Insulin-resistance and benign prostatic hyperplasia: The connection

Association between dietary niacin intake and benign prostatic hyperplasia: a population-based results from NHANES 2003-2008

PURPOSE

Benign prostatic hyperplasia (BPH) commonly impacts the quality of life in older men. However, there is lack of research on relationship between dietary niacin intake and the risk of BPH. The purpose of this study was to investigate the relationship between dietary niacin intake and the risk of BPH.

METHODS

Data from the NHANES spanning 2003 to 2008 were utilized. BPH was determined using a self-report questionnaire, while dietary niacin intake was calculated based on the mean of two distinct diet interviews. Multivariate logistic regressions were performed to explore the association, supplemented with restricted cubic splines and subgroup analysis.

RESULTS

A total of 700 males were enrolled, of which 653 men had BPH. After adjusting for all covariates, a high dietary intake of niacin was associated with an increased risk of BPH (OR: 1.04; 95%CI: 1.01-1.07). Furthermore, when the lowest dietary niacin intake is used as the reference, the highest tertile is associated with an increased risk of BPH (OR: 2.34, 95% CI: 1.24-4,42). Restricted cubic splines demonstrated a positive correlation between dietary niacin intake and BPH risk.

CONCLUSIONS

The study results demonstrated a positive association between dietary niacin intake and the risk of BPH in elderly men in the US. These findings underscore the importance of systematic assessment before supplementing micronutrients in elderly men.

Aging and "Age-Related" Diseases - What Is the Relation?

The study explores the intricate relationship between aging and the development of noncommunicable diseases [NCDs], focusing on whether these diseases are inevitable consequences of aging or primarily driven by lifestyle factors. By examining epidemiological data, particularly from hunter-gatherer societies, the study highlights that many NCDs prevalent in modern populations are rare in these societies, suggesting a significant influence of lifestyle choices. It delves into the mechanisms through which poor diet, smoking, and other lifestyle factors contribute to systemic physiological imbalances, characterized by oxidative stress, insulin resistance and hyperinsulinemia, and dysregulation of the sympathetic nervous system, the renin-angiotensin-aldosterone system, and the immune system. The interplay between this pattern and individual factors such as genetic susceptibility, biological variability, epigenetic changes and the microbiome is proposed to play a crucial role in the development of a range of age-related NCDs. Modified biomolecules such as oxysterols and advanced glycation end products also contribute to their development. Specific diseases such as benign prostatic hyperplasia, Parkinson's disease, glaucoma and osteoarthritis are analyzed to illustrate these mechanisms. The study concludes that while aging contributes to the risk of NCDs, lifestyle factors play a crucial role, offering potential avenues for prevention and intervention through healthier living practices. One possible approach could be to try to restore the physiological balance, e.g. through dietary measures [e.g. Mediterranean diet, Okinawan diet or Paleolithic diet] in conjunction with [a combination of] pharmacological interventions and other lifestyle changes.

High-fat diet during sexual maturation induces hyperplastic differentiation of rat prostate and higher expression of AR45 isoform and ERα

We examined the consequences of high-fat diet (HFD) on prostate histophysiology in two periods along sexual maturation of rats and the impact on the gland in adulthood. After weaning, male Wistar rats were fed a balanced diet (4 % fat-C3, C6, C9) or a HFD (20 % fat- HF3, HF6, HF9) for 3, 6 or 9 weeks. Fat deposit weights, blood glucose and levels of serum testosterone and estrogen were measured. Prostate was evaluated for histology, proliferative and apoptotic cell index, and for the expression of androgen (AR), estrogen receptors type α (ERα) and aromatase. HFD did not affect estrogen levels and elevated serum testosterone only in HF9. HFD reduced prostate weight in HF6 and increased it in adulthood (HF9) but relative prostate weight was unchanged among groups. Cell proliferation, height and density were higher in epithelium of all HFD-groups, compared to controls, featuring the epithelial hyperplasia. Epithelial apoptosis was lower in HF9. HF3 and HF9 exhibited higher expressions of ERα, indicating that HFD triggers a new activation of ERα expression in the acinar epithelium. The content of prostatic aromatase was also elevated in HF9. Increased numbers of AR-positive cells were observed in all HFD groups, and western blotting analysis showed an increase in the truncated form of 45 kDa (AR45) and a reduction in the expression of 110 kDa-AR for HF3 and HF9. In conclusion, excessive dietary fats during sexual maturation of rats led to developmental programming of the prostate, inducing a hyperplastic status with perturbations in AR isoforms expression and reactivation of ERα in adulthood, whose implications for posterior prostatic health could be detrimental.

