The Experimental Study On Microcystin-LR Induced The Lipid Metabolism Disorders Of C57BL/6 Mice

The experimental study on microcystin-LR induced the lipid metabolism disorders of C57BL/6 miceBackground and Objective:Because of eutrophication, Algae toxin produced by algal and water blooms has become an important public health problem. MCs are monocyclic peptides and more than 80 variants have been found, MC-LR of which is a subtype with the most toxicity. As a special kind of environmental pollutants, little research about the metabolic system has been reported about MCs. The purpose of this project is to study the lipid metabolism effects of the exposure to the long-term, low-doses of MC-LR in C57BL/6 mice, further to explore the molecular mechanisms, the targets and the regulatory pathways about MC-LR which may cause the metabolic disorders in the mice.Materials and Methods:1. The C57BL/6 mice exposure to MC-LR C57BL/6 mice were randomly divided into four groups (three experimental groups and a control group) (n= 10). After one week’s adaptation, Four groups of male C57BL/6 mice were intraperitoneal (i.p.) administration of MC-LR at concentrations of 0,0.25,2.5, or 20μg/kg·body weight (bw) twice per week for 12 weeks. The mice were sacrificed by CO2 asphyxiation, blood was collected by cardiac puncture. Then the mice were perfused with saline, the liver, kidney,and abdominal fat have been harvested and weighed, frozen in liquid nitrogen immediately, stored at -80℃ for further analysis.2. The effects on the livers of mice exposure to MC-LR The liver tissues were fixed and sections were analyzed by standard hemotoxylin and eosin (HE) staining. the mice serum were tested by the Biochemical Laboratory and the inflammatory factors in the serum were detected by ELISA.3. The gene expressions of the mice exposure to MC-LR Total RNA and protein were isolated from the liver tissues of mice, the expressions of the genes and miRNA involved in the lipid metabolism were analysed.Results:Compared with the mice in the control group, the experimental mice showed significant body weight gain decreased, body fat increased, they were in the dose-dependent manner.Our results in the lipid metabolism-related markers in serum were indicated that high-density lipoprotein (HDL), fasting blood glucose (FBG) and triglyceride(TRIG) were decreased. Serum alanine aminotransferase (ALT) decreased in the experimental groups within the normal range. The mice in 20μg/kg·bw group showed pathological changes.The results displayed that the expressions of Angptl3 and PPARα were changed at mRNA and protein levels by the exposure to MC-LR. The relative amount of Angptl3 showed a significant reduction that may be correlated with the MC-LR dosage compared with the control.The bioinformatics software suggestted that miR-27b and miR-21 regulated Angtl3 and PPARα, respectively. We further studied their expressions by TaqMan miRNA assay, and the results demonstrated the expression of Angptl3 and PPARα protein were negatively correlated with miR-27b, miR-21.Conclusion:MC-LR chronic exposure in the environment is capable of impairing lipid metabolism, exhibiting the characteristics of increased body fat and the abnormal biomarkers in serum involved in lipid metabolism. This may be associated with the change expressions of Angptl3 and PPARα induced by MC-LR and regulated by miR-27b and miR-21, respectively. Therefore, MC-LR is a special environmental toxicant to increase the prevalence of lipid disorders.We supports the adventurous idea that MC-LR is a potential contributor, we should be particularly concerned with the non-pathological change of approximately 2.5 μg MC-LR/kg·bw group. When exposure to MC-LR for long term, it may lead the bodies to the high incidence of matabolism disorders such as type 2 diabetes mellitus (T2DM) and metabolic syndromeOur study may provide for the work basis and potential proof to assess the risk of dyslipidemia and blue-green algae pollution on human health,further to develop appropriate control measures and safety standards.