Expression of Raf kinase inhibitor protein and p-ERK in renal tissues of diabetic rats

AIM: To investigate the expression of Raf kinase inhibitor protein (RKIP) and phosphorylated extracellular signal-regulated kinase (p-ERK) in the renal tissues of diabetic rats. METHODS: Forty SD rats were randomly divided into normal control group and diabetic nephropathy group. The pathological changes of the renal tissues were observed under microscope with HE and periodic acid-Schiff (PAS) staining. The expression of RKIP and p-ERK1/2 was detected by the methods of immunohistochemistry and Western blotting. RESULTS: Following the extension of duration, the blood sugar of the rats in diabetic nephropathy group increased, with the appearance of proteinuria, increase in kidney weight, increase in renal p-ERK1/2 expression and decrease in RKIP expression as compared with control group. CONCLUSION: The development of diabetic nephropathy may be accelerated by the decrease in RKIP and the increase in p-ERK.     

Mechanism of vascular endothelial growth factor in diabetic rat retinopathy

AIM: To study the molecular mechanism of vascular endothelial growth factor (VEGF) in pathogenesis of diabetes in rats. METHODS: The diabetic rat model was established by using streptozocin. The animals were divided into normal control (C group), diabetic for one month (M₁ group), for three months (M₃ group) and for five months (M₅ group). In situ hybridization and immunohistochemistry were conduced to observe the expression of VEGF on retinal digest preparation and paraffin section. RESULTS: 1. On paraffin section: the positive rate of VEGF expression in M₅ group was 67% by in situ hybridization and 89% by immunohistochemistry. There was only 34% positive expression of VEGF in M₃ group by immunohistochemistry. 2. On retinal digest preparation: the VEGF positive expression rate in M₅ group was 34% by in situ hybridization and 56% by immunohistochemistry. CONCLUSION: Both endothelial cells and Mural cells and Müller cells express VEGF. The source of VEGF may be from the paracrine pathway in early stage of diabetic retinopathy.     

Alleviation of aortic vascular dysfunction in STZ/HFD-induced type 2 diabetic rats by nFGF1

AIM: To investigate the protective effect of non-mitogenic fibroblast growth factor 1 (nFGF1) on the aortic vascular function in streptozotocin (STZ)/high-fat diet (HFD)-induced type 2 diabetic rats and its underlying mechanisms. METHODS: Five-week-old male SD rats (n=30) were randomly divided into 3 groups (n=10 in each group), including normal control group, type 2 diabetic group and nFGF1 treatment group (type 2 diabetic rats were intraperitoneally injected with 0.5 mg/kg nFGF1 every other day for 4 weeks). After the rats were sacrificed, blood glucose, cholesterol and triglyceride levels, aorta diastolic function and superoxide dismutase (SOD) level in the aorta of each group were measured. Besides, the protein levels of cyclooxygenase-2 (COX-2), phosphorylated extracellular signal-regulated kinase (p-ERK) and endothelial nitric oxide synthase (eNOS) in the aorta were determined by Western blot. RESULTS: nFGF1 markedly lowered blood glucose, cholesterol and triglyceride levels, enhanced aorta SOD activity and upregulated protein level of eNOS in the type 2 diabetic rats. Furthermore, the increased protein levels of COX-2 and p-ERK in the type 2 diabetic rats were largely abrogated by nFGF1. CONCLUSION: nFGF1 effectively attenuates aortic vascular dysfunction in the type 2 diabetic rats, which may be associated with decreasing blood glucose, cholesterol and triglyceride levels, reducing inflammation and oxidative stress response, and activating eNOS signaling pathway.     

