Neuroprotective Effects of Pharmacological Hypothermia on Glucose Metabolism in Ischemic Rats

Abstract Stroke is a leading threat to human life. Metabolic dysfunction of glucose may play a key role in stroke pathophysiology. Pharmacological hypothermia (PH) is a potential neuroprotective strategy for stroke in which the temperature can be decreased safely. The present study determined whether neuroprotective PH with chlorpromazine and promethazine (C+P) plus dihydrocapsaicin (DHC) improved glucose metabolism in acute ischemic stroke. A total of 208 adult male Sprague-Dawley rats were randomly divided into the following groups: sham, stroke, and stroke with various treatments including C+P, DHC, C+P+DHC, phloretin (glucose transporter (GLUT)-1 inhibitor), cytochalasin B (GLUT-3 inhibitor), TZD (thiazolidinedione, phosphoenolpyruvate carboxykinase (PCK) inhibitor) and apocynin (nicotinamide adenine dinucleotide phosphate oxidase (NOX) inhibitor). Stroke was induced by middle cerebral artery occlusion (MCAO) for 2 h followed by 6 or 24 h of reperfusion. Rectal temperature was monitored before, during, and after PH. Infarct volume and neurological deficits were measured to assess the neuroprotective effects. Reactive oxygen species (ROS), NOX activity, lactate, apoptotic cell death, glucose, and ATP levels were measured. Protein expressions of GLUT-1, GLUT-3, phosphofructokinase (PFK), lactate dehydrogenase (LDH), PCK1, PCK2, and NOX subunit gp91 were measured with Western blotting. PH with combination of C+P and DHC induced a faster, longer, and deeper hypothermia as compared to each alone. PH significantly improved every measured outcome as compared to stroke and monotherapy. PH reduced brain infarction, neurological deficits, protein levels of glycolytic enzymes (GLUT-1, GLUT-3, PFK and LDH), gluconeogenic enzymes (PCK1 and PCK2), NOX activity and its subunit gp91, ROS, apoptotic cell death, glucose, and lactate, while raising ATP levels. In conclusion, stroke impaired glucose metabolism by enhancing hyperglycolysis and gluconeogenesis, which led to ischemic injury, all of which were reversed by PH induced by a combination of C+P and DHC.

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Abstract TMP3: Low Concentration Normobaric Oxygen Enhanced Therapeutic Effect of Mild Hypothermia or Ethanol Through a Reduction in Apoptosis

Stroke ◽

10.1161/str.47.suppl_1.tmp3 ◽

2016 ◽

Vol 47 (suppl_1) ◽

Author(s):

Kaiyin Liu ◽

Lipeng Cai ◽

Changya Peng ◽

Xiaokun Geng ◽

Xunming Ji ◽

...

Keyword(s):

Cell Death ◽

Therapeutic Effect ◽

Mild Hypothermia ◽

Apoptotic Cell ◽

Artery Occlusion ◽

Apoptotic Cell Death ◽

Tissue Type ◽

Neuroprotective Effects ◽

Normobaric Oxygen ◽

Low Concentration

Introduction: Neuroprotective effects of normobaric oxygen (NBO) and ethanol (EtOH) has been shown. In a clinically relevant autologous embolus rat stroke model in which reperfusion was established by tissue-type plasminogen activator (rt-PA), the present study further evaluated whether low concentration NBO enhanced therapeutic effect of mild hypothermia (Hypo) or EtOH through a reduction in apoptosis and whether EtOH can substitute for hypothermia. Hypothesis: Hypo and EtOH has been shown to have neuroprotective effects through similar mechanisms. We assessed the hypothesis that low concentration NBO, whose neuroprotective effects are currently debated, has benefit in our stroke models, and we further assessed the hypothesis that EtOH can substitute for Hypo in the presence of tPA and NBO. Methods: At 1 hour of middle cerebral artery occlusion (MCAO) by an autologous embolus, rats (96 total, 12 in each treatment group) received rt-PA and other treatments of either EtOH (1.0 g/kg) or Hypo (33 °C for 3 hours) in combination with NBO (60% for 3 hours). Apoptotic cell death was measured by ELISA. Western immunoblotting was performed for pro- (AIF, Caspase-3, Bax) and anti-apoptotic (Bcl-2) protein expression at 3 and 24 hours of reperfusion. Results: Compared to ischemic rats treated only with rt-PA, animals with NBO, hypothermia or EtOH had significantly reduced apoptotic cell death by 32.5%, 43.1% and 36.0% respectively. However, combination therapy that included NBO+EtOH or NBO+Hypo with rt-PA exhibited a much larger decline (p<0.01) in the cell death by 71.1% and 73.6%, respectively. Similarly, NBO+EtOH or NBO+Hypo treatment in addition to rt-PA enhanced beneficial effects on both pro- and anti-apoptotic protein expressions as compared to other options. Conclusions: Neuroprotection after reperfusion with rt-PA in ischemic stroke induced by thromboembolism are enhanced by combination treatment with either EtOH or Hypo in the presence of 60% NBO through reduced apoptosis. Since the effects produced by EtOH and Hypo are comparable, their mechanism of action may not only be similar but also could be interchangeable. Since EtOH administration does not lead to temperature decrease, EtOH may a better alternative than Hypo.

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