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

Abstract

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.