title: The effect of okadaic acid on meiotic maturation of canine oocytes of different size.
abstract: The present study was conducted to determine the effect of okadic acid (OA), a potent inhibitor of seronine/treonine 1 and 2A phosphatase, on meiotic resumption and progression in canine oocytes with different diameters. Cumulus-oocyte complexes were collected from ovaries of bitches at different oestrous phases. In Experiment 1, to determine the optimal concentration of OA (0.5 or 2 μM), the oocytes were pre-incubated for 1, 3, and 20 h in TCM 199 supplemented with 20% SCE and thereafter cultured in the same medium without OA. In Experiment 2, the selected oocytes were divided into three groups according to their diameter: <110 μm, 110-120 μm, >120 μm, and pre-incubated in OA 0.5 μM for 1 h. Oocytes were cultured in vitro as previously described. After 72 h of IVM, in Experiment 1, significantly more oocytes reached MII stage with 0.5 μM for 1 h (30.8% P<0.001%) for oocytes cultured in other OA condition and in control group. In Experiment 2, OA induced a significantly higher incidence of MII oocytes in the 110-120 μm and >120 μm groups (P<0.001) compared to control group, but a significantly higher proportion of the oocytes>120 μm pre-incubated with OA progressed to MII (51.3% P<0.001). In contrast, smaller oocytes (<110) did not develop to MII stage with or without OA. In conclusion, treatment of canine oocytes with 0.5 μM for 1 h, improves meiotic maturation. The culture of fully grown (>120 μm) oocytes with OA at the onset of in vitro maturation can result in a higher frequency of meiotic maturation.
authors.affiliation: Department of Pathology and Veterinary Clinic, University of Sassari, Via Vienna 2 07100 Sassari, Italy. federica@uniss.it
authors.forename: Federica
authors.initials: F
authors.lastname: Ariu
authors.forename: Stefano
authors.initials: S
authors.lastname: Fois
authors.forename: Daniela
authors.initials: D
authors.lastname: Bebbere
authors.forename: Sergio
authors.initials: S
authors.lastname: Ledda
authors.forename: Irma
authors.initials: I
authors.lastname: Rosati
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Zedda
authors.forename: Salvatore
authors.initials: S
authors.lastname: Pau
authors.forename: Luisa
authors.initials: L
authors.lastname: Bogliolo
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000662:veterinary; D048429:Cell Size; D004285:Dogs / Q000254:growth & development; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D008540:Meiosis / Q000187:drug effects*; D019319:Okadaic Acid / Q000494:pharmacology*; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development
chemical_list: D004791:Enzyme Inhibitors; D019319:Okadaic Acid