24 January 2017 Fertility of cold-stored mouse sperm is recovered by promoting acrosome reaction and hyperactivation after cholesterol efflux by methyl-beta-cyclodextrin
Hidetaka Yoshimoto, Toru Takeo, Tetsumi Irie, Naomi Nakagata
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Cold storage of the cauda epididymis, a male reproductive organ, is an efficient means of transporting genetically modified mice, an alternative to live animal shipment. The fertility of cold-stored sperm decreases in a time-dependent manner. However, the cause of the reduction in the fertility of sperm after cold storage remains unclear. It is known that cholesterol efflux from the sperm membrane is a trigger of capacitation. The dysfunction of cholesterol efflux due to changes in the membrane state in low temperatures may explain the reduced fertility. In this study, we examined the fertility (fertilization rate, acrosome reaction, and motility) and the amount of cholesterol and membrane fluidity in cold-stored sperm after treatment with two cholesterol acceptors, bovine serum albumin (BSA), and methyl-beta-cyclodextrin (MBCD). MBCD-treated sperm exhibited the highest rate of fertilization. Two-cell embryos derived from in vitro fertilization using 0.75-mM-MBCD-treated sperm after cold storage for 72 h developed to offspring. MBCD also displayed greater ability to remove cholesterol from the sperm membrane than BSA. The percentage of viable sperm with membrane destabilization was increased by MBCD in cold-stored sperm. The acrosome reaction strongly occurred in MBCD-treated sperm. In motility analysis, MBCD improved the lateral amplitude of head movement and beat frequency. These results suggest that MBCD-induced cholesterol efflux enhances membrane fluidity and promotes acrosome reaction and hyperactivation, resulting in improved fertility of cold-stored sperm.

Summary Sentence

Methyl-β-cyclodextrin removed cholesterol from the entire plasma membrane in cold-stored sperm and restored fertility by inducing the acrosome reaction and hyperactivation.

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Hidetaka Yoshimoto, Toru Takeo, Tetsumi Irie, and Naomi Nakagata "Fertility of cold-stored mouse sperm is recovered by promoting acrosome reaction and hyperactivation after cholesterol efflux by methyl-beta-cyclodextrin," Biology of Reproduction 96(2), 446-455, (24 January 2017). https://doi.org/10.1095/biolreprod.116.142901
Received: 30 June 2016; Accepted: 4 January 2017; Published: 24 January 2017
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