Reduced Apoptosis by Ethanol and Its Association with PKC-δ and Akt Signaling in Ischemic Stroke.

Hafeez Adam

doi:10.14336/ad.2014.0500366

Abstract

Along with thrombolytic therapy, which has a number of limitations, stroke outcome may be improved with neuroprotective therapies that disrupt ischemic cell death. Recent research has shown a neuroprotective role of ethanol administration during ischemic stroke, such as its ability to reduce infarct volume and neurologic deficit. In order to investigate this further, we assessed the hypothesis that ethanol's neuroprotective effect is through reduction of apoptosis and the modulation of the important apoptotic PKC-δ and Akt signaling pathway. Ethanol (1.5 g/kg) was given by intraperitoneal injections to 54 Sprague-Dawley rats after 2 hours of middle cerebral artery (MCA) occlusion, followed by 3 or 24 hours of reperfusion. We measured apoptotic cell death, PKC-δ, and Akt mRNA and protein expressions in each of ischemic groups with or without ethanol treatment using ELISA, real-time PCR and Western blot analysis. Our results showed that cell death was significantly increased in rats following 2 hour MCA occlusion and 24 hour reperfusion. Subsequently, cell death was significantly reduced by an administration of ethanol. We further found that ethanol administration, prior to either 3 or 24 hours of reperfusion, significantly decreased the expression of PKC-δ while simultaneously increasing the expression Akt at both mRNA and protein levels at the two points. In conclusion, our study suggests that ethanol administration following ischemic stroke modulates the gene and protein profile in such a way that it increased expression of anti-apoptotic Akt and decreased the pro-apoptotic PKC-δ. This ultimately results in a decrease in neuronal apoptosis, thus conferring neuroprotection.

Highlights

Ischemic stroke, the most prevalent type of stroke, causes a rapid disruption of blood flow and deprives the brain of vital nutrients due to a thrombosis or embolism all within minutes
We demonstrated that ethanol treatment following ischemic stroke affected the apoptotic protein profile of Protein Kinase C- δ (PKC-δ) and Akt in the brain
Ethanol decreased the levels of PKC-δ mRNA and protein expression significantly when administered following ischemic stroke at 3 and 24 hours after reperfusion. This was in line with our results of a significant decrease in cellular apoptosis and cell death seen in stroke at 24 hours when ethanol was given at the onset of reperfusion [13]

Summary

Introduction

The most prevalent type of stroke, causes a rapid disruption of blood flow and deprives the brain of vital nutrients due to a thrombosis or embolism all within minutes This ischemic crisis initiates a cascade of intracellular events within affected cells, eventually leading to neuronal death and loss of functional brain tissue. Studies have shown that Akt phosphorylates a group of molecules thereby blocking the release of mitochondrial cytochrome c [9] Both PKC-δ and Akt serve as strategic regulators of apoptosis. To understand the biochemical pathway associated with ethanol-induced neuroprotection, we first investigated ethanol’s effect on apoptotic cell death. To further elucidate ethanol’s neuroprotective effect on the apoptotic pathway, we focused on these two important proteins involved in apoptosis, protein kinase C delta (PKC-δ) and Akt, known as Protein Kinase B (PKB)

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Conclusion