No abstract

Allopurinol (ALP) attenuates oxidative stress and diabetic cardiomyopathy (DCM), but the mechanism is unclear. Activation of nuclear factor erythroid 2-related factor 2 (Nrf2) following the disassociation with its repressor Keap1 under oxidative stress can maintain inner redox homeostasis and attenuate DCM with concomitant attenuation of autophagy. We postulated that ALP treatment may activate Nrf2 to mitigate autophagy over-activation and consequently attenuate DCM. Streptozotocin-induced type 1 diabetic rats were untreated or treated with ALP (100 mg/kg/d) for 4 weeks and terminated after heart function measurements by echocardiography and pressure-volume conductance system. Cardiomyocyte H9C2 cells infected with Nrf2 siRNA or not were incubated with high glucose (HG, 25 mmol/L) concomitantly with ALP treatment. Cell viability, lactate dehydrogenase, 15-F2t-Isoprostane and superoxide dismutase (SOD) were measured with colorimetric enzyme-linked immunosorbent assays. ROS, apoptosis, was assessed by dihydroethidium staining and TUNEL, respectively. The Western blot and qRT-PCR were used to assess protein and mRNA variations. Diabetic rats showed significant reductions in heart rate (HR), left ventricular eject fraction (LVEF), stroke work (SW) and cardiac output (CO), left ventricular end-systolic volume (LVVs) as compared to non-diabetic control and ALP improved or normalized HR, LVEF, SW, CO and LVVs in diabetic rats (all P < .05).Hearts of diabetic rats displayed excessive oxidative stress manifested as increased levels of 15-F2t-Isoprostane and superoxide anion production, increased apoptotic cell death and cardiomyocytes autophagy that were concomitant with reduced expressions of Nrf2, heme oxygenase-1 (HO-1) and Keap1. ALP reverted all the abovementioned diabetes-induced biochemical changes except that it did not affect the levels of Keap1. In vitro, ALP increased Nrf2 and reduced the hyperglycaemia-induced increases of H9C2 cardiomyocyte hypertrophy, oxidative stress, apoptosis and autophagy, and enhanced cellular viability. Nrf2 gene silence cancelled these protective effects of ALP in H9C2 cells. Activation of Nrf2 subsequent to the suppression of | 1761 LUO et aL.

Reactive oxygen species (ROS) play a critical role in renal ischemia-reperfusion injury (IRI). Intermedin (IMD) reportedly protected against myocardial IRI via its antioxidant effects; however, its protective role in renal IRI has not been investigated. We overexpressed IMD in rat kidneys and examined how the kidneys respond to renal IRI. Eukaryotic expression plasmid encoding the rat IMD gene or control empty vector was transfected into the left kidney using an ultrasound-microbubble-mediated delivery system. This method yielded high expression of IMD in kidney cells. Renal IRI was induced by clamping the left renal artery followed by reperfusion. In response to IRI, overexpression of IMD in the kidney significantly improved renal function and pathology compared with the kidney transfected with control plasmid. We investigated the mechanisms by which IMD protects against renal IRI. We examined renal superoxide dismutase (SOD) activity and malondialdehyde (MDA) content and found SOD activity was significantly increased, while MDA level was markedly decreased in kidneys transfected with IMD, suggesting ROS production and oxidative stress were reduced by IMD overexpression. We also measured myeloperoxidase (MPO) activity, tubular cell apoptosis, and the expression of intercellular adhesion molecule-1 (ICAM-1), P-selectin, and endothelin-1 (ET-1) in the kidney. Renal MPO activity and the expression of ICAM-1, P-selectin, and ET-1 stimulated by IRI were significantly inhibited by IMD overexpression. Moreover, IMD overexpression prevented kidney cells from apoptosis caused by IRI. Our results demonstrate that overexpression of IMD in the kidney protects against renal IRI, apparently by reducing oxidative stress, consequently suppressing inflammation and vasoconstrictor production and apoptosis.

Aim: To investigate the protective effect of tribulosin, a monomer of the gross saponins from Tribulus terrestris, against cardiac ischemia/reperfusion injury and the underlying mechanism in rats. Methods: Isolated rat hearts were subjected to 30 min of ischemia followed by 120 min of reperfusion using Langendorff's technique. The hearts were assigned to seven groups: control, ischemia/reperfusion (I/R), treatment with gross saponins from Tribulus terrestris (GSTT) 100 mg/L, treatment with tribulosin (100, 10, and 1 nmol/L) and treatment with a PKC inhibitor (chelerythrine) (1 μmol/L). Infarct size was assessed by triphenyltetrazolium chloride staining. Malondialdehyde (MDA), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) contents as well as superoxide dismutase (SOD) and creatine kinase (CK) activities were determined after the treatment. Histopathological changes in the myocardium were observed using hematoxylin-eosin (H&E) staining. Apoptosis was detected with terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) assay. Bcl-2, Bax, caspase-3, and PKCε protein expression were examined using western blotting. Results: Tribulosin treatment significantly reduced MDA, AST, CK and LDH contents, and increased the activity of SOD. The infarct size of I/R group was 40.21% of the total area. GSTT and various concentrations of tribulosin treatment decreased the infarct size to 24. 33%, 20.24%, 23.19%, and 30.32% (P<0.01). Tribulosin treatment reduced the myocardial apoptosis rate in a concentrationdependent manner. Bcl-2 and PKCε protein expression was increased after tribulosin preconditioning, whereas Bax and caspase-3 expression was decreased. In the chelerythrine group, Bcl-2 and PKCε expression was decreased, whereas Bax and caspase-3 expression was increased. Conclusion: Tribulosin protects myocardium against ischemia/reperfusion injury through PKCε activation.

Ubiquinol cytochrome c reductase core protein I (UQCRC1) is a component of the complex III in the respiratory chain. Its biological functions are unknown. Here, we showed that knockout of UQCRC1 led to embryonic lethality. Disrupting one UQCRC1 allele in mice (heterozygous mice) of both sexes did not affect their growth but reduced UQCRC1 mRNA and protein in the brain. These mice had decreased complex III formation, complex III activity and ATP content in the brain at baseline. They developed worsened neurological outcome after brain ischemia/hypoxia or focal brain ischemia compared with wild-type mice. The ischemic cerebral cortex of the heterozygous mice had decreased mitochondrial membrane potential and ATP content as well as increased free radicals. Also, the heterozygous mice performed poorly in the Barnes maze and novel object recognition tests. Finally, UQCRC1 was expressed abundantly in neurons and astrocytes. These results suggest a critical role of UQCRC1 in embryo survival. UQCRC1 may also be important by forming the complex III to maintain normal brain ischemic tolerance, learning and memory.