Nicorandil protects against ischaemia-reperfusion injury in newborn rat kidney

Nicorandil and carvedilol mitigates motor deficits in experimental autoimmune encephalomyelitis-induced multiple sclerosis: Role of TLR4/TRAF6/MAPK/NF-κB signalling cascade

Multiple sclerosis (MS) is an inflammatory demyelinating neurodegenerative disease that negatively affects neurotransmission. It can be pathologically mimicked by experimental autoimmune encephalomyelitis (EAE) animal model. ATP-sensitive potassium channels (KATP) plays a crucial role in the control of neuronal damage, however their role in MS are still obscure. Additionally, Carvedilol showed a promising neuroprotective activity against several neurological disorders. Therefore, the present study aimed to investigate the potential neuroprotective effect of KATP channel opener (nicorandil) as well as α and β adrenoceptor antagonist (Carvedilol) against EAE induced neurodegeneration in mice. Mice was treated with nicorandil (6 mg/kg/day; p.o.) and carvedilol (10 mg/kg/day; p.o.) for 14 days. Nicorandil and carvedilol showed improvement in clinical scoring, behaviour and motor coordination as established by histopathological investigation and immunohistochemical detection of MBP. Furthermore, both treatments downregulated the protein expression of TLR4/ MYD88/TRAF6 signalling cascade with downstream inhibition of (pT183/Y185)-JNK/p38 (pT180/Y182)-MAPK axis leading to reduction of neuroinflammatory status, as witnessed by reduction of NF-κB, TNF-α, IL-1β and IL-6 contents. Moreover, nicorandil and carvedilol attenuated oxidative damage by increasing Nrf2 content and SOD activity together with reduction of MDA content. In addition, an immunomodulating effect via inhibiting the gene expression of CD4, TGF-β, and IL-17 as well as TGF-β, IL-17, and IL-23 contents along with anti-apoptotic effect by decreasing Bax protein expression and Caspase-3 content and increasing Bcl-2 protein expression was observed with nicorandil and carvedilol treatments. In conclusion, nicorandil and carvedilol exerted a neuroprotective activity against EAE induced neuronal loss via inhibition of TLR4/MYD88/TRAF6/JNK/p38-MAPK axis besides antioxidant and anti-apoptotic effects.

Oral Nicorandil effectively attenuates the incidence of contrast-induced nephropathy in patients undergoing cardiac catheterization: a randomized, controlled, open-label clinical trial

PURPOSE

The contrast-induced nephropathy (CIN) rate is increasing globally and can increase the rate of mortality and long-term problems. This study aims to determine the effect of Nicorandil on preventing CIN among patients undergoing cardiac catheterization.

METHODS

In a controlled randomized open-labeled clinical trial, all included patients undergoing cardiac catheterization due to coronary problems and possessing at least two risk factors of contrast nephropathy were divided into two groups of intervention and control. The intervention group received oral Nicorandil and normal saline, while the control group was treated with intravenous normal saline. Serum creatinine was measured before and 48 h after the procedure, and patients were assessed regarding CIN.

RESULTS

In this study, 172 patients entered each group; 41.86% and 45.34% were male in the control and Nicorandil groups. We showed that the incidence of CIN was meaningfully lower in the Nicorandil group (12, 7%) than in the control group (34, 19.8%, P = 0.001). Additionally, the incidence of CIN was notably lower in the female patients in the Nicorandil (85.7%) than in the control group (14.3%, P = 0.001); however, these numbers were not significantly different among men (64.0% and 36.0%, respectively, P = 0.850). After the injection of the contrast agent, the serum levels of blood urea nitrogen (P = 0.248), creatinine (P = 0.081), and glomerular filtration rate (P = 0.386) showed no significant differences between the control and Nicorandil groups. Multivariate regression analysis showed that Nicorandil significantly lowered the odds of CIN [odds ratio (OR) = 0.299, 95% confidence interval (CI) 0.149-0.602; P = 0.001] after adjustment for baseline creatinine (OR = 1.404, 95% CI 0.431-4.572; P = 0.574).

CONCLUSION

Our results indicate that pre-procedural treatment with Nicorandil may be effective against CIN in contrast to agent-exposed patients.

