Cholesterol-loaded-cyclodextrins improve the post-thaw quality of stallion sperm

• Published in: Animal reproduction science Vol. 145; no. 3-4; pp. 123 - 129
• Main Authors: Murphy, C., English, A.M., Holden, S.A., Fair, S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2014
• Subjects: Animals; Cholesterol; Cholesterol - chemistry; Cholesterol - pharmacology; Cryoprotective Agents - chemistry; Cryoprotective Agents - pharmacology; Cyclodextrins - chemistry; Cyclodextrins - pharmacology; Equine; Horses - physiology; Male; Membrane fluidity; Reactive oxygen species; Semen Analysis; Semen Preservation - methods; Semen Preservation - veterinary; Sperm; Spermatozoa - drug effects; Viability; Reactive oxygen species; Membrane fluidity; Equine; Sperm; Viability; Cholesterol
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/j.anireprosci.2014.01.013

An unacceptable proportion of stallion sperm do not survive the freeze-thaw process. The hypothesis of this study was that adding cholesterol to a stallion semen extender would stabilise the sperm membrane, resulting in an improved post-thaw semen quality in terms of increased sperm viability, membrane integrity and fluidity, and reduced oxidative stress. Semen was collected from three stallions and diluted in four extenders: TALP; TALP+0.75mg methyl-β-cyclodextrin–cholesterol (MβCD)/mL (MβCD0.75); TALP+1.5mg MβCD-cholesterol/mL (MβCD1.5); and Equipro. Following 15min incubation, samples were centrifuged and diluted to 100×106sperm/mL, frozen in 0.5mL straws and stored in liquid nitrogen. Sperm from each treatment was assessed for progressive linear motility (PLM) and acceptable membrane integrity under hypotonic conditions on a phase contrast microscope at 1000× while viability, membrane fluidity and superoxide generation were assessed by flow cytometry. The MβCD1.5 and MβCD0.75 treatments had a greater proportion of viable sperm than the TALP treatment (P<0.01). There was no effect of treatment on PLM or membrane integrity. The MβCD1.5 treatment had a greater proportion of viable sperm positive for membrane fluidity than the TALP treatment (P<0.05). The MβCD1.5 and MβCD0.75 treatments had a lesser proportion of viable sperm positive for superoxide generation than the TALP treatment (P<0.001). This study has demonstrated that adding cholesterol to stallion sperm prior to cryopreservation increases post-thaw viability, with these viable sperm being of better quality in terms of increased membrane fluidity and reduced superoxide generation.