Effect of exogenous lipids on cryotolerance of Atlantic salmon (Salmo salar) spermatozoa

Abstract

The development of semen cryopreservation strategies is necessary to improve the semen storage technologies of species of great commercial interest for aquaculture. Recent studies demonstrate that lipids play an important role in the fertility and cryotolerance of fish gametes. This study investigated the effect of exogenous lipids in the freezing medium on the post-thaw functional parameters of Salmo solar spermatozoa. Semen samples (n = 12) were incubated in standard extender supplemented with different concentrations of oleic acid (OA, C18:1n9), linoleic acid (LA, C18:2n6), arachidonic acid (ARA, C20:4n6) and cholesterol-loaded cyclodextrin (CLC). Post-thaw motility, membrane integrity, mitochondrial membrane potential (Delta Psi m), superoxide anion (O-2(center dot-)) and fertility rates were analyzed. The results revealed that the semen incubated with 0.003 mmol/L OA increased the motility (similar to 7%) and Delta Psi m (similar to 2%) (P < 0.05), but membrane integrity and fertility were not increased. The addition of 0.003 mmol/L LA increased the motility (similar to 4%) and all LA extenders increased the Delta Psi m (P < 0.05); however, LA increased the (1) O-2(center dot-) levels and decreased the membrane integrity and fertility (P < 0.05). Semen incubated with ARA improved sperm motility (similar to 5%), membrane integrity (similar to 10.5%) and fertility rates (similar to 11%) (P < 0.05). The maximum improvement in post-thaw sperm functionality was observed by adding 0.003 mmol/L ARA. In contrast, sperm quality parameters and fertility were decreased by the CLC addition (P < 0.05). This study showed that ARA could be considered as an additive for semen cryopreservation and could be relevant in the reproductive process and reproductive management of Salmo solar.

The development of semen cryopreservation strategies is necessary to improve the semen storage technologies of species of great commercial interest for aquaculture. Recent studies demonstrate that lipids play an important role in the fertility and cryotolerance of fish gametes. This study investigated the effect of exogenous lipids in the freezing medium on the post-thaw functional parameters of Salmo solar spermatozoa. Semen samples (n = 12) were incubated in standard extender supplemented with different concentrations of oleic acid (OA, C18:1n9), linoleic acid (LA, C18:2n6), arachidonic acid (ARA, C20:4n6) and cholesterol-loaded cyclodextrin (CLC). Post-thaw motility, membrane integrity, mitochondrial membrane potential (Delta Psi m), superoxide anion (O-2(center dot-)) and fertility rates were analyzed. The results revealed that the semen incubated with 0.003 mmol/L OA increased the motility (similar to 7%) and Delta Psi m (similar to 2%) (P < 0.05), but membrane integrity and fertility were not increased. The addition of 0.003 mmol/L LA increased the motility (similar to 4%) and all LA extenders increased the Delta Psi m (P < 0.05); however, LA increased the (1) O-2(center dot-) levels and decreased the membrane integrity and fertility (P < 0.05). Semen incubated with ARA improved sperm motility (similar to 5%), membrane integrity (similar to 10.5%) and fertility rates (similar to 11%) (P < 0.05). The maximum improvement in post-thaw sperm functionality was observed by adding 0.003 mmol/L ARA. In contrast, sperm quality parameters and fertility were decreased by the CLC addition (P < 0.05). This study showed that ARA could be considered as an additive for semen cryopreservation and could be relevant in the reproductive process and reproductive management of Salmo solar.