Eye-acupuncture intervention reduces cerebro-cortical apoptosis of neurovascular unit in cerebral ischemia-reperfusion injury rats

Abstract

To observe the effect of eye-acupuncture intervention on cerebro-cortical apoptosis of microvascular endothelial cells, neurons and astrocytes (main components of neurovascular unit) and the expression of Bad (an apoptosis promoter) and B-cell lymphoma-extra large(Bcl-xL) proteins in focal cerebral ischemia-reperfusion injury (CIRI) rats, so as to explore its mechanisms underlying improvement of CIRI. SD rats were randomly divided into control, sham-operation, model 3 h, model 24 h, model 72 h, eye-acupuncture 3 h, eye-acupuncture 24 h and eye-acupuncture 72 h groups(n＝12 in each group). The CIRI model was established by middle cerebral artery occlusion/reperfusion (MCAO/R). Eye-acupuncture was applied to bilateral "Gan" (Liver) regions, "Shen" (Kidney) regions, "Shangjiao" (Upper-energizer) and "Xiajiao" (Lower-energizer) for 20 min, once 3 h and every 12 h after modeling. The expression levels of Bad and Bcl-xL in the ischemic cerebral cortex tissue were detected by Western blot. The apoptotic neurons, microvascular endothelial cells and astrocytes were assayed by immunofluorescence double labeling (Nestin/TUNEL, CD34/TUNEL and glial fibrillary acidic protein [GFAP]/TUNEL) separately. After modeling, the numbers of apoptotic neurons, microvascular endothelial cells and astrocytes in the ischemic cerebral cortex tissue were significantly increased in the model 72 h group than in the sham-operation group (P<0.01). Following the treatment, the numbers of the 3 types of apoptotic cells were markedly lower in the eye-acupuncture 72 h group than in the model 72 h group(P<0.01). The expression levels of Bad and Bcl-xL proteins were notably up-regulated in the model 3 h, model 24 h and model 72 h groups than in the sham operation group(P<0.01). Following eye-acupuncture intervention, modeling induced increase of the Bad expression were obviously reversed in eye-acupuncture 24 h and eye-acupuncture 72 h groups than those in the 2 model groups(P<0.05). And the increase of Bcl-xL expression levels were further increased in the eye-acupuncture groups in comparison with those in the 3 model groups (P<0.01). Eye-acupuncture can down-regulate the expression of Bad protein, and up-regulate the expression of Bcl-xL protein in the ischemic cerebral cortex in CIRI rats, which may contribute to its function in reducing apoptotic neurons, microvascular endothelial cells and astrocytes, suggesting a protective effect of eye-acupuncture intervention on neurovascular unit.