Regulation of oxytocin action at the receptor level

Abstract

Prior exposure of certain target cells to elevated concentrations of a hormone can cause a reduction in the concentration of receptors for that hormone. Following the initial findings (1–6), many examples of the regulation of receptor concentrations by hormones and drugs have been reported (for a partial list see 7). In most cases a hormone regulates its own receptor concentration. There are examples, however, of hormones that can regulate the concentration of receptors for other hormones. The oxytocin (OT) receptor is a prime example of a system that is regulated by estrogens and progestins. Although changes in receptor concentration can play an important role in modifying the response to a hormone, in most systems studied it has not been possible to relate the changes in receptor concentration to an altered biological response to the hormone. Regulation of the OT receptor system, however, has been shown to have a very important bearing in the initiation of labor and parturition and these aspects of OT action are part of the subject of this review.