Nitric Oxide Modulation as a Potential Molecular Mechanism Underlying the Protective Role of NaHS in Liver Ischemia Reperfusion Injury.

BACKGROUND: Liver IR is a frequent clinical complication with high morbidity and mortality. The present study evaluated the possible protective effect of sodium hydrosulfide (NaHS), a H2S donor, in IR-induced hepatic injury and explored the mechanisms of actions of the investigated drug. METHODS: Male albino rats (200-230 g) were divided into the following groups: group 1:Sham-operated non treated rats, group 2: IR non treated rats, group 3: L-NNA + IR rats, group 4: NaHS + IR rats, group 5: L-NNA + NaHS + IR rats. Blood samples were collected for ALT determination. Liver tissue samples were used for the assessment of GPx, catalase, SOD, MDA, total nitrites and TNF- α. Parts from the liver were fixed in 10% formalin solution for histopathological examination and immunohistochemical examination of iNOS, eNOS and caspase-3. RESULTS: NaHS protected the liver against IR. This hepatoprotection was associated with normalization of antioxidant enzyme activity and decrease in hepatic MDA, TNF-α and expression of caspase- 3 and iNOS. CONCLUSION: NaHS is hepatoprotective in IR injury. The hepatoprotective effects of NaHS are associated with antioxidant, anti-inflammatory and antiapoptotic effects. These effects are probably mediated via NO modulation.

Empagliflozin alleviates neuronal apoptosis induced by cerebral ischemia/reperfusion injury through HIF-1α/VEGF signaling pathway.

Ischemic stroke is a serious condition associated with severe functional disability and high mortality, however; effective therapy remains elusive. Empagliflozin, a sodium-glucose cotransporter 2 inhibitor, has been shown to exert additional non-glycemic benefits including anti-apoptotic effects in different disease settings. Thereby, this study was designed to investigate the ameliorative effect of empagliflozin on the neuronal apoptosis exhibited in cerebral ischemia/reperfusion (I/R) in a rat model targeting HIF-1α/VEGF signaling which is involved in this insult. Global cerebral I/R injury was induced in male Wistar rats through occlusion of the bilateral common carotid arteries for 30 min followed by one-hour reperfusion. Empagliflozin doses of 1 and 10 mg/kg were administered 1 and 24 h after reperfusion. In I/R-injured rats, empagliflozin treatments significantly reduced infarct size and enhanced neurobehavioral functions in a dose-dependent manner. The drug alleviated neuronal death and cerebral injury inflicted by global ischemia as it suppressed neuronal caspase-3 protein expression. In parallel, protein expressions of HIF-1α and its downstream mediator VEGF were upregulated in the ischemic brain following empagliflozin treatment. The results indicated that empagliflozin attenuates cerebral I/R-induced neuronal death via the HIF-1α/VEGF cascade.

Empagliflozin attenuates transient cerebral ischemia/reperfusion injury in hyperglycemic rats via repressing oxidative-inflammatory-apoptotic pathway.

Hyperglycemia is one of the ischemic neuronal damage triggers that exacerbate the response to oxidative stress, inflammation, and apoptosis induced by cerebral ischemia/reperfusion (I/R) injury. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT 2) inhibitor, was shown to effectively reduce hyperglycemia and glucotoxicity besides improving glycemic control in diabetics. Therefore, the present study was conducted to investigate the neuroprotective effect of empagliflozin against cerebral I/R injury in hyperglycemic rats. Hyperglycemia was induced by streptozotocin (55 mg/kg), and transient cerebral I/R was induced by bilateral common carotid occlusion for 30 min followed by 24-h reperfusion. Either empagliflozin (10 mg/kg; i.p.) or gliclazide (2 mg/kg, p.o.) was administered at 1 and 24 h after reperfusion. Treatment with empagliflozin showed a significant amelioration of behavioral/neurological functions and histopathological changes observed in brain tissues of hyperglycemic rats subjected to cerebral I/R injury. Comparable to gliclazide, empagliflozin decreased cerebral infarct volume along with suppression of cerebral oxidative stress, inflammatory, and apoptotic markers in brain tissues of hyperglycemic I/R-injured rats. These findings suggested that empagliflozin can significantly alleviate neuronal damage resulting from global I/R injury induced in hyperglycemic rats. The proposed neuroprotective effect of empagliflozin may be attributed to its glycemic control effect and related antioxidant, anti-inflammatory, and antiapoptotic effects.

