Mechanism of Paraquat Action Shows Interference in Spermatogenesis and Epididymal Maturation of Sperm in Mice.

Abstract

Studies have shown mammalian spermatogenesis and sperm maturation processes are in danger from environmental pollutants but detailed mechanisms of such actions are rare. Paraquat is a broad-spectrum weedicide, potent free radical former and readily soluble in water. The present study aimed to investigate mechanism(s) of toxic effects of Paraquat on mice epididymal sperm. Mice (5 groups, n=10) were exposed with four concentrations i.e. 8(T1), 4(T2), 2(T3), 1(T4) mg/kg bodyweight of Paraquat and distilled water alone to control group, by way of inter-dermal exposure to scrotal sac for a week on the day other day and sacrificed on the day 14th. Testicular and epididymal sperm parameters were measured. DNA integrity of epididymal sperm and abnormalities were assessed using acridine orange staining. There was a marked increase in epididymal weight among treatment groups and significant (P<0.05) in T2. Testicular weights did not show changes indicating reduced effects on testicular endocrine milieu. However, testicular sperm count differed significantly (P<0.05) for treated groups T1, T2 and T3. Percentage fast moving, slow moving, twitching and immotile sperm in the epididymis were significantly reduced in all treated groups. DNA integrity test and abnormalities revealed marked damages to epididymal sperm. From the present study it is not exactly clear whether reduction in sperm number and sperm count were due to free radical formation by Paraquat. But present findings suggest whether sperm membrane damage in vivo make sperm storage vulnerable in mammalian epididymis.