| Objective:The liver has robust regenerative potential.After alcohol,drugs and other poisons induce liver injury,or the liver is removed partially by operation,the residual hepatocytes under the stimulation of a variety of stress signals rapidly proliferate as compensation,so that the liver restores the original volume and function.Liver regeneration is a complex process controlled by a variety of cytokines and signaling pathways.A large number of studies have indicated that the metabolic change of glucose,lipid,protein and other substances caused by hepatic injury or partial resection is one of the decisive factors in liver regeneration,which plays an important role in the regulation of liver regeneration.It was found that the supplementation of glucose had inhibitory effect on liver regeneration after liver resection and liver injury,while supplementation with branched chain amino acid could promote the regeneration of liver.There are a large number of studies about the effects of hepatic lipid metabolism which is changed by drugs,food or genetic modification on the liver regeneration.The ketogenic diet(KD)is composed by high fat,low carbohydrate and appropriate protein.Fat replaces glucose as main energy source and blood sugar is lower and the generation of ketone bodies is increased in KD.It is used in treatment of children with intractable epilepsy and pleomorphic glial tumors.Effect of ketogenic diet on liver regeneration has not been reported.In this study,we establish the mice 70%liver removal model,to study the effect of ketogenic diet on mice liver regeneration,and to explore its mechanism.Methods:The BALB/c mice were randomly divided into two groups.They were given normal diet(ND)or ketogenic diet(KD)for four days,and the effect of ketogenic diet on the metabolism of mice was observed.Partial hepatectomy(PH),resulting in 70%removal of the liver was used toestablish a model of mouse liver regeneration and the mice wre divided into two groups postoperatively.One is ND group,the other is KD group.The mice of KD group were postoperatively given the ketogenic diet for 48 hours then the KD was changed to ND,but the mice of ND group was always given normal diet.After Oh,24h,36h,48h,72h,96h,144h,168h,192h and 240h,the livers were collected.The liver and body was weighed and liver weight/body weight was calculated.The liver HE staining was observed through microscopy and percentage of mitotic cells at different time points was determined.BrdU immunohistochemical staining was performed to count the number of BrdU positive cells in 100 hepatocytes under high magnification.Serum triglyceride,total cholesterol,free fatty acids,transaminase and beta-hydroxybutyric acid(?-HB)level was tested.The triglyceride,cholesterol and glycogen in liver were determined.The expression of metabolism related genes in liver tissue was detected by Realtime-PCR in the two groups of mice.TNF-a and IL-6 in plasma was detected by ELISA after 48 hours.The expression of the protein related to the signal pathway of proliferation by western blott in the liver.Results:Fatty acid oxidation was enhanced and blood glucose was decreased by ketogenic diet in a short time(24 hours).No obvious liver injury was observed in short term ketogenic diet.We found that after 7 days and 8 days,the liver weight/body weight of mice in KD group was significantly lower than that of ND group postoperatively.However,the two groups had no significant difference after 10 days.HE staining showed that hepatocytes in the state of mitosis of mice in KD group were obviously less than group ND after 48 hours and 72 hours.BrdU immunohisto-chemical staining showed that the number of BrdU positive cells in KD group was significantly less than that of ND group after 36 hours and 48 hours.We examined the expression of cell proliferation related protein PCNA by WB in two groups.We found that the peak of PCNA of mice in KD group was significantly later than that in ND group.QRT-PCR analysis showed that mRNA of IL-6 significantly decreased and mRNA of TNF-a decreased(p=0.07).ELISA analysis showed that TNF-a in plasma of mice in KD group was significantly lower than that of ND group and IL-6 in plasma of mice in KD group decreased compared with the ND group(p=0.10).WB showed that phosphorylation of STAT3 in the liver of mice in KD group was significantly lower than that in ND group postoperatively after 48 hours.Phosphorylation of ERK1/2 in the liver of mice in KD group was significantly lower than that in ND group after 24h and 36h postoperatively.Phosphorylation of AKT was the strongest after 24h in the ND group,while the KD group was the strongest after 36h postoperatively.Conclusion:Fat is used as the main source of energy in short-term ketogenic diet.The ketogenic diet delays but does not inhibit liver regeneration after partial hepatectomy secondary to weaked TNF a-IL6-STAT3 signaling pathway activiation and ERK and delayed phosphorylation of AKT. |
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