Possible Protective Effect of Diacerein on Doxorubicin-Induced Nephrotoxicity in Rats.

Nephrotoxicity is one of the limiting factors for using doxorubicin (DOX). Interleukin 1 has major role in DOX-induced nephrotoxicity, so we investigated the effect of interleukin 1 receptor antagonist diacerein (DIA) on DOX-induced nephrotoxicity. DIA (25 and 50 mg/kg/day) was administered orally to rats for 15 days, in the presence or absence of nephrotoxicity induced by a single intraperitoneal injection of DOX (15 mg/kg) at the 11th day. We measured levels of serum urea, creatinine, renal reduced glutathione (GSH), malondialdehyde (MDA), total nitrites (NO x ), catalase, and superoxide dismutase (SOD). In addition, caspase-3, tumor necrosis factor alpha (TNFα), nuclear factor kappa B (NFκB) expressions, and renal histopathology were assessed. Our results showed that DOX-induced nephrotoxicity was ameliorated or reduced by both doses of DIA, but diacerein high dose (DHD) showed more improvement than diacerein low dose (DLD). This protective effect was manifested by significant improvement in all measured parameters compared to DOX treated group by using DHD. DLD showed significant improvement of creatinine, MDA, NO x , GSH, histopathology, and immunohistochemical parameters compared to DOX treated group.

Potential protective effect of etanercept and aminoguanidine in methotrexate-induced hepatotoxicity and nephrotoxicity in rats.

Methotrexate (MTX), a chemotherapeutic and immunosuppressant drug, is generally well-tolerated by most patients. However, its cytotoxic nature contributes to life-threatening side effects including hepatotoxicity and nephrotoxicity. The present study investigated the possible role of tumor necrosis factor-alpha (TNF-α) inhibitor, etanercept and inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine, on MTX-induced hepatotoxicity and nephrotoxicity in rats. Rats were divided into 7 groups: control group, etanercept group, aminoguanidine group, MTX group, MTX+etanercept group, MTX+aminoguanidine group, and MTX+etanercept+aminoguanidine group. MTX caused hepatotoxicity and nephrotoxicity as evidenced biochemically by significant increase in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea and creatinine, respectively as well as by histopathological changes. Such effects were associated with significant changes in oxidative stress markers (malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), catalase, and glutathione (GSH)) as well as by upregulation of TNF-α, iNOS and caspase-3 expressions in hepatic and renal tissues. Etanercept and aminoguanidine significantly attenuated MTX-hepatotoxicity and nephrotoxicity. The protective effect of either agent was associated with significant improvement in oxidative stress parameters as well as by downregulation of TNF-α, iNOS and caspase-3 expressions in hepatic and renal tissues. The study suggested that inhibitors of either TNF-α and/or iNOS have protective effect in MTX-induced hepatotoxicity and nephrotoxicity. The protective effect of either agent relies, at least partially, on their antioxidant effects and decreased TNF-α, iNOS, and caspase-3 expressions.

Effect of selective versus non-selective cyclooxygenase inhibitors on ischemia-reperfusion-induced hepatic injury in rats.

AIM: Ischemia-reperfusion (IR) injury represents an important pathological process of liver injury during major hepatic surgery. The role of cyclooxygenase (COX) enzymes in the pathogenesis of ischemia-reperfusion (IR)-induced liver injury is not clear. This study investigated the effect of a selective COX-2 inhibitor, celecoxib, versus non-selective, indomethacin, on hepatic IR injury in rats. MATERIALS AND METHODS: Hepatic IR was induced in adult male rats. The animals were divided into 4 groups: normal control (sham group), IR non-treated group; IR-indomethacin-treated group; and IR-celecoxib-treated group. Liver injury was evaluated by serum alanine aminotransferase (ALT) and a histopathological examination of liver tissues. Hepatic tissue content of oxidative stress parameters glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase, malondialdehyde (MDA), nitric oxide (NO) and the inflammatory marker, tumor necrosis factor-alpha, (TNF-α) were measured. Moreover, the immunohistochemical detection of endothelial NO synthase (eNOS), inducible NO synthase (iNOS), and caspase-3 in the hepatic tissue was performed. KEY FINDINGS: Celecoxib, but not indomethacin, significantly attenuated hepatic IR injury as evidenced by reduction in serum ALT as well as by improvement in the histopathological scoring. Such effect was associated with attenuation in oxidative stress and TNF-α, along with modulation of immunohistochemical expression of eNOS, iNOS and caspase-3 in the hepatic tissue. SIGNIFICANCE: The present study concluded that selective COX-2 inhibition (but not non-selective), is hepatoprotective against liver IR injury; indicating a differential role of COX-1 versus COX-2. Modulation of iNOS, eNOS and caspase-3 might participate in the protective effect of selective COX-2-inhibitors.

