Abstract
Vol.42 No.1
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Original
Effect of sulfasalazine supplementation to the maturation medium on glutathione synthesis in porcine oocytes
JMOR, 42(1) 31-36, 2025
It is thought that cysteine supplemented to the maturation medium of porcine oocytes for glutathione (GSH) synthesis is rapidly oxidized to cystine and then taken up by cumulus cells via the cystine-glutamate transporter (xc-); however, the details of this process are unclear. We used sulfasalazine, a system xc- inhibitor, to determine whether the system xc- is involved in cystine uptake in the porcine cumulus-oocyte complex. Porcine oocytes were cultured for 22 h in NCSU23 medium containing porcine follicular fluid, cysteine and hormones, and then cultured for an additional 22 h in hormone-free medium. When sulfasalazine was supplemented at 0.3 mM or more, the oocyte GSH content decreased significantly compared to the control. Moreover, oocyte GSH content did not decrease when sulfasalazine was supplemented only during the first half of the culture, but significantly decreased when sulfasalazine was supplemented only during the latter half of the culture. These results indicate that the cysteine used for GSH synthesis in porcine oocytes is derived from cystine, which is taken up by the cumulus cells via the system xc-, and also suggest that cysteine transport to the oocyte is not mediated by gap junctions.