Nicorandil protects podocytes via modulation of antioxidative capacity in acute puromycin aminonucleoside-induced nephrosis in rats

Nephrotic syndrome, characterized by proteinuria and hypoalbuminemia, results from the dysregulation of glomerular podocytes and is a significant cause of end-stage kidney disease. Patients with idiopathic nephrotic syndrome are generally treated with immunosuppressive agents; however, these agents produce various adverse effects. Previously, we reported the renoprotective effects of a stimulator of the mitochondrial ATP-dependent K⁺ channel (MitK_ATP), nicorandil, in a remnant kidney model. Nonetheless, the cellular targets of these effects remain unknown. Here, we examined the effect of nicorandil on puromycin aminonucleoside-induced nephrosis (PAN) rats, a well-established model of podocyte injury and human nephrotic syndrome. PAN was induced using a single intraperitoneal injection. Nicorandil was administered orally at 30 mg/kg/day. We found that proteinuria and hypoalbuminemia in PAN rats were significantly ameliorated following nicorandil treatment. Immunostaining and ultrastructural analysis under electron microscopy demonstrated that podocyte injury in PAN rats showed a significant partial attenuation following nicorandil treatment. Nicorandil ameliorated the increase in the oxidative stress markers nitrotyrosine and 8-hydroxy-2-deoxyguanosine in glomeruli. Conversely, nicorandil prevented the decrease in levels of the antioxidant enzyme manganese superoxide dismutase in PAN rats. We found that mitochondrial Ca²⁺ uniporter levels in glomeruli were higher in PAN rats than in control rats, and this increase was significantly attenuated by nicorandil. We conclude that stimulation of MitK_ATP by nicorandil reduces proteinuria by attenuating podocyte injury in PAN nephrosis, which restores mitochondrial antioxidative capacity, possibly through mitochondrial Ca²⁺ uniporter modulation. These data indicate that MitK_ATP may represent a novel target for podocyte injury and nephrotic syndrome.NEW & NOTEWORTHY Our findings suggest that the mitochondrial Ca²⁺ uniporter may be an upstream regulator of manganese superoxide dismutase and indicate a biochemical basis for the interaction between the ATP-sensitive K⁺ channel and Ca²⁺ signaling. We believe that our study makes a significant contribution to the literature because our results indicate that the ATP-sensitive K⁺ channel may be a potential therapeutic target for podocyte injury and nephrotic syndrome.

Nicorandil mitigates amiodarone-induced pulmonary toxicity and fibrosis in association with the inhibition of lung TGF-β1/PI3K/Akt1-p/mTOR axis in rats

The long-term side effect of the antiarrhythmic drug, amiodarone (AMIO), such as lung toxicity, remains a critical clinical issue. The previous knowledge denotes diverse antioxidant, anti-inflammatory, and antifibrotic properties of the anti-anginal drug, nicorandil (NI). Therefore, we aimed to investigate the possible protective effect of NI on pulmonary tissue remodelling following AMIO-induced lung toxicity. The included rats were assigned into four equal groups (n = 8): (1) control, (2) control group that received NI 10 mg kg^-1  day^-1 , (3) model group that received AMIO in a dose of 60 mg kg^-1  day^-1 , and (4) treated group (AMIO-NI) that were treated with AMIO plus NI as shown above. Drug administration continued for 10 weeks. AMIO resulted in deteriorated (p < 0.001) pulmonary functions accompanied by respiratory acidosis. AMIO showed an obvious histological injury score with intense collagen deposition, disturbed nitric oxide synthase enzymes (NOS/iNOS), and increased alpha smooth muscle actin expression. Furthermore, AMIO upregulated the transforming growth factor (TGF-β1)/phosphoinositide-3 kinase (PI3K)-Akt1-p/mammalian target of rapamycin (mTOR) axis, which determined the possible mechanism of AMIO on pulmonary remodelling. NI treatment significantly (p < 0.001) prevented the AMIO-induced lung toxicity, as well as inhibited the TGF-β1/PI3K/Akt1-p/mTOR axis in the lung tissue of rats. The results were confirmed by an in-vitro study. CONCLUSION: The current results revealed that NI was effective in preserving the lung structure and functions. Amelioration of the oxidative stress and modulation of TGF-β1/PI3K/Akt1-p/mTOR have been achieved. This study suggests NI administration as a preventive therapy from the serious pulmonary fibrosis side effect of AMIO.

