Effectiveness of a single versus repeated administration of trimetazidine in the protection against warm ischemia/reperfusion injury of rat liver.

BACKGROUND/AIM: The aim of this study was to compare the effects of single and repeated trimetazidine (TMZ) administration against warm hepatic ischemia/reperfusion (I/R) injury and to explore the possible mechanisms affected by TMZ. MATERIALS AND METHODS: Wistar rats were divided into 4 groups (n = 6). Sham: rats were subjected to dissection. I/R: rats were subjected to 60 min of partial hepatic ischemia followed by 24 h of reperfusion. TMZ1: Same as I/R group but rats were pretreated with a single dose of TMZ (10 mg/kg, intraperitoneal injection) 30 min before warm ischemia. TMZ3: Same as I/R but rats were treated with 10 mg/kg TMZ for 3 successive days. RESULTS: TMZ treatment decreased liver injury, lipid peroxidation, and apoptosis. The repeated administration of TMZ conferred more protection than the single dose treatment concerning all studied parameters. In parallel, we noted a significant increase in phosphorylated adenosine monophosphate activated protein kinase (p-AMPK) and endothelial nitric oxide synthase (eNOS) levels in TMZ3 as compared to TMZ1. CONCLUSION: Repeated administration of TMZ for 3 days was more efficient than a single dose of TMZ in protecting the liver against I/R induced apoptosis and lipid peroxidation. These effects implicate AMPK and eNOS activation.

Attenuation of endoplasmic reticulum stress and mitochondrial injury in kidney with ischemic postconditioning application and trimetazidine treatment.

BACKGROUND: Endoplasmic reticulum (ER) and mitochondria have been implicated in the pathology of renal ischemia/reperfusion (I/R). In the present study, we investigated whether the use of ischemic postconditioning (IPostC) and trimetazidine (TMZ) separately or combined could reduce ER stress and mitochondria damage after renal ischemia. METHODS: Kidneys of Wistar rats were subjected to 60-min of warm ischemia followed by 120-min of reperfusion (I/R group, n = 6), or to 6 cycles of ischemia/reperfusion (10-s each cycle) just after 60-min of warm ischemia (IPostC group, n = 6), or to i.p. injection of TMZ (3 mg/kg) 30-min before ischemia (TMZ group, n = 6), or to the combination of both treatments (IPostC+TMZ group, n = 6). The results of these experimental groups were compared to those of a sham-operated group in which rat renal pedicles were only dissected. Sodium reabsorption rate, creatinine clearance lactate deshydrogenase (LDH) activity in plasma, and concentration of malonedialdehyde (MDA) in tissue were determined. In addition, Western blot analysis was performed to identify the amounts of cytochrome c, c-JunNH2-terminal kinase (JNK), voltage-dependent anion channel (VDAC), glycogen synthase kinase 3-beta (GSK3-ß), and ER stress parameters. RESULTS: IPostC or/and TMZ significantly decreased cytolysis, oxidative stress and improved renal function in comparison to I/R group. IPostC but not TMZ significantly attenuated ER stress parameters versus I/R group. Indeed, it down-regulated the glucose-regulated protein 78 (GRP78), the activating transcription factor 4 (ATF4), the RNA activated protein kinase (PKR)-like ER kinas (PERK), the X box binding protein-1 (XBP-1) and the caspase12 protein levels. TMZ treatment significantly augmented GSK3-ß phosphorylation and reduced levels of cytochrome c and VDAC phosphorylation in comparison to IPostC application. The combination of both treatments gave a synergetic effect. It significantly improved the survival rate, attenuated cytolysis, oxidative stress and improved renal function. CONCLUSION: This study revealed that IPostC protects kidney from I/R injury by suppressing ER stress while the beneficial effects of TMZ are mediated by mitochondria protection. The combination of both treatments ameliorated functional recovery.

Ischemic preconditioning reduces endoplasmic reticulum stress and upregulates hypoxia inducible factor-1α in ischemic kidney: the role of nitric oxide.

BACKGROUND: Although recent studies indicate that renal ischemic preconditioning (IPC) protects the kidney from ischemia-reperfusion (I/R) injury, the precise protective mechanism remains unclear. In the current study, we investigated whether early IPC could upregulate hypoxia inducible transcription factor-1α (HIF-1α) expression and could reduce endoplasmic reticulum (ER) stress after renal I/R and whether pharmacological inhibition of nitric oxide (NO) production would abolish these protective effects. METHODS: Kidneys of Wistar rats were subjected to 60 min of warm ischemia followed by 120 min of reperfusion (I/R group), or to 2 preceding cycles of 5 min ischemia and 5 min reperfusion (IPC group), or to intravenously injection of NG-nitro-L-arginine methylester (L-NAME, 5 mg/kg) 5 min before IPC (L-NAME+IPC group). The results of these experimental groups were compared to those of a sham-operated group. Sodium reabsorption rate, creatinine clearance, plasma lactate dehydrogenase (LDH) activity, tissues concentrations of malonedialdehyde (MDA), HIF-1α and nitrite/nitrate were determined. In addition, Western blot analyses were performed to identify the amounts of Akt, endothelial nitric oxide synthase (eNOS) and ER stress parameters. RESULTS: IPC decreased cytolysis, lipid peroxidation and improved renal function. Parallelly, IPC enhanced Akt phosphorylation, eNOS, nitrite/nitrate and HIF-1α levels as compared to I/R group. Moreover, our results showed that IPC increased the relative amounts of glucose-regulated protein 78 (GRP78) and decreased those of RNA activated protein kinase (PKR)-like ER kinase (PERK), activating transcription factor 4 (ATF4) and TNF-receptor-associated factor 2 (TRAF2) as judged to I/R group. However, pre treatment with L-NAME abolished these beneficial effects of IPC against renal I/R insults. CONCLUSION: These findings suggest that early IPC protects kidney against renal I/R injury via reducing oxidative and ER stresses. These effects are associated with phosphorylation of Akt, eNOS activation and NO production contributing thus to HIF-1α stabilization. The beneficial impact of IPC was abolished when NO production is inhibited before IPC application.