小檗碱预处理激活P13K／Akt／mTOR信号通路减轻大鼠肝脏冷缺血再灌注损伤

Berberine preconditioning protects against hepatic cold ischemia reperfusion injury through the modulation of PI3K/Akt/mTOR signaling pathway Sheng Mingwei

目的观察小檗碱预处理减轻大鼠肝脏冷缺血再灌注（IR）损伤的作用，探讨磷脂酰肌醇3激酶（P13K）／蛋白激酶B（Akt）／雷帕霉素靶蛋白（mTOR）信号通路在该作用中的分子机制。方法采用随即数字表法将雄性SD大鼠分为4组，小檗碱组（给予大鼠小檗碱100mg·kg^-1·d^-1灌胃2周后建立大鼠肝脏冷IR损伤模型）、二甲基亚砜（DMSO）组（操作同小檗碱组，用DMSO代替小檗碱）、IR组（操作同小檗碱组，用生理盐水代替小檗碱）及假手术组（给予生理盐水灌胃2周后行开腹和关腹处理）。再灌注后3、6、24h，通过血清学和组织学指标的检测，观察肝脏的损伤情况；比较各组肝细胞凋亡情况，检测P13K／Akt／mTOR通路相关蛋白的表达情况。结果与假手术组比较，IR组和DMSO组肝细胞出现肿胀、坏死，肝脏氧化应激水平升高，细胞凋亡明显增加，Akt和mTOR磷酸化显著上调；小檗碱组大鼠肝功能得到明显改善，肝细胞肿胀、水肿减轻，缓解氧化应激损伤，肝细胞凋亡率显著降低，Bcl-2／Bax比值及caspase-3的表达水平显著升高，与此同时，Akt磷酸化也显著上调，而mTOR磷酸化水平相对降低。结论小檗碱可通过抑制肝脏氧化应激反应等途径缓解细胞大鼠肝脏后IR后的凋亡，改善大鼠肝功能，其机制与P13K／Akt／mTOR信号通路的激活有关。

Objective To confirm the protective effect of berberine （BBR） on cold ischemia reperfusion （I/R）-induced liver injury and to show whether the hepatic protection conferred by BBR involves the activation of phosphatidylinositol 3 kinase （PBK）/ protein kinase B （Akt）/mammalian target of rapamyein（mTOR） signal pathway. Method Adult male Sprague-Daw[ey rats were assigned randomly to four groups.. BBR group （BBR was intragastrically administered at a dose of 100 mg·kg^-1·d^-1 2 weeks before hepatic cold I/R treatment）, dimethyl sulfoxide （DMSO） group （BBR was replaced by DMSO, and others were the same as BBR group）, I/R group （BBR was replaced by normal saline, and others were the same as BBR group） and sham group （normal saline was administered 2 weeks before opening and closing abdomen treatment）. Then the rats were sacrificed at 3, 6, and 24 h after reperfusion. The liver function, oxidative stress level, apoptosis rate, and the expression of PI3K/Akt/mTOR related pathway proteins were assayed. Result As compared with sham group, the I/R-induced liver tissue displayed severe lobular distortion with widespread necrosis, high level of oxidative stress and apoptosis rate. As compared with I/R group, BBR dramatically attenuated the histopathologic damage, restored the liver function and decreased the oxidative stress level. Simultaneously, BBR significantly ameliorated the apoptosis by decreasing the apoptosis rate, increasing the Bcl-2/Bax ratio and inhibiting caspase-3 activity in rats subjected to hepatic I/R. The expression of p-Akt was effectively upregulated with the inhibited expression of p-mTOR. Conclusion Our result provides robust in vivo evidence that BBR can prevent I/R-induced oxidative stress and apoptosis. The mechanisms involved can be attributed to the activation of PI3K/Akt/mTOR signal pathway.