Expression of superoxide dismutases in the bovine oviduct during the estrous cycle

The superoxide dismutases (SODs) are first-line enzymatic antioxidants that dismute superoxide anion (O2−) to produce hydrogen peroxide (H2O2). The primary objective was to characterize, by western blot analysis, the expression of two SODs, the cytosolic (Cu,ZnSOD or SOD1) and the mitochondrial (MnSOD or SOD2) forms in three sections of the oviduct, i.e. isthmus (I), ishtmic–ampullary junction (IA), and ampulla (A), during the estrous cycle. The Cu,ZnSOD and MnSOD proteins were mostly expressed in the ampulla (I < IA < A; P < 0.0093). Expression of Cu,ZnSOD was lowest during metestrus (P < 0.0041) and it was mostly expressed in the oviduct contralateral to the CL (P = 0.0019). The expression of MnSOD was consistent throughout the cycle. Based on immunohistochemistry, the SODs were present in all cell types of the oviduct, with variations among oviductal sections. We inferred that the expression of Cu,ZnSOD was influenced by the hormonal milieu. Furthermore, variations among oviduct sections in protein expression profile of SODs suggested they have an important role in preserving and capacitating sperm.