Targeted Mitochondrial Drugs for Treatment of Ischemia-Reperfusion Injury

Ischemia-reperfusion injury is a complex hemodynamic pathology that is a leading cause of death worldwide and occurs in many body organs. Numerous studies have shown that mitochondria play an important role in the occurrence mechanism of ischemia-reperfusion injury and that mitochondrial structural abnormalities and dysfunction lead to the disruption of the homeostasis of the whole mitochondria. At this time, mitochondria are not just sub-organelles to produce ATP but also important targets for regulating ischemia-reperfusion injury; therefore, drugs targeting mitochondria can serve as a new strategy to treat ischemia-reperfusion injury. Based on this view, in this review, we discuss potential therapeutic agents for both mitochondrial structural abnormalities and mitochondrial dysfunction, highlighting the application and prospects of targeted mitochondrial drugs in the treatment of ischemia-reperfusion injury, and try to provide new ideas for the clinical treatment of the ischemia-reperfusion injury.

Nicorandil prevents the nephrotoxic effect of cyclosporine-A in albino rats through modulation of HIF-1α/VEGF/eNOS signaling

Despite that cyclosporine-A (CsA) is a widely used immunosuppressive drug, its nephrotoxic effect limits its long-term administration. Herein we tried to investigate its renal effect on endothelial dysfunction targeting the hypoxia-inducible factor (HIF-1α) / vascular endothelial growth factor (VEGF) / endothelial nitric oxide synthase (eNOS) pathway and the possible modulation by nicorandil. Eight groups of adult male Wistar rats were included: (1) control; (2) vehicle group (received oil); (3) glibenclamide 5 mg·kg-1·day-1 administered orally; (4) nicorandil 10 mg·kg-1·day-1 administered orally; (5) CsA 25 mg·kg-1·day-1 administered orally; (6) combined administration of CsA and nicorandil; (7) glibenclamide was added to CsA; and (8) both CsA and nicorandil were combined with glibenclamide. The treatment continued for six weeks. Combined nicorandil with CsA improved renal function deterioration initiated by CsA. CsA decreased the renal expression levels (P < 0.001) of HIF-1α, eNOS, and VEGF, inducing endothelial dysfunction and triggering inflammation, and upregulated the profibrotic marker transforming growth factor (TGF-β). Nicorandil fixed the disturbed HIF-1α/VEGF/eNOS signaling. Nicorandil corrected the renal functions, confirmed by the improved histological glomerular tuft retraction that was obvious in the CsA group, without significant influence by glibenclamide. Proper protection from CsA-induced nephrotoxicity was achieved by nicorandil. Nicorandil reversed the disturbed HIF-1α/VEGF/eNOS pathway created by CsA.

Role of nitric oxide donor in methotrexate-induced testicular injury via modulation of pro-inflammatory mediators, eNOS and P-glycoprotein

Methotrexate (MTX) is a widely used chemotherapeutic agent but its clinical use is challenged with different forms of toxicities including testicular injury. The aim of the current study was to evaluate the potential protective effect of potassium channel opener, nicorandil (NIC) (3 and 10 mg/kg/day) on MTX-induced testicular injury in a rat model. Rats were randomly divided into four groups (nine rats each) and treated for 2 weeks as follows: (I) normal control (CON group) received vehicle, (II) model group (MTX group) given MTX (20 mg/kg) single intraperitoneal (i.p.) injection dose on 11th day, (III) MTX + NLD group treated with NIC (3 mg/kg/day) orally for 2 weeks and MTX (20 mg/kg) single i.p. dose on 11th day, and (IV) MTX + NHD group treated with NIC (10 mg/kg/day) orally for 2 weeks and MTX (20 mg/kg) single i.p. injection on the 11th day. The testicular injury was assessed biochemically via serum testosterone, total antioxidant capacity, testicular oxidative stress parameters, P-glycoprotein, tumor necrosis factor-alpha, and interleukin-1β. Furthermore, histopathological evaluation, endothelial nitric oxide synthase (eNOS) immunoexpression, and detection of p53 expression level using Western blotting were performed. Results showed that MTX induced testicular injury which was proved by both biochemical and histopathological evaluations. Our results concluded that NIC pretreatment attenuated MTX-induced testicular injury via significantly increased eNOS immunoexpression, antiapoptotic, anti-inflammatory, and antioxidant properties. Interestingly, NIC high dose is more protective than low dose.

