Which play a more important role in the development of large-sized prostates (≥80 ml), androgen receptors or oestrogen receptors? A comparative study

The effect of acupuncture on oestrogen receptors in rats with benign prostatic hyperplasia

The effects of acupuncture on the protein and gene expression of oestrogen receptors (ERs) alpha (α) and beta (β) in testosterone-induced benign prostatic hyperplasia (BPH) in rats remains unclear. In this study, rats were randomly divided into four groups (n = 10 per group). The rats in the blank group did not receive any treatment, while the rats in the model group were injected intraperitoneally with testosterone propionate for 28 days to establish the BPH model and then randomly sub-divided into a control group, an acupuncture group and a finasteride group (positive control group). Dissections were performed after rats were anesthetized with isoflurane, and then the weight and volume of the prostate were then measured. The expression of ERs was detected via immunohistochemistry, western blot and real-time polymerase chain reaction. The results showed that ERα was discontinuously distributed in epithelial cells and expressed in large quantities in stromal cells, and ERβ was aggregated and expressed in hyperplastic nodules. Acupuncture and finasteride could significantly improve the distribution of ERα and ERβ which suggested that acupuncture and finasteride could improve BPH. There was no significant difference in ERα messenger ribonucleic acid (mRNA) expression among the groups, but the ERβ mRNA expression in the finasteride group showed a significant difference compared with the control and acupuncture groups. The mechanism of the acupuncture treatment of BPH may be related to the increased transcription level of ERβ mRNA in prostate tissues, the improved distribution of ERα expression in epithelial cells and the aggregation expression of ERs in hyperplastic nodules.

Expression and functional activity of myosin II in hyperplastic prostates of varying volumes

Prostate volume (PV) differs dramatically among benign prostatic hyperplasia (BPH) patients. Estimation of PV is important to guide the most appropriate pharmacologic or interventional treatment approach. However, the underlying pathophysiological mechanisms for the differences in PV remain unknown. We recently found that the myosin II system might participate in the etiology and development of BPH via static and dynamic factors. Our present study aims to explore the expression and functional activities of myosin II isoforms including smooth muscle (SM) myosin II (SMM II) and non-muscle myosin II (NMM II) in hyperplastic prostates with varied PV. Human hyperplastic prostates and the testosterone-induced rat BPH model were employed for this study. Hematoxylin and Eosin (H&E), Masson's trichrome, immunohistochemical staining, in vitro organ bath, RT-polymerase chain reaction (PCR) and Western-blotting were performed. Also, a BPH tissue microarray (TMA) was constructed to determine the correlations between myosin II isoforms with clinical parameters of BPH patients. With the increase of PV, the expression of NMMHC-A, NMMHC-C, SM-A and LC_17b isoforms were increased, and the contractility of prostate smooth muscle was enhanced but force developed more slowly. Consistently, NMMHC-A, NMMHC-C, SM-A and LC_17b were correlated positively with PV. Similar outcomes were also observed in the BPH rat model with different PVs. Alterations in the expression and function of myosin the II system may be involved in the pathophysiological mechanism of PV differences between BPH patients.

Current evidence for the involvement of sex steroid receptors and sex hormones in benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a pathology that affects 50% of men over 50 years of age and 90% of men develop BPH in their eighth decade of life. In 2018, more than 1 billion men will be affected by this disease worldwide. However, the progression of BPH is highly complex and has been debated and studied for approximately four decades. Recent studies indicate that BPH can originate from the alteration of different hormone synthesis pathways, and that it is also linked to the function of hormone receptors. There is a close relationship between the progression of BPH and sexual hormones, such as progesterone, testosterone, dihydrotestosterone, and estrogen. The focus of this study was to characterize the interactions of these hormones and investigate the direct or indirect role of each sex hormone receptor in the progression of BPH. Although several studies have described the effects of these hormones on BPH, no conclusions have been drawn regarding their role in disease progression. Here, we present a literature review on the sexual receptors possibly involved in the progression of BPH.

