| Objective: To study the therapeutic effect of benzoquinone isolated from the roots of Averrhoa Carambola L.(BACR)on streptozotocin(STZ)-induced diabetic mice,and to elucidate the in vivo effect and mechanism of BACR in the treatment of diabetes from thepoint of viewof TLR4 target and its downstream or related signaling pathways,so as to provide theoretical basis for the prevention and treatment of diabetes by BACR.Methods: The diabetic mice were induced by intravenous injection of STZ(120 mg/kg)after 3 days of adaptive feeding in male Kunming mice.All diabetic mice were randomly divided into five groups: model group,metformin group(320 mg/kg),BACR high,medium and low dosage,group(120 mg/kg,60 mg/kg,30 mg/kg),and then another normal group was set up.Drugs were intragastrically administered to mice for 21 days.Fasting blood glucose(FBG)and the change of body weight were measured in mice every 7 days,and oral glucose tolerance test(OGTT)was performed after the administration;biochemical indexes of serum were detected with automatic biochemical instrument;the serum levels of glycosylated hemoglobin(GHb),free fatty acid(FFA),monocyte chemoattractant protein-1(MCP-1),interleukin-1β(IL-1β)Interleukin-6(IL-6),tumor necrosis factor-α(TNF-α)were measured by ELISA;antioxidant capacity of liver tissue were measured by commercial kits.The pathological changes of liver and pancreas tissue were observed by HE staining;The expression of TLR4,My D88,NF-κB,IL-6,TNF-α,Bax,Bcl-2,Caspase-3were observed by immunohistochemistry and RT-q PCR.Furthermore,the expression levels of protein TLR4,My D88,IκBα(p-IκBα),NF-κB(p-NF-κB),Bax,Bcl-2 and Caspase-3 were detected by Western-blot.Results:1.Compared with the model group,the levels of FBG,TC,TG,LDL-C,BUN,Scr were significantly decreased in BACR groups,while the level of HDL-C was markedly increased(P < 0.05 or P< 0.01)as well as improved the glucose tolerance of mice.2.Compared with the model group,the serum levels of FFA,GHB,insulin,IL-1β,MCP-1,TNF-α and IL-6 were markedly reduced in BACR groups(P <0.05 or P < 0.01).3.Compared with the model group,the activities of SOD and GSH-Px in the liver significantly increased by BACR,whereas the content of MDA was decreased(P < 0.05 or P< 0.01).4.The pathological observation of liver and pancreas demonstrated that BACR significantly reduced the damage of liver cells,improved the pathological changes of liver caused by diabetes,as well as improved the morphology of pancreas,the islet were almost complete,and protected the isletβ cells.5.The results of immunohistochemistry in liver and pancreasshowed that the expression of TLR4,My D88,NF-κB,IL-6,TNF-α,Bax and Caspase-3 were significantly down-regulated in the BACR groups,whereas the expression of Bcl-2significantly increased.6.RT-qPCR results in liver and pancreasshowed that the expression of TLR4,My D88,NF-κB,IL-6,TNF-α,Bax and Caspase-3 m RNA significantly decreased,however,Bcl-2 m RNA was significantly elevated(P < 0.05 or P<0.01).7.Western-blot results in liver and pancreas showed that the expression of TLR4,My D88,IκBα(p-IκBα),NF-κB(p-NF-κB),Bax,Caspase-3 significantly decreased,the expression of Bcl-2 was increased(P < 0.05 or P< 0.01).Conclusions:BACR has potential benefits for the treatment by ameliorating metabolic functions on STZ induced diabetic mice,and its mechanism may be related to improving insulin resistance,inhibiting the release of inflammatory factors,enhancing antioxidant capacity,inhibiting apoptosis and regulating the TLR4/My D88/NF-κB signaling pathway. |
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