An investigation of the characteristics and mechanisms of action of the progestin receptor in the rat brain

This investigation was able to demonstrate physico-chemical characteristics of the progestin receptor in rat brain cytosol that agree closely with those reported by other workers. Translocation of progestin receptors in utirine cytosol was also shown. However, this study was unable to demonstrate either depletion of cytosol progestin receptors, or accumulation of nuclear progestin receptors in the brain after progesterone administration. Such direct experimental evidence is necessary to support the hypothesis that in the brain, the progestin receptor acts via the classical steroid mechanism of action. Few studies have been published in this field. There is indirect evidence to support the theory that progesterone exerts certain effects on the brain by interaction with the genome. The issue remains a controversial one. In view of the very low levels of progestin receptors in the brain and varying levels in individual animals, the synthesis of a gamma-labelled synthetic progestin, which to date has not been successful, could be instrumental in resolving this contraversial issue