Vitamin E improves testicular damage in streptozocin-induced diabetic rats, via increasing vascular endothelial growth factor and poly(ADP-ribose) polymerase-1.

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The precise mechanism by which diabetes impairs spermatogenesis and testicular function is not exactly known. Vascular endothelial growth factor (VEGF) and poly(ADP-ribose) polymerase-1 (PARP-1) are important for germ cell homeostasis and repair of DNA respectively. The aim of this study was to investigate the correlation between diabetes-induced testicular damage and testicular VEGF and PARP-1 expression and the possible protective role of vitamin E supplementation. A total of 45 male Wistar albino rats were randomly divided into three groups: Group I (nondiabetic rats), Group II (streptozocin-induced diabetic rats) and Group III (streptozocin-induced diabetic rats treated orally with 0.4mg/kg vitamin E). Five weeks later, testicular tissue was used for assessment of MDA concentration by colorimetry, histopathological examination and immunostaining for PARP-1 and VEGFIn diabetic rats, testicular weight, seminiferous tubule diameter and germinal epithelial thickness were decreased, basement membrane was thickened and Johnsen score decreased. Reduced VEGF and PARP-1 immunostaining were associated with decreased Johnsen score in diabetic rats. Vitamin E administration was protective against oxidative stress-associated damage evidenced by lower MDA levels, improved testicular weight, spermatogenesis and higher immunostaining for VEGF and PARP-1. Testicular VEGF and PARP-1 might therefore be helpful biomarkers for diabetic testicular damage. Administration of vitamin E may have a protective role against diabetes-induced testicular damage.