INT-777 通过激活 TGR5 减轻大鼠蛛网膜下腔出血后氧化应激和神经元凋亡：涉及 cAMP/PKCε/ALDH2 通路。
Activation of TGR5 with INT-777 attenuates oxidative stress and neuronal apoptosis via cAMP/PKCε/ALDH2 pathway after subarachnoid hemorrhage in rats.
机构信息
Department of Neurosurgery, The Affiliated Taicang Hospital, Soochow University, Taicang, Suzhou, Jiangsu, 215400, China; Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, 92350, USA.
Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, 92350, USA; Department of Neurosurgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, 150001, China.
出版信息
Free Radic Biol Med. 2019 Nov 1;143:441-453. doi: 10.1016/j.freeradbiomed.2019.09.002. Epub 2019 Sep 4.
BACKGROUND
Oxidative stress and neuronal apoptosis play important roles in the pathogenesis of early brain injury (EBI) after subarachnoid hemorrhage (SAH). The activation of TGR5, a novel membrane-bound bile acid receptor, possesses anti-oxidative stress and anti-apoptotic effects in hepatobiliary disease and kidney disease. The present study aimed to explore the neuroprotective effect of TGR5 activation against EBI after SAH and the potential underlying mechanisms.
METHODS
The endovascular perforation model of SAH was performed on 199 Sprague Dawley rats to investigate the beneficial effects of TGR5 activation after SAH. INT-777, a specific synthetic TGR5 agonist, was administered intranasally at 1 h after SAH induction. TGR5 CRISPR and ALDH2 CRISPR were administered intracerebroventricularly at 48 h before SAH to illuminate potential mechanisms. The SAH grade, short-term and long-term neurobehavioral tests, TUNEL staining, Fluoro-Jade C staining, Nissl staining, immunofluorescence staining, and western blots were performed at 24 h after SAH.
RESULTS
The expressions of endogenous TGR5 and ALDH2 gradually increased and peaked at 24 h after SAH. TGR5 was expressed primarily in neurons, as well as in astrocytes and microglia. The activation of TGR5 with INT-777 significantly improved the short-term and long-term neurological deficits, accompanied by reduced the oxidative stress and neuronal apoptosis at 24 h after SAH. Moreover, INT-777 treatment significantly increased the expressions of TGR5, cAMP, phosphorylated PKCε, ALDH2, HO-1, and Bcl-2, while downregulated the expressions of 4-HNE, Bax, and Cleaved Caspase-3. TGR5 CRISPR and ALDH2 CRISPR abolished the neuroprotective effects of TGR5 activation after SAH.
CONCLUSIONS
In summary, the activation of TGR5 with INT-777 attenuated oxidative stress and neuronal apoptosis via the cAMP/PKCε/ALDH2 signaling pathway after SAH in rats. Furthermore, TGR5 may serve as a novel therapeutic target to ameliorate EBI after SAH.
背景
氧化应激和神经元凋亡在蛛网膜下腔出血（SAH）后早期脑损伤（EBI）的发病机制中起重要作用。TGR5 是一种新型的膜结合胆汁酸受体，其在肝胆疾病和肾病中的激活具有抗氧化应激和抗细胞凋亡作用。本研究旨在探讨 TGR5 激活对 SAH 后 EBI 的神经保护作用及其潜在机制。
方法
对 199 只 Sprague Dawley 大鼠进行血管内穿孔模型的 SAH，以研究 SAH 后 TGR5 激活的有益作用。在 SAH 诱导后 1 小时给予 TGR5 特异性合成激动剂 INT-777 经鼻内给药。在 SAH 前 48 小时给予 TGR5 CRISPR 和 ALDH2 CRISPR 以阐明潜在机制。在 SAH 后 24 小时进行 SAH 分级、短期和长期神经行为测试、TUNEL 染色、Fluoro-Jade C 染色、尼氏染色、免疫荧光染色和 Western blot。
结果
内源性 TGR5 和 ALDH2 的表达在 SAH 后 24 小时逐渐增加并达到峰值。TGR5 主要表达于神经元，也表达于星形胶质细胞和小胶质细胞。用 INT-777 激活 TGR5 可显著改善 SAH 后 24 小时的短期和长期神经功能缺损，同时减少氧化应激和神经元凋亡。此外，INT-777 治疗可显著增加 TGR5、cAMP、磷酸化 PKCε、ALDH2、HO-1 和 Bcl-2 的表达，同时下调 4-HNE、Bax 和 Cleaved Caspase-3 的表达。TGR5 CRISPR 和 ALDH2 CRISPR 消除了 SAH 后 TGR5 激活的神经保护作用。
结论
总之，用 INT-777 激活 TGR5 通过 cAMP/PKCε/ALDH2 信号通路减轻了 SAH 后大鼠的氧化应激和神经元凋亡。此外，TGR5 可能成为改善 SAH 后 EBI 的一种新的治疗靶点。
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