No abstract

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.

Background and purpose:The pleiotropic effects of HMG-CoA inhibitors (statins), which include anti-inflammation, antioxidation and immunomodulation, are not yet fully understood. The present study was designed to elucidate the role of nitric oxide (NO), peroxynitrite (ONOO -) and haem oxygenase-1 (HO-1) in the anti-atherogenic effect of statins. Experimental approach: Normal and atherosclerotic New Zealand rabbits were treated with atorvastatin or simvastatin in the presence or absence of inhibitors and promoters of endothelial nitric oxide synthase (eNOS) and HO-1. NO and ONOO -released from isolated aortae by calcium ionophore were measured with nanosensors placed 6 Ϯ 2 nm from aortic endothelium. Expression of eNOS and HO-1 protein, HO activity, plasma malondialdehyde (MDA) and vessel wall thickness were also measured.

Vascular endothelial dysfunction is a complex phenomenon that might be caused by a deficiency of nitric oxide (NO) and an overproduction of peroxynitrite (ONOO-). This study used a nanotechnological approach to monitor the in vitro effect of statins on the [NO]/[ONOO-] balance in normal and dysfunctional endothelial cells. NO and (ONOO-) were measured by electrochemical nanosensors in a single human umbilical vein endothelial cell (HUVEC) treated with atorvastatin or simvastatin for 24 hours in the presence or absence of 50 microg/mL oxidized-LDL. An imbalance between [NO]/[ONOO-] concentrations was used as an indicator of endothelial dysfunction and correlated with endothelial nitric oxide synthase (eNOS) expression. Ox-LDL induced dysfunction of the endothelium by uncoupling eNOS. NO concentration decreased from 300 +/- 12 to 146 +/- 8 nmol/L and (ONOO-) increased from 200 +/- 9 to 360 +/- 13 nmol/L. The [NO]/[ONOO-] balance decreased from 1.50 +/- 0.04 (control) to 0.40 +/- 0.03 for cells co-incubated with ox-LDL. Treatment with statins reversed eNOS uncoupling, induced by oxidized-LDL and significantly increased the [NO]/[ONOO-] balance to 1.2 +/- 0.1. These results demonstrate that statins can restore endothelial function by increasing eNOS expression, decreasing eNOS uncoupling, reducing the (ONOO-) level (nitroxidative stress), and shifting the [NO]/[ONOO-] balance towards NO.

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.

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.

No abstract

Hydrogen sulfide (H2S) is an endogenous gaseous mediator plays a potential role in modulating gastric inflammatory responses. However, its putative protective role remains to be defined. The present study aimed to evaluate role of the exogenously released and endogenously synthesized H2S in cold restraint stress (CRS)-induced oxidative gastric damage in rats. Rats were restrained, and maintained at 4 °C for 3 h. The H2S donor, sodium hydrosulfide (NaHS) (60 μmol/kg) was injected intraperitoneally (i.p.) before CRS. Our results revealed that NaHS pretreatment significantly attenuated ulcer index, free and total acid output, and pepsin activity in gastric juice along with decreased gastric mucosal carbonyl content and reactive oxygen species production. This was accompanied by increased gastric juice pH and mucin concentration in addition to restoring the deficits in the gastric reduced glutathione, catalase as well as superoxide dismutase enzyme activities. NaHS pretreatment markedly reduced the serum level of tumor necrosis factor (TNF-α) and myeloperoxidase activity compared to CRS-non-treated. Moreover, NaHS preadministration significantly abrogated the inflammatory and the deleterious responses of gastric mucosa in CRS. The protective effects of H2S were confirmed by gastric histopathological examination. However, pretreatment with the H2S-synthesizing enzyme, cystathionine-gamma-lyase inhibitor, beta-cyano-L-alanine (50 mg/kg, i.p.) reversed the gastroprotection afforded by the endogenous H2S. Collectively, our results suggest that H2S can protect rat gastric mucosa against CRS-induced gastric ulceration possibly through mechanisms that involve anti-oxidant and anti-inflammatory actions alongside enhancement of gastric mucosal barrier and reduction in acid secretory parameters.