Sexual environment and molybdate: Two factors influencing the androgen-receptor quantification in prostate, bulbocavernosus/levator ami and heart muscle of male wistar rats

Abstract

To improve the androgen-receptor quantification we studied the effect of molybdate (MoO 4 2−) on the androgen receptor (AR) in the heart muscle (HM), prostate (PR) and bulbocavernosus/levator ani muscle (BCLA) of male adult Wistar rats, which lived either under homosexual (HO-rats) or heterosexual (HE-rats) conditions. Receptor analysis was done in 100 000 X g·cytosol by agar-gel electrophoresis and Sephadex G25 gel filtration after incubating the organ homogenates of the 24 h castrated rats for 2 h at 0°C with methyltrienolone (R1881). The main findings are: (1) MoO 4 2− did not change the qualitative binding characteristics of the AR in the various organs of HE- and HO-rats, the binding affinity remained unaltered ( K d 1.1 nM). (2) The assayable AR concentration in HM of HO-rats, analyzed by agar-gel electrophoresis, increased significantly ( P < 0.0001) from 1.9 fmoles/mg protein in the absence of MoO 4 2− to 3.8 fmoles/mg protein in the presence of MoO 4 2−. Similar results were found for the AR concentration in the HM of HE-rats. The assayable AR concentration in PR and BCLA of HO-rats remained unaffected by MoO 4 2−. (3) Compared to HO-rats the assayable receptor concentrations in PR and BCLA of HE-rats were significantly lower ( P < 0.05 for PR, n = 9; P< 0.01 for BCLA, n = 7) in the absence of MoO 4 2− as analyzed by agar-gel electrophoresis; the means were 117 ± 22 (SEM) fmoles/mg protein for PR and 14 ± 1.1 (SEM) for BCLA. Adding MoO 4 2− to the buffer medium, the significantly ( P < 0.02 for PR, n = 9; P < 0.001 for BCLA, n = 7) higher amounts of assayable AR sites were nearly the same as in the HO-rats (PR: 224 ± 30; BCLA 24 ± 1.9). (4) Concerning the organ weights, no significant differences could be found between the heart weights of HO- and HE-rats. On the other hand, the weights of PR and BCLA of HO-rats were significantly lower than those of the HE-rats i.e. with regard to PR and BCLA in the absence of MoO 4 2− the organ weights correlated inversely with the assayable AR concentrations. The results indicate that the quantitative AR assay depends on the status of the rats (HE-versus HO-rats). Furthermore, MoO 4 2− does not alter the qualitative binding characteristics of the AR, but is under definite circumstances able to enhance markedly the amounts of bonding sites. This enhancement depends on the organ and/or the status of the rats which were used.