Abstract:

Objective To explore the effects of folic acid combined with vitamin B₁₂ on lipid metabolism in rats with high-fat diet，and to provide a reference for the prevention and treatment of lipid metabolism-related diseases. Methods Totally 30 SD rats were divided into 2 groups randomly by body weight，10 SD male rats were fed by conventional diet as control group. After 28 days of high fat diet，the other 20 rats were allotted into 2 groups equally depending on total cholesterol and triglyceride，including folic acid combined with vitamin B₁₂ group（folic acid dose 1.00 mg/kg and vitamin B₁₂ dose 0.06 mg/kg） and high-fat diet group. All rats were oral gavaged daily for 40 days. The high-fat diet group and the control group were given an equivalent amount of 0.9% saline solution. The levels of total cholesterol，triglyceride，low density lipoprotein cholesterol（LDL-C） and high density lipoprotein cholesterol（HDL-C） in the serum were measured on 0th day，20th day and 40th day of intervention，and the body weight of rats were recorded. At the end of intervention，the levels of total cholesterol and triglyceride in liver tissue homogenate were detected，and the level of adiponectin，resistin and interleukin（IL）-6 were measured using ELISA method. The qPCR method were used to determine the hepatic mRNA expression of lipid metabolism enzymes including cholesterol 7α-hydroxylase（CYP7A1），3-hydroxy-3-methyl glutaryl coenzyme A reductase（HMGCR），fatty acid synthase（FAS） and acetylcoenzyme A carboxylase（ACC）. Results At 0th，20th and 40th day of intervention，the levels of serum total cholesterol，triglyceride and LDL-C in high-fat diet group were higher than those in the control group，and the differences were statistically significant（all P<0.05）. At 20th day and 40th day of intervention，the levels of serum total cholesterol，triglyceride and LDL-C in folic acid combined with vitamin B₁₂ group were lower than those in the high fat diet group，and the differences were statistically significant（all P<0.05）. At 40th day of intervention，the levels of hepatic total cholesterol and triglyceride in high fat diet group were higher than those in the control group，the level of serum adiponectin in high fat diet group was lower than that in the control group，the level of serum resistin and IL-6 in high fat diet group were higher than those in the control group，the hepatic mRNA expression of CYP7A1 in high fat diet group was lower than that in the control group，the hepatic mRNA expression of HMGCR，FAS and ACC in high fat diet group were higher than those in the control group，and the differences were statistically significant（all P<0.05）. The levels of hepatic total cholesterol and triglyceride in folic acid combined with vitamin B₁₂ group was significantly lower than that in high fat group，the levels of serum adiponectin in folic acid combined with vitamin B₁₂ group was significantly higher than that in high fat group，and the levels of serum resistin and IL-6 in folic acid combined with vitamin B₁₂ group were significantly lower than those in the high-fat group（all P<0.05），and the hepatic mRNA expression of HMGCR and FAS were significantly lower than those in the high-fat group（all P<0.05）. Conclusion Folic acid combined with vitamin B₁₂ can improve the lipid metabolism in rats with high-fat diet. The possible molecular mechanism may be related to inhibiting the expression of key lipid metabolic enzymes including FAS and ACC，and regulating the secretion of adipokines such as adiponectin，resistin and IL-6.

Key words: Folic acid, Vitamin B₁₂, Combined effect, High-fat diet, Lipid metabolism, Rats