Exogenous gamma-glutamyl cycle compounds supplemented to in vitro maturation medium influence in vitro fertilization, culture, and viability parameters of porcine oocytes and embryos.

High concentrations of intracellular glutathione (GSH) enhance in vitro production of porcine embryos. Objectives were: (1) to determine the effects of gamma-glutamyl cycle compound supplements to the IVM medium on IVF and IVC; and (2) to evaluate embryo viability. Porcine oocytes were matured in NCSU 23 medium supplemented with either l-cysteine (3.3 mM), l-cysteamine (150 P < 0.05microM), l-cysteine and l-cystemaine, l-glycine (1, 2.5, or 5 mM), l-glutamate (1, 2.5, or 5 mM), l-alpha-aminobutyrate (3.3mM), beta-mercaptoethanol (BME) (25 microM), l-cysteine and BME, or l-alpha-aminobutyrate and BME. Increases (P < 0.05) in GSH concentrations were observed using l-cysteine, 1.0 mM l-glutamate, l-alpha-aminobutyrate, and l-alpha-aminobutyrate with BME. Oocytes matured with l-alpha-aminobutyrate and BME had a lower (P < 0.05) occurrence of polyspermy during IVF compared to controls and a greater percentage (P < 0.05) of embryos reaching the blastocyst stage compared to other treatment groups. For Objective 2, oocytes were matured in NCSU 23 or NCSU 23 supplemented with l-alpha-aminobutyrate with BME. Embryo cell death was determined using an Annexin V-FITC assay. Supplementation had no effect on the time of cell death. Embryo mortality was increased (P < 0.05) from 24 to 42 h post-IVF, with the greatest occurrence around 36 h. In conclusion, supplementing l-alpha-aminobutyrate and BME into the IVM medium increased intracellular GSH concentrations, decreased the occurrence of polyspermy during IVF, and increased embryo development parameters during IVC, but did not affect cell death during embryo development. The onset of cell death occurred from 24 to 42 h post-IVF, with the greatest occurrence around 36 h post-IVF.