Matem Tunçdemir

Renoprotective effects of valsartan and enalapril in STZ-induced diabetes in rats

Effects of the angiotensin II type 1 (AT1) receptor antagonist valsartan and the angiotensin-converting enzyme (ACE) inhibitor enalapril were studied in streptozotocine (STZ)-induced diabetes in rats on the basis of microalbuminuria (Ma) and renal morphology. Five groups of Wistar rats were used, one group was the non-diabetic control, one group consisted of untreated STZ-diabetics and 3 groups of STZ-diabetics were treated with either enalapril and/or valsartan for 30 days. Blood glucose (BG) and Ma levels, body and kidney weight and glomerular size were measured. Immunohistochemical staining with an anti-transforming growth factor-beta1 (TGF-beta1) antibody was performed as well. In STZ-diabetics, BG and Ma levels were significantly increased when compared with the non-diabetic group. Although Ma levels in the valsartan-treated group was found to be higher than those in the non-diabetics group after 15 days of treatment, in all treated diabetic groups Ma levels were significantly decreased as compared with STZ-diabetics at the end of the experiment. Thickening of the glomerular and tubular basement membranes, increased mesangial matrix and glomerular size were found in the untreated diabetic group. All these changes were less in the treated groups. A significant increase in TGF-beta1 immunoreactivity was found in glomeruli of untreated STZ-diabetics as compared with non-diabetics. Again, TGF-beta1 expression was decreased in the treated groups as compared with untreated STZ-diabetics. We conclude that valsartan and enalapril have renoprotective effects in diabetic nephropathy. A combined therapy has an advantage because lower dosages of these drugs can be used. Their beneficial effects are related to a blockade of the renin-angiotensin system (RAS) and a decrease in TGF-beta1 expression in glomeruli.

The effects of angiotensin-II receptor blockers on podocyte damage and glomerular apoptosis in a rat model of experimental streptozotocin-induced diabetic nephropathy

The aim of the study was to determine in a rat model of streptozotocin-induced diabetic nephropathy the expression of: WT-1 (for podocyte loss in the glomerulus), TGF-beta 1 (for tissue damage), caspase-3 and bax (for glomerular apoptosis) and the possible protective effects of an angiotensin II type 1 receptor blocker. Three groups of male Wistar albino rats were used. The first group consisted of non-diabetic control rats. The second group was the untreated diabetic rats. The third group consisted of diabetic rats treated with Irbesartan, which is an angiotensin II receptor antagonist, widely used in treatment for hypertension. Immunohistochemical stainings for TGF-beta 1, bax, caspase-3 and WT-1 were performed. The microalbuminuria levels of the Irbesartan-treated diabetic group were lower than those of the untreated diabetic group (P<0.01). The immunostaining of TGF-beta 1, bax and caspase-3 was decreased in glomeruli of the Irbesartan-treated diabetic group compared to the untreated diabetic group. WT-1 immunopositive podocyte numbers were found to be significantly lower in the untreated diabetic group than in the other groups (P<0.01). In the Irbesartan-treated diabetic group, the WT-1 immunopositive cell numbers were higher compared to the untreated diabetic group (P<0.01). We conclude that the decrease in the number of podocytes is an early marker of diabetic nephropathy, AT1 receptor blocker has renoprotective effects on the regulation of renal hemodynamics and on the control of tissue damage by preventing podocyte loss, which leads to decrease of bax and caspase-3 expressions of apoptosis related proteins, and may prevent glomerular cell apoptosis via angiotensin II.

