Effects Of Ketogenic Diet On Pancreatic β-cell Dedifferentiation And Liver Lipid Deposition In Db/db Mice

Objectives:To evaluate the effects of KD on pancreatic β-cell dedifferentiation and hepatic lipid deposition in db/db mice.Methods:In animal study,8-week-old db/db male mice with T2DM were randomly divided into three groups:T2DM group(ND),KD group(KD),75%CR group(CR),and 8-week-old C57BL/6 male mice were used as control group(C),which were fed with standard diet.The C and ND groups were free to eat the standard feed,the KD group was free to eat the ketogenic feed,and the CR group was the positive control group,and the standard feed was consumed with 75%of the calories of the ND group every day.4 weeks after the KD intervention,body weight,fasting blood glucose(FBG),fasting insulin(FINS),fasting blood lipid,glucose tolerance and blood(3-hydroxybutyric acid(BHB)were measured in each group.Morphology and structure of pancreatic islet and liver were observed by hematoxylin-eosin staining(HE).Immunofluorescence co-staining(IF)was used to observe the expression of mouse pancreatic βcell specific transcription factors.The size and number of lipid droplets in liver tissues of mice were observed by oil red O staining.qPCR was used to detecte the mRNA expression levels of sterol regulatory element binding protein 1c(SREBP1c),stearyl coenzyme A desaturase 1(Scd1),acyl coenzyme A oxidase 1(Acox1),peroxisome proliferator-activated receptor α(PPARa),Cluster of differentiation 36(CD36),tumor necrosis factor α(TNFα),interleukin β(IL1β),matrix metalloproteinase-13(Mmpl3),matrix metalloproteinase-inhibitor 1(Timp1),Collagen type Ⅲ alpha 1(COL3al)and Collagen type Ⅱ alpha 1(COL1a1)and other relevant factors.Immunohistochemistry(IHC)was used to detect the expression of fatty acid translocase(CD36)in liver tissues.Results:In animal study,after 1month intervention,the FBG,FINS in serum and the area under the curve of glucose were significantly reduced in KD group(P<0.05).HE showed that in KD mice,the morphology and structure of islets were more regular,and the number of β cells in the islets increased.IF showed that KD restored the number and arrangement of a cells,the ratio of β/cells,and the expression of specific β cell transcription factors such as pancreatic duodenal homeobox factor-1(PDX1),suggesting that KD significantly improved glucose metabolism and pancreatic β-cell dedifferentiation in db/db mice,alleviating the progression of T2DM.Compared with ND and CR groups,HE and oil red O staining showed that liver vacuolar degeneration and lipid deposition increased in KD group.qPCR showed that compared with ND group,the expressions of adipogenic factors SREBPlc and Scdl in liver tissue of KD group were significantly decreased(P<0.05),while the expressions of PPARa and Acox1 had no significant changes.The expression of inflammation-related genes such as IL1β and TNFα were significantly increased(P<0.05).The expression of Mmp13 was significantly decreased,while the expression of other hepatic fibrosis related genes was not significantly changed.qPCR and IHC results showed that compared with the ND group,the expression level of CD36 protein in the KD group was significantly increased(P<0.05).Conclusions:KD can not only reduce FBG and FINS,but also improve glucose tolerance in db/db mice,which may be related to its ability to restore the expression of specific β cell transcription factors and reverse the dedifferentiation of pancreatic β cells.KD can aggravate liver inflammation and may induces liver lipid deposition through CD36 in db/db mice.