Changes in spermatozoa due to large doses of pyridoxine (vitamin B6)

To investigate the changes of spermatozoa by high doses of vitamin B6 (B6), the alterations in spermatozoa and testis of rats after the administration of high doses of B6 were evaluated quantitatively and morphometrically. Wistar rats of 11 weeks of age were intraperitoneally injected with 63, 125, 250 and 500 mg/kg of B6 daily 5 times per week for 6 weeks. Using the spermatozoa taken from the epididymis and ductus deferens, the number, motility and nuclear morphology of spermatozoa were examined. After preparing 7 parameters for the nuclear morphology, the morphometry was performed by an IBAS version 2 (Zeiss) image analysis system. The number of spermatocytes and spermatids in representative stages of spermatogenesis was counted per Sertoli cell histologically. Mild deformation of spermatozoa nuclei occurred in the 63 mg or more exposure groups. In the 125 and 250 mg groups, the decrease in number as well as motility of spermatozoa together with slight decrease of spermatids in late maturation phase (mature spermatids) and the delay in spermiation appeared. Phagocytosis of mature spermatids by Sertoli cells was clearly increased in the 250 mg group. The alteration and the decreased number of spermatozoa are suggested to have mainly resulted from alteration of mature spermatids and the increased phagocytosis of mature spermatids by Sertoli cells. Computer-assisted morphometry of spermatozoa nuclei was useful not only to evaluate morphological changes objectively but also to discern them early.