RTN1A induces renal tubular epithelial cells to secrete VEGF and IL-8 and promotes diabetic nephropathy renal fibrosis via ERK signaling pathway

AIM:To investigate the effects of reticulon 1A (RTN1A) on the secretion of vascular endothelial growth facter (VEGF) and interleukin-8 (IL-8) in renal tubular epithelial cells, and on the diabetic nephropathy (DN) renal fibrosis, and to explore the underlying mechanism. METHODS:The mouse model of DN was established, and the blood glucose, kidney index, urine microalbumin (UMA) and creatinine clearance (CCr) were measured. The protein levels of RTN1A, p-ERK, ERK, VEGF, IL-8 and renal fibrosis markers α-smooth muscle actin (α-SMA) and fibronectin (FN) were determined by Western blot. Human renal tubular epithelial cell line HK-2 was treated with high glucose, and the ERK signaling proteins, fibrosis markers and secretion of cytokines were detected by Western blot and ELISA. The cells were treated with high glucose combined with RTN1A silencing or ERK inhibitor PD98059 for 24 h, and the ERK signaling proteins, fibrosis markers and secretion of cytokines were also detected by Western blot and ELISA. RESULTS:The blood glucose, kidney index, UMA and CCr in the DN mice were significantly higher than those in control group (P<0.05), suggesting that DN model was successfully constructed. The protein levels of RTN1A and its downstream protein p-ERK, the cytokines VEGF and IL-8, and the fibrosis markers α-SMA and FN were significantly increased in the DN model mice (P<0.05). The protein levels of RTN1A, p-ERK, VEGF, IL-8, α-SMA and FN were also significantly increased in the HK-2 cells after treated with high glucose for 24 h, while these proteins were significantly decreased after silencing of RTN1A expression. CONCLUSION:RTN1A may be associated with the occurrence and development of DN. Silencing of RTN1A expression inhibits DN renal inflammation and fibrosis through ERK signaling. RTN1A may be an effective therapeutic target.     

Effect of curcumin on p-ERK1/2-AP-1 cascade and diabetic neuropathic pain in rats

AIM: To evaluate the role of p-ERK1/2-AP-1 cascade in the process of curcumin against diabetic neuropathic pain (DNP) in rats.METHODS: Ninety-six male Sprague-Dawley rats were randomly divided into 4 groups (n=24): normal control group, DNP group, DNP with solvent group and DNP with curcumin (100 mg/kg) group. The rat model of diabetes was induced by a single intraperitoneal injection of streptozotocin (STZ, 75 mg/kg). Mechanical allodynia and thermal hyperalgesia were tested by mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) 2 weeks after induction,respectively. The diabetic rats were treated with curcumin (100 mg·kg^-1·d^-1, ip) for 2 weeks. The conditions of hyperalgesia and allodynia were determined 2 d before STZ injection, 14 d after STZ injection, and 3 d, 7 d, 14 d after administered with curcumin. The change of p-ERK1/2 was measured by the methods of Western blotting and immunohistochemistry. The expression of AP-1 in spinal cord dorsal horn and dorsal root ganglion (DRG) was detected by electromobility shift assay (EMSA).RESULTS: Compared with normal control group, the rats in DNP group developed hyperglycemia and a decrease in MWT and TWL associated with an increase in the activity of p-ERK1/2 and AP-1 in dorsal horn and DRG(P<0.05). Compared with DNP group, 7-day treatment with curcumin significantly attenuated mechanical allodynia and thermal hyperalgesia, and these effects were correlated with inhibiting the hyper-activation of p-ERK1/2 and AP-1 14 days after treatment with curcumin (P<0.05).CONCLUSION: Curcumin has beneficial effects on hyperalgesia in STZ-induced peripheral neuropathic pain. Activation of p-ERK1/2 and AP-1 may be the key mechanism of DNP in spinal cord and DRG.     

