Are sperm parameters the best indicator of 2,5-hexanedione reproductive toxicity in male rats?

In this study on 40 male Wistar rats of approximately 3-weeks-old, the effects of 2,5-hexanedione on sperm principal parameters were examined by subcutaneously administering 100, 200 and 400 mg/(kgday) for 12 weeks. Other indicators of 2,5-hexanedione intoxication were examined: testes, epididymides, body weight, limb paralysis and histology. The sperm motility was adversely affected in all of the three treatment groups. No sperm motility at all was observed in the 200 and 400 mg/(kgday) treatment groups and rapid progressive motility was significantly reduced in the 100 mg/(kgday) group (P<0.05). The sperm concentration and morphology, testes, epididymides and body weight were significantly affected in the 200 and 400 mg/(kgday) groups but not in the 100 mg/(kgday) group (P<0.05). All the rats in the 400 mg/(kgday) group could not move due to leg paralysis, whereas only 50% of the rats in the 200mg/(kgday) group and none in the 100 mg/(kgday) were affected. Histological examination of the testes in the 400, 200 and 100 mg/(kgday) groups revealed Sertoli cell-only syndrome in 70, 30 and 0% of the rats, respectively. In conclusion, this study has shown that sperm motility was the most significantly sensitive indicator of 2,5-hexanedione intoxication in all the treatment groups.