The antioxidative enzyme SOD2 is important for physiological persistence of corpora lutea in lynxes

Corpora lutea (CL) are transient endocrine glands supporting pregnancy by progesterone production. They develop at the site of ovulation from the remaining follicle, are highly metabolically active and undergo distinct, transformative processes during their lifetime. In contrast to other species, CL of lynxes do not regress at the end of cycle, but remain functionally active (persist) for years. Reactive oxygen species (ROS) and anti-oxidative enzymes are described to be important for the functionality of CL. We examined ten anti-oxidative enzymes in fresh and persistent CL of lynxes as well as in domestic cat CL of different luteal stages. The gene expression profiles, especially those of SOD1 and SOD2, showed some remarkable differences between CL stages during non-pregnant and pregnant cycles of domestic cats and between fresh and persistent CL of lynxes. Lynx gene expression profiles of SODs were confirmed by western blot analysis, immunohistochemistry and activity assays. SOD2 was characterized by a conspicuous high expression and enzyme activity exclusively in persistent CL. We suggest that SOD2 is required to detoxify potential elevated superoxide anion levels by producing H₂O₂ in the physiologically persistent CL. This product might also act as a signaling molecule, securing the CL from apoptosis and insuring long-term luteal cell survival.