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Abstract
Valproic acid (VPA) is a well-known anti-epileptic and mood stabilizing drug. A growing number of reports demonstrate that VPA is neuroprotective against various insults. Despite intensive efforts to develop new therapeutics for stroke over the past two decades, all treatments have thus far failed to show clinical effect because of treatment-limiting side effects of the drugs. Therefore, a safety-validated drug like VPA would be an attractive candidate if it has neuroprotective effects against ischemic insults. The present study was undertaken to examine whether pre- and post-insult treatments with VPA protect against brain infarct and neurological deficits in mouse transient (tMCAO) and permanent middle cerebral artery occlusion (pMCAO) models. In the tMCAO (2 hr MCAO and 22 hr reperfusion) model, intraperitoneal injection of VPA (300 mg/kg, i.p.) 30 min prior to MCAO significantly reduced the infarct size and the neurological deficit. VPA treatment immediately after reperfusion significantly reduced the infarct size. The administration of VPA at 4 hr after reperfusion failed to reduce the infarct size and the neurological deficit. In the pMCAO model, treatment with VPA (300 mg/kg, i.p.) 30 min prior to MCAO significantly attenuated the infarct size, but did not affect the neurological deficit. Western blot analysis of acetylated H3 and H4 protein levels in extracts from the ischemic cortical area showed that treatment with VPA increased the expression of acetylated H3 and H4 at 2 hrs after MCAO. These results demonstrated that treatment with VPA prior to ischemia attenuated ischemic brain damage in both mice tMCAO and pMCAO models and treatment with VPA immediately after reperfusion reduced the infarct area in the tMCAO model. VPA could therefore be evaluated for clinical use in stroke patients.
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Fig. 1.
Representative infarcted brain slices subjected to 2 hr ischemia and 22 hr reperfusion showing effect of treatment with valproic acid (VPA, 300 mg/kg) 30 min prior to MCAO (Pre 30 m), immediately after reperfusion (Post 2 hr) and 4 hr after reperfusion (Post 6 hr) in mice. The slices were stained with 2% TTC.
Fig. 2.
Effect of treatments with valproic acid (VPA, 300 mg/kg, i.p.) at various time-points on % cerebral infarct of total brain (A), % cerebral infarct of each section (B) and neurological deficit score (C) in the tMCAO model. Each column/point and the vertical bars represent mean±SEM from 9∼12 animals. Asterisks represent significant difference vs. vehicle-treated group (∗p<0.05, ∗∗p<0.01).
Fig. 3.
Effect of pretreatment with valproic acid (VPA, 300 mg/kg, i.p.) on % cerebral infarct of total brain (A), % cerebral infarct of each section (B) and neurological deficit score (C) in the pMCAO model. Each column/point and the vertical bars represent mean±SEM from 9 animals. Asterisk represents significant difference from vehicle-treated group (∗p<0.05).
Fig. 4.
Effect of valproic acid on the expression of acetylated histone H3 and H4 in the cortices of mouse brain. (A) Western blot analysis of acetylated H3 (Ac-H3), acetylated H4 (Ac-H4) and β-actin in extracts from cortical areas in sham-operated animals (sham), and ischemic cortical area at 2 hr after MCAO in mice treated with saline (vehicle) and valproic acid (VPA). (B) Quantified results of Ac-H3 and Ac-H4. Each column and vertical bar represents mean±SEM from 3∼4 animals. Asterisks represent significant difference vs. vehicle-treated group (∗p<0.05, ∗∗p<0.01).
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