Erectile dysfunction and diabetes: A melting pot of circumstances and treatments

Diabetes mellitus (DM), a chronic metabolic disease characterised by elevated levels of blood glucose, is among the most common chronic diseases. The incidence and prevalence of DM have been increasing over the years. The complications of DM represent a serious health problem. The long-term complications include macroangiopathy, microangiopathy and neuropathy as well as sexual dysfunction (SD) in both men and women. Erectile dysfunction (ED) has been considered the most important SD in men with DM. The prevalence of ED is approximately 3.5-fold higher in men with DM than in those without DM. Common risk factors for the development of DM and its complications include sedentary lifestyle, overweight/obesity and increased caloric consumption. Although lifestyle changes may help improve sexual function, specific treatments are often needed. This study aims to review the definition and prevalence of ED in DM, the impact of DM complications and DM treatment on ED and, finally, the current and emerging therapies for ED in patients with DM.

Aerobic exercises ameliorate benign prostatic hyperplasia via IGF-1/IGF-1R/ERK/AKT signalling pathway in prostate tissue of high-fat-diet-fed mice with insulin resistance

This study investigated the changes in the prostate of high-fat diet (HFD)-fed mice with insulin resistance (IR) and explored the possible mechanisms of the effects of 8-week treadmill aerobic exercise on prostatic hyperplasia in insulin-resistant mice through the IGF-1/IGF-1R/ERK/AKT signalling pathway. Results showed IR in mice caused an increase in prostate-related indicators, such as prostate weight (PW) and prostate volume (PV), resulting in prostatic hyperplasia. The area of the glandular lumen and the height of the glandular epithelium in mice with IR were increased, which indicating that it caused prostatic hyperplasia through epithelial cell proliferation. In addition, the level of IGF-1 in serum and the expression of IGF-1R, ERK and AKT in prostate tissue of high-fat diet induced IR mice increased significantly, which might be related to the proliferation of prostate cells. However, aerobic exercise lowered the blood sugar, serum insulin and IGF-1; inhibited the combination of IGF-1 and IGF-1R on the prostate; down-regulated the expression of IGF-1R, ERK and AKT proteins; and then suppressed the expression of downstream proliferation genes, thereby achieving the purpose of inhibiting the proliferation of prostate epithelial cells. In conclusion. Eight weeks of aerobic exercise might improve the prostate hyperplasia in mice via down-regulating the serum insulin and IGF-1, thus enhancing the insulin sensitivity of insulin-resistant mice and regulating the IGF-1/IGF-1R/ERK/AKT signalling pathway by inhibiting the expression of IGF-1R, ERK and AKT in the prostate tissue. However, this exercise had no significant effect on PV, PW and prostate index (PI).

The association between metabolic syndrome and benign prostatic hyperplasia: a systematic review and meta-analysis

OBJECTIVE

We performed this meta-analysis to assess the association between metabolic syndrome (MetS) and benign prostatic hyperplasia (BPH).

METHOD

We conducted extensive searches on the PubMed, Science and Cochrane Library to identify all articles. Outcomes including annual prostate growth rate, prostate volume (PV), International Prostate Symptom Score (IPSS), IPSS sub-scores (voiding and storage), prostate- specific antigen (PSA), maximum urine flow rate (Qmax), post-void residual urine volume (PVR) and quality of life (QoL) were assessed.

RESULTS

21 studies with 15,317 patients were included. Patients with MetS had higher annual prostate growth rate [weighted mean difference (WMD) = 0.79; p < .001], larger PV (WMD = 2.62; p < .001), lower Qmax (WMD = -0.48; p = .001) and more PVR (WMD = 8.28; p < .001). However, no significant differences were found between two groups in IPSS (WMD = 0.20; p = .37), IPSS-voiding (WMD = -0.05; p = .78), IPSS-storage (WMD = -0.22; p = .26), PSA (WMD = 0.04; p = .43), and QoL (WMD = -0.01; p = .70).

