Effect of zinc on in vitro development of porcine embryos

This study aimed to investigate the effect of zinc on in vitro development of porcine embryos. We evaluated the effects of zinc on blastocysts formation and investigated gene expression at zinc-deficient and supplemented conditions. Zinc-deficient in vitro condition was induced by 10-μM N,N,N′,N′-tetrakis-(2-pyridylmethyl)-ethylendiamine (TPEN) (zinc chelator) treatment during IVC. On parthenogenetic activated embryos, this treatment significantly decreased cleavage rate and blastocyst formation compared with the control (0.0% and 0.0% vs. 69.0% and 36.0%, respectively). And time effect of the zinc deficiency exposure is observed. Blastocyst formation rate was significantly decreased as zinc-deficient time increases (54.1%, 31.0%, 9.0%, and 1.2% for zinc deficiency during 0, 3, 5, and 7 hours). However, zinc supplementation during IVC supported in vitro embryonic development. On parthenogenetic activated embryos, supplementation of 0.8 μg/mL of zinc during IVC significantly increased blastocyst formation compared with other groups (43.9%, 57.8%, 67.1%, 51.4%, and 52.6% for zinc supplementation of 0, 0.4, 0.8, 1.2, and 1.6 μg/mL). In vitro-fertilized (IVF) embryos showed similar results. The blastocyst formation rate was significantly higher in the 0.8 μg/mL of zinc-supplemented group than in the other groups (21.3%, 24.1%, 36.1%, 25.9%, and 25.2% for zinc supplementation of 0, 0.4, 0.8, 1.2, and 1.6 μg/mL). PCNA, POU5F1, and Bcl2 messenger RNA expressions were unregulated in IVF-derived blastocysts in the 0.8 μg/mL of zinc-supplemented group compared with the control. These results suggest that zinc is required for embryonic development, and supplementation with adequate zinc concentrations during IVC improved the viability of porcine embryos, possibly by increasing PCNA, POU5F1, and Bcl2 gene expression of embryos.