Glutathione and adenosine triphosphate content of in vivo and in vitro matured porcine oocytes

Glutathione (GSH) content in mature porcine oocytes is correlated with subsequent fertilization and developmental success. Adenosine triphosphate (ATP) is an important energy source for maintaining cellular activities and protein synthesis. The objective of this study was to compare GSH and ATP concentrations of in vivo and in vitro matured porcine oocytes. Ovulated, in vivo matured oocytes were frozen at -80°C in groups of 10-20 (GSH) or 5-10 (ATP). In vitro oocytes were matured in either tissue culture medium-199 (TCM199) supplemented with polyvinyl alcohol (PVA) or hyaluronic acid (MAP5), or North Carolina State University-23 (NCSU23) supplemented with porcine follicular fluid (pFF) and frozen as described, or fertilized and cultured. GSH content was determined by the dithionitrobenzoic acid-glutathione disulfide (DTNB-GSSG) reductase recycling assay. ATP content was determined by using the Bioluminescent Somatic Cell Assay Kit. Oocytes matured in vitro in defined TCM199 with PVA or hyaluronic acid, or NCSU23 with pFF had significantly lower concentrations (P < 0.05) of GSH (n = 207, 9.82 ± 0.71 pmol/oocyte; n = 104, 9.73 ± 0.81 pmol/oocyte; n = 108, 7.89 ± 0.66 pmol/oocyte, respectively) compared to in vivo matured oocytes (n = 217, 36.26 ± 11.00 pmol/oocyte). Concentrations of ATP were not different between treatments (in vivo, n = 70, 0.97 ± 0.07 pmol/oocyte; TCM-PVA, n = 117, 0.81 ± 0.13 pmol/oocyte; TCM-MAP, n = 107, 1.02 ± 0.18 pmol/oocyte; NCSU-pFF, n = 134, 0.71 ± 0.08 pmol/oocyte). Intracellular ATP content does not appear to be related to developmental potential in porcine oocytes. Low intracellular GSH may be responsible, in part, for lower developmental competence observed in in vitro matured porcine oocytes.