Protective Effect of Melatonin and 1,25-Dihydroxyvitamin D3 on Renal Ischemia–Reperfusion Injury in Rats

Ischemia–reperfusion (I/R) injury induces the generation of reactive oxygen species (ROS) which affect many organs. This study was designed to investigate the roles of melatonin and 1,25-dihydroxyvitamin D3 (VD3) on renal I/R injury. Thirty male Wistar albino rats were divided into five groups: group 1, control; group 2, right nephrectomy (RN) + I/R in the contralateral kidney; group 3, melatonin + RN + I/R; group 4, VD3 + RN + I/R; and group 5, melatonin + VD3 + RN + I/R. Melatonin (10 mg/kg), VD3 (0.5 μg/kg), and melatonin plus VD3 were injected intraperitoneally for 7 days before renal I/R. After 7 days, right nephrectomy was initially performed and left renal artery was clamped for 45 min. After 45-min reperfusion, the serum and kidney tissue samples were obtained for assays. Melatonin and VD3 had an ameliorative effect on biochemical parameters such as serum creatinine (SCr) and blood urea nitrogen (BUN). Renal tissue malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO) levels, and superoxide dismutase (SOD) activity were determined. Renal I/R decreased the kidney tissue GSH levels and SOD activity and increased the NO levels as compared with control group. However, melatonin and VD3 and melatonin plus VD3 treatment significantly increased the tissue GSH levels and SOD activity and decreased the NO levels compared with those of I/R group. Meanwhile, MDA levels were not different between the control and I/R groups. But, MDA levels decreased in all treated groups compared to I/R and control groups. These data support that melatonin and VD3 have beneficial effects on renal injury.

Evaluation of trace elements and oxidative stress levels in the liver and kidney of streptozotocin-induced experimental diabetic rat model.

In this study, we aimed to investigate the relationship among trace elements (Cu, Fe, Zn and Mg) on oxidative and anti-oxidative substances in liver and kidneys tissues in streptozotocin (STZ) diabetic rat model. The mean levels of Fe and Cu were found significantly higher in the liver and kidneys of the diabetic rats, in comparison to the control rats. On the other hand, the mean levels of Zn and Mg in the liver and kidneys of the diabetic rats were significantly lower than in the control rats. The liver and kidneys malonaldehyde (MDA) levels of the experimental group were found to be higher than in the control group (p < 0.001; p < 0.01, respectively) after 4 weeks of the experimental period. Superoxide dismutase (SOD) activities and glutathione (GSH) levels in the liver tissue of STZ-induced diabetic rats were found to be lower in the experimental group than in the control group (p < 0.01). SOD activity and GSH concentration in kidneys of the diabetic rats were significantly diminished with respect to the control group (p < 0.01). In conclusion, the present results indicate that the increase of Fe and Cu together with decreas of Zn and Mg concentration in liver and kidney of STZ-induced diabetic rats may be involved in disturbances of oxidative balance in both the tissues. Therefore, these findings may contribute to explain the role of impaired ion metabolism of some elements in the progression of diabetic oxidative complications.

Melatonin with 1,25-Dihydroxyvitamin D3 Protects against Apoptotic Ischemia–Reperfusion Injury in the Rat Kidney

This study was designed to evaluate the preventive role of melatonin (Mel) and 1,25-dihydroxyvitamin D3 (VD3) in biochemical and apoptotic events leading to tissue injury and renal dysfunction after ischemia–reperfusion (I/R). Thirty male Wistar rats were divided into five groups: sham-operated, I/R, Mel + I/R, VD3 + I/R, and Mel + VD3 + I/R. The rats were intraperitoneally administered with Mel (10 mg/kg), VD3 (0.5 μg/kg), or Mel (10 mg/kg) plus VD3 (0.5 μg/kg) each day at 1 week prior to ischemia. Right nephrectomy was initially performed and left renal I/R injury was induced by 45 min of bilateral renal ischemia followed by 45 min of reperfusion. After reperfusion, kidneys and blood were obtained for histopathologic and biochemical evaluation. Mel and VD3 had an ameliorative effect on biochemical parameters such as serum creatinine, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, and apoptosis (caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP–biotin nick end labeling staining) in the kidneys against renal I/R injury in rats. Additionally, VD3 combined with Mel significantly reduced apoptotic and histological alterations when compared with Mel or VD3 alone. This preventive effect on renal tubular apoptosis was remarkable when Mel was combined with VD3.

