Oestrogen supplementation following castration promotes stromal remodelling and histopathological alterations in the Mongolian gerbil ventral prostate

Abstract

The effect of oestradiol on the intact and castrated adult gerbil prostate was evaluated by focussing on stromal and epithelial disorders, and hormonal receptor immunoreactivity. The experimental animals were studied by histological, histochemical and immunohistochemical techniques, morphometric-stereological analysis and transmission electron microscopy. Epithelial alterations in the oestradiol-treated animals were frequent, with an increase in epithelial cell height, areas of intense dysplasia and hyperplasia and formation of prostatic intraepithelial neoplasia (PIN). Another aspect that did not depend on the presence of testosterone was the arrangement of the fibrillar and non-fibrillar elements of the extracellular matrix among smooth muscle cells (SMC), suggesting a possible role of these cells in rearrangement and synthesis of these components, after oestrogenic treatment. In the castrated animals, an accumulation of extracellular matrix elements under the epithelium was evident, while in the intact animals the same compounds were dispersed and scarce. In the groups of intact and castrated animals, SMC and fibroblasts exhibited a secretory phenotype, which was accentuated after oestradiol administration. There was an increase of the immunoreactivity to alpha-oestrogen and androgen receptors in hyperplastic areas compared to normal epithelium, revealing the involvement of these steroid receptors in the hyperplasia and PIN development.

Figures 1–4

Histological sections stained by haematoxylin–eosin. 1(a,b): Intact control group (C) – 1(a) general aspect of the prostate acinus; 1(b) detail of the epithelium (e) and smooth muscle cells layer (SMC) of adult prostate acinus. 2(a–d): Oestradiol-treated group (E) – 2(a) general aspect of a prostate acinus with high epithelium and dysplasia; 2(b) cells dislocated to the apical regions (arrow), simulating a possible detachment and secretory granules in the lumen were observed; 2(c) detail of the transition epithelium-stroma; arrow point the subepithelial stroma and the fusiforms smooth muscle cells. Between the SMC conjunctive tissue was observed; 2(d) a high-grade prostate intraepithelial neoplasia (PIN). 3(a,b): Castrated group (Ca) – 3(a) prostate acinus with a low epithelium (ep), SMC and evident subepithelial conjunctive stroma (arrow); 3(b) detail of the prostate acinus where a prominent subepithelial conjunctive stroma (arrow) and SMC with irregular aspect were noticed. 4(a–d): Oestradiol-treated castrated group (CaE) – 4(a) prostate acinus showing the epithelial enfolding (ep). Arrow points to subepithelial connective stroma; 4(b) arrows point to basal membrane with sinuous aspect (e) abundant conjunctive stroma. Arrow head show the SMC with irregular spine-like cytoplasmic projections. Notice the high epithelial cells (ep); 4(c) presence of PIN and abundant subepithelial stroma (arrow) and a substantial layer of SMC; 4(d) detail of epithelium-stroma transition showing the subepithelial connective tissue (arrow), the SMC and the dysplasic epithelium (ep).

Figures 13–22

Transmission electron microscopy: ultrastructural aspects – (13) epithelial cells (ep) from intact control prostate. Arrow points to secretion organelles, bar = 2.60 μm; (14) epithelium-stroma transition. Arrow point to basal laminae; in the stroma the smooth muscle cells (SMC), fibroblasts (fib) and scarce collagen fibres (col); intact control group, bar = 0.94 μm; (15) abundance of bunches of collagen fibres (col) in the subepithelial stroma and fibroblasts (fib), epithelium (ep), Ca group, bar = 1.56 μm; (16) detail of the activated fibroblast (fib) with dilated endoplasmic reticulum cisternae (arrow), Ca group, bar = 0.72 μm; (17) sinuous aspect of basal laminae (bl) with collagen deposition (col) in the subepithelial stroma, Ca group, bar = 0.72 μm; (18) irregular arrangement of SMC and collagen fibres (col), Ca group, bar = 1.56 μm; (19) epithelial cells from oestradiol-treated castrated prostate, bar = 2.60 μm; (20) PIN in oestradiol-treated prostate. The epithelial stratification with loose chromatin and conspicuous nucleolus were used here as morphological parameters for PIN diagnosis, bar = 3.36 μm; (21) detail of an epithelial cell from oestradiol-treated prostate, showing the circular endoplasmic reticulum, bar = 0.56 μm; (22) a high epithelial cell from oestradiol-treated group. The arrow points to dilated cisternae, bar = 2.01 μm. n, nuclei; ep, epithelium; st, stroma; SMC, smooth muscle cells.

Figures 23–30

Transmission electron microscopy – ultrastructural aspects –(23) general aspect of stromal compartment showing the SMC with ER prominent in oestradiol-treated castrated prostate, bar = 1.21 μm; (24) the SMC with dilated Golgi apparatus cisternae (arrow), E group, bar = 0.56 μm; (25) the SMC with irregular spine-like cytoplasmic projections surrounded by collagen fibres (col), CaE group, bar = 1.21 μm; (26) the activated fibroblast replete of ER and with dilated Golgi apparatus cisternae (Ga). Notice the prominent nucleolus, E group, bar = 1.21 μm; (27 and 28) detail of SMC prolongations and collagen (col) arrangement between them. elastic fibers (el), CaE group; (27) bar = 1.56 μm; (28) bar = 1.21 μm; (29 and 30) detail of SMC showing the intimate contact with elastic fibres (el) in cytoplasmic prolongations and collagen fibres (col), E group; (29) bar = 0.72 μm; (30) bar = 0.94 μm. n, nuclei; nu, nucleolus.

Figures 5–8

5(a), 6(a), 7(a) and 8(a) Histological sections stained by Gömöri’s reticulin; 5(b), 6(b), 7(b) and 8(b): histological sections submitted to chondroitin sulphate IHC – 5(a,b) intact control group; 6(a,b) oestradiol-treated group; 7(a,b) castrated group; 8(a,b) oestradiol-treated castrated group. Arrows point positive demarcation to reticulin fibres and chondroitin sulphate respectively. *collagen fibres; ep, epithelium; l, lumen.

Figures 9 and 10

Histological sections submitted to ERα IHC – 9(a) intact control group; 9(b–c) oestradiol-treated group; 10(a) castrated group; 10(b–c) oestradiol-treated castrated group. Brown stain means positive demarcation.

Figures 11 and 12

Histological sections submitted to AR IHC – 11(a) intact control group; 11(b) oestradiol-treated group; 12(a) castrated group; 12(b) oestradiol-treated castrated group. Brown stain means positive demarcation.

Figure 31

Mean ± SD values of serum testosterone levels (ng/ml) from experimental groups (C, control; Ca, castrated; E, oestradiol-treated; CaE, catrated oestradiol-treated animals). Statistical analysis based on anova and Tukey tests. Different superscript letters (a, b) indicate statistically significant difference (P ≤ 0.05).