ABSTRACT
Objective: The present work was to investigate the protective effects of the aqueous extract of Gynura procumbens (GPAE) against nonalcoholic steatohepatitis (NASH) in mice and NCTC-1469 cells. Methods: C57BL/6J mice were fed with methionine and choline-deficient (MCD) diet and administered simultaneously with GPAE (500 and 1000 mg/kg/d, respectively) by gavage for six weeks. The biomarkers of NASH in serum and liver were determined. NCTC-1469 cells were pretreated with 0.25 mmol/L palmitic acid (PA) plus 0.5 mmol/L oleic acid (OA) for 24 h or treated with adenovirus expressing short-hairpin RNA against CFLAR (Ad-shCFLAR) for 24 h and then treated with GPAE (80 and 160 µg/mL, respectively) for 24 h, and the content of cellular biomarkers of NASH was detected. Results: In mice treated with MCD, GPAE could decrease the levels of serum ALT, AST, the content of hepatic TG, TC and MDA, repress the activities and protein expression of CYP2E1 and CYP4A and the phosphorylation of JNK, increase the activities of HO-1, CAT and GSH-Px, up-regulate the mRNA expression of PPARα, FABP5, CPT1α, ACOX, SCD-1, mGPAT, MTTP and the protein expression of CFLAR and NRF2. In NCTC-1469 cells treated with PA and OA, GPAE could decrease the content of cellular TG and ROS, promote the uptake of 2-NBDG, up-regulate the protein expression of CFLAR and NRF2. In NCTC-1469 cells treated with Ad-shCFLAR, GPAE up-regulated the mRNA and protein expression of CFLAR, down-regulated the phosphorylation of JNK, and increased the protein expression of NRF2 and pIRS1. Conclusion: These results indicated that the activation on CFLAR-JNK pathway might be the main anti-NASH mechanism of GPAE, which on the one hand promote the β-oxidation and efflux of fatty acids in liver, and finally reduce hepatic lipid accumulation, on the other hand increase the activities of anti-oxidant enzymes and inhibit the activities of ROS generation enzymes by activating NRF2, and therefore attenuates hepatic oxidative stress damage.
ABSTRACT
Objective To explore the expression of chemerin and chemerin receptor ( chemokine-like receptor 1, CMKLR1) during different periods of non-alcoholic fatty liver disease ( NAFLD) rat model induced by methionine- and choline-deficient ( MCD) diet. Methods Thirty-six Wistar rats were divided into control group and MCD group in random. After one week quarantine and acclimation period, these two groups were fed either normal chow or MCD diet. The animals were respectively sacrificed at the first week, the forth week, and the tenth week. The levels of alanine transaminase (ALT), blood lipid profile, liver function, and the content of triglyceride in liver were detected. HE staining was done to observe the morphologic change of liver. The mRNA expression changes of chemerin and CMKLR1 in liver were measured using real-time PCR, and the change in chemerin mRNA level was further confirmed in liver by Northern blot. Finally, the concentration of chemerin in serum was measured by Western blot. Results The mRNA level of chemerin decreased significantly after four and ten weeks MCD feeding, although no obvious changes were found at first week, similar changes were found in serum chemerin (1.00±0.11 vs 0.96±0.39; 1.00±0.12 vs 0.21 ±0.77; 1.00±0.42 vs 0.21 ±0. 11). Contrasting with the change of chemerin(1.00±0.08 vs 0.72±0.10;1.00±0.24 vs 0.63±0. 31 ;1.00±0.05 vs 0.50±0.13), the mRNA level of CMKLR1 increased after MCD feeding( 1.00±0. 14 vs 0. 84±0. 26; 1.00±0. 38 vs 1. 51 ±0. 33; 1. 01 ±0. 13 vs 1. 84 ± 0. 39 ). Conclusion The change of chemerin and its receptor may participate in the process of the nonalcoholic fatty liver disease.