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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Cholesterol-Loaded Cyclodextrin on the Cryosurvival of Bull Sperm

Authors
item PURDY, PHIL
item Graham, James - COLORADO STATE UNIVERSITY

Submitted to: Cryobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2003
Publication Date: February 1, 2004
Citation: Purdy, P.H., Graham, J.K. 2004. Effect of cholesterol-loaded cyclodextrin on the cryosurvival of bull sperm. Cryobiology. 48:36-45.

Interpretive Summary: Bull sperm were treated with several levels of cholesterol-loaded cyclodextrin (CLC) and frozen in egg yolk diluents containing either Tris or sodium citrate, to determine the CLC concentration that best benefits bull sperm cryosurvival. After thawing, higher percentages of motile and viable sperm were obtained with CLC. The beneficial effects of CLC addition were observed regardless of whether sperm incubated with CLC at 22 or 37 degrees C and maximum effects were observed when sperm incubated with CLC for 15min. The amount of cholesterol that incorporated into sperm, increased with increasing CLC concentration, in a linear fashion, and each sperm incorporates a similar amount of cholesterol. In addition, the cholesterol incorporates into all sperm membranes. Increasing membrane cholesterol levels, by adding CLCs to cells, prior to freezing, is a simple technology that increases the cryosurvival of bull sperm, and may benefit the cryosurvival of many cell types.

Technical Abstract: Bull sperm were treated with several levels of cholesterol-loaded cyclodextrin (CLC) and frozen in egg yolk diluents containing either Tris or sodium citrate, to determine the CLC concentration that best benefits bull sperm cryosurvival. After thawing, higher percentages of motile (60%) and viable (55%) sperm were obtained when 1.5mg/ml CLC was added to sperm prior to freezing, than for sperm frozen in egg yolk Tris alone (42 and 46%, respectively; P < 0.05). Increasing concentration of CLCs, maintained higher percentages of viable sperm up to addition of 6.0mg/ml CLC when the percentages of viable sperm began to decline (50%; P < 0.05). Addition of 1.5mg/ml CLC to sperm frozen in sodium citrate diluent resulted in 53% motile sperm compared to 37% for control, although these were not different (P > 0.05). The beneficial effects of CLC addition were observed regardless of whether sperm incubated with CLC at 22 or 37 degrees C (P > 0.05) and maximum effects were observed when sperm incubated with CLC for 15min. Longer incubation times, up to 60min, resulted in similar results (P > 0.05). The amount of cholesterol that incorporated into sperm, increased with increasing CLC concentration, in a linear fashion, and each sperm incorporates a similar amount of cholesterol (coefficient of variation=12.9+/-0.7%). In addition, the cholesterol incorporates into all sperm membranes. Increasing membrane cholesterol levels, by adding CLCs to cells, prior to freezing, is a simple technology that increases the cryosurvival of bull sperm, and may benefit the cryosurvival of many cell types.

Last Modified: 9/10/2014
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