Abstract
Oestrogens are part of a large group of steroid hormones involved in various regulatory processes in the organism. Their activity is not limited to the reproductive system but extends also to bone and adipose tissues, as well as the nervous and muscular systems, among others. In these tissues, oestrogens exert their effects through their receptors (ERα, ERβ and GPER), which are expressed not only in the cell membrane and the nucleus but also in mitochondria. Consequently, oestrogens influence several mitochondrial processes, such as ATP production, mitochondrial fusion and fission, oxidative stress, apoptosis and others. It is also important to emphasise the effects, when the oestrogen production increases or decreases resulting in oestrogen-dependent diseases. All of this makes oestrogens important molecules that deserve considerable attention in research. The aim of this review is to present (1) the pathways of oestrogen synthesis and (2) the broad scope of their activity in the organism, including their relation to the oxidative stress.