Effect of EGB on pituitary-testicular axis and expressions of LHR and StAR in type II diabetic rats

AIM: To observe the effect of the extract of Ginkgo biloba(EGB) on pituitary-testicular axis and the mRNA expressions of luteinizing hormone receptor (LHR) and steroidogenic acute regulatory protein (StAR). METHODS: Thirty male Sprague-Dauley rats were divided into three groups randomly: normal control group, type II diabetic group and EGB treatment group. After fed with high-fat diet for 4 weeks, the later two groups were injected with strepozotocin intraperitoneally to induce type II diabetes mellitus. The EGB treatment group was given EGB at the dose of 50 mg/kg once a day for 12 weeks by intragastric administration. The normal control and diabetic group were given normal saline of equal volume per day for 12 weeks. The indices of blood glucose, insulin and low-density lipoprotein-cholesterol (LDL-c) were measured. The morphologic change of testicular tissue was observed under light microscopy (LM) and transmission electron microscopy (TEM) respectively. The concentrations of blood luteinizing hormone (LH) and testosterone (T) were assayed by the technique of enzyme linked immunosorbent assay (ELISA). The mRNA expressions of LHR and StAR from Leydig cells were detected by RT-PCR. RESULTS: The concentrations of blood glucose, insulin and LDL-c increased obviously, and the testis weights lessened obviously in type II diabetic groups compared to those in normal control groups. Rare spermatogenic cells of seminiferous tubule and germinal arrest were observed in diabetic group under LM. Ultrastructural analysis of testicular tissue by TEM showed dilation of the endoplasmic reticulum and mitochondrial swelling in Leydig cell and sertoli cell in diabetic group. The level of blood LH and T decreased in type II diabetic groups in comparison with that in the normal control group. Compared to normal groups, the mRNA expression of StAR in type II diabetic groups decreased, while the mRNA expression of LHR increased. After the treatment of EGB, the pathological change of testis was relieved, the concentrations of blood glucose, insulin and LDL-c were decreased, the level of blood LH and T, and the mRNA expression of StAR were increased, and the mRNA expression of LHR descended compared to type II diabetic groups. CONCLUSION: EGB may increase the LH-induced testosterone production by correcting metabolic disorder of glucose and lipid, improving the function of pituitary-testicular axis and regulating the expression of LHR and StAR mRNA.     

Expression and significance of stanniocalcin 2 in diabetic retinopathy

AIM To investigate the expression level of stanniocalcin 2 (STC2) in vitreous tissues of rats with diabetic retinopathy (DR), and to explore the relationship between STC2 and vascular endothelial growth factor (VEGF). METHODS Wistar rats were randomly divided into control group and DR group. The DR model was constructed by injection of streptozotocin. RT-qPCR, Western blot and ELISA were used to detect the expression levels of STC2 and VEGF in rat vitreous tissues. Rat retinal ganglion cells were treated with VEGFA, and the expression of STC2 was detected by RT-qPCR, Western blot and ELISA. The retinal ganglion cells were also treated with STC2 protein, and then the expression of VEGF was detected by RT-qPCR, Western blot and ELISA. Co-immunoprecipitation was used to detect the interaction between VEGF and STC2. RESULTS Compared with control group, the mRNA and protein levels of STC2 were significantly increased in vitreous tissues of the rats with DR, and the expression level of VEGF was also significantly increased in DR group (P<0.01). The expression level of STC2 was positively correlated with VEGF expression. VEGF induced the expression of STC2 in rat retinal ganglion cells and promoted its secretion. STC2 protein induced the expression and secretion of VEGF in rat retinal ganglion cells, and VEGF had certain interaction with STC2. CONCLUSION STC2 expression is significantly increased in vitreous tissues of the rats with DR, and is closely related to VEGF.     

