Combination of running exercise and high dose of anabolic androgenic steroid, nandrolone decanoate, increases protamine deficiency and DNA damage in rat spermatozoa

Summary High doses of anabolic‐androgenic steroids (AAS) are used by some athletes to increase muscle mass, that is often associated with male infertility. The aim of this study was to investigate the possible cause/s of male infertility using a rat model by analysing sperm quality, including its protamine content and DNA integrity, as well as pregnancy rate. Five groups of male Wistar rats were treated for 10 weeks as follows: nandrolone decanoate (10 mg kg−1 per week) (ND); running exercise (50 min per day, 5 days a week) (EX); Combination of ND and exercise (ND‐EX); nandrolone decanoate solvent (Sham); and control without any injection or exercise (CO). Deterioration in sperm quantity was observed in all test groups (P ≤ 0.01). The frequency of fertile rats was decreased in the ND‐EX and ND groups (P ≤ 0.05). Chromomycin‐A3 staining showed a protamine deficiency in the epididymal spermatozoa in the ND‐EX rats (P ≤ 0.05). Chromatin analysis indicated an abnormal maturation of the sperm nuclei in all test groups compared with the controls (P ≤ 0.05). TUNEL analyses showed a highly significant increase in apoptosis in the EX, ND, and ND‐EX groups (P ≤ 0.01). Our data show that a combination of exercise and high doses of nandrolone decanoate negatively influences the DNA integrity and protamine content resulting in lower sperm quality and reduced pregnancy rate.