Egg yolk and glycerol requirements for freezing boar spermatozoa treated with methyl β-cyclodextrin or cholesterol-loaded cyclodextrin.
Egg yolk (EY) and glycerol are common constituents of extenders used for sperm cryopreservation. It has been demonstrated that using cholesterol-loaded cyclodextrins (CLC) improves sperm cryosurvival in several species. However, standard freezing extenders might not be the most appropriate for CLC-treated sperm. This study evaluated the EY and glycerol requirements for freezing CLC-treated boar spermatozoa. Semen samples from 34 ejaculates coming from 4 boars were used. Each ejaculate was split into three aliquots: one was used untreated (control), and the other two were treated with 1 mg of CLC or methyl-β-cyclodextrin/120 × 10(6) sperm for 15 min at 22 C prior to cryopreservation. Our results indicated that reducing the concentration of EY was detrimental for sperm viability after thawing (31.57 ± 2 vs. 19.89% ± 2 for 20 and 10% EY, respectively; P <0.05), even in semen treated with CLC. On the other hand, it was observed that the traditional concentration of glycerol (3%) was not the appropriate for freezing CLC-treated sperm (61.10 ± 3 vs. 47.87% ± 3 viable sperm for control and CLC-treated sperm, respectively; P <0.05). Thus, CLC-treated sperm showed a higher tolerance to high glycerol concentrations (5%) in terms of sperm viability (59.19% ± 3) than non-treated sperm (45.58% ± 3; P<0.05). Therefore, it could be necessary to modify the freezing extenders for CLC-treated sperm. Nevertheless, additional studies will be needed to evaluate alternative cryoprotectants and to determine the effect of high glycerol concentrations on sperm functionality.
Centro de Tecnología Animal - Instituto Valenciano de Investigaciones Agrarias (CITA-IVIA), 12400-Segorbe (Castellón), Spain.
Eva
E
Blanch
Cristina
C
Tomás
Marta
M
Hernández
Jordi
J
Roca
Emilio A
EA
Martínez
Juan M
JM
Vázquez
Eva
E
Mocé
D000818:Animals; D002784:Cholesterol / Q000494:pharmacology*; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D003505:Cyclodextrins / Q000494:pharmacology; D004530:Egg Yolk; D005434:Flow Cytometry / Q000662:veterinary; D005990:Glycerol / Q000494:pharmacology; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013081:Sperm Motility / Q000502:physiology; D013552:Swine / Q000502:physiology*
D003451:Cryoprotective Agents; D003505:Cyclodextrins; D002784:Cholesterol; D005990:Glycerol