The effect of trehalose on post-thaw viability and fertility of European brown hare (Lepus europaeus Pallas, 1778) spermatozoa

Influence of Different Combinations of Permeable and Nonpermeable Cryoprotectants on the Freezing Capacity of Equine Sperm

This study was aimed to evaluate the effect of permeable cryoprotectants in combination with trehalose or sucrose on the freezing capacity of stallion sperm. For this purpose, the ejaculates (n = 24) were collected from four healthy mature Turkmen stallions. The ejaculates were pooled and diluted with one of the extenders containing a combination of 5% of permeating (dimethylacetamide [DMA]; dimethylformamide [DMF] or glycerol) and 50 mM of nonpermeating cryoprotectant agents (CPAs) (sucrose or trehalose) to a final concentration of 200 × 10⁶ spermatozoa/mL. The extended samples were cryopreserved and thawed using a standard protocol. The samples were evaluated for motion kinetics, morphological abnormalities, plasma membrane functionality (PMF), viability, and lipid peroxidation. The results showed that the sperm cryopreserved in extender containing DMA produced higher (P ≤ .05) total motility, straightness, straight line velocity, curvilinear velocity, and lower (P ≤ .05) lipid peroxidation (malondialdehyde [MDA] concentration) compared with DMF and glycerol groups. Overall, both DMA and DMF have shown higher (P ≤ .05) sperm motion kinetics, viability, PMF, and lower (P ≤ .05) morphological abnormalities and MDA concentration compared with the glycerol. However, except morphological abnormalities, all of the other parameters did not differ between trehalose and sucrose. Likewise, there was no interaction between permeating and nonpermeating CPAs (P ≥ .05) except in terms of sperm abnormalities (P ≤ .05). In conclusion, the use of DMA or DMF as alternative CPAs of glycerol could be more effective for successful cryopreservation of stallion sperm. The nonsignificant interaction between permeating and nonpermeating CPAs for most of the post-thaw sperm parameters negates possible synergism among these compounds.

Effect of different concentrations of trehalose and glycerol on the freezability of ram semen using soybean lecithin-based diluents

This study was conducted to determine the effect of different levels of trehalose and glycerol on ram sperm cryosurvival using lecithin-based diluents. Ejaculates were collected from four rams, pooled after initial evaluation, diluted with Tris-soybean lecithin extender and split into nine equal parts. A total of 0 (T0), 50 (T50) or 100 (T100) mM of trehalose and 3% (G3), 5% (G5) or 7% (G7) of glycerol were added to each part. Sperm motility, viability, plasma membrane integrity and acrosome integrity were evaluated immediately after thawing (0 h), and subsequently after 3 h and 6 h post-thawing incubation at 37°C. Results indicated that there was interaction between trehalose and glycerol on sperm motility. In addition, interaction of trehalose and glycerol with incubation time on sperm motility, viability, plasma membrane integrity and acrosome integrity was not significant (P > 0.05). Sperm motility was greatest in the sperm treated with 100 mM trehalose and 7% glycerol (27%; P < 0.05). The effect of trehalose was significant on viability and plasma membrane integrity of ram spermatozoa (P < 0.05). The main effect of trehalose showed that sperm viability was higher in T100 (47.06%) than T50 (53.96%; P < 0.05). The highest membrane integrity was observed in T100 (47.04%; P < 0.05). Membrane integrity was higher (P < 0.05) in G5 (49.97%) than G3 (41.56%) and there was no difference between G7 (46.86%) and G3 (41.56%; P > 0.05). The best sperm viability and plasma membrane integrity was observed at 0 h (65.75% and 51.58%, respectively). It was concluded that simultaneous use of 7% glycerol and 100 mM trehalose had a desirable effect on motility of ram frozen–thawed sperm.

Trehalose and glycerol have a dose-dependent synergistic effect on the post-thawing quality of ram semen cryopreserved in a soybean lecithin-based extender

The objective of this study was to examine the interaction of different concentrations of trehalose [0 (T0), 50 (T50) or 100 (T100) mM] and glycerol [5% (G5) or 7% (G7)] on post-thawed quality of ram semen, cryopreserved in a soybean lecithin (SL)-based extender. Twenty-eight ejaculates were collected from four rams and diluted with six trehalose/glycerol combinations: T0G5, T50G5, T100G5, T0G7, T50G7, and T100G7. Sperm motility (CASA), membrane integrity (eosin/nigrosin) and functionality (HOST), abnormal forms, capacitation status (CTC), mitochondrial activity (rhodamine 123), apoptotic features (Annexin V/propidium iodide) and lipoperoxidation (malondialdehyde production) were evaluated after thawing. Extender T100G5 yielded the highest results for total and progressive motility, sperm velocity, normal morphology, functional membranes, active mitochondria and membrane integrity, with P<0.05 in general, except for T50G7 (P>0.05). The combinations T0G5, T0G7 and T100G7 yielded the lowest post-thaw quality. We could not detect significant changes in other kinematic parameters, capacitation status or lipoperoxidation. We conclude that, in our SL-based extender, a combination of 100 mM trehalose and 5% glycerol was the most adequate combination to achieving post-thawing quality in our soybean lecithin-based extender, and our results support that a synergistic effect among trehalose and glycerol exists. We suggest that other combinations could improve these results.