CONCLUSIONS

The study suggested that MetS may be one of the risk factors for the clinical progress of BPH. However, further study is warranted to support these results.

Insulin exacerbated high glucose-induced epithelial-mesenchymal transition in prostatic epithelial cells BPH-1 and prostate cancer cells PC-3 via MEK/ERK signaling pathway

As two most common progressive diseases of aging, type 2 diabetes mellitus (T2DM) and benign prostatic hyperplasia (BPH) were all characterized by endocrine and metabolic disorders. Here, our clinical study showed that there were significant differences in fasting blood glucose (FBG), fasting insulin (FINS), insulin resistance index (HOMA-IR) and prostate volume (PV) between simple BPH patients and BPH complicated with T2DM patients. Further analysis showed that HOMA-IR was positively correlated with PV in BPH complicated with T2DM patients. The in vitro experiment results showed that high glucose (HG) promoted EMT process in a glucose-dependent manner in human prostate hyperplasia cells (BPH-1) and prostate cancer cells (PC-3), and this pathological process was exacerbated by co-culture with insulin. Mechanistically, insulin-induced exacerbation of EMT was depended on the activation of MEK/ERK signaling pathway, and we suggested that insulin and its analogs should be used very carefully for the clinical antihyperglycemic treatment of BPH complicated with T2DM patients.

Toll-like receptor 9 regulates metabolic profile and contributes to obesity-induced benign prostatic hyperplasia in mice

BACKGROUND

Benign prostatic hyperplasia (BPH) is associated with obesity and prostatic inflammation. The present study investigated the participation of toll-like receptor 9 (TLR9) in obesity-induced BPH, focusing on metabolic impairments, damage-associated molecular patterns (DAMP) levels and prostatic oxidative stress generation.

METHODS

C57BL/6 (WT) and TLR9 mutant male mice were fed with regular or high-fat diet for 12 weeks. Metabolic profile, functional protocols, reactive-oxygen species (ROS) generation, prostatic histological analysis and DAMP levels were analyzed. Western blotting for prostatic TLR9 signaling pathway was also performed.

RESULTS

BPH in WT obese animals was characterized by increased prostate weight, smooth muscle hypercontractility and prostatic epithelial hyperplasia. Higher epididymal fat weight and prostatic ROS generation along with increased fasting glucose, triglyceride and circulating DAMP levels were also observed in WT obese group. Conversely, TLR9 mutant obese animals exhibited lower epididymal fat weight, fasting glucose and triglyceride levels associated with reduced prostate hypercontractility, prostatic ROS and circulating DAMP levels. However, TLR9 mutant obese mice were not protected from obesity-associated prostatic overgrowth and epithelial hyperplasia. Interestingly, TLR9 mutant lean mice exhibited augmented fasting glucose and prostatic ROS levels compared with WT lean mice. Despite increased prostatic expression of TLR9 in WT obese mice, no differences were seen in MyD88 expression between groups.

CONCLUSION

Improved obesity-induced BPH-related prostatic smooth muscle hypercontractility in TLR9 obese mice may be associated with amelioration in the metabolic profile, ROS and DAMP generation. Therefore, TLR9 could be a valuable target to improve obesity-associated metabolic disorders and prostate smooth muscle hypercontractility in BPH.

Diet-Induced Hyperinsulinemia as a Key Factor in the Etiology of Both Benign Prostatic Hyperplasia and Essential Hypertension?

Benign prostatic hyperplasia and hypertension are common age-related comorbidities. Although the etiology of benign prostatic hyperplasia (BPH) is still largely unresolved and poorly understood, a significant age-independent association was found between BPH and hypertension, indicating a common pathophysiological factor for both diseases. It has previously been suggested that the development of essential hypertension may be related to diet-induced hyperinsulinemia. This study follows the question, whether BPH may develop due to the same mechanism, thereby explaining the well-known comorbidity of these 2 disorders. The scientific evidence presented shows that BPH and hypertension share the same pathophysiological changes, with hyperinsulinemia as the driving force. It further shows that significant dietary changes during human history cause disruption of a finely tuned metabolic balance that has evolved over millions of years of evolution: high-insulinemic food, typical of current “Western” diets, has the potential to cause hyperinsulinemia and insulin resistance, as well as an abnormally increased activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, alterations that play a pivotal role in the pathogenesis of BPH and hypertension.

