Teng Zhipeng, Jiang Li, Hu Qin, He Yue, Guo Zhenni, Wu Yue, Huang Zhijian, Cao Fang, Cheng Chongjie, Sun Xiaochuan, Guo Zongduo
From the Department of Neurosurgery, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China (Z.T., L.J., Y.W., Z.H., F.C., C.C., X.S., Zongduo Guo); Discipline of Neuroscience and Department of Anatomy, Histology and Embryology, Collaborative Innovation Center for Brain Science, and Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, China (Q.H.); Department of Neurosurgery, Tong-ji Hospital, Wuhan, China (Y.H.); and Department of Neurology, the First Hospital of Jilin University, Changchun, China (Zhenni Guo).
Stroke. 2016 Jan;47(1):196-205. doi: 10.1161/STROKEAHA.115.011701. Epub 2015 Dec 1.
Early brain injury is proposed to be the primary cause of the poor outcome after subarachnoid hemorrhage (SAH), which is closely related to the neural apoptosis. To date, the relationship between peroxisome proliferator-activated receptor β/δ (PPARβ/δ) and nuclear factor-κB/matrix metalloproteinase-9 (NF-κB/MMP-9) pathway, both of which are closely related to apoptotic effects, has been poorly studied in SAH. The present study was undertaken to evaluate the effects of PPARβ/δ on early brain injury and NF-κB/MMP-9 pathway after SAH in rats.
SAH model was established by injecting nonheparinized autologous arterial blood into the prechiasmatic cistern in male Sprague-Dawley rats. Adenoviruses or small interfering RNAs were injected into the right lateral cerebral ventricle to, respectively, up- or downregulate PPARβ/δ expression before SAH. All animals were assessed with a neurological score and then killed at 24 hours after SAH surgery. The indexes of brain water content, blood-brain barrier permeability, and apoptosis were used to detect brain injury. The expression of PPARβ/δ, NF-κB, and MMP-9 were measured by immunohistochemistry, gelatin zymography, and Western Blot methods, respectively. In addition, GW0742, a specific agonist of PPARβ/δ, was used to treat SAH in rats, the effects of which were evaluated by neurological scoring and Evans blue extravasation.
Overexpression of PPARβ/δ by adenoviruses treatment significantly ameliorated brain injury with improvement in neurological deficits, brain edema, blood-brain barrier impairment, and neural cell apoptosis at 24 hours after SAH in rats, whereas downregulation of PPARβ/δ by small interfering RNAs administration resulted in the reverse effects of the above. The expression levels of NF-κB and MMP-9 were markedly downregulated when PPARβ/δ increased after PPARβ/δ adenovirus transfection and upregulated when PPARβ/δ decreased by PPARβ/δ small interfering RNAs treatment. Moreover, GW0742 improved neurological deficits and reduced Evans blue extravasation at 24 hours after SAH.
PPARβ/δ's overexpression may attenuate early brain injury after rats' SAH administration, which reduces neural apoptosis possibly through blocking NF-κB/MMP-9 pathway.
早期脑损伤被认为是蛛网膜下腔出血（SAH）后预后不良的主要原因，这与神经细胞凋亡密切相关。迄今为止，过氧化物酶体增殖物激活受体β/δ（PPARβ/δ）与核因子-κB/基质金属蛋白酶-9（NF-κB/MMP-9）通路之间的关系，这两者都与凋亡效应密切相关，在SAH中尚未得到充分研究。本研究旨在评估PPARβ/δ对大鼠SAH后脑损伤及NF-κB/MMP-9通路的影响。
采用将未肝素化的自体动脉血注入雄性Sprague-Dawley大鼠视交叉前池的方法建立SAH模型。在SAH前，将腺病毒或小干扰RNA注入右侧侧脑室，分别上调或下调PPARβ/δ表达。所有动物均进行神经功能评分，然后在SAH手术后24小时处死。采用脑含水量、血脑屏障通透性和凋亡指标检测脑损伤。分别用免疫组织化学、明胶酶谱法和蛋白质印迹法检测PPARβ/δ、NF-κB和MMP-9的表达。此外，使用PPARβ/δ特异性激动剂GW0742治疗大鼠SAH，通过神经功能评分和伊文思蓝外渗评估其效果。
腺病毒治疗使PPARβ/δ过表达可显著改善大鼠SAH后24小时的脑损伤，神经功能缺损、脑水肿、血脑屏障损伤和神经细胞凋亡均得到改善，而小干扰RNA下调PPARβ/δ表达则产生上述相反的效果。PPARβ/δ腺病毒转染后PPARβ/δ增加时，NF-κB和MMP-9的表达水平明显下调，而PPARβ/δ小干扰RNA处理使PPARβ/δ降低时，NF-κB和MMP-9的表达上调。此外，GW0742可改善SAH后24小时的神经功能缺损并减少伊文思蓝外渗。
PPARβ/δ过表达可能减轻大鼠SAH后的早期脑损伤，可能通过阻断NF-κB/MMP-9通路减少神经细胞凋亡。
