176. INHIBITION OF PORCINE OOCYTE NUCLEAR MATURATION IN VITRO USING A PHOSPHODIESTERASE INHIBITOR AND AN ADENYLATE CYCLASE ACTIVATOR
M. Bertoldo A , T. Sellens A and C. G. Grupen AFaculty of Veterinary Science, University of Sydney, Camden, NSW, Australia.
Reproduction, Fertility and Development 22(9) 94-94 https://doi.org/10.1071/SRB10Abs176
Published: 6 September 2010
Abstract
Asynchronous nuclear and cytoplasmic maturation is thought to contribute to poor embryo production in vitro. Nuclear arrest is mediated by cAMP and can be maintained within the oocyte using non-specific phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine ; IBMX) and the adenylate cyclase activator forskolin (FSK) (1). The aim of this study was to investigate the effect of IBMX and FSK supplementation on porcine oocyte nuclear maturation during COC recovery and IVM using a defined culture system. In all experiments, cAMP modulators were added to Hepes-buffered media held in collection tubes. COCs recovered from 3–5 mm diameter follicles of prepubertal ovaries were cultured in basic maturation media in the absence of FSH. Nuclear maturation was assessed using orcein dye. In Experiment 1, IVM media was supplemented with 0, 50 or 500 µM IBMX. In Experiment 2, IVM media was supplemented with 0, 5, 10, 50 and 100µM FSK. In Experiment 3, IVM medium was supplemented with combinations of IBMX and FSK to give the treatments; control, 50IBMX/50FSK, 50IBMX/100FSK, 500IBMX/50FSK and 500IBMX/100FSK. Nuclear maturation was assessed at 0, 2, 4 and 18 h after the onset of IVM. At 18 h of culture, there were no differences in the proportion of oocytes supplemented with 0, 50 or 500 µM IBMX reaching MII. Incubation with 10, 50 or 100 µM FSK resulted in 8-16% of oocytes at MII at 18 h compared to the other groups (25–29%; P < 0.001). The combinations of IBMX and FSK resulted in greater proportions (86–98%) of oocytes remaining at the GV stage at 18 h compared to the control (16%; P < 0.001). There were no differences in the proportion of oocytes remaining at the GV stage at the earlier time points (P > 0.05). The results demonstrate that these cAMP modulators, in combination, are highly effective in maintaining porcine oocyte meiotic arrest in vitro for an extended period.
(1) Albuz FK et al., Proceedings of the 25th Annual Meeting of ESHRE, Amsterdam, The Netherlands, 2009.
