A CLP polymicrobial sepsis model was applied to the rats. All groups were killed 16 h later, and lung, kidney and blood samples were analysed histopathologically and biochemically. Sildenafil increased glutathione (GSH) and decreased the activation of myeloperoxidase (MPO) and of lipid peroxidase (LPO) and levels of superoxide dismutase (SOD) in the septic rats. We observed a significant decrease in LPO and MPO and a decrease in SOD activity in the Metformin sildenafil-treated CLP rats compared with the sham group. In addition, 20 mg/kg sildenafil treatment in

the sham-operated rats improved the biochemical status of lungs and kidneys. Histopathological analysis revealed significant differences Selleck Proteasome inhibitor in inflammation scores between the sepsis group and the other groups, except the CLP + sildenafil 10 mg/kg group. The CLP + sildenafil 20 mg/kg group had the lowest inflammation score. Sildenafil treatment decreased the serum tumour necrosis factor (TNF)-α

level when compared to the CLP group. Our results indicate that sildenafil is a highly protective agent in preventing lung and kidney damage caused by CLP-induced sepsis via maintenance of the oxidant–anti-oxidant status and decrease in the level of TNF-α. Sepsis is a systemic inflammatory response to infection and a major cause of morbidity and mortality worldwide. Sepsis may result in hypotension and organ dysfunction called septic shock [1]. Sepsis/septic shock is characterized by profound hypotension, progressive metabolic acidosis, systemic inflammatory response syndrome (SIRS), tissue damage and multiple Amino acid organ dysfunction syndrome (MODS), acute respiratory distress syndrome (ARDS) and/or acute lung injury (ALI), or even death. Although its pathophysiology is not well defined, monocytes orchestrate the innate immunity response to Gram-positive and Gram-negative bacteria by expressing a variety of inflammatory cytokines, including tumour necrosis factor (TNF)-α and interleukin (IL)-6, which are considered to play an essential role in the pathogenesis

of sepsis [2–6]. These mediators extend the inflammatory response and can lead to multiple organ dysfunction syndrome [7] and, ultimately, death [8]. Some of these oxidants are known to modulate the expression of various genes that are involved in immune and inflammatory responses [9]. Sepsis and endotoxaemia lead to the production of reactive oxygen species (ROS) [10,11], which have been assumed to play a role in the induction of many proinflammatory cytokines and mediators important in producing the acute inflammatory responses associated with sepsis [12]. Endotoxaemia and sepsis are associated with a reduced endogenous antioxidant capacity, and may therefore result in an oxidant–anti-oxidant imbalance [13].