Objective: Various defects, dysfunctions and organ failures may occur due to long term effects of diabetes mellitus (DM) especially in eye, kidney, heart and vascular system. Irisin increases expression and mitochondrial density of uncoupling proteins (UCPs) which are very important in the neurodegenerative process. In this study we aimed to investigate the effects of enalapril (EN) on irisin immunoreactivity in the brain tissue of streptozotocin (STZ)-induced diabetic rats.

Material and method: In this study, 18 adult Wistar albino male rats were used. The study group was divided into 3 equal groups each containing 6 rats. The control group wasn\'t exposed to any kind of drugs during the 6 weeks of study period. 50 mg/kg single dose STZ was injected to DM group intraperitoneally. DM+EN group rats were given single 50 mg/kg intraperitoneal injection of STZ, oral 5 mg/kg/day enalapril for 6 weeks. Brain tissues of the rats were removed just after the decapitation under the anesthesia. Tissues were embedded into paraffin blocks after the routine histological preparations. Avidin-biotin-peroxidase technique was used in determination of irisin expression. Histoscore was created based on the diffusiveness and severity of immunoreactivity in assessment of immunohistochemical staining.

Results: There was a significant decrease of irisin immunoreactivity in the DM group. Irisin immunoreactivity was found as significantly increased in DM+EN group compared to DM group.

Conclusion: We can conclude that EN shows its effects due to its relationship with irisin along with other various mechanisms.