problem of PSH because they have used either the STZ model of type I diabetes or extremely high glucose loads. Insulin had a nonsignificant and significantly heterogeneous effect. Further studies with relevant models may inform clinical trial design.

Laboratory models available to study alcohol-induced organ damage and immune variations: choosing the appropriate model

The morbidity and mortality resulting from alcohol-related diseases globally impose a substantive cost to society. To minimize the financial burden on society and improve the quality of life for individuals suffering from the ill effects of alcohol abuse, substantial research in the alcohol field is focused on understanding the mechanisms by which alcohol-related diseases develop and progress. Since ethical concerns and inherent difficulties limit the amount of alcohol abuse research that can be performed in humans, most studies are performed in laboratory animals. This article summarizes the various laboratory models of alcohol abuse that are currently available and are used to study the mechanisms by which alcohol abuse induces organ damage and immune defects. The strengths and weaknesses of each of the models are discussed. Integrated into the review are the presentations that were made in the symposium "Methods of Ethanol Application in Alcohol Model-How Long is Long Enough" at the joint 2008 Research Society on Alcoholism (RSA) and International Society for Biomedical Research on Alcoholism (ISBRA) meeting, Washington, DC, emphasizing the importance not only of selecting the most appropriate laboratory alcohol model to address the specific goals of a project but also of ensuring that the findings can be extrapolated to alcohol-induced diseases in humans.

Effect of chronic alcohol consumption on brain damage following transient focal ischemia

Chronic alcohol consumption impairs cerebral vasoreactivity, and thus, may result in an increase in ischemic brain damage. The goal of this study is to examine the influence of chronic alcohol consumption on transient focal ischemia-induced brain damage. Sprague-Dawley rats were divided into two groups, a control group and an alcohol group. Eight weeks after being fed a liquid diet with or without alcohol, responses of parietal pial arterioles to systemic hypoxia and hypercapnia were measured using a cranial window technique. In separate experiments, rats were subjected to right middle cerebral artery occlusion (MCAO) for 2 h under ketamine/xylazine or isoflurane anesthesia. Regional cerebral blood flow (rCBF) was monitored through a Laser-Doppler flow probe attached to the lateral aspect of the skull. Neurological evaluation and ischemic lesion were assessed 24 h after reperfusion. Dilation of pial arterioles in response to hypoxia and hypercapnia was significantly reduced in alcohol-fed rats. Alcohol-fed rats had significantly larger infarct volumes and worse neurological outcomes than non-alcohol-fed rats under ketamine/xylazine or isoflurane anesthesia. In addition, rCBF measurement indicated that alcohol-fed rats had less regulatory rebound increase in rCBF after the initial drop in rCBF at the onset of MCAO. Our findings suggest that chronic alcohol consumption exacerbates transient focal ischemia-induced brain damage. Increased ischemic brain damage during alcohol consumption may be related to an impaired cerebral vasoreactivity.

Low doses of ethanol and hypoxia administered together act synergistically to promote the death of cortical neurons

The majority of clinically relevant injuries to the developing brain are increasingly being recognized as the result of a combination of least two insults. Evidence from epidemiologic and clinical studies suggests that many of these insults do not cause injury in and of themselves. Rather, they act as predisposing factors (pre-conditioning cytotoxic factors, such as chronic ethanol consumption), increasing the susceptibility to a second, injury-producing (precipitating), unfavorable event (such as hypoxia-ischemia). In this study we make use of primary neuronal cultures to test, in a reproducible system, this two-hit hypothesis. We show that, when administered in combination, low levels of two clinically important environmental insults, hypoxia and ethanol, despite having minimal effects on their own, can act synergistically produce a significant degree of neuronal injury. We further show that one indicator of apoptotic cell death, activated caspase 3, undetectable in neurons subjected to low levels of either insult alone, is detectable when they are administered together.