Efficacy of nicorandil on the prevention of contrast-induced nephropathy in patients with coronary heart disease undergoing percutaneous coronary intervention

OBJECTIVES

The purpose of this study was to explore the effect of nicorandil on the incidence of contrast-induced nephropathy in patients with coronary heart disease undergoing percutaneous coronary intervention.

METHODS

This study randomized 300 patients undergoing percutaneous coronary intervention to receive conventional treatment in the control group (hydration only; n = 150) vs. nicorandil therapy (nicorandil 10 mg three times daily plus hydration; n = 150). The primary endpoint was the incidence of contrast-induced nephropathy, defined as rise in serum creatinine ≥44.2 μmol/L or >25% above baseline within 72 hours after exposure to contrast administered during percutaneous coronary intervention. Secondary endpoints included differences in post-percutaneous coronary intervention serum creatinine, blood urea nitrogen, creatinine clearance rate, cystatin-C, and occurrence of major adverse events.

RESULTS

Contrast-induced nephropathy incidence was 3.3% (5/150) in the nicorandil group vs. 10.7% (16/150) in the control group (P < 0.05). At 48 and 72 hours after contrast administration, cystatin-C levels were significantly lower and creatinine clearance rate were significantly higher with nicroandil therapy compared to conventional treatment (all P values <0.05). No statistical difference was observed in the incidence of major post-procedure side effect events in hospital and fourteen days of follow-up period between the nicorandil group and control group (3.3% vs. 4.0%, P > 0.05).

CONCLUSION

Compared to conventional treatment, oral nicorandil therapy was associated with less contrast-induced nephropathy and improved renal function following contrast administration during percutaneous coronary intervention.

Efficacy of Oral Nicorandil to Prevent Contrast-Induced Nephropathy in Patients with Chronic Renal Dysfunction Undergoing an Elective Coronary Procedure

Objectives: This prospective, randomized study was to investigate the role of nicorandil in the prevention of contrast-induced nephropathy (CIN) in patients with chronic renal dysfunction undergoing an elective coronary procedure. Methods: A total of 252 eligible patients were enrolled in this study and allocated into the control group (n = 125) or nicorandil group (n = 127). Both groups received the standard hydration treatment, and patients in the nicorandil group were orally administrated 10 mg of nicorandil (t.i.d.) beginning 2 days before and continuing for 2 days after an elective coronary procedure. Serum creatinine (SCr) and cystatin C (CysC) were measured at 24 h before and 24, 48, and 72 h after the procedure. The occurrences of CIN and adverse events within 1 year were recorded. Results: The nicorandil group had relatively lower SCr and CysC levels and a higher eGFR at 24 and 48 h after the procedure than the control group (p < 0.05). The incidence of CIN was significantly decreased in the nicorandil group compared to the control group. The multivariate logistic regression model revealed that nicorandil treatment was an independent protective factor for CIN (OR 0.669, 95% CI 0.522–0.857, p = 0.001). The multivariate COX proportional hazard model showed that nicorandil treatment was an independent protective predictor for adverse events (HR 0.881, 95% CI 0.781–0.993, p = 0.037). Conclusions: Nicorandil could exhibit a protective effect against CIN in patients with chronic renal dysfunction undergoing an elective coronary procedure and reduce the adverse events within 1 year after the procedure, which is superior to hydration treatment only.

Different sulfonylureas induce the apoptosis of proximal tubular epithelial cell differently via closing KATP channel

BACKGROUND

Sulfonylureas (SUs) are widely prescribed for the treatment of type 2 diabetes (T2DM). Sulfonylurea receptors (SURs) are their main functional receptors. These receptors are also found in kidney, especially the tubular cells. However, the effects of SUs on renal proximal tubular epithelial cells (PTECs) were unclear.

