Tanshinone I’effect On Fasting Blood Glucose Of Mice With Type 2 Diabetes Mellitus And Its Partial Mechanism

The disease of Type 2 diabetes mellitus(T2DM) has a large proportion in diabetes and the proportion of patients who are sufferring from T2DM is 90%in all diabetics. T2DM has threaten our health badly for a long time. Tanshinone I is usually extracted from salvia miltiorrhiza quinone I which is a liposoluble compound.There isn’t any report about the anti-diabetic effect of Tanshinone I so far. The essay aims to observe the anti-diabetic effect of tanshinone I on mice with T2DM, induced by high-fat diet and consecutive low-dose streptozotocin (STZ) intraperitoneal injections or insulin-resistant HepG2 cells and to explore its potential mechanism.In vivo experiments, ICR mice were randomly allocated into normal-fat diet (NFD) group and high-fat diet (HFD) group. The mice were fed on normal chow and high-fat diet respectively for four weeks. STZ was administrated through intraperitoneal (i.p.) injection (40mg/kg) on the HFD mice every third day for five consecutive times. Mice remained the state of fasting before STZ injection. After two weeks of STZ administration, the HFD mice exhibiting fasting blood glucose (FBG) levels≥ 13.89 mmol/L were considered to be diabetic and then divided randomly into the model group,high-dose tanshinone I group, medial-dose tanshinone I group, low-dose tanshinone I group, the metformin(Met) group and the pioglitazone (Pio) group. The groups above were fed with high-fat diet and received daily injections of various-dose drugs as previously described for a period of three weeks. Body weight and FBG level were monitored weekly to mice of all the seven groups. Resuts showed that Mice in the model group showed less activity and the body weight was significantly lower than that in high-dose tanshinone I group(P<0.05) at the third week. FBG was significantly higher than that in NFD group, high-dose tanshinone I group, Met group and Pio group(P<0.05).Livers were rapidly isolated from mice at the end of the 3-week period of drug intervention. Observe pathological changes in lives and protein expression levels of PTP1B, Akt, P-Akt of all the groups by means of hematoxylin and eosin (HE) staining, the immunohistochemical experiment, tissue microarray and Western blot. Immunohistochemistry showed that the protein expression of PTP1B was significantly higher than that in NFD group, high-dose tanshinone I group, Met group and Pio group(P<0.05). Analysis of Western blot revealed that PTP1B expressed significantly higher in the model group than that in NFD group, high-dose tanshinone I group, medial-dose tanshinone I group, Met group and Pio group(P<0.05). P-Akt expressed significantly lower in the model group than that in NFD group, high-dose tanshinone I group, Met group and Pio group(P<0.05).The above results suggested that tanshinone I in high concentration could lessen fast blood glucose(FBG) and protect from the liver injury.At the same time, it could reduce the protein expression levels of PTP1B in T2DM mice, induced by STZ injections.In vitro experiments, Insulin-resistant HepG2 cells were cultivated by insulin in high dose and they had been cultivated eventually. The accurate concentration of insulin and appropriate periods of time had been determined:10-7 mol/L insulin for 24 hours. The proper concentration of tanshinone I was determined by the MTT assay and ultimate concentrations of tanshinone I had also been determined(78,156 and 312 ng/ml). The glucose consumption were detected by the glucose assay kit. Results showed that the glucose consumption would be larger while the concentration of tanshinone I was increasing for insulin-resistant HepG2 cells. Finally, observe protein expression levels of PTP1B, Akt and P-Akt by means of Western blot.Western blot showed that PTPIB expressed higher in model groups than that in normal groups and P-Akt expressed lower in model groups than that in normal groups. the expression of PTPIB and decreased expression of P-Akt in model group compared with the normal group. Moreover, tanshinone I could increase the protein expression levels of P-Akt and lower that of PTPIB with the comparison of model groups.Our research has drawn several conclusions as follows:(1) The protein expression levels of PTP1B inT2DM mice induced by STZ increased obviously.(2) Tanshinone I in high concentration could lessen fast blood glucose(FBG) and protect from the liver injury. At the same time,it could reduce the the protein expression levels of PTPIB in T2DM mice, induced by STZ injections. The potential mechanism might be that tanshinone I could increase the protein expression levels of P-Akt.(3) Tanshinone I could improve insulin resistance in HepG2 cells.The potential mechanism may be that tanshinone I could inhibit the protein expression levels of PTP1B and activate the PI3K/Akt signaling pathway.