Supplementation of Estradiol Into Semen Extender Improved Goat Sperm Cryopreservation

Estradiol is a steroid hormone excreted from the female gonads, mainly during the pre-estrus. However, the potential effects of estradiol are yet to be explored on sperm parameters through cryopreservation. In this study, we supplemented estradiol, 3 and 5 μM, in the goat semen extender and assessed the sperm parameters after a freeze-thawing process. Sperm motility was assessed using the computer-assisted sperm analysis system. Sperm viability and membrane integrity improved using both 3 and 5 μM concentrations of estradiol. The highest rate of progressive motility was observed in the 3 μM estradiol group. However, a higher concentration of estradiol (5 μM) reduced the progressive motility. Then, we were interested to see if the supportive effect of estradiol on sperm motility is mediated through the intracellular concentration of calcium ionophore. We supplemented the semen extender with 1 and 10 mM ethylenediaminetetraacetic acid (EDTA) and showed that 1 mM has no adverse effect on progressive sperm motility. Then, estradiol (3 μM) was supplemented with or without EDTA (1 mM) into the semen extender. Individual EDTA treatment improved the progressive sperm motility compared to the control group. However, in the presence of estradiol, EDTA treatment reduced the progressive motility compared to the individual estradiol group. This indicated a considerable interaction between estradiol and EDTA for progressive sperm motility. Indeed, EDTA reduced the supportive effects of estradiol on sperm cryopreservation parameters. These results indicated that induction of higher progressive sperm motility in response to estradiol is a calcium-dependent process, as the EDTA did completely abrogate the estradiol-mediated effect.