Protection of boar spermatozoa from cold shock damage by 2-hydroxypropyl-beta-cyclodextrin

This study examined whether 2-hydroxypropyl-beta-cyclodextrin (HBCD) could play a role in protecting spermatozoa from cold shock, as judged by motility parameters, intact acrosomes, and membrane integrity. Motility parameters were assessed by a computer-assisted sperm motility analysis (CASA) system, and the acrosome and membrane integrity were evaluated by fluorescent staining with FlTC-labeled peanut agglutinin and SYBR-14 plus Propidium Iodide, respectively. The addition of HBCD to the BF5 extender significantly increased the percentages of spermatozoa with intact acrosomes and increased membrane integrity after cold shock. The motility, progressive motility, and progressive velocity of the cold-shocked spermatozoa in the presence of HBCD were significantly higher than in the absence of HBCD. In contrast, further supplement of HBCD with cholesterol-3-sulfate (a cholesterol analogue) resulted in a decrease in all the aforementioned criteria, suggesting that the ability of HBCD to protect spermatozoa from cold shock injury is blocked by saturating the cholesterol binding sites of HBCD. It is therefore concluded that HBCD protects spermatozoa against cold shock injury, possibly due to its ability to remove membrane cholesterol.