Effects of PTEN/AKT/mTOR signalling pathway on regulation of autophagy in renal tissues of diabetic rats

ATM:To observe the expression change of PTEN and autophagy in the renal tissues of diabetic rats, and to explore the regulatory mechanism of PTEN/AKT/mTOR pathway to autophagy in diabetic nephropathy. METHODS: The Sprague-Dawley rats were randomly divided into normal control group and diabetic group (8 in each group). The diabetic rat model was established by injection of streptozotocin. The biochemical and kidney indexes were measured after the model of diabetic nephropathy was successfully established. The expression location of PTEN in the renal tubular epithelial cells was observed by the method of immunohistochemistry. The protein levels of autophagy-related protein LC3, PTEN and PTEN/AKT/mTOR signalling molecules were determined by Western blotting. The mRNA expression of PTEN was detected by real-time PCR. RESULTS: The blood glucose, 24 h urine protein and kidney index in diabetic group were all obviously higher than those in control group. Compared with control group, the protein levels of LC3I and LC3II in diabetic group were obviously decreased. PTEN was mainly located in the renal tubular epithelial cells. Compared with control group, the protein expression of PTEN was significantly down-regulated in diabetic group. Furthermore, the activity of PTEN/AKT/mTOR pathway increased in diabetic nephropathy rats. CONCLUSION: The level of autophagy in renal tissues of diabetic rats is decreased, whereas the activity of PTEN/AKT/mTOR pathway is increased. The level of autophagy may be mediated by PTEN/AKT/mTOR pathway.     

Expression of zinc-finger transcription factor Snail 1 in the kidney of diabetic rats

AIM: To explore the expression of Snail 1 in renal tissues of diabetic rats, and to investigate its contribution to the progression of diabetic nephropathy. METHODS: Streptozotocin-induced diabetic rats were randomly divided into 2, 4, 8, 12, 16, 20, 24 weeks groups and 16 week A, 20 week A and 24 week A groups. A groups were treated with insulin to control blood glucose to normal level from the 13th week. Control groups were set up in age-matched time points. Blood glucose, 24 h urine protein, serum creatinine (Scr) and kidney index of rats were measured. Periodic acid-silver (PAS) staining was used to observe the renal pathological changes. The mRNA and protein expressions of Snail 1 and FN in renal cortex were detected by RT-PCR and immunohistochemical staining, respectively. Western blotting was employed to detect the expression of Snail 1 protein in the renal cortex. RESULTS: The levels of blood glucose, Scr, kidney weight index were increased remarkably in diabetic rats as compared with those in control groups (P<0.05, P<0.01), and decreased remarkably in the insulin-treated rats as compared with those in the diabetic rats (P<0.05, P<0.01). The Snail 1 protein was not detected by immunohistochemical staining in normal renal tissues. However, strongly positive staining was observed in renal tubules of diabetic rats. A time-dependent loss of Snail 1 expression was detected in the kidney in insulin-treated rats. The Snail 1 protein and mRNA of Snail 1 and FN were significantly up-regulated in the diabetic rats as compared with those in controls (P<0.01), while down-regulated in the insulin-treated diabetic rats (P<0.01). A close positive relationship existed between the mRNA expression of Snail 1 and FN (r=0.800, P<0.01). The level of Snail 1 protein expression was positively correlated with blood glucose, urine protein, Scr, kidney index (r=0.877, 0.694, 0.522, 0.875, P<0.01).CONCLUSION: These findings suggest that Snail 1 gene and protein expression are up-regulated in the kidney of rats with diabetes and may be involved in the pathogenesis of diabetic nephropathy.     

Effects of extract of Ginkgo biloba on cognitive function and apoptosis of hippocampus neuronal cells in type 1 diabetic rats