Molecular mechanisms contributing to the protective effect of levosimendan in liver ischemia-reperfusion injury.

Ischemia-reperfusion injury (IRI) is an important cause of liver damage in many clinical situations. Levosimendan is a promising therapy for prevention of IRI. The present work investigated the possible contribution of nitric oxide (NO), cyclooxygenase (COX) enzymes, and adenosine triphosphate sensitive potassium channel (K-ATP) in the protective effect of levosimendan in liver IRI in rats. Rats were divided into 7 groups. Sham-operated group (negative control group); IR-nontreated group (positive control group), levosimendan-treated group (treated with levosimendan); indomethacin, nonselective COX inhibitor,+levosimendan group (cotreated with indomethacin+levosimendan); celecoxib (selective COX-2 inhibitor)+levosimendan group; L-NNA (Nitro- ω-L-arginine, nonselective NO synthase inhibitor)+levosimendan group; and glibenclamide (K-ATP blocker)+levosimendan group. Liver injury was evaluated biochemically (by serum level of alanine aminotransferase (ALT)) as well as by histopathology. Hepatic tissue content of oxidative stress markers, tumor necrosis factor-alpha (TNF-α), along with immunohistochemical expression of induced NO synthase (iNOS), endothelial NO synthase (eNOS), and caspase-3 in hepatic tissue were assayed. The study showed that levosimendan attenuated liver IRI as evidenced by a decrease in serum ALT level and confirmed by histopathology. The protective effect of levosimendan was associated with modulation of oxidative stress, TNF-α, iNOS, eNOS, and caspase-3. The hepatoprotective effect of levosimendan was partially attenuated by pretreatment by either nonselective COX inhibitor, NOS inhibitor, or K-ATP channel blocker; indicating that the hepatoprotective effect of levosimendan was attributed, at least in part to activation of COX-1, modulation of NO, and opening of K-ATP channel.

Sildenafil Ameliorates Gentamicin-Induced Nephrotoxicity in Rats: Role of iNOS and eNOS.

Gentamicin, an aminoglycoside antibiotic, is used for the treatment of serious Gram-negative infections. However, its usefulness is limited by its nephrotoxicity. Sildenafil, a selective phosphodiesterase-5 inhibitor, was reported to prevent or decrease tissue injury. The aim of this study is to evaluate the potential protective effects of sildenafil on gentamicin-induced nephrotoxicity in rats. Male Wistar rats were injected with gentamicin (100 mg/kg/day, i.p.) for 6 days with and without sildenafil. Sildenafil administration resulted in nephroprotective effect in gentamicin-intoxicated rats as it significantly decreased serum creatinine and urea, urinary albumin, and renal malondialdehyde and nitrite/nitrate levels, with a concomitant increase in renal catalase and superoxide dismutase activities compared to gentamicin-treated rats. Moreover, immunohistochemical examination revealed that sildenafil treatment markedly reduced inducible nitric oxide synthase (iNOS) expression, while expression of endothelial nitric oxide synthase (eNOS) was markedly enhanced. The protective effects of sildenafil were verified histopathologically. In conclusion, sildenafil protects rats against gentamicin-induced nephrotoxicity possibly, in part, through its antioxidant activity, inhibition of iNOS expression, and induction of eNOS production.

Carvedilol ameliorates early diabetic nephropathy in streptozotocin-induced diabetic rats.

