Reactive oxygen and nitrogen species: multifaceted regulators of ovarian activity.

Abstract

Reactive oxygen and nitrogen species (RONS) are essential components of diverse intracellular signalling pathways. In addition to their involvement in apoptosis, RONS are crucial in the regulation of multiple developmental and physiological processes. This review aims to summarise their role in the regulation of key ovarian stages: ovulation, maturation and postovulatory ageing of the oocyte, and the formation and regression of the corpus luteum. At the cellular level, a mild increase in RONS is associated with the initiation of a number of regulatory mechanisms, which might be suppressed by increased activity of the antioxidant system. Moreover, a mild increase in RONS has been linked to the control of mitochondrial biogenesis and abundance in response to increased cellular energy demands. Thus, RONS should also be perceived in terms of their positive role in cellular signalling. On the other hand, an uncontrolled increase in ROS production or strong-down regulation of the antioxidant system results in oxidative stress and damage of cellular components associated with ovarian pathologies and ageing. Similarly, the disturbance of signalling functions of RNS caused by dysregulation of NO production by NO synthases in ovarian tissues interferes with the proper regulation of physiological processes in the ovary.