AIM: To investigate the protective mechanism of extract of Ginkgo biloba (EGB) on apoptosis of hippocampus neuronal cells in type 1 diabetic encephalopathic rats. METHODS: Thirty-six male Sprague-Dauley rats were divided into 3 groups: control group, diabetic group and EGB-treated group. Streptozotocin was injected intraperitoneally to the animals in later two groups to induce diabetes. The rats in EGB-treated group were injected intraperitoneally with EGB, and the same volume of normal saline was injected to the rats in other groups. At the end of the 12th week, the spatial learning and memory abilities of rats in each group were examined by Morris water maze test. Blood glucose and serum insulin concentration were measured. The neuron densities in hippocampus were measured by Image-Pro Plus 6.0 software. The expressions of Bax, Bcl-2, caspase-3 were assayed by Western blotting and immunohistochemistry. RESULTS: Compared to control group, the level of blood glucose (P<0.01), the protein expression of Bax (P<0.01) and caspase-3 (P<0.01) in hippocampus neuronal cells, and the ratio of Bax/Bcl-2 (P<0.01) and the escape latency (P<0.01) in diabetic group, were significantly increased, while the serum insulin concentration (P<0.01), the neuronal density (P<0.05) in CA1,CA2 hippocampal regions and the platform searching score (P<0.01) were significantly deceased. After treated with EGB, the serum insulin concentration (P<0.05), the neuronal density (P<0.05) in CA1,CA2 hippocampal regions and the platform searching score (P<0.01) were significantly increased, while the level of blood glucose (P<0.01), the protein expression of Bax (P<0.05), caspase-3 (P<0.05) in hippocampus neuronal cells, the ratio of Bax/Bcl-2 (P<0.01) and the escape latency (P<0.05) were significantly deceased than those in diabetic group. The protein expression of Bcl-2 in hippocampus neuronal cells did not alter in any experimental rats. CONCLUSION: EGB improves the spatial learning and memory capacity in diabetic rats by decreasing the expression of Bax, Bax/Bcl-2 ratio and down-regulating caspase-3 to reduce neurocyte apoptosis and increase the neuron density in CA1, CA2 hippocampal regions, suggesting that effective regulation of neuron apoptosis associated genes may be one of the mechanisms for EGB to treat diabetic encephalopathy.     

Effects of extract of gingko biloba on expression of glucocorticoid receptor in hepatic tissues from type 2 diabetic rats

AIM: To study the effect and mechanism of extract of ginkgo biloba (EGB) on liver glucocorticoid receptor (GR) expression in type 2 diabetic rats. METHODS: Thirty male Sprague-Dawley rats were divided randomly into three groups: normal control group (n=10), type 2 diabetic group (n=10) and ginkgo biloba treated group (n=10). After fed with high-fat feeding for 4 weeks, the later two groups were injected with streptozotocin at a dose of 30 mg/kg intraperitoneally to induce type 2 diabetic rat model. The EGB treated group was gavaged with EGB at the dose of 50 mg·kg-1·d-1 for 12 weeks. At the end of experiment, the rats were sacrificed, the blood glucose, serum lipid and blood insulin were measured. The morphology of liver tissue was observed under light microscopy with HE staining. GR mRNA expression in liver was measured by RT-PCR. The level of GR protein expression in liver tissue was detected by immunohistochemistry. RESULTS: EGB reduced the levels of blood glucose, blood lipids, blood insulin in diabetic rats. EGB also relieved fatty degeneration and necrosis of the hepatic cells, ameliorated infiltration of inflammatory cells in the liver; and decreased GR expression at both mRNA and protein levels in diabetic liver. CONCLUSION: EGB may inhibit GR expression in liver of type 2 diabetic rats, which results in decreasing the level of blood glucose, blood lipid, blood insulin and relieving the liver damage in type diabetic rats.     

Grape seed proanthocyanidin regulates expression of GSTM through Nrf2 in renal tissues of STZ-induced diabetic rats

