How Changes in Cytosol and Nuclear Androgen Receptors Relate to the Testosterone Responses: Studies with New Exchange Assays

Abstract

Testosterone and other androgenic steroids facilitate synthesis of several renal proteins in the mouse (reviewed in Bardin and Catterall, 1981). The postulate that androgen receptors participate in this regulation has been supported by experiments on androgen-insensitive (Tfm/Y) animals (Bardin et al. 1973; Bullock and Bardin 1974; Attardi and Ohno 1974), by studies on the uptake of radioactive testosterone by renal nuclei in vivo and in vitro (Bullock and Bardin 1975; Janne et al. 1976; Bardin and Catterall 1981), and by the demonstration that the binding affinity of androgens to cytoplasmic androgen receptors relates to their biological potency in mouse kidney (Brown et al. 1979). However, the lability of renal androgen receptors has until recently hampered acquisition of data correlating changes in nuclear and cytosol androgen receptor concentrations to subsequent biological responses. The cytosol androgen receptor assays from mouse kidney were recently improved in our laboratory by taking advantage of the stabilizing effect of sodium molybdate on the unoccupied androgen receptors (Wright et al. 1981). In subsequent studies, a reliable method was devised for measurement of nuclear androgen receptors in this tissue (Isomaa et al. 1982).