[Effects and mechanism of diammonium glycyrrhizinate on liver injury in severely scalded rats].

Objective: To investigate the effects and mechanism of diammonium glycyrrhizinate (DG) on liver injury in severely scalded rats. Methods: The experimental research method was used. Fifty-four female Sprague-Dawley rats aged 7-9 weeks were divided into sham injury group with simulated injury on the back, and simple scald group and scald+DG group with scald of 30% total body surface area on the back, with 18 rats in each group. Rats in sham injury group were not specially treated after injury, and rats in simple scald group and scald+DG group were rehydrated for antishock. Besides, rats in scald+DG group were injected intraperitoneally with 50 mg/kg DG at post injury hour (PIH) 1, 25, and 49. Rats in the three groups were collected, the serum content of liver function injury related indexes including aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), total protein, and albumin was measured by automatic biochemical assay analyzer, and serum content of ornithine carbamoyl transferase (OCT) was measured by enzyme-linked immunosorbent assay method at PIH 24, 48, and 72; hepatic histopathological changes at PIH 72 were observed by hematoxylin-eosin staining; the mRNA expressions of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), glucose regulated protein 78 (GRP78), activating transcription factor 4 (ATF4), and protein kinase R-like endoplasmic reticulum kinase (PERK) in liver tissue were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction at PIH 24, 48, and 72. The protein expressions of Bcl-2, Bax, GRP78, PERK, and ATF4 in liver tissue were detected by Western blotting at PIH 72 in sham injury group and PIH 24, 48, and 72 in simple scald group and scald+DG group. The number of samples was 6 in each group at each time point. Data were statistically analyzed with analysis of variance for factorial design, one-way analysis of variance, and Bonferroni test. Results: Compared with that in sham injury group, the serum content of AST, ALT, and LDH was significantly increased (P<0.01), and the serum content of total protein and albumin was significantly decreased (P<0.05 or P<0.01) of rats in simple scald group at all post-injury time points. Compared with those in simple scald group, the serum AST content of rats in scald+DG group at PIH 24 was decreased significantly (P<0.05); the serum AST, ALT, and LDH content of rats in scald+DG group at PIH 48 was decreased significantly (P<0.01), and the serum total protein content was increased significantly (P<0.01); the serum AST, ALT, and LDH content of rats in scald+DG group at PIH 72 was decreased significantly (P<0.01), and the serum total protein and albumin content was increased significantly (P<0.01). At PIH 24, 48, and 72, the serum OCT content of rats in simple scald group was (48.5±3.9), (40.8±2.4), and (38.7±2.0) U/L, which was significantly higher than (15.1±2.5), (15.7±2.6), and (16.4±3.7) U/L in sham injury group (P<0.01), and (39.0±4.5), (31.8±2.0), and (22.1±2.6) U/L in scald+DG group (P<0.05 or P<0.01). At PIH 72, the cells in liver tissue of rats in sham injury group had normal morphology and regular arrangement, with no obvious inflammatory cell infiltration; the cells in liver tissue of rats