EGCG-mediated Regulation Of Lipid Metabolism In Mastitis Cows By AMPK

The health of mammary glands is an important guarantee for dairy cows’ normal lactation function.Mastitis can significantly reduce udder health and lactation performance in dairy cows,leading to lipid metabolism disorders in milk and reducing milk quality.Therefore,in-depth analysis of lipid metabolism changes in dairy cows with mastitis and the development of corresponding regulatory strategies are important issues that the dairy industry urgently needs to pay attention to and solve.AMP-activated protein kinase,as a regulator of nutrition and energy,is activated under conditions of energy deficiency and has anti-inflammatory and regulatory effects on lipid metabolism;epigallocatechin gallate(EGCG)is a polyphenolic substance that has antiinflammatory and regulatory effects on lipid metabolism.In order to explore the role of EGCG mediated AMPK in regulating lipid metabolism in mastitis cows,this study used Illumina HiSeq to sequence the transcriptome(RNA Seq)of blood samples from 10 healthy cows and 10 mastitis cows,and to determine the blood biochemical indicators and milk composition of each cow;cell culture experiments were used to analyze the mechanism of AMPK regulating lipid metabolism in dairy cows with mastitis.Bovine mammary epithelial cells(BMECs)were first cultured in a 6well plate until the growth density reached 70%～80%.After adding AMPK inhibitor(CSN15887)for 1 hour,lipopolysaccharide(LPS)was added to construct a control group(CON),LPS,LPS+CSN15887,and EGCG+LPS+CSN15887 group.In vivo results of cows revealed that:(1)there were significant changes in cellular immune response,immune related pathways(including IL-1β,IL17,NF-κB),and lipid metabolism related pathways(AMPK and other related signaling pathways)in mastitis cows;(2)the activity of superoxide dismutase(SOD)in the serum of mastitis cows was significantly reduced,the content of malondialdehyde(MDA)was significantly increased,the content of milk fat and milk protein was significantly reduced,and the pH was significantly reduced;(3)AMPK was highly expresses in the breast and activate in mastitis cows.The BMECs test results found that:(4)The optimal concentration of LPS-induced inflammatory injury in BMECs was 1 μg/mL,and the optimal treatment time was 12 h.The expression of inflammatory factors was significantly up-regulated in inflammation-injured BMECs,and lipid metabolism was disturbed;the expression of lipid synthesis-related genes and lipid oxidation genes in AMPK downstream pathway was down-regulated;and the disturbed lipid metabolism in inflammation-injured BMECs was alleviated after inhibition of AMPK signaling pathway,and it was determined that inhibition of AMPK pathway had the effect of promoting lipid deposition in inflammation-injured BMECs.(5)The optimal concentration of EGCG to alleviate inflammatory injury BMECs was 5 μg/mL,and the optimal treatment time was 6 h.EGCG could down-regulate inflammatory factor expression and promote lipid synthesis by significantly reducing AMPK expression in inflammatory injury BMECs.In conclusion,EGCG-mediated AMPK can play a role in regulating lipid metabolism in mastitis cows,improving mammary gland health and milk quality,providing theoretical basis and technical support for the study of EGCG effectively alleviating lipid metabolism in mastitis cows.