Oxytocin Protects Rat Skeletal Muscle Against Ischemia/Reperfusion Injury

BACKGROUND Oxytocin (OXY) is a well-known nonapeptide that functions in reproduction. It is also known as an antioxidant in several organs. However, little is about its role in the protection of tissue against ischemia/reperfusion injury in skeletal muscle. The aim of this study was to evaluate the protective and therapeutic antioxidant effect of oxytocin in skeletal muscle during ischemia/reperfusion (I/R) injury. METHODS Rats were divided into 4 groups. Hindlimb ischemia was achieved by clamping the common femoral artery in 3 of the groups, but not a control group. OXY was injected before ischemia in the preoperative (preop) I/R + OXY group and after the onset of ischemia in the postoperative (postop) I/R + OXY group. Saline solution was injected in the I/R group. Limbs were rendered ischemic for 90 min. At the end of 90-min reperfusion period, skeletal muscle tissue samples were taken from the ischemic muscle for evaluation at light and transmission electron microscopic levels. Biochemical analysis was done for malonedialdehyde and glutathione levels. Caspase immunohistochemistry was applied for apoptosis. RESULTS The light- and electron-microscopic scores of the OXY-treated groups were significantly lower than in the I/R group. The degree of tissue damage was ameliorated in the OXY-treated groups. The number of apoptotic cells was decreased in the OXY-treated groups compared with the I/R group. In OXY-treated groups, the malonedialdehyde level was lower than in the I/R group. Glutathione levels were found to be increased in the OXY-treated groups compared with the I/R group. CONCLUSIONS Oxytocin has a protective effect against I/R injury in skeletal muscle and may reduce the incidence of compartment syndrome.

AR-A014418 as a glycogen synthase kinase-3 inhibitor: Anti-apoptotic and therapeutic potential in experimental spinal cord injury

OBJECTIVES We aimed to investigate the effects of AR-A014418, a strong inhibitor specific to GSK-3beta, on neuronal apoptosis and neuroprotection in the traumatic SCI model. MATERIALS AND METHODS In this study, three groups were generated from 36 Wistar rats; (1) control, (2) spinal cord trauma group created by clip compression technique after laminectomy, and (3) AR-A014418 (4mg/kg, i.p., DMSO) treatment group after laminectomy and spinal cord trauma. The TUNEL assay for apoptosis detection, immunohistochemical staining for bax and TGF-beta were applied in spinal cord tissues. For light microscopic examination, necrotic, and apoptotic cells were counted, and PMNL counting was applied to detect inflammation. Functional recovery was tested by field locomotor test in the 3rd and 7th days following surgery. RESULTS In the trauma group, diffuse hemorrhage, cavitation, necrosis and edematous regions, degeneration in motor neurons and leukocyte infiltration were observed in gray matter. In the AR-A014418-treated groups, healthy cells were observed in more places compared to the trauma groups, however, cavitation, hemorrhagic, and edematous areas were seen in gray matter. In the AR-A014418-treatment groups, the number of apoptotic cells in the 3rd and 7th days (respectively; p<0.05, p<0.01), were significantly decreased compared to the trauma groups, as were the levels of bax (p<0.01) and TGF-beta 1 immunoreactivity. Results of the locomotor test were significantly increased in the treatment group (p<0.001) as compared to the trauma group. CONCLUSIONS In this experimental spinal cord trauma model study neural apoptosis was significantly triggered in secondary damage developed after trauma, however, neurological healing was expedited by preventing mitochondrial apoptosis and reducing the inflammation by the potent inhibitor AR-A014418, which is GSK-3beta selective.

Investigation of lipid peroxidation and antiapoptotic effects of zinc aganist liver damage in diabetic rats

