Berna Karakoyun

The effect of phosphodiesterase-5 inhibition by sildenafil citrate on inflammation and apoptosis in rat experimental colitis.

AIMS To investigate the effect of sildenafil citrate (SIL) on the extent of tissue integrity, oxidant-antioxidant status and apoptosis in rats with colitis. MAIN METHODS Colitis was induced by trinitrobenzenesulphonic acid (TNBS) in 40% ethanol (30 mg/ml; 0.8 ml) given intrarectally to Sprague-Dawley rats. Sildenafil (25 mg/kg/day) was administered after the induction of colitis and the treatment was continued for 7 days. Other groups received subcutaneously either N(G)-nitro- L-arginine methyl ester (l-NAME; 25 mg/kg) or N(G)-nitro-d-arginine methyl ester (d-NAME; 25 mg/kg) before SIL. After decapitation, the distal colon was scored and stored for the measurement of malondialdehyde (MDA) level, glutathione (GSH) content, myeloperoxidase (MPO) activity and apoptosis. Oxidant generation was monitored by using chemiluminescence (CL). Blood was collected for tumor necrosis factor (TNF)-α and interleukin (IL)-10 assays. KEY FINDINGS The macroscopic lesion score of the colitis group was reduced by SIL (p < 0.01) and this effect was abolished by l-NAME (p < 0.01). Increase in colonic MDA along with a concomitant decrease in GSH of the colitis group was reversed by SIL (p < 0.01 and p < 0.001, respectively). l-NAME prevented the effect of SIL on GSH content (p < 0.001). Sildenafil also reduced the elevated MPO of the colitis group (p < 0.001) and this effect was reversed by L-NAME (p < 0.01). Increase in lucigenin CL and serum TNF-α levels in the colitis group were also prevented by SIL (p < 0.001 and p < 0.01, respectively). SIGNIFICANCE Sildenafil is beneficial in TNBS-induced rat colitis partially by nitric oxide-dependent mechanisms via the maintenance of oxidant-antioxidant status, prevention of apoptosis, superoxide production and cytokine release.

Treatment with either obestatin or ghrelin attenuates mesenteric ischemia-reperfusion-induced oxidative injury of the ileum and the remote organ lung.

To evaluate the effects of exogenous ghrelin or obestatin on intestinal injury and accompanying pulmonary injury, intestinal ischemia-reperfusion (I/R) was induced in rats by obstructing the superior mesenteric artery for 60min, whereas laparotomy was performed in the sham group. At the beginning of the 90-min reperfusion period, the rats were injected with obestatin (100μg/kg), ghrelin (10ng/kg), or saline intravenously (iv). At the end of reperfusion, the blood, ileum, and lung samples were taken for the histological and biochemical assays. In the saline-treated I/R group, the increased serum interleukin (IL)-1β level, high damage scores, and elevated tissue malondialdehyde level and collagen content in both tissues were significantly reduced by obestatin or ghrelin. Increased ileal myeloperoxidase activity of the saline-treated I/R group was reduced by treatment with obestatin or ghrelin, whereas increased pulmonary myeloperoxidase activity was reduced with administration of obestatin. Increased DNA fragmentation in the ileum of the saline-treated I/R group was reduced by both peptides. Elevated luminol-lucigenin chemiluminescence levels and nuclear factor kappa B (NF-κB) messenger RNA (mRNA) expression in the ileum of the saline-treated-I/R group were significantly decreased by obestatin or ghrelin treatment. I/R-induced depletion of the antioxidant glutathione in both ileal and pulmonary tissues was prevented with either obestatin or ghrelin treatment. Administration of either obestatin or ghrelin exerts similar protective effects against I/R-induced ileal and pulmonary injury, thus warranting further investigation for their possible use against ischemic intestinal injury.

Halofuginone has a beneficial effect on gentamicin-induced acute nephrotoxicity in rats.

The aim of this study was to investigate the putative beneficial effect of halofuginone on gentamicin- induced nephrotoxicity in rats. Sprague-Dawley rats were treated with gentamicin sulphate (GEN; 80 mg/kg) or saline intraperitoneally (i.p.) for 7 days. Halofuginone was administered (0.1 mg/kg/day; i.p.) following GEN or saline injections. Blood and urine samples were collected to measure the renal function tests. Kidneys were excised for histological evaluation and for the measurement of malondialdehyde (MDA), glutathione (GSH), myeloperoxidase (MPO) activity, and chemiluminescence (CL). Halofuginone treatment to animals with GEN-induced renal injury caused a significant decrease in serum blood urea nitrogen level and reduced the elevated MDA, GSH content, and MPO activity. It was also effective in reversing the elevated CL values of rats with GEN-induced nephrotoxicity and preserving renal morphology, as examined microscopically. In conclusion, halofuginone was beneficial in GEN-induced acute nephrotoxicity. The mechanism could be attributed, at least in part, to decreased tissue leukocyte infiltration and reactive metabolite production.

