Investigating the Effects of Camellia petelotii Chi Extract on Nonalcoholic Fatty Liver Disease Based on TLR-4/NF-κB Signaling Pathway

Abstract

To examine the effects and mechanisms of Camellia petelotii Chi extract on the rat model of non-alcoholic fatty liver disease (NAFLD), a set of ten SD rats was randomly chosen as the blank group, while the remaining 50 rats were given a high-sugar, high-fat emulsion to develop the model of non-alcoholic fatty liver disease. After 14 days, the rats were separated into different groups based on their serum total cholesterol (TC) levels. These groups included the model group, the simvastatin group (8 mg/kg), and the Camellia petelotii Chi high, medium, and low dose groups (260, 130, 65 mg/kg). The medication was administered continuously for 6 weeks. Before the last administration, an oral glucose tolerance test (OGTT) was performed, and the area under the blood glucose curve (AUC) was calculated. Both serum and liver tissues were collected to examine the concentrations of total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), and free fatty acid (FFA). In addition, TC and TG were measured to evaluate the amount of lipids in the liver, while glutamic-pyruvic transaminase (ALT) and glutamic oxaloacetic transaminase (AST) were examined to assess liver function. The levels of malondialdehyde (MDA) was measured to evaluate the extent of lipid peroxidation in the liver, while the activity of superoxide dismutase (SOD) was also evaluated. Serum inflammatory factors interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor (TNF-α) were determined in rats. Serum insulin (FINS) was measured and the insulin resistance index (HOMA-IR) was calculated. The HE staining technique was employed to examine the pathomorphological alterations in the liver and determine the non-alcoholic fatty liver disease activity score (NAS). The gene and protein expression of Toll-like receptor 4 (TLR-4) and nuclear factor κB (NF-κB) were determined in liver tissue. The results showed that compared with the model group, AUC, HOMA-IR and serum levels of FINS, TG, TC, LDL-C, FFA, ALT, AST, IL-6, IL-8, TNF were significantly lower (P<0.05), and HDL-C levels was significantly higher in the Camellia petelotii Chi groups (P<0.05). The content of TG, TC and MDA in liver were significantly reduced (P<0.05), and the SOD activity was significantly increased (P<0.05). There was a significant improvement in the condition of hepatic steatosis, abnormal hepatocyte shape, and inflammatory infiltration, leading to a noticeable decrease in the NAS score. The protein and mRNA levels of TLR-4 and NF-κB were exhibited a substantial decrease (P<0.05). The high dose of Camellia petelotii Chi had the best improvement effect among these groups. In conclusion, Camellia petelotii Chi extract would improve liver damage in NAFLD rats by regulating glucose and lipid metabolism, and reducing inflammatory reaction and inflammatory infiltration through the TLR-4/NF-κB signaling pathway.

Keywords

• non-alcoholic fatty liver disease
• camellia petelotii chi extract
• lipid metabolism
• tlr-4/nf-κb signaling pathway