Abstract

PIP: It has been established that when a steroid sex hormone is administered, an apparent and orderly biochemical change will take place in the target organs. The flow of activation mechanism is as follows: the steroid sex hormone binds with receptor forming a complex which transforms into a cellular receptor. This activates the genes in DNA resulting in protein synthesis. With the recent introduction of an exchange assay of nuclear and cytoplasmic receptor exchange, it has been demonstrated clearly that intracellular activities of steroid receptors including replenishment and recycling takes place. Furthermore, antiestrogen action of non-steroid substances such as nafoxidine, clomiphene, and tamoxifen has been previously interpreted as a competitor in the receptor sites. Now it appears that the action is related to the retention of the receptors in the nucleus. Thus, the activity of the receptor in the cell plays a major role in the action mechanism of steroid hormones. It is also recognized that the interaction of steroid hormones exists in the steroid receptor synthesis control mechanism. The effect of these hormones cannot be produced by themselves alone but also with the action of a receptor protein. Concurrently, the extent of this hormonal effect is not only due to the amount of hormone reaching the target organ but also the amount of receptor protein present in the target organ.