title: Soy lecithin interferes with mitochondrial function in frozen-thawed ram spermatozoa.
abstract: Egg yolk and milk are the 2 major membrane cryoprotectants commonly used in  freezing media for the long-term preservation of semen (alone or in  combination with others). However, in recent years, there have been increasing  arguments against the use of egg yolk or milk because of the risk of  introducing diseases through the use of cryopreserved semen. In this study, we  analyzed the protective effect of lecithin as an alternative to egg yolk for  the cryopreservation of ram semen, using a range of functional markers for  sperm viability, motility, apoptosis, and mitochondrial functionality analyses  (mitochondrial inner membrane surface [MIMS], mitochondrial inner membrane  potential [MIMP], and cell membrane potential) as methods of assessment in  samples diluted in 3 different media: Tris-citrate-glucose as control and 2  media supplemented with soy lecithin or egg yolk. The results showed that  lecithin was able to effectively protect certain sperm quality characteristics  against freezing-induced damage. However, lecithin induced loss of  mitochondrial membrane potential or mitochondrial loss that was not reflected  by modifications in sperm motility in fresh semen. MIMS and MIMP values  decreased in thawed lecithin-treated samples, concomitant with a lower  (P < .05) percentage of total and progressively motile cells,  compared with those in egg yolk-containing samples. Further incubation  of thawed samples revealed changes in motility and mitochondrial functionality  that otherwise would not have been detected. These results indicated that  lecithin may have affected the inner mitochondrial membrane in frozenthawed  spermatozoa and confirmed that sublethal damages that seriously affect sperm  functionality, not detected by classic sperm quality analyses, can be  evidenced by changes in the inner mitochondrial membrane surface. These  findings strengthen the relationship between mitochondrial membrane potential  and motility and show that the mitochondrial alterations induced by the  cryopreservation process could be specific targets for the improvement of  semen cryopreservation protocols.
authors: Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Miguel Servet, 177, 50013 Zaragoza, Spain.
authors: I
authors: I
authors: Del Valle
authors: A
authors: A
authors: Gómez-Durán
authors: W V
authors: WV
authors: Holt
authors: T
authors: T
authors: Muiño-Blanco
authors: J A
authors: JA
authors: Cebrián-Pérez
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods; D003451:Cryoprotective Agents; D004530:Egg Yolk; D005615:Freezing; D054709:Lecithins / Q000009:adverse effects*; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D012662:Semen Preservation / Q000379:methods*; D034561:Sheep, Domestic; D013025:Glycine max / Q000737:chemistry; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects*
chemical_list: D003451:Cryoprotective Agents; D054709:Lecithins