AIM: To investigate the potential mechanisms of renoprotective effect of grape seed proanthocyanidin (GSP) on diabetic nephropathy.METHODS: Male Wistar rats were injected with 1% streptozotocin (STZ) intravenously to induce diabetes mellitus (DM). The diabetic rats were randomly divided into 2 groups: diabetes group (DM group) and GSP treatment group (GSP group, GSP 250 mg·kg^-1·d^-1). The normal Wistar rats served as control (C group). Body weight (BW), systolic pressure, kidney weight/body weight (KW/BW), fasting plasma glucose (FPG), blood urea nitrogen (BUN), serum creatinine (SCr), glycosylated hemoglobin (HbA1c) and 24 h urine protein were determined 24 weeks after STZ intervention. The pathological changes of the renal tissues were observed. The protein levels of glutathione S-transferase mu (GSTM) and nuclear factor-erythroid 2-related factor 2 (Nrf2) in the renal tissues were determined by Western blotting and immunohistochemistry. RESULTS: Compared with C group, BW in diabetic rats decreased (P<0.01). The levels of systolic pressure, FPG, HbA1c, KW/BW, 24 h urine protein, BUN and SCr in DM group were higher than those in C group (P<0.01). After treated with GSP, the levels of systolic pressure, KW/BW, 24 h urine protein, BUN and SCr in DM rats were lower than those in DM rats without treatment (P<0.01 or P<0.05). The pathological changes were ameliorated in GSP group. The expression of GSTM and Nrf2 was up-regulated in the kidneys of diabetic rats and down-regulated to the normal levels after GSP treatment. CONCLUSION: The renoprotective effect of GSP is associated with the down-regulation of GSTM through modulating the expression of Nrf2.     

Effect of curcumin derivative B06 Bob on synthesis of testosterone from type 2 diabetic rats

AIM: To investigate the effect of curcumin derivatives B06(B06) on the synthesis of testosterone from type 2 diabetic rats. METHODS: Male Sprague-Dawley rats were evenly divided into 5 groups randomly: normal control group (C group), high fat group (H group), high fat treatment group (HT group), diabetes mellitus group (D group) and diabetes treatment group (DT group). The rats in the later 4 groups were fed with high fat diet, after 4 weeks of high fat diet feeding, the rats from D group and DT group were injected with low dose of streptozotocin intraperitoneally to induce diabetes mellitus, while the rats in HT group and DT group were gavaged with B06 at the dose of 0.2 mg·kg^-1·d^-1 for 8 weeks. The blood glucose was detected by glucometer, blood insulin was assayed by ELISA and the insulin resistance index was calculated. The morphology of testes were observed by light and transmission electron microscopy. Serum testosterone and estradiol were measured by radioimmunoassay. The protein expression of steroidogenic acute regulatory protein (StAR) was detected by immunohistochemistry. The mRNA expression of StAR, cholesterol side-chain cleavage enzyme (P450scc), cytochrome P450 17A1 (P450c17), cytochrome P450 aromatizing enzyme (P450arom), 3β-hydroxysteroid dehydrogenase (HSD) and 17β-HSD was detected by RT-PCR. RESULTS: The levels of blood glucose and insulin resistance index were increased in H group and D group, and serum testosterone was decreased, all of which were reversed after the treatment of B06. Testicular seminiferous tubule was distorted, spermatogenic cells were dropped in H group and D group. In addition, leydig cells were found to have swelling mitochondria in H group and D group, endoplasmic reticulum was reduced, and there was karyopyknosis accompany with sparse chromatin, all of which were ameliorated by B06. The protein expression of StAR was decreased in D group. The mRNA expression of StAR and P450scc was decreased in H group and D group, all of which were increased in B06 treatment group. There was no significant difference in the mRNA expression of P450c17, P450arom, 3β-HSD and 17β-HSD. CONCLUSION: B06 may increase serum testosterone and relieve the damage of testes from type 2 diabetic rats. B06 improves metabolic disorder by up-regulating mRNA expression of StAR and P450scc.     

