Non-genomic actions of steroids

Steroid hormones can act as chemical messengers mediating not only slow genomic actions but also rapid non-genomic actions in a wide range of target tissues. Although non-genomic actions of steroids had been described for several decades, until recently the physiological implications were not clear in many cases because of the type of receptors that participate in such phenomena was always controversial. Recently, new findings have been accumulated which indicate that non-genomic actions of steroids are mediated by receptors associated with the plasma membrane or its caveolae components, including membrane-associated nuclear receptors. Here we summarize the advances made in our understanding of the structure and functions of the recently identified steroid membrane receptors for estrogen and progestin.