Quercetin Attenuates Testicular Damage and Oxidative Stress in Streptozotocin-induced Diabetic Rats

The present study aims to examine the influence of Quercetin (QR) in testis of Streptozotocin (STZ)induced diabetic rats. Diabetes was induced by a single injection of STZ (65 mg/kg, ip). Quercetin (25 and 50 mg/kg/day) was treated to normal and diabetic rats for 5 weeks. In serum, glucose, testosterone, Interleukin-6 (IL-6), Interleukin-1beta (IL-1β) and Tumor Necrosis Factor-α (TNF-α) levels were estimated and in testis tissues Thiobarbituric Acid Reactive Substances (TBARS), sulfhydryl groups, nucleic acids and Total Protein (TP) levels were estimated. Superoxide Dismutase (SOD), Catalase (CAT) and Glutathione-S-Transferase (GST) activities were also determined in testicular cells. In penile tissue cyclic Guanosine Monophosphate (cGMP) levels were measured. Histopathological changes were evaluated in a cross-section of testis. Testosterone levels were decreased while proinflammatory markers were increased in diabetic rats. QR treatment to diabetic rats corrected these changes. In penile tissues cGMP content was markedly inhibited and normalized by the QR treatment. In STZ-induced diabetic rats, TBARS levels were significantly increased while T-GSH, NP-SH, DNA, RNA and TP levels were decreased and in QR treated groups showed significant inhibition in increased TBARS levels and decreased T-GSH and NPSH levels. The inhibited activities of SOD, CAT and GST in testicular cells of diabetic rats were increased after QR treatment. The reduced levels of nucleic acids and TP in diabetic rats were markedly corrected in QR treated groups. Histopathological evaluation revealed damage in testicular cells of diabetic rats and the treatment with QR showed protection. These results suggest that, QR supplementation to STZ-induced diabetic rats for five consecutive weeks is a potentially beneficial agent to reduce testicular damage in adult diabetic rats, probably by decreasing oxidative