College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an City 271018, Shandong Province, China.
Department of Reproduction and Genetics, Tai'an City Central Hospital, Tai'an, Shandong Province, China.
Zygote. 2023 Aug;31(4):393-401. doi: 10.1017/S0967199423000291. Epub 2023 May 22.
Although ethanol treatment is widely used to activate oocytes, the underlying mechanisms are largely unclear. Roles of intracellular calcium stores and extracellular calcium in ethanol-induced activation (EIA) of oocytes remain to be verified, and whether calcium-sensing receptor (CaSR) is involved in EIA is unknown. This study showed that calcium-free ageing (CFA) significantly decreased intracellular stored calcium (sCa) and CaSR expression, and impaired EIA, spindle/chromosome morphology and developmental potential of mouse oocytes. Although EIA in oocytes with full sCa after ageing with calcium does not require calcium influx, calcium influx is essential for EIA of oocytes with reduced sCa after CFA. Furthermore, the extremely low EIA rate in oocytes with CFA-downregulated CaSR expression and the fact that inhibiting CaSR significantly decreased the EIA of oocytes with a full complement of CaSR suggest that CaSR played a significant role in the EIA of ageing oocytes. In conclusion, CFA impaired EIA and the developmental potential of mouse oocytes by decreasing sCa and downregulating CaSR expression. Because mouse oocytes routinely treated for activation (18 h post hCG) are equipped with a full sCa complement and CaSR, the present results suggest that, while calcium influx is not essential, CaSR is required for the EIA of oocytes.
虽然乙醇处理被广泛用于激活卵母细胞，但其中的机制在很大程度上还不清楚。细胞内钙库和细胞外钙在乙醇诱导的卵母细胞激活（EIA）中的作用仍有待验证，钙敏感受体（CaSR）是否参与 EIA 也是未知的。本研究表明，无钙老化（CFA）显著降低了细胞内储存的钙（sCa）和 CaSR 的表达，并损害了小鼠卵母细胞的 EIA、纺锤体/染色体形态和发育潜能。尽管在老化后用钙使 sCa 完全的卵母细胞中，EIA 不需要钙内流，但钙内流对于 CFA 后 sCa 减少的卵母细胞的 EIA 是必需的。此外，CFA 下调 CaSR 表达的卵母细胞中 EIA 率极低，以及抑制 CaSR 显著降低 CaSR 完全补充的卵母细胞的 EIA 这一事实表明，CaSR 在老化卵母细胞的 EIA 中发挥了重要作用。总之，CFA 通过降低 sCa 和下调 CaSR 的表达来损害小鼠卵母细胞的 EIA 和发育潜能。由于用于激活的小鼠卵母细胞（hCG 后 18 小时）通常都配备有完整的 sCa 补充和 CaSR，因此本研究结果表明，虽然钙内流不是必需的，但 CaSR 是卵母细胞 EIA 所必需的。
