Preventive effect of rolipram, a phosphodiesterase 4 enzyme inhibitor, on oxidative renal injury in acute ascending pyelonephritis model in rats

OBJECTIVES To evaluate the effects of rolipram, a phosphodiesterase 4 enzyme inhibitor, on Escherichia coli-induced renal oxidative damage in an acute pyelonephritis (PYN) rat model. METHODS A total of 35 male Wistar albino rats were randomly divided into 7 groups (n = 5) as follows: control (uninfected), PYN 24 hours, PYN 48 hours, PYN 72 hours, PYN + rolipram 24 hours, PYN + rolipram 48 hours, and PYN + rolipram 72 hours. Ascending PYN was induced in the study groups by E. coli inoculation into the bladder, and the urethras were then occluded by collodium for 4 hours. Rolipram injections (1 mg/kg) were started before bacterial inoculation and repeated at 24-hour intervals in the PYN + rolipram groups until death. The rats were killed at the indicated times. Malondialdehyde and nitric oxide levels and superoxide dismutase and catalase activities were determined in kidney homogenates. Histopathologic examinations were also performed. RESULTS Tissue malondialdehyde and nitric oxide levels and superoxide dismutase and catalase activities were significantly increased in the kidneys from the PYN groups. However, rolipram administration reduced renal malondialdehyde and nitric oxide levels and enhanced superoxide dismutase and catalase activities. The histopathologic examinations demonstrated that rolipram treatment reduced the inflammation grade in the kidney specimens. CONCLUSIONS The results of our study have shown that rolipram has a protective effect on renal tissue from E. coli-induced oxidative injury. Therefore, phosphodiesterase 4 inhibitors might be a novel therapeutic option for the prevention and/or management of acute PYN.