Androgen binding in the baboon prostate

Induction of benign prostatic hypertrophy in baboons

Hormonal manipulation of intact male baboons has produced prostatic features resembling benign prostatic hypertrophy (BPH) in man. Long-acting androgen, testosterone enanthate (TE), given weekly (200 mg i.m.) for up to six months, caused significant gravimetric and volumetric increases in the prostate; a definite glandular and marked stromal hyperplasia with fibrosis developed in the caudal lobe (CD). After twenty weeks of TE treatment, there were dysplastic (atypical) changes in the glandular lining epithelium in the CD, causing pseudostratification of the lining cells with nuclear hyperchromatism. By the twenty-eighth week, there was an increase of stromal tissue with papillary ingrowth or invagination of glandular epithelium in the CD. Serum levels of testosterone and dihydrotestosterone were significantly elevated from 10 nm/ml and 2-3 ng/ml to 30-40 ng/ml and 5-6 ng/ml, respectively. There was a 3 to 4-fold increase in androstenedione levels and an increase in estradiol-17 beta from 20 pg/ml to 80-90 pg/ml. These steroidal levels may have played a direct role in the induction of early BPH in the baboons. Cytoplasmic and nuclear androgen receptor levels were higher in the CD compared to those of the cranial lobe (CR); AR concentration was increased in the cytosol and decreased in the nuclei of both lobes in TE treated animals. Scanning and transmission electron microscopy revealed heavy deposition of collagen fibers (fibrosis) in the central and periurethral regions of the CD after the administration of TE. Glandular as well as epithelial hyperplasia was most notable in the peripheral zone of the CD. These findings are similar to observations established in human BPH, indicating that the baboon prostate may be a useful model for studying various parameters of BPH.

[Comparative study on the concentrations of steroid receptors in adenomatous and cancerous prostatic tissue]

In this preliminary study, we have determined the receptors in normal human prostatic tissue or from patients with benign prostatic hypertrophy and patients with prostatic cancer. A single point assay using a dextran-coated-charcoal treatment of cytosol is utilized. This method permits the elimination of endogenous steroids and is also useful when specimens are too small to provide the larger number of aliquots necessary for multiple steroid receptor analyses. The results are discussed in the light of several problems inherent to this assay. We conclude that adenoma-tissue contains more receptors than neoplasic tissues for the progesterones receptors but that there is no significant difference for the estrogen-receptor and the androgen-receptors. For all the adenoma tissues and some neoplasic tissues the level of the estrogen-receptors is always lower than the one for androgen-receptor which itself is lower than the one for progesterone-receptors. We think that the expression of the results as a ratio of two levels of steroid-receptors gives a better evaluation of the receptors. The ratios Progesterone-receptor Estrogen-receptor and Androgen-receptor/Estrogen-receptor are always greater than 1.5, except for some neoplasic tissues and we think that, as in breast tumors, there are perhaps two kinds of neoplastic tissues, one hormone-dependent, the other not.

Regional variations in the testicular dependence of prolactin binding and its possible relationship to castration-induced involution in rat prostate gland

Prolactin binding sites of ventral, lateral, and dorsal lobes of rat prostate were examined immunohistochemically 1, 2, 4, and 8 days after castration or sham operation. In sham-operated rats each lobe exhibited a distinct pattern of intracellular and intraluminal prolactin binding. A loss in prolactin binding from epithelial cells of ventral prostate, which was visualized postcastration, was quantitated with the aid of an image analyzer and then statistically evaluated. The proportion of ventral prostate epithelial cells devoid of prolactin binding increased from approximately 13% in sham-operated rats to approximately 29% 1 day after castration, and reached a peak level of about 71% 4 days postcastration. No loss of prolactin binding was evident in either lateral or dorsal prostate up to 8 days postcastration. Direct measurement of epithelial cell heights and subsequent statistical evaluation revealed similar regional differences in the rates and extent of prostate involution. Eight days after castration ventral prostate epithelial cell heights decreased by 56% whereas lateral and dorsal lobe epithelial cells heights decreased about 25% and 14%, respectively. The apparent relationship between testicular dependence of prostatic prolactin binding and castration-induced prostatic involution are discussed in terms of possible regional variations in the prolactin-androgen interplay in prostate.

Endocrine control and physiology of the prostate

The endocrine control of prostatic physiology and anatomy is reviewed with emphasis on those factors in the hypothalamus and anterior adenohypophysis which affect the gland either directly or through the testes. The role of circulating estrogens and androgens and their binding to plasma proteins is presented, and the intracellular metabolism of testosterone, particularly in relation to specific receptors, is summarized. The possible significance of intracellular events in prostate cancer development is considered with particular emphasis on those parameters which may reside outside the endocrine effects on the prostatic cells.

Steroid hormone receptors in the prostate

Specific receptors for dihydrotestosterone and estradiol-17-beta have been identified in cytosols of the human and baboon prostate. Binding of radioactive estradiol-17-beta to the 0.4 M potassium chloride extractable component of human prostate nuclei also was demonstrated. Cyproterone acetate and diethylstilbestrol, agents of known high affinity for dihydrotestosterone and estradiol-17-beta receptors, respectively, did not bind significantly to sex hormone binding globulin and, therefore, were useful as competitors in distinguishing binding of dihydrotestosterone and estradiol-17-beta to sex hormone binding globulin and to their specific receptors. Displacement of [3H]-estradiol-17-beta binding by diethylstilbestrol in cytosols of 11 needle biopsy specimens (mean equals 16.8 mg.) from prostatic cancer patients was analyzed. These preliminary data indicated a trend towards greater competition by diethylstilbestrol for high affinity binding sites in differentiated tumor specimens from men who were not receiving estrogen therapy. Objective and subjective responses to hormone therapy were recorded in these patients, whereas the disease in those men with low displacement assay values progressed.