In vitro biological assessment of Homalium zeylanicum and isolation of lucidenic acid A triterpenoid

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Current investigation supports antioxidant, anti-diabetic activities of H. zeylanicum.

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Current investigation also supports anti-inflammatory activity of H. zeylanicum.

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The research successfully isolated and analysed structure of lucidenic acid A.

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Lucidenic acid A reported first time in the bark of H. zeylanicum.

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Lucidenic acid A produces a significant anti-inflammatory activity.

Homalium zeylanicum (Gardner) Benth. (Flacourtiaceae) is a medicinal plant useful in controlling rheumatism, inflammation and diabetes. The objective of this work evaluates in vitro antioxidant, antidiabetic, and antiinflammatory properties of hydroalcohol extract of bark of H. zeylanicum (HAHZ). It also describes isolation and structure determination of lucidenic acid A, which is the first report in this plant. In order to explain the role of antioxidant principles, DPPH, nitric oxide, hydroxyl, superoxide and metal chelating assays were performed. Antidiabetic and anti-inflammatory activities were investigated by quantifying α-amylase, α-glucosidase and protein denaturation inhibitory activities of HAHZ. Biochemical estimations were performed. The chemical structure of the triterpenoid was elucidated using ¹H, ¹³C NMR and high resolution-MS. IC₅₀ of DPPH, nitric oxide, hydroxyl, superoxide and metal chelating activities were of 36.23 ± 0.27, 40.11 ± 0.32, 35.23 ± 0.57, 43.34 ± 0.22 and 11.54 ± 0.08 μg/mL, respectively. IC₅₀ of α-amylase and α-glucosidase activities were 29.12 ± 0.54, and 18.55 ± 0.15 μg/mL. Total phenolic and total flavonoid contents were recorded at 233.65 mg/g GAE and 172.7 mg/g QE. Regarding kinetic behaviour, HAHZ showed competitive inhibition on α-glucosidase and mixed competitive inhibition on α-amylase. Lucidenic acid A was confirmed by spectroscopic studies. Anti-inflammatory activity of lucidenic acid A was determined by using protein denaturation assay with IC₅₀ 13 μg/mL but HAHZ showed 30.34 ± 0.13 μg/mL. Phenols and flavonoids could be attributed to inhibition of intestinal carbohydrases for anti-diabetic activities whereas triterpenoids could be responsible for anti-inflammatory activity of H. zeylanicum.

Parental High-Fat Diet Promotes Inflammatory and Senescence-Related Changes in Prostate

Background. Obesity and dietary habits are associated with increased incidences of aging-related prostatic diseases. The present study was aimed to investigate transgenerational effects of chronic high-fat diet (HFD) feeding on inflammation and senescence-related changes in prostate. Methods. Sprague-Dawley rats were kept on either normal or HFD one. Senescence-associated β-galactosidase (SA β-gal) activity, inflammation, and cellular proliferation were determined in the prostate. Results. Increased SA β-gal activity, expression of p53, and cell proliferation marker PCNA were observed in ventral prostate of HFD-fed rats. Immunostaining for p53 and PCNA revealed that the p53 immunopositive cells were primarily in stroma while PCNA immunopositive cells were epithelial cells. An increase in expression of cycloxygenase-2 (COX-2) and phosphorylation of nuclear factor-kappa B (NF-kB) was observed in prostate of weaning pups HFD-fed parents. However, in adult pups, irrespective of dietary habit, a significant increase in the expression of COX-2, PCNA, phosphorylation of NF-kB, infiltration of inflammatory cells, and SA β-gal activity was observed. Conclusions. Present investigation reports that HFD feeding promotes accumulation of p53 expressing cells, proliferation of epithelial cells, and senescence-related changes in prostate. Further, parental HFD-feeding upholds inflammatory, proliferative, and senescence-related changes in prostate of pups.