Inhibitory effects of Pycnogenol®, a pine bark extract, in a rat model of testosterone propionate-induced benign prostatic hyperplasia

Benign prostate hyperplasia (BPH) is a male reproductive disease that has gained increasing importance in recent years. The present study investigated whether Pycnogenol® (PYC), a standardized French maritime pine bark extract, could prevent BPH induced by testosterone propionate (TP) in rats. Male Sprague-Dawley rats were randomly divided into five groups of six rats. One group was used as a normal control rats and the other groups received subcutaneous injections of TP for 4 weeks to induce BPH. In the two treatment groups, PYC (20 or 40 mg/kg) was administered daily for 4 weeks by oral gavage concurrently with the induction of TP. All rats were sacrificed at the scheduled termination time, the prostates were weighed, and histopathologic examinations were conducted. Dihydrotestosterone (DHT) levels in serum and the prostate were measured, and the expression of proliferating cell nuclear antigen (PCNA) and Ki-67 proteins was investigated. BPH-treated animals showed increases in the relative weight of the prostate, higher concentrations of DHT in serum and the prostate, and higher expression of PCNA and Ki-67 in the prostate; in contrast, PYC-treated animals had significant reductions in these factors compared with the BPH animals. These findings indicated that PYC inhibited the development of BPH and that this was closely associated with a reduction in DHT concentration.

Serotonin regulates prostate growth through androgen receptor modulation

Aging and testosterone almost inexorably cause benign prostatic hyperplasia (BPH) in Human males. However, etiology of BPH is largely unknown. Serotonin (5-HT) is produced by neuroendocrine prostatic cells and presents in high concentration in normal prostatic transition zone, but its function in prostate physiology is unknown. Previous evidence demonstrated that neuroendocrine cells and 5-HT are decreased in BPH compared to normal prostate. Here, we show that 5-HT is a strong negative regulator of prostate growth. In vitro, 5-HT inhibits rat prostate branching through down-regulation of androgen receptor (AR). This 5-HT’s inhibitory mechanism is also present in human cells of normal prostate and BPH, namely in cell lines expressing AR when treated with testosterone. In both models, 5-HT’s inhibitory mechanism was replicated by specific agonists of 5-Htr1a and 5-Htr1b. Since peripheral 5-HT production is specifically regulated by tryptophan hydroxylase 1(Tph1), we showed that Tph1 knockout mice present higher prostate mass and up-regulation of AR when compared to wild-type, whereas 5-HT treatment restored the prostate weight and AR levels. As 5-HT is decreased in BPH, we present here evidence that links 5-HT depletion to BPH etiology through modulation of AR. Serotoninergic prostate pathway should be explored as a new therapeutic target for BPH.

Differential expression of androgen, estrogen, and progesterone receptors in benign prostatic hyperplasia

This study aimed to identify the differential expression levels of androgen receptor (AR), estrogen receptors (ERα, ERβ), and progesterone receptor (PGR) between normal prostate and benign prostatic hyperplasia (BPH). The combination of immunohistochemistry, quantitative real-time reverse transcription polymerase chain reaction, and Western blotting assay was used to identify the distribution and differential expression of these receptors at the immunoactive biomarker, transcriptional, and protein levels between 5 normal human prostate tissues and 40 BPH tissues. The results were then validated in a rat model of BPH induced by testosterone propionate and estradiol benzoate. In both human and rat prostate tissues, AR was localized mainly to epithelial and stromal cell nuclei; ERα was distributed mainly to stromal cells, but not exclusively; ERβ was interspersed in the basal layer of epithelium, but sporadically in epithelial and stromal cells; PGR was expressed abundantly in cytoplasm of epithelial and stromal cells. There were decreased expression of ERα and increased expression of PGR, but no difference in the expression of ERβ in the BPH compared to the normal prostate of both human and rat. Increased expression of AR in the BPH compared to the normal prostate of human was observed, however, the expression of AR in the rat prostate tissue was decreased. This study identified the activation of AR and PGR and repression of ERα in BPH, which indicate a promoting role of AR and PGR and an inhibitory role of ERα in the pathogenesis of BPH.