Correlation between morphometric differences and norepinephrine content in benign prostatic hyperplasia

Neonatal exposure to estrogen in the Wistar rat decreases estrogen receptor-beta and induces epithelial proliferation of the prostate in the adult

BACKGROUND/AIMS

The effects of environmental endocrine disruptors on the male reproductive system have received much attention. We attempted to assess the responsible reproduction period vulnerable to decrease in ER beta mRNA by exposing neonate rats to disruptors.

METHODS

Each of 64 male Wistar rats was given an injection of estradiol at a dose of 25 mug or oil on days 1, 3 and 5 after birth. These rats were sacrificed on days 80, 120, 160 and 180 and then subjected to measurements of both serum and tissue testosterone levels. Real-time quantitative polymerase chain reaction (PCR) was used to measure the levels of androgen receptor (AR) and estrogen receptor-beta (ER beta) mRNA of the ventral prostate. Histological compositions were analyzed by quantitative morphometry. Immunohistochemical analysis of proliferating cell nuclear antigen (PCNA) was determined.

RESULTS

The incidence of epithelial components by histomorphometry and the expression of PCNA was significantly higher in the estrogen group in the mature adult (day 160). Levels of AR and ER beta mRNAs in the estrogen group were significantly lower in middle-aged rats (day 180).

CONCLUSION

Estrogen exposure in the neonatal period to Wistar rats decreases the number of ER beta in the mature adult and accelerates cell proliferation.

Current models of human prostate contractility

1. The human prostate is a compact gland contributing to seminal fluid. With increasing age, most humans will develop benign prostatic hyperplasia, a condition of prostatic enlargement and contractility that leads to occlusion of the urethra. Over many years, investigators have used a variety of animal and cell culture models to elucidate some of the contractile and proliferative mechanisms that may be associated with the development of this condition. 2. This review briefly assesses the current state of knowledge of the mechanisms underlying human prostatic contractility and compares it with that of animal and cell culture models. It is not intended as a comprehensive methodological review, nor is it intended to indicate our preferences for either model. Our aim is to correlate findings from animal and cell culture models with the current understanding of human prostate contractility. 3. We hope that the present review will increase awareness of the suitability of the current models in developing our understanding of benign prostatic hyperplasia.

The value of power Doppler imaging to predict the histologic components of benign prostatic hyperplasia

BACKGROUND

The response of symptoms caused by benign prostate hypertrophy (BPH) to alpha blockade is related to the area density of the smooth muscle of the prostate. If this density could be determined by ultrasound examination, ultrasound might be useful in predicting the efficacy of alpha-blocker therapy. In this study, various ultrasonographic parameters obtained by transrectal method (TRUS) were compared with histologically measured components.

METHODS

Before surgery, ultrasonic power Doppler imaging (PDI) of the prostate was performed using a transrectal probe. The volume of total prostate, transition zone (TZ), and the presumed circle area ratio (PCAR) [1,2] were calculated. Pulsatile blood flow was recorded, and the resistive index (RI) was calculated. Based on the serum concentration of total prostate specific antigen (PSA), ratio of PSA to prostate volume (PSAD), and ratio of PSA to TZ (PSAT) were calculated. Prostate tissues were obtained from 26 patients undergoing transurethral resection, suprapubic prostatectomy, or radical cystectomy, and were analyzed by quantitative morphometry. Computer image analysis was used to determine the mean area densities of the smooth muscle (SM), connective tissue (CT), glandular epithelium (GE) and lumen (GL), and vascular lumen (V). Correlations between ultrasonographic parameters and morphometric data were studied.

RESULTS

On microscopic examination, the specimens showed a wide variety, ranging from normal prostate to typical glandular hyperplasia. There was a correlation between RI and the ratios of the four components (SM: r = -0.42 P = 0.034; CT: r = -0.42 P = 0.030; GE: r = 0.42 P = 0.032; GL: r = 0.46 P = 0.018). However, correlations between the other five transrectal parameters and the composition of the prostate were not so clear. This may have been because the blood vessels are compressed within the surgical capsule together with the urethra.

CONCLUSIONS

The present study demonstrates that when RI is calculated by PDI, it can be quite useful for predicting component ratios, thereby making it possible to predict the therapeutic efficacy of alpha-blockers in individual patients.

Videoimaging of prostatic stromal-cell contraction: an in vitro model for studying drug effects

BACKGROUND

Stromal-cell contractility is known to play an important role in the development of bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH). An in vitro model of single-cell contraction was developed to investigate the effect of alpha1-adrenoceptor agonists and antagonists.

METHODS

Human prostatic stromal cells were isolated from prostatectomy and cystoprostatectomy specimens. The cells were cultured in a selective medium supplemented with growth factors and steroid hormones. The culture flasks were coated with a viscous agent to allow cell contraction. Contractions were visualized by means of a cell-culture microscope fitted with a time-lapse video system. For quantitative analysis, the percentage of contracting cells was evaluated.

RESULTS

Nineteen percent of the cells were found to contract without stimulation. Following incubation with doxazosin (10 nM, 100 nM, and 1 mM), there was a slight dose-dependent decrease in the number of spontaneously contracting cells, whereas adrenergic stimulation using 10 microM of phenylephrine led to a significant increase in the percentage of contracting cells (55%). Following incubation with 100 nM of doxazosin, the phenylephrine-induced effect was significantly reduced.

CONCLUSIONS

This simple in vitro model of cell contraction in the prostate provides a useful means of investigating drug effects on prostatic stromal cells.

Functional property, norepinephrine content and morphometric findings in human hyperplastic prostate

BACKGROUND

Although alpha-adrenergic blockers are widely used as a treatment of benign prostatic hyperplasia (BPH), it is not clear whether contractile property of hyperplastic prostate to alpha-adrenergic agonist depends upon an area of density of smooth muscle within the respective BPH tissue.

METHODS

Functional study and quantitative morphometric analysis were performed on human prostatic specimens obtained by transurethral resection from 22 men with symptomatic BPH. Tissue norepinephrine content was also evaluated.

RESULTS

There was a linear correlation between the area of density of smooth muscle and maximum response to phenylephrine (r = 0.457, P = 0.0362). Although the area of density of smooth muscle showed a positive correlation with norepinephrine content (r = 0.437, P = 0.0471), norepinephrine content was not correlated with maximum phenylephrine response.

CONCLUSIONS

Contractile response to alpha-adrenergic agonist was directly influenced by the area of density of the smooth muscle within an individual prostate.

Effect of the alpha-1 adrenoceptor blocker on tissue norepinephrine contents in human benign prostatic hyperplasia

To see the effect of the alpha-adrenergic blocking agent on tissue norepinephrine contents of the prostate, norepinephrine (NE) levels were investigated in patients with symptomatic benign prostatic hyperplasia (BPH). Morphometrical analyses were also performed to detect the differences in tissue composition. Nineteen patients were subdivided into two groups. Patients in Group 1 were given tamsulosin hydrochloride (0.2 mg/day) for at least 4 weeks before transurethral resection of the prostate (TURP), while patients in the control group (Group 2) underwent no previous treatment for BPH before TURP. Tissue NE contents were investigated by high performance liquid chromatography on a chip of the prostate obtained by TURP. These two groups were closely similar in age distribution, prostatic size, results of preoperative symptom scoring and relative proportion of smooth muscle component within the evaluated specimen. In the present series, tissue NE contents in these groups were not statistically different (p = 0.64). Chronic and acute administration of the alpha-1 antagonist did not apparently influence the tissue NE level in patients with BPH.