| [Objective]The experiment used ZDF as T2DM models to observe the effect of CA alcohol extract (CA) on islet function. It revealed the effect of centella asiatica alcohol extract on ZDF rat intestinal flora, inflammation, and the regulation mechanism of islet beta cells apoptosis.[Methods]In vivo experiment:8 male ZDF thin type rats were used as normal group of rats.24 male ZDF rats were divided into model group, Metformin group (M group) and CA group respectively. For the six-week gavage, the body weight and fasting blood glucose were measured every week, OGTT tested every two weeks, and GLU, TG, TC, HDL, LDL of serum were tested after sacrificed. The islet tissue was imbed and sliced for HE staining, immunohistochemistry, and TUNEL test. Rats’colon dung was taken for high-throughput 16s rDNA sequencing amplification. Detection was taken of the protein and mRNA of NADPH oxidase Phox p22, iNOS, Bcl-2, Caspase-3 in islet with Western blot and RT-PCR.[Results]In the sixth week, the body weight, FBG and RBG of model group increased significantly (P<0.01) compared with the normal group. For the CA group and M group, these items decreased significantly compared with the model group (P<0.05). The serum GLU, TG and LDL were significantly lowered (P<0.05) after treatment. The results of fasting insulin level showed that each group of ZDF fat rats were significant decrease (P<0.01) compared with normal group. CA group and M group were significant increase (P<0.05) compared with medol group. The results of insulin tolerance showed that the ITT AUC of each group of ZDF fat rats was significant increase (P<0.01) compared with normal group. The ITT AUC of CA group and M group were significant decrease (P<0.01) compared with medol group. The results of QUICK index showed that each group of ZDF fat rats were significant decrease (P<0.01) compared with normal group. CA group and M group were significant increase (P<0.01) compared with medol group.The TNF-α level of each group of ZDF fat rats were significant increase (P<0.05) compared with normal group. The CA group and M group were significant increase(P<0.01) compared with medol group. TUNEL detection results show that CA treatment could reduce the degree of islet cells apoptosis. According to 16 s rDNA sequences, the Prevotella species, Bacteroides and Firmicutes of model group on ZDF fat rats intestinal tract were significant increase compared with normal group. The CA was significant inhibited the abundance of the Prevotella species, Bacteroides and Firmicutes compared with model group. The results of Western blot and real-time PCR detection showed the protein and gene expressions of pancreatic tissue NADPH oxidase Phox p22 subunits, iNOS and Caspase-3 of model group were significant increased compared with normal group (P<0.05). The protein and gene expression of Bcl-2 was significant decrease compared with model group (P<0.01). The CA were significant inhibited the protein and gene expressions of NADPH oxidase Phox p22 subunits and Caspase-3, and increased the protein and gene expression of Bcl-2 compared with model group (P<0.05).(Conclusions]1 CA can significantly decrease blood glucose and inflammation level and increase insulin level of DM rats and has the effect of treating diabetes.2 CA can regulate inflammation of islet cells in diabetic rats and inhibit its cell apoptosis.3 CA can improve ZDF fat rat intestinal flora, regulate gene and protein expression of NADPH oxidase Phox p22, Bcl-2 and Caspase-3. In the present study, we have studied the hypoglycemic effect of CA on the ZDF rats. The underlying mechanism was revealed from the perspective of the gut microbiota, anti-inflammatory effect and inhibition effect of the pancreas islet cell apoptosis, which provides a new thought and method for screening the herbal drugs which protect the function of islet.
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