Zhixiong Li1, Guangxu Xiao1, Huanyi Wang1, Shuang He1, Yan Zhu2. 1. State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China; Research and Development Center of TCM, Tianjin International Joint Academy of Biotechnology and Medicine, Tianjin, 300457, China. 2. State Key Laboratory of Component-based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, China; Research and Development Center of TCM, Tianjin International Joint Academy of Biotechnology and Medicine, Tianjin, 300457, China. Electronic address: yanzhu.harvard@icloud.com.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE: Shuxuening injection (SXNI) is a Chinese medicine of Ginkgo biloba L. leaves extract (GBE), which is widely used clinically for cardiovascular diseases such as stroke and myocardial infarction, but the pharmacological mechanism of its therapeutic effect is not fully understood. AIM OF THE STUDY: Preclinical studies suggested that inhibition of neuronal apoptosis effectively improves brain damage after ischemic stroke. The purpose of this study was to investigate the inhibitory effect of SXNI on neuronal apoptosis in post-stroke mice and its underlying mechanism. MATERIALS AND METHODS: A mouse cerebral ischemia-reperfusion injury (CIRI) model was constructed by middle cerebral artery occlusion (MCAO) and treated with 3 mL/kg SXNI. TUNEL and immunohistochemistry experiments were performed on brain slices on the 7th day after stroke. The protein was extracted from the hippocampus region of the brain for western-blot assay. To simulate the in vivo ischemia-reperfusion process, the hippocampal neuron cell line HT-22 was subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro, and 200 μg/mL SXNI was administered. The HT-22 cells were then studied by RT-PCR and immunocytochemistry. RESULTS: In vivo, SXNI treatment significantly reduced hippocampal neuronal apoptosis. Immunohistochemistry showed that SXNI inhibited the activation of Caspase-3 protein in the hippocampus after ischemic stroke. Western blot analysis further confirmed that SXNI regulated the expression of the antagonizing protein pair Bax and Bcl-2 to exert anti-apoptotic effect in addition to reducing the expression of Cleaved-Caspase-3 in the hippocampus. In vitro, 200 μg/mL SXNI treatment significantly improved HT-22 apoptosis caused by OGD/R. Further RT-PCR and immunocytochemistry study showed that 200 μg/mL SXNI inhibited apoptosis of hippocampal neurons by regulating the mRNA and protein expressions of apoptotic molecules Bax, Bcl-2 and Caspase-3. CONCLUSIONS: CIRI can induce hippocampal neuronal apoptosis, which is inhibited by SXNI via regulating Bax/Bcl-2 and blocking Caspase-3 activation. Therefore, SXNI may be a promising treatment strategy to improve the prognosis of ischemic stroke.
ETHNOPHARMACOLOGICAL RELEVANCE: Shuxuening injection (SXNI) is a Chinese medicine of Ginkgo biloba L. leaves extract (GBE), which is widely used clinically for cardiovascular diseases such as stroke and myocardial infarction, but the pharmacological mechanism of its therapeutic effect is not fully understood. AIM OF THE STUDY: Preclinical studies suggested that inhibition of neuronal apoptosis effectively improves brain damage after ischemic stroke. The purpose of this study was to investigate the inhibitory effect of SXNI on neuronal apoptosis in post-stroke mice and its underlying mechanism. MATERIALS AND METHODS: A mouse cerebral ischemia-reperfusion injury (CIRI) model was constructed by middle cerebral artery occlusion (MCAO) and treated with 3 mL/kg SXNI. TUNEL and immunohistochemistry experiments were performed on brain slices on the 7th day after stroke. The protein was extracted from the hippocampus region of the brain for western-blot assay. To simulate the in vivo ischemia-reperfusion process, the hippocampal neuron cell line HT-22 was subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro, and 200 μg/mL SXNI was administered. The HT-22 cells were then studied by RT-PCR and immunocytochemistry. RESULTS: In vivo, SXNI treatment significantly reduced hippocampal neuronal apoptosis. Immunohistochemistry showed that SXNI inhibited the activation of Caspase-3 protein in the hippocampus after ischemic stroke. Western blot analysis further confirmed that SXNI regulated the expression of the antagonizing protein pair Bax and Bcl-2 to exert anti-apoptotic effect in addition to reducing the expression of Cleaved-Caspase-3 in the hippocampus. In vitro, 200 μg/mL SXNI treatment significantly improved HT-22 apoptosis caused by OGD/R. Further RT-PCR and immunocytochemistry study showed that 200 μg/mL SXNI inhibited apoptosis of hippocampal neurons by regulating the mRNA and protein expressions of apoptotic molecules Bax, Bcl-2 and Caspase-3. CONCLUSIONS: CIRI can induce hippocampal neuronal apoptosis, which is inhibited by SXNI via regulating Bax/Bcl-2 and blocking Caspase-3 activation. Therefore, SXNI may be a promising treatment strategy to improve the prognosis of ischemic stroke.