in simple scald group had disordered arrangement, diffuse steatosis, and moderate inflammatory cell infiltration; the cells in liver tissue of rats in scald+DG group arranged regularly, with scattered steatosis and a small amount of inflammatory cell infiltration. Compared with those in sham injury group, the Bcl-2 mRNA (P<0.05 or P<0.01) and protein expressions of liver tissue were significantly decreased, and the mRNA (P<0.01) and protein expressions of Bax were significantly increased in rats in simple scald group at PIH 24, 48, and 72. Compared with those in simple scald group, the mRNA (P<0.05) and protein expressions of Bax in liver tissue of rats in scald+DG group were decreased significantly at PIH 48; the mRNA (P<0.01) and protein expressions of Bax in liver tissue of rats in scald+DG group were significantly decreased, and the mRNA (P<0.01) and protein expressions of Bcl-2 were significantly increased at PIH 72. Compared with those in sham injury group, the mRNA (P<0.05 or P<0.01) and protein expressions of ATF4, GRP78, and PERK in liver tissue were significantly increased in rats in simple scald group at all post-injury time points. Compared with those in simple scald group, the mRNA (P<0.01) and protein expressions of ATF4 in liver tissue of rats in scald+DG group at PIH 48 were significantly decreased, and the mRNA (P<0.05 or P<0.01) and protein expressions of ATF4, GRP78, and PERK were significantly decreased in liver tissue of rats in scald+DG group at PIH 72. Conclusions: DG can effectively reduce the degree of liver injury in rats after severe scald, and the mechanism may involve alleviating endoplasmic reticulum stress and mitigating mitochondrial damage.目的： 探讨甘草酸二铵对严重烫伤大鼠肝损伤的影响及其机制。 方法： 采用实验研究方法。取54只7~9周龄雌性SD大鼠，按随机数字表法分为背部模拟致伤的假伤组及背部造成30%体表总面积Ⅲ度烫伤的单纯烫伤组及烫伤+甘草酸二铵组，每组18只。假伤组伤后不行特殊处理；单纯烫伤组及烫伤+甘草酸二铵组大鼠进行补液抗休克，烫伤+甘草酸二铵组大鼠分别于伤后1、25、49 h经腹腔注射50 mg/kg甘草酸二铵溶液。取3组大鼠，伤后24、48、72 h，采用全自动生化检测分析仪检测血清肝功能损伤相关指标天冬氨酸转氨酶（AST）、丙氨酸转氨酶（ALT）、乳酸脱氢酶（LDH）、总蛋白、白蛋白含量，采用酶联免疫吸附测定法检测血清鸟氨酸氨甲酰基转移酶（OCT）含量；行苏木精-伊红染色观察伤后72 h肝组织病理学变化；采用实时荧光定量反转录PCR法检测伤后24、48、72 h肝组织B淋巴细胞瘤-2（Bcl-2）、Bcl-2相关X蛋白（Bax）、葡萄糖调节蛋白78（GRP78）、转录激活因子4（ATF4）、蛋白激酶R样内质网激酶（PERK）的mRNA表达。采用蛋白质印迹法检测假伤组伤后72 h及烫伤2组伤后24、48、72 h肝组织Bcl-2、Bax、GRP78、PERK、ATF4的蛋白表达。各组各时间点样本数均为6。对数据行析因设计方差分析、单因素方差分析及Bonferroni检验。 结果： 与假伤组比较，单纯烫伤组大鼠伤后各时间点血清中AST、ALT、LDH含量均明显升高（P<0.01），总蛋白、白蛋白含量均明显降低（P<0.05或P<0.01）。相较于单纯烫伤组，烫伤+甘草酸二铵组大鼠伤后24 h血清中AST含量明显下降（P<0.05）；烫伤+甘草酸二铵组大鼠伤后48 h血清中AST、ALT、LDH含量均明显下降（P<0.01），总蛋白含量明显升高（P<0.01）；烫伤+甘草酸二铵组大鼠伤后72 h血清中AST、ALT、LDH含量均明显下降（P<0.01），总蛋白和白蛋白含量均明显升高（P<0.01）。伤后24、48、72 h，单纯烫伤组大鼠血清OCT含量分别为（48.5±3.9）、（40.8±2.4）、（38.7±2.0）U/L，均明显高于假伤组的（15.1±2.5）、（15.7±2.6）、（16.4±3.7）U/L（P<0.01）和烫伤+甘草酸二铵组的（39.0±4.5）、（31.8±2.0）、（22.1±2.6）U/L（P<0.05或P<0.01）。伤后72 h，假伤组大鼠肝组织中细胞形态正常，排列规则，未见明显炎症细胞浸润；单纯烫伤组大鼠肝组织中细胞排列紊乱，伴有弥漫性的脂肪病变和中等量炎症细胞浸润；烫伤+甘草酸二铵组大鼠肝组织中细胞排列较规则，可见散在的脂肪变性，伴有少量炎症细胞浸润。与假伤组比较，单纯烫伤组大鼠伤后24、48、72 h肝组织Bcl-2 mRNA（P<0.05或P<0.01）和蛋白表达均明显减少，Bax的mRNA（P<0.01）和蛋白表达均明显增加。与单纯烫伤组比较，烫伤+甘草酸二铵组大鼠伤后48 h肝组织Bax 的mRNA（P<0.05）和蛋白表达均明显减少；烫伤+甘草酸二铵组大鼠伤后72 h肝组织Bax的mRNA（P<0.01）和蛋白表达均明显减少，Bcl-2的mRNA（P<0.01）和蛋白表达均明显增加。与假伤组比较，单纯烫伤组大鼠伤后各时间点肝组织ATF4、GRP78、PERK的mRNA（P<0.05或P<0.01）和蛋白表达均明显增加。与单纯烫伤组相比，烫伤+甘草酸二铵组大鼠伤后48 h肝组织ATF4的mRNA（P<0.01）和蛋白表达均明显减少，伤后72 h肝组织ATF4、GRP78、PERK的mRNA（P<0.05或P<0.01）和蛋白表达均明显减少。 结论： 甘草酸二铵能有效降低严重烫伤后大鼠肝损伤的程度，其机制可能是通过缓解内质网应激及减轻线粒体损伤。.