title: Vitrification procedure decreases inositol 1,4,5-trisphophate receptor expression, resulting in low fertility of pig oocytes.
abstract: Although cryopreservation of mammalian oocytes is an important technology, it is well known that unfertilized oocytes, especially in pigs, are highly sensitive to low temperature and that cryopreserved oocytes show low fertility and developmental ability. The aim of the present study was to clarify why porcine in vitro matured (IVM) oocytes at the metaphase II (MII) stage showed low fertility and developmental ability after vitrification. In vitro matured cumulus oocyte complexes (COCs) were vitrified with Cryotop and then evaluated for fertility through in vitro fertilization (IVF). Although sperm-penetrated oocytes were observed to some extent (30-40%), the rate of pronuclear formation was low (9%) and none of them progressed to the two-cell stage. The results suggest that activation ability of cryopreserved oocytes was decreased by vitrification. We examined the localization and expression level of the type 1 inositol 1,4,5 trisphosphate receptor (IP3 R1), the channel responsible for Ca(2+) release during IVF in porcine oocytes. Localization of IP3 R1 close to the plasma membrane and total expression level of IP3 R1 protein were both decreased by vitrification. In conclusion, our present study indicates that vitrified-warmed porcine COCs showed a high survival rate but low fertility after IVF. This low fertility seems to be due to the decrease in IP3 R1 by the vitrification procedure.
authors.affiliation: Laboratory of Animal Reproduction, Graduate School of Veterinary Sciences, Sagamihara, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hirose
authors.forename: Maki
authors.initials: M
authors.lastname: Kamoshita
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Kato
authors.forename: Ayaka
authors.initials: A
authors.lastname: Nakamura
authors.forename: Richard J H
authors.initials: RJ
authors.lastname: Wojcikiewicz
authors.forename: Jan B
authors.initials: JB
authors.lastname: Parys
authors.forename: Junya
authors.initials: J
authors.lastname: Ito
authors.forename: Naomi
authors.initials: N
authors.lastname: Kashiwazaki
mesh_terms: D000818:Animals; D005260:Female; D005298:Fertility / Q000502:physiology*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000032:analysis*; D009865:Oocytes / Q000502:physiology*; D013552:Swine / Q000502:physiology*; D058989:Vitrification
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors
keywords: inositol trisphosphate receptor; oocyte; pig; vitrification