The effect of zinc acexamate on oxidative stress, inflammation and mitochondria induced apoptosis in rat model of renal warm ischemia.

AIM: Zinc has proved its efficacy in many models of ischemia reperfusion (I/R) injury. In this study, we used zinc acexamate (ZAC) as an exogenous source of zinc against renal I/R injury and we investigated whether its protective effects are mediated by the decrease of oxidative stress, inflammation, and mitochondria induced-apoptosis. METHODS: Rats were orally pretreated with vehicle or ZAC (10 or 100 mg/kg) 24 h and 30 min prior to 1 h of bilateral renal warm ischemia and 2 h of reperfusion. RESULTS: Our data showed that 10 mg/kg of ZAC, but not 100 mg/kg, improved renal architecture and function. Also, the low dose of ZAC up-regulated antioxidant enzymes activities and glutathione level and decreased lipids and proteins oxidation. Interestingly, the use of ZAC resulted in a significant reduce of pro-inflammatory cytokines (IL-1ß, IL-6 and MCP-1), enhanced mitochondria integrity and decreased expression of the pro-apoptotic protein caspase-9. CONCLUSION: We conclude that renal I/R induced oxidative stress, inflammation and apoptosis and that the use of ZAC at 10 mg/kg, but not 100 mg/kg, protects rat kidneys from I/R injury by down-regulating these processes.

Zinc mitigates renal ischemia-reperfusion injury in rats by modulating oxidative stress, endoplasmic reticulum stress, and autophagy.

Oxidative stress is a major factor involved in the pathogenesis of renal ischemia/reperfusion (I/R). Exogenous zinc (Zn) was suggested as a potent antioxidant; however, the mechanism by which it strengthens the organ resistance against the effects of reactive oxygen species (ROS) is not yet investigated. The present study aims to determine whether acute zinc chloride (ZnCl2 ) administration could attenuate endoplasmic reticulum (ER) stress, autophagy, and inflammation after renal I/R. Rats were subjected to either sham operation (Sham group, n = 6), or 1 hr of bilateral ischemia followed by 2 hr of reperfusion (I/R groups, n = 6), or they received ZnCl2 orally 24 hr and 30 min before ischemia (ZnCl2 group, n = 6). Rats were subjected to 1 hr of bilateral renal ischemia followed by 2 hr of reperfusion (I/R group, n = 6). Our results showed that ZnCl2 enhances renal function and reduces cytolysis (p < 0,05). In addition, it increased significantly the activities of antioxidant enzymes (SOD, CAT, and GPX) and the level of GSH in comparison to I/R (p < 0,05). Interestingly, ZnCl2 treatment resulted in significant decreased ER stress, as reflected by GRP78, ATF-6,p-eIF-2α, XPB-1, and CHOP downregulaion. Rats undergoing ZnCl2 treatment demonstrated a low expression of autophagy parameters (Beclin-1 and LAMP-2), which was correlated with low induction of apoptosis (caspase-9, caspase-3, and p-JNK), and reduction of inflammation (IL-1ß, IL-6, and MCP-1) (p < 0,05). In conclusion, we demonstrated the potential effect of Zn supplementation to modulate ER pathway and autophagic process after I/R.

Thymoquinone protects rat liver after partial hepatectomy under ischaemia/reperfusion through oxidative stress and endoplasmic reticulum stress prevention.

Ischaemia reperfusion (I/R) is associated with liver injury and impaired regeneration during partial hepatectomy (PH). The aim of this study was to investigate the effect of thymoquinone (TQ), the active compound of essential oil obtained from Nigella sativa seeds, on rat liver after PH. Male Wistar rats were divided equally into four groups (n = 6) receiving an oral administration of either vehicle solution (sham and PH groups) or TQ at 30 mg/kg (TQ and TQ + PH groups) for 10 consecutive days. Then, rats underwent PH (70%) with 60 minutes of ischaemia followed by 24 hours of reperfusion (PH and TQ + PH groups). Alanine aminotransferase (ALT) activity and histopathological damage were determined. Also, antioxidant parameters, liver regeneration index, hepatic adenosine triphosphate (ATP) content, endoplasmic reticulum (ER) stress and apoptosis were assessed. In response to PH under I/R, liver damage was significantly alleviated by TQ treatment as evidenced by the decrease in ALT activity (P < .01) and histological findings (P < .001). In parallel, TQ preconditioning increased hepatic antioxidant capacities. Moreover, TQ improved mitochondrial function (ATP, P < .05), attenuated ER stress parameters and repressed the expression of apoptotic effectors. Taken together, our results suggest that TQ preconditioning could be an effective strategy to reduce liver injury after PH under I/R. The protective effects were mediated by the increase of antioxidant capacities and the decrease of ER stress and apoptosis.

Thymoquinone prevents endoplasmic reticulum stress and mitochondria-induced apoptosis in a rat model of partial hepatic warm ischemia reperfusion.

This study was undertaken to evaluate the protective effect of thymoquinone (TQ), the bioactive compound of Nigella sativa seeds, against warm ischemia-reperfusion (I/R) injury in liver. Rats were given an oral administration of a vehicle solution (sham group) or TQ at the appropriate dose (10, 20, 30 and 40mg/kg) for ten days consecutively. Following, they were subjected to 60min of partial hepatic ischemia followed by 24h of reperfusion. .Transaminase activities, histopathological changes, TNFα and antioxidant parameters were evaluated. Also, endoplasmic reticulum (ER) stress, mitochondrial damage and apoptosis were studied. In addition, ERK and P38 phosphorylation was determined by Western blot technique. We found that TQ at 30mg/kg is the effective dose to protect rat liver against I/R injury. Moreover, 30mg/kg of TQ prevented histological damages, inflammation and oxidative stress. Interestingly, it decreased the expression of ER stress parameters including GRP78, CHOP and caspase-12. In parallel, it improved mitochondrial function and attenuated the expression of apoptotic parameters. Furthermore, TQ significantly enhanced ERK and P38 phosphorylation. In conclusion, we demonstrated the potential of TQ to protect the rat liver against I/R injury through the prevention of ER stress and mitochondrial dysfunction. These effects implicate the prevention of oxidative stress.

Nitrite enhances liver graft protection against cold ischemia reperfusion injury through a NOS independent pathway.

INTRODUCTION: Nitrite has been found to protect liver graft from cold preservation injury. However, the cell signaling pathway involved in this protection remains unclear. Here, we attempt to clarify if the NOS pathway by using the NOS inhibitor, L-NAME (L-NG-Nitroarginine methyl ester). ANIMALS AND METHODS: Rat livers were conserved for 24 h at 4°C in (IGL-1) solution enriched or not with nitrite at 50 nM. In a third group, rats were pretreated with 50 mg/kg of L-NAME before their liver procurement and preservation in IGL-1 supplemented with nitrite (50 nM) and L-NAME (1 mM). After 24 h of cold storage, rat livers were ex-vivo perfused at 37°C during 2 h. Control livers were perfused without cold storage. RESULTS: Nitrite effectively protected the rat liver grafts from the onset of cold I/R injury. L-NAME treatment did not abolish the beneficial effects of nitrite. Liver damage, protein oxidation and lipid peroxidation remained at low levels in both nitrite-treated groups when compared to IGL-1 group. Antioxidant enzyme activities and functional parameters were unchanged after NOS inhibition. CONCLUSION: Despite NOS inhibition by L-NAME, nitrite can still provide hepatic protection during cold I/R preservation. This suggests that nitrite acts through a NOS-independent pathway.