Lipossomas na criopreservação de sêmen de suínos

Abstract

In Brazil, artificial insemination represents 95% of mating, and more than 99% are performed with semen refrigerated at 17°C, because the cryopreservation process causes various damage to spermatozoa. Such as, greater cellular dehydration, resulting from the removal of polar molecules from phospholipids, resulting in changes in functionality. With this, pesquisas point out that keeping the semen diluted for up to 24 hours at a temperature above 15°C is beneficial to sperm. In addition, studies indicate that adding liposomes to the diluent during the cryopreservation process provides greater resistance of sperm to cold. Therefore, the objectives of this study were: a) to value the cytotoxicity of commercial liposome S100 with 98% phosphatidylcholine in swine spermatic cells; (b) evaluate of commercial liposome S45 with refrigeration diluent in swine swine cells stored at 17°C and 5°C. In the first study, the cytotoxicity of the commercial liposome S100, manufactured by the ethanol injection process, with 98% of commercial phosphatidylcholine Lipoid GmbH (Germany), was evaluated, being added to the plasma lactose diluent, being tested four dilutions at 5°C and 17°C of cooling for up to four days. In the second study, we evaluated the addition of commercial liposome S45, produced with defatted soy lecithin with >45% m/m phosphatidylcholine, 10–18% m/m phosphatidyllectolamine, <4% m/m lysophosphatidylcholine and <3% m/m triacylglycerols, along with the cooling diluent in the holding time process for up to 72h to 17°C and 5°C. In both studies, sperm cells of ten different males (~ 80mL with ~2.6 billion sperm, each dose) of the same lineage, kept in individual stalls and receiving the same ration, were used. In addition, in both studies, four dilutions of liposomes (5nM, 3.75nM, 2.5nM, 1.25nM and 0nM) were used, the spermatic kinetics was evaluated by the automated CASA system, evaluating MT, MP, VCL, VSL, VAP, STR, LIN, WOB, BCF, ALH, DCL, DSL, DAP. From the results, it was observed that in the first study, the liposome S100 presents a high cytotoxicity in all concentrations evaluated, especially when storing the spermatic cells at 5°C, and when stored at 17°C the concentration of 1.25nM. In the second study, the results showed that storage at 17°C with the addition of liposomes provided gain in sperm kinetics, and doses stored at 5°C, with the addition of liposomes remained viable for 24 h of storage. Thus, it is concluded that the use of liposome S45 may be feasible in the cryopreservation process of swine semen by providing an improvement in the results of the parameters of the kinetic spermatids. And use of liposomes with high concentration of phosphatidylcholine, as the case of liposome S100, is cytotoxic to use.