Potential Novel Biomarkers for Diabetic Testicular Damage in Streptozotocin-Induced Diabetic Rats: Nerve Growth Factor Beta and Vascular Endothelial Growth Factor

Abstract

Background. It is well known that diabetes mellitus may cause testicular damage. Vascular endothelial growth factor (VEGF) and nerve growth factor beta (NGF-β) are important neurotrophic factors for male reproductive system.Objective. We aimed to investigate the correlation between testicular damage and testicular VEGF and NGF-βlevels in diabetic rats.Methods. Diabetes was induced by streptozotocin (STZ, 45 mg/kg/i.p.) in adult rats. Five weeks later testicular tissue was removed; testicular VEGF and NGF-βlevels were measured by ELISA. Testicular damage was detected by using hematoxylin and eosin staining and periodic acid-Schiff staining, and apoptosis was identified by terminal-deoxynucleotidyl-transferase-mediated dUTP nick end labeling (TUNEL). Seminiferous tubular sperm formation was evaluated using Johnsen’s score.Results. In diabetic rats, seminiferous tubule diameter was found to be decreased; basement membrane was found to be thickened in seminiferous tubules and degenerated germ cells. Additionally, TUNEL-positive cells were increased in number of VEGF+ cells and levels of VEGF and NGF-βwere decreased in diabetic testes. Correlation between VEGF and NGF-βlevels was strong.Conclusion. These results suggest that the decrease of VEGF and NGF-βlevels is associated with the increase of the apoptosis and testicular damage in diabetic rats. Testis VEGF and NGF-βlevels could be potential novel biomarkers for diabetes induced testicular damage.