The antifibrotic drug halofuginone reduces ischemia/reperfusion-induced oxidative renal damage in rats

AIM The objective of the present study was to evaluate the protective effects of halofuginone against renal ischemia/reperfusion (I/R) injury. MATERIALS AND METHODS Male Wistar albino rats were unilaterally nephrectomized and the left renal pedicles were occluded for 45 min to induce ischemia and then reperfused for 6 h (early) or for 72 h (late). The rats were treated intraperitoneally with either halofuginone (100 μg/kg/day) or saline 30 min prior to ischemia and the dose was repeated in the late reperfusion groups. In the sham groups, rats underwent unilateral nephrectomy and were treated at similar time points. The animals were decapitated at either 6 h or 72 h of reperfusion and trunk blood and kidney samples were obtained. RESULTS I/R injury increased renal malondialdehyde levels, myeloperoxidase activity and reactive oxygen radical levels, and decreased the renal glutathione content. Halofuginone treatment was found to reduce oxidative I/R injury and improve renal function in the rat kidney, as evidenced by reduced generation of reactive oxygen species, depressed lipid peroxidation and myeloperoxidase activity, and increased glutathione levels. CONCLUSIONS The present findings demonstrate the anti-inflammatory and antioxidant effects of halofuginone in renal I/R injury, supporting its potential use where renal I/R injury is inevitable.

Halofuginone Alleviates Burn-Induced Hepatic and Renal Damage in Rats.

The aim of this study was to evaluate the possible protective effects of halofuginone on burn-induced oxidative injury of the liver and kidney. For the induction of burn, backs of Wistar albino rats were shaved and exposed for 10 seconds to water bath at 90°C, whereas rats in the control group were exposed for 10 seconds at 25°C. Rats were then administered either saline (1 ml/kg) or halofuginone (100 &mgr;g/kg/day) intraperitoneally and decapitated at the 24th hour (early burn) or on the 7th day (late burn). Serum concentrations of creatinine, blood urea nitrogen, alanine aminotransferase, and aspartate aminotransferase were determined. Renal and hepatic tissue samples were used for microscopic analysis, and glutathione, malondialdehyde, and myeloperoxidase activity and chemiluminescence levels were measured. Halofuginone treatment improved renal functions in late burn group and hepatic functions in early burn group as demonstrated by decreased serum creatinine, blood urea nitrogen, and alanine aminotransferase levels. Increased serum lactate dehydrogenase level measured in late phase was reduced by halofuginone treatment. Generation of reactive oxygen metabolites measured by chemiluminescence, indicating burn-induced renal and hepatic oxidative injury in both the early and late burn groups, was reduced by halofuginone. Increased hepatic malondialdehyde levels accompanied with high microscopic damage scores were reversed by halofuginone in early burn group, while depleted renal glutathione levels were replenished. The present findings demonstrate that halofuginone preserved renal and hepatic functions and alleviated oxidative tissue damage insulted by burn trauma, suggesting an anti-inflammatory and antioxidant potential for halofuginone in providing protection against burn-induced renal and hepatic injury.

Ameliorative effects of riboflavin on acetic acid‐induced colonic injury in rats

Riboflavin (RF) has been found to be a promising antioxidant and/or anti‐inflammatory agent in several studies. However, the effect of RF against acetic acid (AA)‐induced colonic injury is currently unknown. This study aimed to investigate the potential antioxidant and protective effects of RF in a rat model of ulcerative colitis. Starting immediately after the colitis induction (AA+RF group) or 1 week before the colitis induction (RF+AA+RF group), the rats were treated with RF (25 mg/kg per day; p.o.) for 3 days. The control and AA groups received saline (1 mL; p.o.) whereas AA+SS group (positive control) received sulfasalazine (100 mg/kg per day; p.o.) for 3 days. Colonic samples were taken for the biochemical and histological assessments on the third day. High damage scores, elevated tissue wet weight index (WI), tissue myeloperoxidase (MPO) activity, 8‐hydroxy‐2′‐deoxyguanosine levels and chemiluminescence values, and a pronounced decrease in antioxidant glutathione (GSH) levels of the AA group were all reversed by RF pretreatment (RF+AA+RF group) and SS treatment (AA+SS group) (P < .05‐.001). Tissue WI, MPO activity and GSH levels were not statistically changed in the AA+RF group. Western blot analysis revealed that the decreased protein expressions of tissue collagen (COL) 1A1, COL3A1 and transforming growth factor‐β1 in the AA group were elevated in all the treatment groups (P < .05‐.001). In conclusion, RF exerts both the antioxidant and anti‐inflammatory effects against AA‐induced colonic inflammation by suppressing neutrophil accumulation, inhibiting reactive oxidant generation, preserving endogenous glutathione, improving oxidative DNA damage and regulating inflammatory mediators, suggesting a future potential role in the treatment and prevention of ulcerative colitis.