METHODS

Three commonly used SUs were included in this study to investigate if different SUs have different effects on the apoptosis of PTECs. HK-2 cells were exposed to SUs for 24 h prior to exposure to 30 mM glucose, the apoptosis rate was evaluated by Annexin/PI flow cytometry. Bcl-2, Bax and the ratio of LC3II to LC3I were also studied by western blot in vitro. Diazoxide was used to evaluate the role of KATP channel in SUs-induced apoptosis of PTECs. A Student's t-test was used to assess significance for data within two groups.

RESULTS

Treatment with glibenclamide aggravated the apoptosis of HK-2 cells in high-glucose, as indicated by a significant decrease in the expression of Bcl-2 and increase in Bax. Additionally, the decreased LC3II/LC3I reflects that the autophagy was inhibited by glibenclamide. Similar but less pronounced change was found in glimepiride group, however, nearly opposite effects were found in gliclazide group. Further, the effects of glibenclamide on apoptosis promotion and the decreased LC3II/LC3I were ameliorated obviously by treatment with 100uM diazoxide. The potential protection effect of gliclazide was also inhibited after opening the KATP channel.

CONCLUSION

Our results suggest that, the effects of glibenclamide and glimepiride on PTECs apoptosis, especially the former, were achieved in part by closing the KATP channel. In contrast to glibenclamide and glimepiride, therapeutic concentrations of gliclazide showed an inhibitory effect on apoptosis of PTECs, which may have a benefit in the preservation of functional PTECs mass.

The Free Radical Diseases of Prematurity: From Cellular Mechanisms to Bedside

During the perinatal period, free radicals (FRs) are involved in several physiological roles such as the cellular responses to noxia, the defense against infectious agents, the regulation of cellular signaling function, and the induction of a mitogenic response. However, the overproduction of FRs and the insufficiency of an antioxidant mechanism result in oxidative stress (OS) which represents a deleterious process and an important mediator of damage to the placenta and the developing fetus. After birth, OS can be magnified by other predisposing conditions such as hypoxia, hyperoxia, ischemia, hypoxia ischemia-reperfusion, inflammation, and high levels of nonprotein-bound iron. Newborns are particularly susceptible to OS and oxidative damage due to the increased generation of FRs and the lack of adequate antioxidant protection. This impairment of the oxidative balance has been thought to be the common factor of the so-called “free radical related diseases of prematurity,” including retinopathy of prematurity, bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, kidney damage, and oxidative hemolysis. In this review, we provide an update focused on the factors influencing these diseases refining the knowledge about the role of OS in their pathogenesis and the current evidences of such relationship. Mechanisms governing FR formation and subsequent OS may represent targets for counteracting tissue damage.

Nicorandil for the prevention of contrast-induced nephropathy: A meta-analysis of randomized controlled trials

INTRODUCTION

Nicorandil has been suggested as a preventative strategy against the incidence of contrast-induced nephropathy (CIN). However, results of relevant randomized controlled trials (RCTs) were inconsistent.

AIMS

We performed a meta-analysis of RCTs to evaluate the preventive efficacy of periprocedural treatment of nicorandil against the incidence of CIN.

METHODS

Relevant RCTs were identified via search of PubMed, Embase, and Cochrane's Library databases. Results were pooled using a random-effect model. Subgroup analyses were performed to evaluate the potential influence of administering routes on the efficacy of nicorandil against CIN incidence.

RESULTS

Four RCTs with 709 patients were included. Treatment of nicorandil significantly reduced the incidence of CIN as compared with controls (risk ration [RR]: 0.38, 95% confidence interval [CI]: 0.19 ~ 0.74, P = .005) with moderate heterogeneity (I²  = 33%). Results of subsequent subgroup analysis showed that nicorandil significantly reduced the risk of CIN if orally administered (RR: 0.32, P < .001), but did not if intravenously administered (RR: 0.47, I²  = 68%). Moreover, treatment with nicorandil was associated with significantly less increment of SCr (weight mean difference [WMD]: -3.98%, P < .001) and a tendency of less increment of cystatin C (WMD: -3.86%, P = .08) after 48-hour contrast exposure as compared with controls.

