Effect Of Chitooligosaccharides On Lowering Triglyceride In Non - Alcoholic Fatty Liver Model In Vitro And In Vivo And Its Mechanism

Objective:To explore the effects of chitooligosaccharides(COS) on triglycerides(TG) of non-alcoholic fatty liver disease(NAFLD) model in vitro and vivo and its possible mechanism. Methods:1mmol/L free fatty acids mixture was used to induce fatty degeneration of LO2 cells(model group). LO2 cells treated with 1mmol/L FFA mixture and 0.5mg/mL COS were as COS treatment group(COS group), while untreated cells were as normal control(control group). After 24 hours, Oil red O staining and intracellular triglycerides contents were detected in the three groups. The mRNA and protein levels of sterol regulatory element binding protein 1c(SREBP-1c), fatty acid synthase(FAS) and carnitine palmitoyl transferase 1A(CPT1A) were measured by real-time reverse transcription polymerase chain reaction(RT-PCR) and Western blot.2mmol/L FFA was used to induce apoptosis, protective effect of COS was detected by Hoechst staining. In vivo, male C57BL/6J mice were randomly divided into three groups given different treatments: the control group, high fat group and COS group. After 16 weeks, the mice livers were stained with HE and oil red O and determined the content of TG. The results were analyzed by one-way ANOVA test using SPSS ver.17.0. Statistical differences between each experimental group were determined by SNK. Results :(1)Lipid droplets of LO2 in model group were observed through Oil red O staining. The level of hepatocytes TG was increased, while COS could inhibit the increase of TG.(2)The SREBP-1c, FAS mRNA expression in model group were significantly increased(2.306 ± 0.239 VS 1.010 ± 0.174, P <0.05; 1.788 ± 0.192 VS 1.006 ± 0.139, P <0.05),while the level of CPT1 A mRNA(1.355 ± 0.145 VS 1.010 ± 0.176, P> 0.05) was a slightly higher. COS treatment could down-regulate SREBP-1c, FAS m RNA relative expression levels(1.039 ± 0.107, 1.212 ± 0.180, P <0.05) and up-regulate CPT1 A mRNA expression levels(1.911 ± 0.773, P <0.05).(3)The expression of SREBP-1c and FAS protein in model group was higher than control group and COS group(0.351±0.016 VS0.206±0.012, 0.161±0.081, P<0.05;1.238±0.051 VS 0.287±0.031, 0.332±0.023, P<0.05).The expression of CPT1 A protein in COS group(1.014±0.033)was higher than control group and model group(0.547±0.075、0.561±0.046,P<0.05).(4) COS could protect apoptosis induced by FFA.(5) The mice experiment proved that COS could ameliorate the lipid accumulation and TG content of high-fat mice liver. Conclusion : COS can reduce the accumulation of TG in NAFLD model, which may be mediated by inhibiting the gene expression of SREBP-1c and FAS, and increasing CPT1 A expression.