Efeitos anti-inflamatório e antioxidante do sildenafil em modelo experimental de mucosite intestinal induzida por 5-fluorouracil

Abstract

Intestinal mucositis (IM) is one of the most common adverse effects of 5-fluorouracil (5-FU) chemotherapy, being considered a limiting factor mainly in the treatment of breast and colorectal cancer. The present work evaluated the possible anti-inflammatory, antioxidant and protective effect of sildenafil (phosphodiesterase type 5 inhibitor) in an experimental model of intestinal mucositis induced by 5-FU. For this, IM was induced in Swiss mice (25-30g) by the administration of a single intraperitoneal dose of 5-FU (450mg/kg). The animals were treated with sildenafil (SIL) at doses of 5, 10 and 25mg/kg orally thirty minutes before induction and; 24, 48 and 72 hours post-induction of mucositis. Thirty minutes after the last administration of SIL, the animals were euthanized with an overdose of ketamine and xylasin. Intestinal segments were collected for analysis of nitrate/nitrite (NO3/NO2) and reduced glutathione (GSH) concentration to choose the best dose. Weight loss was assessed for 3 days. Treatment with SIL at a dose of 25 mg/kg was the most effective. It significantly reduced the concentration of nitrate/nitrite compared to the other two doses in the duodenum (1.478±0.20 μM), jejunum (1.245±0.02 μM) and ileum (1.273±0.15 μM) when compared to the group 5-FU+vehicle (duodenum: 2.590±0.11 µM, jejunum: 2.748±0.21 µM and in the ileum: 2.588±0.06 µM) and; avoided the consumption of GSH (duodenum: 182.7±26.53 μg/g; jejunum: 155.4±13.43 μg/g and ileum 202.5±24.32 μg/g) when compared with group 5- FU+vehicle (duodenum: 94.64±11.51 µg/g; jejunum: 114.7±4.6 µg/g and ileum: 95.76±9.01 µg/g). It was observed that treatment with SIL prevented the worsening of the intestinal lesion, which is characterized by the shortening of the intestinal villi, partial necrosis of the crypts, vacuolization of cells and the presence of polymorphonuclear infiltrates. Treatment with SIL (1388±233.7 cells/mm3) did not significantly improve the leukopenia caused by 5-FU (1331±83.77 cells/mm3) and attenuated MPO activity (duodenum: 0.92±0, 43 U/mg, jejunum: 2.036±0.28 U/mg and ileum: 2.82±0.67 U/mg) compared to mice with IM (duodenum: 6.67±1.3 U/mg; jejunum: 7.52±0.71 U/mg and ileum: 8.29±1.37 U/mg). In the evaluation of the integrity of the ileal epithelium, protection was observed in the groups that received treatment with SIL both in the RETE (25.0±3.512 Ω/cm2) and in the permeability of the mucosa in the times of 60 minutes (32.93±6.013 µmol/ cm2) and 90 minutes (51.63±8.295 µmol/cm2). These results demonstrate that sildenafil treatment attenuates oxidative stress, inflammation and maintains epithelial integrity, which may guide future clinical studies. Thus, sildenafil may have a relevant therapeutic impact aiming its repositioning as an effective drug in the treatment or as an adjuvant agent for IM.