Diabetic nephropathy results in end-stage renal disease. On the other hand, carvedilol has been reported to have various pharmacological properties. The aim of this study therefore is to evaluate the possible protective effect of carvedilol on streptozotocin-induced early diabetic nephropathy and various mechanisms underlie this effect in rats. Single i.p. injection of streptozotocin (65 mg/kg) was administered to induce early diabetic nephropathy in Wistar rats. Oral administration of carvedilol at a dose level of 1 and 10 mg/kg daily for 4 weeks resulted in nephroprotective effect as evident by significant decrease in serum creatinine level, urinary albumin/creatinine ratio, and kidney index as well as renal levels of malondialdehyde, nitric oxide, tumor necrosis factor- α , and cyclooxygenase-2 with a concurrent increase in creatinine clearance and renal reduced glutathione level compared to diabetic untreated rats. The protective effect of carvedilol was confirmed by renal histopathological examination. The electron microscopic examination indicated that carvedilol could effectively ameliorate glomerular basement membrane thickening and podocyte injury. In conclusion, carvedilol protects rats against streptozotocin-induced early diabetic nephropathy possibly, in part, through its antioxidant as well as anti-inflammatory activities, and ameliorating podocyte injury.

Montelukast and irbesartan ameliorate metabolic and hepatic disorders in fructose-induced metabolic syndrome in rats.

Metabolic syndrome (MetS) is a global health problem. Elucidation of the role of 5- lipooxygenase/leukotriene pathway and renin angiotensin system in the pathogenesis of MetS suggests a variety of potential therapies worthy of testing. The present work investigated the effect of montelukast, a leukotriene antagonist and/or irbesartan, an angiotensin II-receptor blocker, in the prevention of fructose-induced MetS in rats. Rats were allocated into 9 groups and treated for 6 weeks as follow: normal control; MetS group (received 20% fructose); MetS+montelukast groups (treated with montelukast, 5, 10, and 20 mg/kg/day, respectively); MetS+irbesartan groups (treated withirbesartan 15, 30, and 45 mg/kg/day, respectively); and MetS+montelukast+irbesartan group (co treated with montelukast 5 mg/kg plus irbesartan 15 mg/g). Metabolic parameters (visceral fat index, liver index, insulin resistance, and serum lipid profile), oxidative stress markers (malondialdehyde, reduced glutathione, and catalase), and inflammatory mediators (tumor necrosis factor-α, and uric acid) were measured. Expression of caspase-3 in hepatic tissues was detected by immunohistochemistry. Liver injury was evaluated by histopathological examination and serum alanine aminotransferase (ALT). Montelukast, irbesartan, and their combination caused significant attenuation in metabolic and hepatic disorders. Their effect was associated with attenuation of oxidative stress markers, inflammatory mediators, and caspase-3 expression. This study highlighted the protective effects of montelukast and irbesartan against fructose-induced metabolic and hepatic disorders. The protective effect of either drug relies, at least in part, on their antioxidant and antiinflammatory effect, as well as on the reduction of caspase-3 expression in hepatic tissue.

Curcumin ameliorates methotrexate-induced nephrotoxicity in rats.

Methotrexate is an effective anticancer and immunosuppressive agent. However, nephrotoxicity is one of the complications of its use. On the other hand, curcumin, a naturally occurring polyphenolic compound, is reported to have antioxidant and anti-inflammatory properties. Those two properties are likely to prevent methotrexate-induced nephrotoxicity. The aim of this study is to evaluate the possible protective effect of curcumin against methotrexate-induced nephrotoxicity and delineate various mechanism(s) underlies this effect in rats. Nephrotoxicity was induced in Wistar rats by intraperitoneal administration of methotrexate (7 mg/kg/day) for three consecutive days. Curcumin administration in methotrexate-intoxicated rats resulted in nephroprotective effects as evidenced by the significant decrease in levels of serum creatinine and urea as well as renal malondialdehyde, nitric oxide, and tumor necrosis factor- α with a concurrent increase in renal glutathione peroxidase and superoxide dismutase activities compared to nephrotoxic untreated rats. Additionally, immunohistochemical analysis demonstrated that curcumin treatment markedly reduced cyclooxygenase-2 expression. Histopathological examination confirmed the protective effects of curcumin. In conclusion, curcumin protected rats from methotrexate nephrotoxicity, at least in part, through its antioxidant and anti-inflammatory activities.