Annexin V as index of apoptosis in aorta of STZ induced diabetic rats

Diabetes mellitus [DM] is a chronic disease associated with hyperglycemia and the production of reactive oxidative intermediates and a disturbed antioxidant defense mechanism. Apoptosis or programmed cell death is a fundamental component of tissue differentiation and development, it also plays a central role in DM. The highly regulated mechanism of apoptosis involves an externalization process of phosphatidylserine [Ps]. Annexin V binds with high affinity to Ps-exposing apoptotic cell and can inhibit thereby the procoagulant and proinflammatory activities of the dying cell. Heat shock proteins have been shown to protect organism in vitro and in vivo against oxidative stress which plays a role in apoptosis in DM. HSP72 inhibits mitochondria! cytochrome release and subsequent caspase activation that leads to apoptosis. Fifty male albino rats weighing 170-200gm were used in this study. They were divided in to 5 equal groups, each of 10 rats. Group I: Control group. Group II: Diabetic group. Type 2 diabetes mellitus was induced by intraperitoneal injection of streptozotocin at a dose of 40mg/kg body weight. Group III: Diabetic group, treated with 1 unit insulin injected subcutaneously daily. Group IV: Diabetic group, receiving vit. E 600mg/kg B.Wt injected intramuscularly, 3 times/week, All groups were sacrified one month after the beginning of the experiment. Blood samples were obtained from retro-orbital vein for assessment of glucose and malondialdehyde [MDA], then Animals were sacrificed and aortic tissues were removed,PCR for Annexin V and for HsP72 were done. Compared to control group, fasting serum glucose is significantly higher in the diabetic group [group II] [p<0.05] and it decreased significantly with administration of insulin [group III]. MDA is significantly higher in the diabetic group II compared with control one [p<0.05]. It decreased significantly with administration of insulin [group III] or vitamin E [group IV] in comparison to diabetic group [group II]. Administration of vitamin E and insulin [group V] leads to significant reduction in MDA back to control level. The expression of Annexin V is significantly higher in the diabetic group [group II] compared to control group [p<0.05]. Administration of insulin [group III] or vitamin E [group IV] decreases it significantly. The expression of HSP72 is significantly lower in the diabetic group compared to control one [p<0.05]. It increased significantly with administration of insulin [group III] or vitamin E [group IV]. Serum MDA level rise in STZ induced diabetic rats as a marker of oxidative stress and administration of vitamin E was found to normalize this level, in addition a significant rise in expression of Annexin V as a marker of apoptosis in aorta of STZ induced diabetic rats with decreased expression of HSP72 which may be involved in cellular protection against oxidative stress in DM

Induction of vascular endothelial growth facor and erythrpoeitin by rat cardiomyocytes exposed to acute intermittent systemic hypoxia: possible role in hypoxic preconditioning

Exposure to systemic hypoxia induces cardiac adaptive responses similar to ischemic preconditioning. However, the subcellular mechanisms involved in hypoxic preconditioning are still unclear. We therefore, tested the role of hypoxia sensitive agents such as VEGF and erythropoietin in mediating hypoxic preconditioning in response to acute intermittent hypoxia. 48 male Wistar rats were randomly assigned into normoxic nx group [n=12], kept in normoxic conditions, Acute intermittent hypoxia AIH group [n=12] subjected to brief cycles [5 min] hypoxia/reoxygenation for one hour hearts from both groups were isolated 24 hours later perfused in a retrograde manner in Langendorff apparatus and subjected to in vitro global ischemia for 30 mins followed by reperfusion. The following parameters were measured at baseline, during and at the end of 120 min reperfusion: Left ventricular developed pressure [LVDP]; left ventricular end diastolic pressure [LVEDP]; rate pressure product [RPP]; peak left ventricular pressure rise [AP/At max] and heart rate [HR] At the end of reperfusion hearts were collected for subsequent reverse transcriptase polymerase chain reaction [RT PCR] and immu-histochemical analysis for VEGF and Erythropoietin. AIH 3 [n=12], AIH8 [n=12] groups, were subjected to one hour brief cycles [5 min] hypoxia reoxygenation as described above, were then sacrificed after 3, 8 hours [respectively], Hearts were collected for studying the time course for the expression pattern of VEGF and erythropoietin: Hearts of AIH displayed a significant improvement in postischemic hemodynamic measures compared to controls, indicated by higher LVDP [76% recovery versus 39% in nx], RPP [76% recovery versus 38%] and AP/At [66% recovery versus 43%]. AIH caused a significant increased expression of VEGF and Epo by cradiomyocytes. This increased expression was detected at 3 and 8hrs [AIH3, AIH8] denoting early induction of VEGF and Epo genes by acute intermittent hypoxia. Increased expression of VEGF and Epo genes was also detected 24 hours [AIH] following hypoxic exposure. Exposure of rat hearts to acute intermittent systemic hypoxia confers cardioprotective effects. This was evident by improved cardiac performance following ischemia reperfusion. The improved postischmeic cardiac function was associated with rapid induction of VEGF and erythropoietin by cardiac cells that lasted for 24 hours later, therefore theses cytokines appear to play a role in mediating early and delayed cardiac adaptive responses to acute intermittent hypoxia. Hypoxic training could thus provide a new approach to enhance endogenous cardioprotective mechanisms