CONCLUSIONS

Periprocedural treatment with nicorandil may be preventative against the incidence of CIN in patients undergoing contrast exposure. The influence of periprocedural nicorandil on clinical outcome in these patients deserves further investigation.

A Protective Role of Glibenclamide in Inflammation-Associated Injury

Glibenclamide is the most widely used sulfonylurea drug for the treatment of type 2 diabetes mellitus (DM). Recent studies have suggested that glibenclamide reduced adverse neuroinflammation and improved behavioral outcomes following central nervous system (CNS) injury. We reviewed glibenclamide's anti-inflammatory effects: abundant evidences have shown that glibenclamide exerted an anti-inflammatory effect in respiratory, digestive, urological, cardiological, and CNS diseases, as well as in ischemia-reperfusion injury. Glibenclamide might block K_ATP channel, Sur1-Trpm4 channel, and NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome activation, decrease the production of proinflammatory mediators (TNF-α, IL-1β, and reactive oxygen species), and suppress the accumulation of inflammatory cells. Glibenclamide's anti-inflammation warrants further investigation.

Terlipressin protects intestinal epithelial cells against oxygen-glucose deprivation/re-oxygenation injury via the phosphatidylinositol 3-kinase pathway

Intestinal ischemia/reperfusion (I/R) injury is associated with a high morbidity and mortality. Vasopressin is administered to critically ill patients with potential intestinal I/R. However, the impacts of vasopressin on intestinal epithelia under ischemic/anoxic conditions remain unclear. The aim of the present study was to evaluate the effects of terlipressin, a highly selective vasopressin V1 receptor agonist, on oxygen and glucose deprivation/re-oxygenation (OGD/R)-induced damage in intestinal epithelial cells (IEC-6). IEC-6 cells were subjected to OGD for 4 h, followed by 4 h re-oxygenation. Terlipressin was incubated with cells for 4 h following OGD. Following OGD/R, IEC-6 cell viability, proliferation and apoptosis, as well as cell cycle dynamics, were assessed and the levels of tumor necrosis factor (TNF)-α and 15-F2t-isoprostane in the culture medium were measured. In addition, wortmannin, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, was administrated to investigate the mechanism of terlipressin action. The results demonstrated that IEC-6 cell viability and proliferation decreased, and cell apoptosis increased, following OGD/R. However, IEC-6 cell cycle dynamics did not significantly change 4 h after OGD. Incubation with 25 nM terlipressin significantly improved cell viability, proliferation and apoptosis. Furthermore, terlipressin inhibited the secretion of TNF-α and 15-F2t-isoprostane from IEC-6 cells following OGD/R. The aforementioned effects of terlipressin were completely abolished following the application of 2 µM wortmannin. Therefore, the current study demonstrated that terlipressin administration following OGD attenuates OGD/R-induced cell damage via the PI3K signaling pathway. These results may help physicians to better understand and more effectively use terlipressin in a clinical setting.

Proinflammatory Cytokines and Potassium Channels in the Kidney

Proinflammatory cytokines affect several cell functions via receptor-mediated processes. In the kidney, functions of transporters and ion channels along the nephron are also affected by some cytokines. Among these, alteration of activity of potassium ion (K(+)) channels induces changes in transepithelial transport of solutes and water in the kidney, since K(+) channels in tubule cells are indispensable for formation of membrane potential which serves as a driving force for the transepithelial transport. Altered K(+) channel activity may be involved in renal cell dysfunction during inflammation. Although little information was available regarding the effects of proinflammatory cytokines on renal K(+) channels, reports have emerged during the last decade. In human proximal tubule cells, interferon-γ showed a time-dependent biphasic effect on a 40 pS K(+) channel, that is, delayed suppression and acute stimulation, and interleukin-1β acutely suppressed the channel activity. Transforming growth factor-β1 activated KCa3.1 K(+) channel in immortalized human proximal tubule cells, which would be involved in the pathogenesis of renal fibrosis. This review discusses the effects of proinflammatory cytokines on renal K(+) channels and the causal relationship between the cytokine-induced changes in K(+) channel activity and renal dysfunction.

