RESUMO
ObjectiveTo investigate the effect and mechanism of Mori Folium extract on the glucose and lipid metabolism disorders in the liver of rats with type 2 diabetes mellitus （T2DM） through the phosphatidylinositol 3-kinase/protein kinase B/peroxisome proliferation-activated receptor α/carnitine palmitoyl transferase-1 （PI3K/Akt/PPARα/CPT-1） signaling pathway. MethodThe T2DM model was induced by the high-fat diet combined with the intraperitoneal injection of streptozotocin （STZ）. The model rats were randomly divided into a model group， a metformin （0.2 g·kg-1） group， and a Mori Folium water extract （4.0 g·kg-1） group according to blood glucose and body weight. In the 8-week administration， fasting blood glucose was measured at the same time every week. The histomorphological and fat changes in the rat liver were observed by hematoxylin-eosin （HE） staining and oil red O staining. The levels of total cholesterol （TC）， triglyceride （TG）， low-density lipoprotein cholesterol （LDL-C）， high-density lipoprotein cholesterol （HDL-C）， alanine aminotransferase （ALT）， and aspartate aminotransferase （AST） in the serum were measured by biochemical methods. Western blot （WB） was used to quantitatively detect the protein expression of p-PI3K，PI3K，p-Akt，Akt，PPARα，and CPT-1 in the rat liver. ResultAfter 8-week administration， the blood glucose of rats was higher in the model group than that in the control group （P<0.01）， and lower in the Mori Folium water extract group than that in the model group （P<0.01）. The results of HE staining showed that the liver tissue structure of the control group was complete， and the hepatocytes were arranged radially around the central vein， while the hepatocyte injury in the model group was obvious. Compared with the model group， the Mori Folium water extract group showed improved vacuolar degeneration and no lesions such as small bile duct hyperplasia. Oil red O staining showed that there was no obvious steatosis and necrosis in the hepatocytes of rats in the control group， and no lipid droplets in the hepatocytes were observed， while the model group showed increased lipid droplets. Mori Folium significantly reduced the lipid droplets in the liver. Biochemical analysis showed that the levels of TC， TG， LDL-C， AST， and ALT in the model group were significantly higher than those in control group （P<0.01）. The levels of TC， TG， LDL-C， AST， and ALT in the Mori Folium water extract group were significantly lower than those in the model group （P<0.05，P<0.01）. WB showed that the protein expression of p-PI3K/PI3K， p-Akt/Akt， PPARα， and CPT-1 in the model group were lower than those in the control group （P<0.01）. Mori Folium water extract could increase the protein expression of p-PI3K/PI3K， p-Akt/Akt， PPARα， and CPT-1 （P<0.05 or P<0.01）. ConclusionThe hypoglycemic mechanism of Mori Folium water extract may be related to the regulation of the PI3K/Akt/PPARα/CPT-1 signaling pathway.