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LEVELS OF ENZYMATIC ANTIOXIDANT DEFENSES ARE MODULATED IN BOVINE OVIDUCTAL FLUID DURING THE ESTROUS CYCLE.
Bilodeau, Jean-François1, Sirard, Marc-André1, 1
ABSTRACT- Little is known on the enzymatic antioxidant status in the bovine oviductal fluid, except that there is an oviductal catalase that binds to spermatozoa (Lapointe et al., Biol Reprod 1998. 58: 747). In this study, we have investigated the enzymatic activities and the protein levels of the major antioxidant defenses in the bovine oviductal fluid at different stage of the estrous cycle. The oviductal fluid was retrieved by perfusion or by mechanical manipulation of the oviduct to get the whole secretion. The measurements were done on both, isthmus and ampulla sections of the oviduct. We have found detectable but low levels of reactive oxygen species (ROS) production in the oviductal fluid. We have also reported that fairly high amount of catalase activity can be retrieved from perfused oviduct (~62 U/mg). However, the catalase specific activity was not dramatically improved when the whole secretion was retrieved (40-78 U/mg). In contrast, total glutathione peroxidase (GPx) activity was very low in flushes of the perfused oviducts, but was very high in the whole secretion (500-1136 mU/mg). Total GPx activity was constituted of about 78% of seleno-dependent GPx activity. The glutathione (GSH) level, cofactor of GPx, is present to M concentration in the oviductal fluid. The GSH level like GPx and catalase activities significantly increased during the estrous cycle while superoxide dismutase (SOD) activity remained constant (from day 1 to 20). These results were also confirmed by western blot analysis with antibodies against GPx-1, catalase and Cu,ZnSOD. This study will greatly improve our understanding of the balance between ROS production and antioxidant defenses in the female tract, and the possible role of this regulation may have on fertility. This work was supported by the Natural Sciences and Engineering Research Council-Canada, and SEMEX-Alliance.
KEY WORDS: oviduct, antioxidants, reactive oxygen species, bovine
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