Several mechanisms for the pathogenesis of diabetic complications have been proposed, one of which is abnormal zinc (Zn) homeostasis. Zn is necessary for proper liver function since it has important antioxidant, anti-inflammatory, and antiapoptotic properties. We aimed to investigate whether or not Zn has morphologically protective effect on diabetes-induced liver damage in rats. In addition, we have investigated the role of Zn supplementation on apoptosis, lipid peroxidation levels, and the distribution of metallothionein (MT) in diabetic liver tissue. Wistar albino rats were divided into four groups: control, Zn, diabetic, and Zn-diabetic group. Experimental diabetes was induced by a single-dose streptozotocin intraperitoneally and Zn was administrated via gastric gavage tube for 6 weeks. MT expressions were showed with immunohistochemical staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used for apoptosis. Also, Zn, MT, and malondialdehyde (MDA) levels were determined in liver of rats. MDA levels of the Zn-supplemented diabetic group was less than the diabetic group though MT levels were increased. The number of apoptotic cells per unit area was found to be significantly decreased in this group. In the Zn-supplemented diabetic group, fibrotic tissue density and the collagen tissue density were observed less than the diabetic group. MT immunoreactivity was observed less in Zn-supplemented diabetic group. In conculusion, the present study indicated that Zn has a potential in preventing or even repairing effect against diabetic damage of the liver cells by increasing expression of MT and by reducing the apoptotic cell death and the oxidative stress.

Regulation of the Ku70 and apoptosis-related proteins in experimental diabetic nephropathy

BACKGROUND Apoptosis contributes nephropathy pathogenesis in diabetes. However, its mechanisms still remain unclear. We examined the extent to which the angiotensin-II type 1 receptor blocker (AT1RB) irbesartan and the angiotensin converting enzyme inhibitor (ACEI) perindopril affected the apoptosis-related proteins Bcl-2, Bax, caspase-3, cytochrome-c and Ku70 in streptozotocin (STZ)-diabetic rats. MATERIALS AND METHODS Animals were divided into five groups of eight each, four of which received STZ (60mg/kg in a single dose, i.p.) to induce diabetes. The groups were performed as untreated diabetic; non-diabetic control; daily irbesartan (15mg/kg/day) or perindopril (6mg/kg/day) and also combined irbesartan and perindopril (respectively, 5mg/kg/day, 3mg/kg/day) were applied by gavage for 30days to STZ-diabetic rats. The kidney tissue analysis was performed by using immunohistochemical staining with Bcl-2, Bax, caspase-3, cytochrome-c and Ku70 antibodies and by using Western blot analysis with caspase-3 and cytochrome-c antibodies. RESULTS Immunoreactivity of Bax, caspase-3, cytochrome-c and Ku70 was increased in the tubuli and glomeruli of the untreated diabetic group, but decreased in all treated diabetic groups. In the irbesartan and perindopril treated diabetic groups Bcl-2 immunoreactivity was higher than that of the untreated diabetic group. Caspase-3 and cytoplasmic cytochrome-c protein levels increased in the untreated diabetic group. CONCLUSIONS We conclude that the increased expression of Bax and caspase-3, and the increased level of cytoplasmic cytochrome-c relate to renal tissue injury. This case is also seen in the early stages of diabetes as a result of the damage caused by local increased expression of renin angiotensin system (RAS) in the renal tissue, which is induced by hyperglycemia. The increase of the cytosolic cytochrome-c, caspase-3 and Ku70 expression in the tubuli is suggestive of apoptosis. Overall, our results show that treatments of irbesartan and perindopril are effective and efficient in preventing renal tissue injury and apoptosis by blocking the RAS in experimental diabetic nephropathy and reducing the expression of proteins associated with apoptosis.

The effects of 5-aminoimidazole-4-carboxamide riboside on the pancreas in neonatal streptozotocin-diabetic rats

In this study, we aimed to determine the alterations of beta-cell ultrastructure, insulin mRNA and protein products of the same gene on the pancreas of rats following long-term treatment of 5-aminoimidazole-4-carboxamide riboside (AICAR). A single dose of streptozotocin (STZ) 100 mg/kg was injected intraperitoneally (i.p.) to 2-day-old newborn (n2) rats. The rats were divided into three groups. The first group was the n2 STZ-diabetic rats. The second group consisted of n2 STZ-diabetic rats treated with AICAR 10 mg/kg/day for one month. The third group was non-diabetic control rats. Our findings demonstrate that AICAR treatment decreases the blood glucose level but increases the body weight in n2 STZ-diabetic rats. In the AICAR-treated group, numerous beta cells showed increased insulin gene expression. We also observed increased exocytosis in this group, in an ultrastructural manner. As a result, it is suggested that AICAR may induce insulin synthesis and betacell regeneration in n2 STZ-diabetic rats.