ANDROGEN BINDING AND ANDROGEN EFFECT IN THE RAT SEMINAL-VESICLES - STUDIES WITH TESTOSTERONE AND 19-NORTESTOSTERONE

In an attempt to correlate androgen bdining and androgen effect, the seminal vesicle of the castrated rat was used as a model system. Competitive binding studies were carried out by incubating the mince of this gland with [3H]-testosterone and various concentrations of 19-nortestosterone (N) or testosterone (T). The binding of [3H]-dihydrotestosterone ([3H]-DHT) to cytosol proteins and nuclei was measured. To compare the competing capacity of N and T, the binding data were graphically analyzed, and the relative competition indices: N/T = 0.44 and 0.40, respectively, were obtained for cytosol binding and nuclear retention. In order to estimate the androgen effect, the increase of the RNA/DNA ratio in response to the in vivo administration of the phenylpropionate esters of these steroids was determined. An analysis of the double reciprocal plot of data showed that the biological activity of N, relative to T, is 0.42, which is strictly consistent with the relative binding of these steroids (and/or their metabolites) in this tissue. Control experiments have demonstrated that the rate of conversion of [3H]-T to [3H]-DHT is identical irrespective of whether N or T is present during incubation. It has also been found that N and T are released and absorbed from their phenylpropionate esters very similarly, although the rate of these processes is markedly influenced by the vehicle used. © 1979.