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Chronic valproate treatment enhances postischemic angiogenesis and promotes functional recovery in a rat model of ischemic stroke.

ABSTRACT: BACKGROUND AND PURPOSE:Enhanced angiogenesis facilitates neurovascular remodeling processes and promotes brain functional recovery after stroke. Previous studies from our laboratory demonstrated that valproate (VPA), a histone deacetylase inhibitor, protects against experimental brain ischemia. The present study investigated whether VPA could enhance angiogenesis and promote long-term functional recovery after ischemic stroke. METHODS:Male rats underwent middle cerebral artery occlusion for 60 minutes followed by reperfusion for up to 14 days. Assessed parameters were: locomotor function through the Rotarod test; infarct volume through T2-weighted MRI; microvessel density through immunohistochemistry; relative cerebral blood flow through perfusion-weighted imaging; protein levels of proangiogenic factors through Western blotting; and matrix metalloproteinase-2/9 activities through gelatin zymography. RESULTS:Postischemic VPA treatment robustly improved the Rotarod performance of middle cerebral artery occlusion rats on Days 7 and 14 after ischemia and significantly reduced brain infarction on Day 14. Concurrently, VPA markedly enhanced microvessel density, facilitated endothelial cell proliferation, and increased relative cerebral blood flow in the ipsilateral cortex. The transcription factor hypoxia-inducible factor-1? and its downstream proangiogenic factors, vascular endothelial growth factor and matrix metalloproteinase-2/9, were upregulated after middle cerebral artery occlusion and significantly potentiated by VPA in the ipsilateral cortex. Acetylation of histone-H3 and H4 was robustly increased by chronic VPA treatment. The beneficial effects of VPA on Rotarod performance and microvessel density were abolished by hypoxia-inducible factor-1? inhibition. CONCLUSIONS:Chronic VPA treatment enhances angiogenesis and promotes functional recovery after brain ischemia. These effects may involve histone deacetylase inhibition and upregulation of hypoxia-inducible factor-1? and its downstream proangiogenic factors vascular endothelial growth factor and matrix metalloproteinase-2/9.

SUBMITTER: Wang Z

PROVIDER: S-EPMC3429729 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Chronic valproate treatment enhances postischemic angiogenesis and promotes functional recovery in a rat model of ischemic stroke.

Wang Zhifei Z Tsai Li-Kai LK Munasinghe Jeeva J Leng Yan Y Fessler Emily Bame EB Chibane Fairouz F Leeds Peter P Chuang De-Maw DM

Stroke 20120717 9

<h4>Background and purpose</h4>Enhanced angiogenesis facilitates neurovascular remodeling processes and promotes brain functional recovery after stroke. Previous studies from our laboratory demonstrated that valproate (VPA), a histone deacetylase inhibitor, protects against experimental brain ischemia. The present study investigated whether VPA could enhance angiogenesis and promote long-term functional recovery after ischemic stroke.<h4>Methods</h4>Male rats underwent middle cerebral artery occ ...[more]

PMID: 22811460

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Project description:Brain injury from stroke is typically considered an event exclusive to the CNS, but injury progression and repair processes are profoundly influenced by peripheral immunity. Stroke stimulates an acute inflammatory response that results in a massive infiltration of peripheral immune cells into the ischemic area. While these cells contribute to the development of brain injury, their recruitment has been considered as a key step for tissue repair. The paradoxical role of inflammatory monocytes in stroke raises the possibility that the manipulation of peripheral immune cells before infiltration into the brain could influence stroke outcome. One such manipulation is remote ischemic limb conditioning (RLC), which triggers an endogenous tolerance mechanism. We observed that mice subjected to poststroke RLC shifted circulating monocytes to a CCR2+ proinflammatory monocyte subset and had reduced acute brain injury, swelling, and improved motor/gait function in chronic stroke. The RLC benefits were observed regardless of injury severity, with a greater shift to a CCR2+ subset in severe stroke. Adoptive transfer of CCR2-deficient monocytes abolished RLC-mediated protection. The study demonstrates the importance of RLC-induced shift of monocytes to a CCR2+ proinflammatory subset in attenuating acute injury and promoting functional recovery in chronic stroke. The defined immune-mediated mechanism underlying RLC benefits allows for an evidence-based framework for the development of immune-based therapeutic strategies for stroke patients.SIGNIFICANCE STATEMENT Stroke is the leading cause of physical disability worldwide but has few treatment options for patients. Because remote ischemic limb conditioning (RLC) elicits endogenous tolerance in neither an organ- nor a tissue-specific manner, the immune system has been considered a mediator for an RLC-related benefit. Application of RLC after stroke increased a proinflammatory CCR2+ monocyte subset in the blood and the brain. RLC reduced acute stroke injury and promoted motor/gait function during the recovery phase. The RLC benefits were absent in mice that received CCR2-deficient monocytes. This preclinical study shows the importance of CCR2+ proinflammatory monocytes in RLC benefits in stroke and provides a therapeutic RLC platform as a novel immune strategy to improve outcomes in stroke patients.

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Chronic valproate treatment enhances postischemic angiogenesis and promotes functional recovery in a rat model of ischemic stroke.

Publications

Chronic valproate treatment enhances postischemic angiogenesis and promotes functional recovery in a rat model of ischemic stroke.

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