Toxicity And Mechanism Of Acrylamide Exposure On Diabetic And Obese Mice

Acrylamide(ACR),an α,β-unsaturated amide,is a by-product of food processing,which produced by the Maillard reaction of starch-rich foods at high temperature.Currently,a large amount of ACR has been found in many common processed foods,which greatly increase the risk of human exposure.ACR is absorbed into the human body through the gastrointestinal tract,respiratory tract and skin,and then distributes to various tissues and organs along with the blood circulation,thereby causing various systemic toxicity and seriously threatening human health safety.Studies have shown that direct exposure of ACR could promote the occurrence of obesity as evidenced by affecting fat differentiation and inducing liver cell fat deposition and degeneration.ACR could also negatively interfere with normal glucose and lipid metabolism by reducing the number of beta cells and insulin secretion,which in turn led to increase of blood sugar levels and abnormal glucose metabolism.However,the mechanism of ACR exposure-induced glucose and lipid metabolism disorder is still unclear and need further study.Diabetes and obesity have become a vital public health issue of global concern and a serious threat to human health.Studies have shown that people with diabetes and obesity were more sensitive to environmental pollutants than normal people,but it is not clear whether people with diabetes and obesity are susceptible to ACR toxicity,and whether ACR exposure will exacerbate the disorder of glucose and lipid metabolism in patients with diabetes and obesity.Therefore,this paper plans to establish model of diabetic mice and obese mice to study the effect of ACR on glucose and lipid metabolism in mice,thereby revealing the susceptibility of diabetic mice and obese mice to the toxicity of acrylamide,and to initially explain acrylamide mechanisms that induce disturbances in glucose and lipid metabolism.(1)A method of liver fatty acid composition analysis based on GC-MS technology was established.The optimal process for liver fatty acid extraction was confirmed: sample was treated with dichloromethane-methanol at 1:20 of the ratio of material-liquid ratio for 6 h at 25 ℃.GC-MS analysis was carried out by BD-5MSIVcapillary column(30 m × 0.25 mm,0.25 μm).The flow rate of carrier gas(helium)was 1 mL/min with a split ratio of 1:10;the injection volume was 0.5 μL.Inlet temperature and detector temperature were 230 ℃ and 250 ℃,respectively.The solvent was delayed for 3 min.Program temperature setting: initial temperature100 ℃,held for 1 min,increased from 20 ℃/min to 205 ℃,increased from 2 ℃/min to 209 ℃,increased from 1 ℃/min to 213 ℃,increased from 12 ℃/min to 220 ℃,increased from 20 ℃/min to 280 ℃,the total duration was 28.75 min.The results showed that the intraday precision was 4.95 ~ 7.46%(n = 5).The stability of fresh liver tissue samples was acceptable(n = 3)with the accurate measurement results,and the samples during the cryopreservation process were unstable,resulting in lower fatty acid measurement results.It could be seen that this method was simple,stable and suitable for GC-MS analysis of fatty acids in liver tissue.(2)The mouse diabetes model was established to study the effect and mechanism of ACR exposure on glucose and lipid metabolism in diabetic mice,which provided a theoretical basis for ACR health risk assessment.The results of the study showed that ACR exposure aggravated the weight loss of diabetic mice,significantly increased the AST enzyme activity in the serum of normal mice and diabetic mice and the MDA content in liver tissue,reduced SOD activity,indicating that ACR caused significant oxidative stress and led to liver damage,in which diabetic mice were more sensitive.ACR exposure had no significant effect on blood glucose,but it could significantly reduce liver glycogen content,suggesting that ACR reduced liver glycogen synthesis and interfered with glucose metabolism.ACR exposure significantly reduced serum and liver TG level,markedly increased serum LDL-C and HDL-C levels,and reduced serum LDL-C level and liver fatty acids levels in diabetic mice,demonstrating that ACR exposure appropriately interfered with lipids,causing disorder of lipid metabolism.ACR exposure significantly affected the expression of transcription factors SREBP2,SREBP1,HNF4α and PPARPα genes and downstream related genes HMG-COAR,Acat1,Fasn,Scd1,Cpt1α in the liver tissues of normal and diabetic mice,and interfered with CD36 and G6 PC,PEPCK,inflammatory factors(IL-1β,IL-6 and TNF-α)and the expression of anti-oxidative stress related genes(Nrf2 andKeap1),indicating that ACR exposure could interfere with the glycolipid metabolism,inflammation factors and redox-related genes in mice,thereby disrupting with the metabolism of glucose and lipid and causing toxic effects.Among them,diabetic mice were particularly sensitive to their interference effects and were susceptible to toxicity.(3)The mouse obesity model was established by a high-fat,high-cholesterol and high-sugar diet to investigate the effects of different doses of ACR on glucose and lipid metabolism in normal and obese mice,and provided data basis and theoretical guidance for ACR health risk assessment.The results of the study showed that long-term exposure of low-dose ACR and synergistic exposure with high-fat,high-cholesterol,high-sugar feeding significantly increased the body weight and liver index of mice,and significantly increased the AST and ALT enzyme activities in serum of mice,indicating long-term exposure of low-dose ACR induced obesity and liver damage,and mice with high-fat,high-cholesterol,high-sugar diet were more sensitive.In addition,synergistic exposure significantly increased TC and TG levels of serum and liver,significantly increased serum LDL-C,reduced serum HDL-C levels,demonstrateing that long-term exposure of low-dose ACR disturbed lipid metabolism and led to lipid metabolism disorders.It could aggravate the abnormal lipid metabolism of mice with high-fat,high-cholesterol and high-sugar diet.Last but not least,synergistic exposure significantly increasesd the levels of insulin and inflammatory factors in the serum and reduced the levels of serum leptin and adiponectin.ACR exposure further interfered with glycolipids balance in mice fed high-fat,high-cholesterol and high-sugar,aggravated the disorder of glucose and lipid metabolism,promoted fat accumulation,and eventually induced obesity.