Protective effect of curcumin on myocardium in diabetic rats

AIM: To study the effects of curcumin (Cur) on diabetic cardiomyopathy (DCM) in rats. METHODS: Male Wistar rats (n=75) were divided into control group and diabetes model group, in which the rats were fed with high-fat diet and then intraperitoneally injected with streptozotocin (STZ, 40 mg/kg). Fasting blood glucose was measured 72 h and 1 week after STZ injection. The diabetic rats were diagnosed when sustained fasting blood glucose levels ≥ 11.6 mmol/L. The diabetic rats were randomly divided into DCM group, DCM+Cur 100 mg/kg group and DCM+Cur 200 mg/kg group. After treatment for 16 weeks, glutathione peroxidase (GSH-Px) activity and malondialdehyde (MDA) level were measured, and the level of cardiac troponin I (cTnI) in the serum was determined by enzyme-linked immunosorbent assay. The protein expression of protein kinase C (PKC) was detected by Western blotting. RESULTS: Curcumin significantly decreased the blood glucose level, increased the body weight, inhibited MDA content and up-regulated the GSH-Px activity in the diabetic rats. Furthermore, curcumin treatment inhibited the diabetes-induced protein expression of PKC. CONCLUSION: Curcumin may have a protective effect on diabetic cardiomyopathy by attenuating oxidative stress.     

Effects of extract of gingko biloba on the lipid metabolism and the function of macrophages from diabetic rats

AIM: To study effect of extract of ginkgo biloba (EGb) on the lipid metabolism and the function of macrophages from diabetic rats.METHODS: Sprague-Dauley rats were divided into four groups: normal control group, high-fat group, diabetic group and EGb treatment group.At the end of experiment, the rats were sacrificed, the blood glucose, blood insulin and serum lipid were measured.The activity of superoxide dismutase (SOD), content of malondialdehyde (MDA), nitric oxide (NO) in alveolar macrophages (AM) and peritoneal macrophages (PM) were assayed.In addition, peroxisome proliferator activated receptor γ (PPARγ), CD36 mRNA expression in AM was measured by RT-PCR.RESULTS: The concentration of the blood glucose, blood insulin and total cholesterol (TC), total triglycerides (TG), low-density lipoprotein- cholesterol (LDL-C) in blood increased significantly in type 2 diabetic group.The supplement of EGb decreased blood glucose, blood insulin and TC, TG, LDL-C levels.The activity of SOD decreased, while the content of NO, MDA increased in the diabetic macrophages, the activity of SOD became increased, but the content of NO and MDA decreased in EGb-treated group.The mRNA expression level of CD36 and PPARγ in alveolar macrophages from diabetic group increased, while expression level of CD36 and PPARγ mRNA in EGb treated rats continued to rise.CONCLUSIONS: EGb corrected insulin resistance and ameliorated disturbance of lipid metabolism caused by type2 diabetes in rats.Adjustment of PPARγ and CD36 mRNA expression of as well as reduction of lipid peroxidation and NO level may be involved in this process.     

Role of focal adhesion kinase expression in renal tissues of type 2 diabetic rats

AIM：To explore the dynamic change of focal adhesion kinase (FAK) in renal tissues of rats with type 2 diabetes mellitus (T2DM), and to investigate its role in the pathogenesis of diabetic nephropathy (DN). METHODS：The rat model of T2DM was established and the diabetic rats were randomly divided into 8-week DM (DM8), 12-week DM (DM12) and 16-week DM (DM16) groups. Meanwhile, normal control (NC) and high-fat high-sucrose control (HC) groups were also established. The protein expression of FAK, transforming growth factor β1 (TGF-β1), extracellular signal-regulated kinase 1/2 (ERK1/2), p-ERK1/2 and fibronectin (FN) was detected by immunohistochemical staining. The protein levels of FAK and p-FAK (Tyr397) were detected by Western blotting. The mRNA level of FAK in the renal cortex was examined by RT-PCR. RESULTS：The expression of FAK protein in renal tubular epithelial cells in DM12 and DM16 groups was significantly higher than that in NC, HC and DM8 groups (P<0.05). Moreover, TGF-β1, p-ERK1/2 and FN protein expression in DM groups was significantly increased compared with NC and HC groups (P<0.05). The levels of FAK and p-FAK (Tyr397) in the renal cortex in DM12 and DM16 groups were significantly up-regulated compared with NC, HC and DM8 groups (P<0.05), and the expression trend of p-FAK in different groups was in accordance with that of total FAK. The FAK protein expression was positively correlated with the expression of TGF-β1, p-ERK1/2 and FN proteins (P<0.01). Compared with NC, HC and DM8 groups, the expression of FAK mRNA increased remarkably in DM12 and DM16 groups (P<0.05). CONCLUSION: There is a possibility that FAK is activated as a downstream effector of TGF-β1 in T2DM, which enhances the expression of FN protein through activating ERK1/2, and therefore plays an important role in the pathogenesis of type 2 diabetic nephropathy.     

