Abstract
This study investigated the effect of ferrous sulfate (Fe$^{2+}$) and/or ascorbic acid (Asc) on fertilizing ability in vitro of frozen-thawed boar spermatozoa. Using chlortetracycline (CTC) fluorescence, the spermatozoa was treated in preincubation medium with control, Fe$^{2+}$(1 mM), Asc (0.5 mM) and Fe$^{2+}$Asc to assessed for acrosome reaction, and the oocyte penetration test to determine whether the Fe$^{2+}$ and/or Asc can promote the penetration ability in vitro. When frozen-thawed spermatozoa was washed with preincubation medium, there were significantly (P ＜ 0.05) more acrosome-reacted in medium with Fe$^{2+}$Asc (38%) than control (27%). The penetration rates were also significantly (P ＜ 0.05) higher in medium with Fe$^{2+}$Asc (76%) than control (55%). Next, the lipid peroxidation of sperm was evaluated on the basis of malondialdehyde production following same treatments. The addition of Fe$^{2+}$Asc to sperm suspension increases the formation of malondialdehyde. However, there were not significantly different under the all conditions. The sperm suspension were also treated with control, Fe$^{2+}$, Asc and Fe$^{2+}$/Asc and assayed for sulfhydry1(-SH) group content. In the Fe$^{2+}$/Asc group, sperm-SH group were higher than another groups. In spermatozoa treated with Fe$^{2+}$ and/or Asc, however, no changes in sperm -SH-groups were detected when compared to controls. In another experiment, the activity of sperm binding to zona pellucida was evaluated through binding to salt-stored porcine oocytes. In control and Asc treatment groups, sperm binding to zona pellucida were significantly (P ＜ 0.05) higher than in medium with Fe$^{2+}$. On the other hand, there is not a significant increase in binding to zona pellucida with spermatozoa treated by Fe$^{2+}$/Asc. In summary, the present study suggests that Fe$^{2+}$/Asc causes an enhancement in fertilizing ability that is associated with penetration rate increased without change of spermatozoa binding capacity to homologous zona pellucida.o homologous zona pellucida.
본 연구는 lipid peroxides를 생산하는 것으로 알려진 ascorbic acid (Asc; 0.5 mM)와 ferrous sulfate (Fe$^{2+}$; 1 mM)가 돼지 동결-융해 정자의 체외수정능력에 미치는 영향을 검토하였다. 그 결과, 동결정액의 융해 처리시 배양액내 Asc/Fe$^{2+}$ (38%)의 동시첨가시 대조구 (27%)에 비해 정자의 첨체반응이 유의적으로 높게 유기되었다 (P＜0.05). 정자침입율 또한 Asc/Fe$^{2+}$ (76%)를 동시에 첨가하므로서 대조구 (55%)에 비하여 유의적으로 높게 나타났다 (P＜0.05). 한편 정자의 peroxidation은 상기의 처리구에서 maiondialdehyde (MDA)의 생성에 기초를 두고 평가하였는데, 정자의 처리시 Asc/Fe$^{2+}$의 동시첨가에 의해 MDA의 생성이 증가하였으나 처리구 사이에서 유의적인 차이는 인정되지 않았다. 또한 sulfhydry1(-SH) group의 용량을 측정한 결과 Asc/Fe$^{2+}$를 동시에 첨가한 실험구에서 가장 높게 나타났으나 타처리구와의 사이에서 유의적인 차이는 인정되지 않았다. 또 다른 연구에서 동결-응해정자가 난자의 투명대에 접착하는 정도를 평가한 결과, 대조구와 Asc처리시 Fe$^{2+}$ 처리에 비하여 유의적으로 (P ＜ 0.05) 높은 정자의 접착을 나타냈으나 Asc/Fe$^{2+}$의 동시 처리에 의한 정자접착의 증가는 인정되지 않았다. 결과적으로 lipid peroxidation의 증가를 야기시키는 Asc/Fe$^{2+}$의 동시첨가는 투명대에서 정자의 접착능력을 증가시키지 않았음에도 불구하고 첨체반응과 침입능력을 향상시키는 것으로 나타났다.