Quantification of androgen binding, androgen tissue levels, and sex hormone-binding globulin in prostate, muscle and plasma of patients with benign prostatic hypertrophy
Krieg, M.; Bartsch, W.; Herzer, S.; Becker, H.; Voigt, K.D.
Acta Endocrinologica 86(1): 200-215
1977
ISSN/ISBN: 0001-5598 PMID: 71838 Document Number: 110148
The in vitro binding of 5.alpha.-dihydrotestosterone (5.alpha.-DHT) in benign prostatic hypertrophy (BPH), rectus abdominis muscle and plasma of 14 patients was characterized and quantified by agar gel electrophoresis. The respective endogenous tissue and plasma levels of 5.alpha.-DHT and testosterone (T) were determined by radioimmunoassay, and the plasmatic sex hormone-binding globulin (SHBG) concentration was estimated in the 14 patients by an (NH4)2SO4 precipitation technique. Finally the in vitro conversion of 5.alpha.-DHT to the 5.alpha.-androstanediols in the BPH at 0.degree. C after a 20-24 h incubation period was analyzed by TLC. In 12 out of 14 BPH cytosols 3 charcoal resistant binding peaks were found, of which peak 1 represents SHBG, peak 2 the specific receptor protein and peak 3 a binding protein with relatively high binding capacity and low affinity for 5.alpha.-DHT. In 2 cases peak 2 was absent. In 11 out of 14 muscle cytosols 3 binding peaks are also present, resembling those of the BPH. The receptor peak is reduced on average 38% by unlabeled 5.alpha.-DHT, 23% by cyproterone acetate (CYAC) and 29% by estradiol. The parallel data for the SHBG peak are: 62% by 5.alpha.-DHT, 22% by CYAC and 49% by estradiol. From displacement studies with unlabeled 5.alpha.-DHT the average concentration of receptor was calculated to be 12.3 fmol/g tissue are present, in muscle 0.45 ng 5.alpha.-DHT/g tissue and 0.71 ng T/g tissue, in plasma 0.47 ng 5.alpha.-DHT/ml and 3.89 ngT/ml. Statistical calculations revealed a significantly (P < 0.05) negative correlation between the endogenous 5.alpha.-DHT and T tissue levels and the available 5.alpha.-DHT receptor sites in BPH cytosol, a positive correlation between plasmatic SHBG concentration and the available SHBG concentration in BPH cytosol. Compared to the rat prostate, where 36% of the incubated 5.alpha.-DHT was converted at 0.degree. C within 20-24 h into the 5.alpha.-androstanediols, in the BPH conversion to 5.alpha.-androstanediols was negligible.