Action of cholesterol-loaded cyclodextrin on viability of ram semen

ABSTRACT

Background: Studies report that cyclodextrins have the property of carrying cholesterol to the membrane, but in some casescan also remove this cholesterol from the plasma membrane. The mechanism of action of CLC is not well understood,however, it seems to involve sperm protection during the freezing and thawing process. Studies show that its use enhancingincreased osmotic tolerance and reduced premature sperm capacitation reaction. In this sense, studies report that cyclodextrins have the property of carrying cholesterol to the membrane, but in some cases can also remove this cholesterol fromthe plasma membrane. Improvements were reported in the sperm parameters of buffaloes, bulls, stallions and sheep. Ramnaturally present less lipids in their membrane, on average 27%, while bulls have 31%, rabbits 62%, and humans 50%.The aim of the present study was to evaluate the use of cholesterol-loaded cyclodextrin (CLC), a commercial diluent, inthe kinetics and viability of frozen and thawed ram spermatozoa.Materials, Methods & Results: Five ejaculates, from five rams of Dorper breed were collected and divided into three groupscontrol, 1 mg CLC and 2 mg CLC. Semen was diluted in different concentrations of CLC (0, 1, and 2 mg/120×106 spermatozoa), and incubated at room temperature (21°C) for 10 min. Samples were conditioned in 0.5 mL straws and incubatedat 5°C for 4 h, exposed to LN2 vapor for 10 min and storing a cryogenic container. The parameters as spermatic kinetics,plasma membrane, acrosomal membrane (MPAI, %), and intracellular levels of superoxide anion (O2-) were evaluated.Sperm progressive motility (PM), rapid spermatozoa percentage (RAP), linearity (LIN, %), average path velocity (VAP,μm/s) and MPAI (%) were more satisfactory with the use of 1 mg compared to 2 mg (P < 0.05). In addition, 1 mg CLCshowed decreased levels of superoxide anion formation (O2-), a free...