Effects of niacin supplementation during in vitro culture on the developmental competence of porcine embryos.

Niacin is a water-soluble vitamin belonging to the vitamin B complex. It has been found to possess various biological activities, including antioxidant and lipid modification capacities. This study aimed to elucidate the effects of niacin treatment in porcine in vitro culture (IVC) medium on embryo developmental competence after parthenogenetic activation. IVC medium was supplemented with different concentrations of niacin (0 [control], 300, 600 and 900 µM). The results showed that embryos cultured in an IVC medium supplemented with 300 and 600 µM niacin had an increased cleavage rate (p < .05). In addition, 300 µM niacin treatment resulted in a higher blastocyst formation rate than the control and other niacin-treated groups. However, the total cell number did not differ significantly among the experimental groups. Niacin supplementation at 600 µM decreased reactive oxygen species, whereas treatment with 300, 600 and 900 µM increased glutathione levels in day two embryos. On day seven, 300 µM niacin exhibited improved fatty acid levels and fewer lipid droplets than the control group. Furthermore, gene expression at the mRNA level was performed on day two and day seven embryos, treated with or without 300 µM niacin. The expression of anti-apoptotic BCL2 and lipid metabolism PLIN2-related genes were upregulated, whereas the pro-apoptotic BAX and CASPASE3 were downregulated with niacin supplementation compared with the control group. However, SIRT1, a gene related to energy and the oxidative state, was up-regulated in niacin-treated day two embryos (p < .05). Overall, the results indicate that niacin has a beneficial effect on pre-implantation embryo development by modulating lipid metabolism and reducing oxidative stress and apoptosis. The expression patterns of PLIN2 and SIRT1 reported here suggest that these transcripts may be involved in the mechanism by which niacin affects the developmental capacity of IVC embryos.

Supplementation with Niacin during in vitro maturation improves the quality of porcine embryos.

Niacin, also known as vitamin B3, has a pivotal role in energy metabolism, cellular signaling cascades regulating gene expression, and apoptosis. However, the effect of Niacin on porcine early embryo developmental competence remains to be elucidated. The present study aimed to assess the effects of Niacin treatment during in vitro maturation (IVM) on the nuclear maturation of porcine oocytes and subsequent development of in vitro embryos. In addition, the expression profiles of selected genes related to lipid metabolism, oxidative stress, and apoptosis were assessed. The IVM medium was supplemented with different concentrations of Niacin (0, 300, 600, and 900 µM). The results showed that a high concentration of Niacin (900 µM) significantly decreased cumulus expansion compared to the other groups (p < 0.05). No significant difference was observed among the experimental groups for nuclear maturation rate. Niacin treatments (300, 600, and 900 µM) during IVM significantly (p < 0.05) enhanced glutathione levels. Treatment with 300 and 600 µM significantly (p < 0.05) lowered the reactive oxygen species levels compared to treatment with 900 µM and the control group. Niacin supplementation to the IVM media significantly improved the cleavage and blastocyst rates compared to the control group. Supplementation with 300 and 600 µM of Niacin significantly increased the total cell number of blastocysts compared to supplementation with 900 µM or the control groups. Cytoplasmic lipid droplets were significantly reduced after 600 µM treatment. Supplementation of Niacin to IVM media positively affected the relative expression of genes related to energy and oxidative status (SIRT1), pro-apoptosis (BAX), anti-apoptosis (BCL2), and lipid metabolism (ACACA and PNPLA2) in cumulus cells and oocytes. Taken together, Niacin supplementation to porcine IVM media improved the developmental competence of early embryos mainly through protection against oxidative stress and its influence on energy metabolism and apoptosis pathways.

Zinc supplementation during in vitro maturation increases the production efficiency of cloned pigs.

Zinc supplementation (0.8 µg/ml) in in vitro maturation (IVM) medium significantly enhances oocyte quality. In this study, we compared the development of somatic cell nuclear transfer (SCNT) embryos produced from conventional IVM (control) and zinc-supplemented IVM oocytes. A total of 1206 and 890 SCNT embryos were produced using control and zinc-supplemented oocytes, respectively, and then were transferred to 11 and 8 recipients, respectively. Five control recipients and three zinc-supplemented recipients became pregnant. Two live piglets and eight mummies were born from two control recipients, and ten live piglets and six stillborn piglets were born from three zinc-supplemented recipients. The production efficiency significantly increased in the zinc-supplemented group (0.33% vs. 3.02%). This report suggests that zinc supplementation in IVM medium improved the production efficiency of cloned pigs.

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.

Supplementation of zinc on oocyte in vitro maturation improves preimplatation embryonic development in pigs.

We investigated the effects of zinc supplementation during the IVM of porcine oocytes. Nuclear maturation, intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, subsequent embryonic development, and gene expression were evaluated. Zinc concentrations in porcine plasma and follicular fluid were 0.82 and 0.84 µg/mL, respectively. Zinc was not detected in IVM medium. After treatment with various zinc concentrations (0.0, 0.4, 0.8, 1.2, and 1.6 µg/mL), no significant difference in IVM was observed among groups (85.7%, 88.7%, 90.4%, 90.3%, and 87.2%, respectively). The effects of different zinc concentrations on porcine oocyte intracellular GSH and ROS levels were examined in mature oocytes. Intracellular GSH levels were significantly higher in the 0.8-, 1.2-, and 1.6-µg/mL groups than in the control (P < 0.05). Intracellular ROS levels of oocytes matured with 0.8, 1.2, and 1.6 µg/mL were reduced significantly (P < 0.05) compared with the control and 0.4-µg/mL groups. The developmental competence of oocytes matured with different zinc concentrations was evaluated after parthenogenetic activation (PA) and in vitro fertilization (IVF). Oocytes treated with zinc during IVM showed no significant difference in cleavage rate after PA. Oocytes treated with 0.8 and 1.2 µg/mL zinc during IVM had significantly higher blastocyst formation rates after PA (41.5% and 41.1%, respectively) than the control (27.2%). IVF embryos showed similar results. The blastocyst formation rate was significantly higher (28.2%) in the 0.8-µg/mL group. TNFAIP2 and Bax were decreased in zinc-treated cumulus cells. Increased POU5F1 and decreased Bax transcript levels were observed in zinc-treated oocytes. POU5F1 and Bcl-2 transcript levels were significantly higher in zinc-treated IVF blastocysts. These results indicate that treatment with adequate zinc concentrations during IVM improved the developmental potential of porcine embryos by regulating the intracellular GSH concentration, the ROS level, and transcription factor expression.