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目的探讨甘氨酸对非酒精性脂肪性肝病(NAFLD)大鼠肝脏趋化因子样受体1(CMKLR1)及脂联素表达的影响及作用机制。方法选取36只10~12周龄雄性SD大鼠,适应性喂养1周后,随机分为三组:对照组、高脂组和甘氨酸组。分别在第8、12周末处死大鼠。测量大鼠的体重及肝重,计算其肝指数;采集大鼠的腹主动脉血液检测血浆丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、甘油三酯(TG)、肿瘤坏死因子-α(TNF-α)及脂联素水平;取肝组织行HE染色、免疫组化和RT-PCR检测肝脏脂联素及CMKLR1蛋白和基因水平的表达。结果 (1)随着饲养时间的延长,各组大鼠体重及肝指数增加,高脂组大鼠体重和肝指数明显高于同期对照组和甘氨酸组(P<0.05)。(2)高脂组大鼠ALT、AST、TG及TNF-α高于同期对照组,甘氨酸组低于同期高脂组(P<0.05)。(3)肝脏免疫组化检测结果显示:在8周、12周,高脂组大鼠的血清脂联素水平低于同期对照组(P<0.05),甘氨酸组高于高脂组(P<0.05);肝组织CMKLR1在同期高脂组高于对照组,甘氨酸组低于高脂组(P<0.05)。(4)PCR结果显示:肝组织中脂联素基因表达在甘氨酸组高于高脂组(P<0.05),CMKLR1的基因表达在甘氨酸组低于高脂组(P<0.05)。(5)血清脂联素与肝组织CMKLR1 m RNA呈负相关(r=-0.527,P=0.001);肝脏脂联素m RNA与肝脏CMKLR1 m RNA呈负相关(r=-0.529,P=0.001)。结论 (1)在NAFLD发生发展中肝组织中CMKLR1水平逐渐升高,可能起到加重炎症程度的作用。(2)甘氨酸可下调肝组织中CMKLR1的表达,上调血清脂联素的表达从而保护肝脏。
Objective To investigate the effects of glycine on the expression of hepatic chemokine receptor 1 (CMKLR1) and adiponectin in nonalcoholic fatty liver disease (NAFLD) rats and its mechanism. Methods Thirty-six male Sprague-Dawley rats aged 10-12 weeks were randomly divided into three groups: control group, hyperlipidemia group and glycine group. Rats were sacrificed on the 8th and 12th week respectively. The body weight and liver weight were measured to calculate the liver index. Blood samples of abdominal aorta were collected to detect the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG) ), Tumor necrosis factor-α (TNF-α) and adiponectin. Liver tissues were harvested for HE staining, immunohistochemistry and RT-PCR for the detection of hepatic adiponectin and CMKLR1 protein and gene expression. Results (1) With the prolongation of feeding time, body weight and liver index of rats in each group increased. The body weight and liver index of rats in high fat diet group were significantly higher than those in the control group and glycine group (P <0.05). (2) The levels of ALT, AST, TG and TNF-α in hyperlipidemia group were higher than those in the control group and glycine group was lower than that in the hyperlipidemia group (P <0.05). (3) The results of liver immunohistochemistry showed that serum adiponectin levels in hyperlipidemic rats were lower than those in the same period (P <0.05) at 8 weeks, 12 weeks, and higher in the glycine group than in the hyperlipidemic rats (P < 0.05). The level of CMKLR1 in liver tissue was higher in the hyperlipidemia group than in the control group and lower in the glycine group than in the hyperlipidemia group (P <0.05). (4) PCR results showed that adiponectin gene expression in liver tissue was higher in glycine group than in hyperlipidemia group (P <0.05), while CMKLR1 gene expression was lower in glycine group than that in hyperlipemia group (P <0.05). (5) Serum adiponectin was negatively correlated with CMKLR1 m RNA in liver tissue (r = -0.527, P = 0.001); hepatic adiponectin m RNA was negatively correlated with CMKLR1 m RNA in liver (r = -0.529, ). Conclusions (1) The level of CMKLR1 in the development of NAFLD gradually increased, which may play a role in aggravating the degree of inflammation. (2) Glycine can downregulate the expression of CMKLR1 in liver tissue and upregulate the expression of serum adiponectin so as to protect the liver.