Antitumor action of the peroxisome proliferator-activated receptor-γ agonist rosiglitazone in hepatocellular carcinoma

The inhibition of apoptosis in cancer cells is the major pathological feature of hepatic carcinoma. Rosiglitazone (RGZ), a ligand for peroxisome proliferator-activated receptor γ (PPAR-γ), has been shown to induce apoptosis in hepatic carcinoma cells. However, the mechanism underlying this effect remains to be elucidated. The present study aimed to investigate the effect of RGZ on cell viability and apoptosis, and its mechanisms in cultured HepG2 cells using MTT assay, flow cytometry and western blotting. The results revealed that treatment with RGZ may attenuate HepG2 cell viability and induce the apoptosis of the cells. The mechanism of RGZ-induced apoptosis involves an increase in the level of activated PPAR-γ (p-PPAR-γ) and a decrease in p85 and Akt expression. In addition, the PPAR-γ antagonist GW9662 suppressed the effect of RGZ in the HepG2 cells. Taken together, the results suggest that RGZ induces the apoptosis of HepG2 cells through the activation of PPAR-γ, suppressing the activation of the PI3K/Akt signaling pathway. Such mechanisms may contribute to the favorable effects of treatment using RGZ in HepG2 cells.

Neuroprotective effect of nicorandil through inhibition of apoptosis by the PI3K/Akt1 pathway in a mouse model of deep hypothermic low flow

OBJECTIVE

Nicorandil exerts a protective effect on ischemia-reperfusion (I/R) injury in the brain and kidney through anti-apoptotic mechanisms. However, the mechanism by which nicorandil protects against I/R injury induced by deep hypothermic low flow (DHLF) remains unclear.

METHODS

We used a cerebral I/R model induced by DHLF to determine the neuroprotective effects and possible mechanisms of nicorandil.

RESULTS

Hematoxylin-eosin (HE) staining and in situ terminal deoxynucleotidyl transferase UTP nick end labeling (TUNEL) assay were used to detect changes in cell morphology and the number of apoptotic cells in hippocampus, respectively. The apoptotic regulators including Bcl-2, Bax, Akt, and p-Akt (the active, phosphorylated form of Akt) were examined by Western blot (WB). Histopathological findings showed that nicorandil significantly alleviated morphological damage in hippocampal and reduced the number of TUNEL-positive nuclei induced by DHLF. Nicorandil also increased the expression of Bcl-2 and decreased the expression of Bax, while increasing p-Akt level. Consistent with these results, nicorandil-mediated neuroprotection was reduced in the Akt1+/- mutant mice and inhibited by LY294002, a PI3K inhibitor.

CONCLUSIONS

These findings showed that nicorandil provides a neuroprotective role in DHLF-induced I/R injury by inhibiting apoptosis via activation of the PI3K/Akt1 signaling pathway.

Combination of ACE inhibitor with nicorandil provides further protection in chronic kidney disease

An inhibition in the renin-angiotensin system (RAS) is one of the most widely used therapies to treat chronic kidney disease. However, its effect is occasionally not sufficient and additional treatments may be required. Recently, we reported that nicorandil exhibited renoprotective effects in a mouse model of diabetic nephropathy. Here we examined if nicorandil can provide an additive protection on enalapril in chronic kidney disease. Single treatment with either enalapril or nicorandil significantly ameliorated glomerular and tubulointerstitial injury in the rat remnant kidney while the combination of these two compounds provided additive effects. In addition, an increase in oxidative stress in remnant kidney was also blocked by either enalapril or nicorandil while the combination of the drugs was more potent. A mechanism was likely due for nicorandil to preventing manganase superoxide dismutase (MnSOD) and sirtuin (Sirt)3 from being reduced in injured kidneys. A study with cultured podocytes indicated that the antioxidative effect could be mediated through sulfonylurea receptor (SUR) in the mitochondrial KATP channel since blocking SUR with glibenclamide reduced MnSOD and Sirt3 expression in podocytes. In conclusion, nicorandil may synergize with enalapril to provide superior protection in chronic kidney disease.