Changes of heart function and serum cardiac troponin I in early type 2 diabetic rats

AIM: To observe the changes of heart function and the expression of serum cardiac troponin I(cTnI) in early type 2 diabetic rats, and to explore the role of cTnI in the development of type 2 diabetes and early diabetic cardiomyopathy.METHODS: The type 2 diabetes rat model was established by an injection of streptozotocin after high fat diet(5 weeks). The rats were randomly divided into control group, model group of 2 weeks, and model group of 4 weeks. M-mode echocardiography was performed for echocardiographic measurements. Fasting blood glucose(FBG), total cholesterol(TC), triglyceride(TG), high density lipoprotein-cholesterol(HDL-C), low density lipoprotein- cholesterol(LDL-C), fasting insulin(FINS) and cTnI levels were tested. HE staining was used to observe the pathological changes of myocardial structures. The alteration of cTnI in myocardium was determined by Western blot.RESULTS: Compared with normal group, the levels of TC, TG and LDL-C in type 2 diabetic rats were significantly increased, HDL-C levels were significantly reduced. Cardiac histological analysis revealed that type 2 diabetes induced cardiomyocytes degeneration and necrosis. The expression of cTnI increased significantly in diabetic groups compared to control group, and that in model group of 4 weeks increased far more than that in model group of 2 weeks(P<0.05).CONCLUSION: The increased level of cTnI and the change of the heart function may be associated with the development diabetic cardiomyopathy. These changes are valuable for the early clinical diagnosis of myocardial injury in diabetic cardiomyopathy.     

Effect of Kechuanning on airway remodeling and protein level of p-ERK1/2 in lung tissues of asthmatic rats induced by virus

AIM:To investigate the effect of Kechuanning on airway remodeling and the protein level of p-ERK1/2 in lung tissues of asthmatic rats induced by virus. METHODS:The asthmatic rat model induced by respiratory syncytial virus was established. The experimental rats were divided into normal group, asthma model group, low dose (0.33 mL/kg), middle dose (3.0 mL/kg) and high dose (10 mL/kg) of Kechuanning groups, and PD98059 (3 mg/kg) group. The airway responsiveness of the rats was measured by animal ventilator. The pathological changes of the lung tissues were observed by HE staining. PAS staining and Masson staining were used to observe goblet epithelial cells metaplasia and airway collagen deposition. The expression of matrix metalloproteinases-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in the lung tissues of the rats was detected by immunohistochemical staining. The protein levels of ERK1/2 and p-ERK1/2 were determined by Western blot. RESULTS:Compared with model group, the airway responsiveness of the rats in middle dose and high dose of Kechuanning groups was significantly decreased (P<0.01), the injury of lung tissues was significantly decreased, the goblet epithelial cells metaplasia and airway collagen deposition were significantly reduced (P<0.01), and the expression of MMP-9 and TIMP-1 in the lung tissues was also significantly decreased (P<0.01). In addition, the protein level of p-ERK1/2 in high dose of Kechuanning group was significantly decreased compared with model group (P<0.01). CONCLUSION:Kechuanning may treat asthma by regulating the expression of p-ERK1/2 in the lung tissues and improving the airway remodeling symptoms of asthmatic rats induced by virus.