title: Characteristics of Okinawan native agu pig spermatozoa after addition of low-density lipoprotein to freezing extender.
abstract: Technical refinement of boar sperm cryopreservation is indispensable for effective breeding of the rare Okinawan native pig, the Agu. The objective of the present study was to determine whether addition of low-density lipoprotein (LDL) extracted from hen egg yolk to the freezing extender improves the characteristics of cryopreserved Agu spermatozoa. Ejaculated Agu sperm frozen in extender supplemented with 2, 4, 6, 8 or 10% LDL instead of egg yolk was thawed, and the post-thaw sperm characteristics were evaluated. Treatment with 4-8% LDL during cooling and freezing significantly increased the intracellular cholesterol content, as compared to that of sperm frozen in extender containing 20% egg yolk (P<0.05). Higher potential resistance to cell damage from cryoinjury was also observed in sperm frozen in extender supplemented with LDL: the integrities of plasmalemma and DNA, mitochondrial activity and proteolytic activity of the acrosomal content in the post-thaw sperm were superior to those of sperm that were not treated with LDL. Moreover, the percentages of total motile sperm and the extent of rapid progressive motility at 1 and 3 h after incubation were markedly higher in sperm treated with 4 or 6% LDL, and these sperm also had more ATP. However, LDL did not inhibit in vitro sperm penetrability, even though the cholesterol content of post-thaw sperm was higher after treatment with LDL. These findings indicate that addition of 4-6% LDL instead of egg yolk to the freezing extender improves the post-thaw characteristics of Agu sperm by protecting sperm against cold shock damage during cryopreservation.
authors: Faculty of Agriculture, University of the Ryukyus, Okinawa, Japan.
authors: Shogo
authors: S
authors: Yamauchi
authors: Satoshi
authors: S
authors: Nakamura
authors: Khin Mar
authors: KM
authors: Lay
authors: Toshiyuki
authors: T
authors: Azuma
authors: Tatsuro
authors: T
authors: Yakabi
authors: Norio
authors: N
authors: Muto
authors: Tadashi
authors: T
authors: Nakada
authors: Koji
authors: K
authors: Ashizawa
authors: Hideki
authors: H
authors: Tatemoto
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004527:Egg Proteins / Q000494:pharmacology; D007564:Japan; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008297:Male; D012098:Reproduction; D013045:Species Specificity; D013081:Sperm Motility; D013094:Spermatozoa / Q000166:cytology*; D013552:Swine
chemical_list: D003451:Cryoprotective Agents; D004527:Egg Proteins; D008077:Lipoproteins, LDL