Oxytocin: its role in benign prostatic hyperplasia via the ERK pathway

The aim of the present study was to evaluate oxytocin and benign prostatic hyperplasia (BPH), and study the cell signalling mechanism. Investigation was performed in patients about the correlation between oxytocin level and BPH. Mice were injected with oxytocin or oxytocin antagonist for 2 weeks and the prostate morphology was studied after their sacrifice. Furthermore, in vitro experiments were performed to evaluate the oxytocin effect through the MEK/ERK/RSK pathway. Oxytocin was significantly elevated in the serum and prostate tissue of patients with BPH, and a positive correlation with prostate volume indicated. In the animal experiments, prostate enlargement was observed in the oxytocin-treated group, whereas oxytocin antagonist reduced prostate hyperplasia. The in vitro study confirmed this result and also revealed activation of the MEK/ERK/RSK pathway. Oxytocin is highly expressed in the serum and prostate tissue of patients with BPH. In addition, oxytocin aggravates BPH and the oxytocin-induced proliferative effect on prostatic cells is mediated through the MEK/ERK/RSK pathway, at least partly. Thus, the hypothalamic regulation may be involved in development of BPH, which may open a new door to more medications for BPH in the future.

Obesity-initiated metabolic syndrome promotes urinary voiding dysfunction in a mouse model

OBJECTIVE

Accumulating evidences suggests that obesity and metabolic syndrome (MetS) contribute towards lower urinary tract symptoms (LUTS) through alterations in the phenotype of bladder and prostate gland. Clinical studies indicate a link between MetS and LUTS. Nevertheless, there is lack of suitable animal model(s) which could illustrate an association linking obesity to LUTS. We examined the lower urinary tract function in an obesity-initiated MetS mouse model.

METHODS

Male C57BL/6N wild-type and obese B6.V-Lepob/J maintained on regular diet for 28 weeks were subjected to the assessment of body weight (BW), body length (BL), waist circumference (WC), body mass index (BMI), blood glucose (BG), plasma insulin (INS), plasma leptin (LEP), total cholesterol (CHO), free fatty acid (FFA), and measurement of urinary functions. Whole animal peritoneal and subcutaneous adipose tissue measurements as well as prostate and bladder volumes were analyzed by MRI followed by histological evaluation. These parameters were used to draw correlations between MetS and LUTS.

RESULTS

Obesity parameters such as BW, WC, and BMI were significantly higher in B6.V-Lepob/J mice compared to C57BL/6N mice (P < 0.01). Higher levels of total CHO and FFA were noted in B6.V-Lepob/J mice than C57BL/6N mice (P < 0.05). These results were concurrent with frequency, lower average urine volume and other urinary voiding dysfunctions in B6.V-Lepob/J mice. MRI assessments demonstrate marked increase in body fat and prostate volume in these mice. Compared to C57BL/6N mice, histological analysis of the prostate from B6.V-Lepob/J mice showed increased proliferation, gland crowding, and infiltration of immune cells in the stroma; whereas the bladder urothelium was slightly thicker and appears more proliferative in these mice. The regression and correlation analysis indicate that peritoneal fat (R = 0.853; P < 0.02), CHO (R = 0.729; P < 0.001), BG (R = 0.712; P < 0.001) and prostate volume (R = 0.706; P < 0.023) strongly correlate with LUTS whereas BMI, WC, INS, and FFA moderately correlate with the prevalence of bladder dysfunction.

CONCLUSION

Our results suggest that LUTS may be attributable in part to obesity and MetS. Validation of an in vivo model may lead to understand the underlying pathophysiological mechanisms of obesity-related LUTS in humans. Prostate 76:964-976, 2016. © 2016 Wiley Periodicals, Inc.

Protective potential of epigallocatechin-3-gallate against benign prostatic hyperplasia in metabolic syndrome rats

Epigallocatechin-3-gallate (EGCG) is a major catechin in green tea with functions of antioxidant, anti-proliferative, anti-inflammatory and attenuating metabolic syndrome. In this study, rat model of benign prostatic hyperplasia (BPH) accompanied with metabolic syndrome was induced by fed on high-fat diet for 12 weeks combined with testosterone injection (10mg/kg/d) from 9th to 12th weeks. EGCG was orally given from 9th to 12th weeks. Finally, the levels of glucose, total cholesterol, triglyceride, prostate weight, insulin-like growth factors (IGFs), inflammatory cytokines, antioxidant enzymes, and prostatic expression of IGF binding protein-3 (IGFBP-3) and peroxisome proliferator activated receptors (PPARs) were evaluated. It was found that EGCG significantly decreased the levels of glucose, total cholesterol, triglyceride, IGFs, and inflammatory cytokines, normalized the activities of antioxidant enzymes, as well as increased the prostatic expression of IGFBP-3 and PPARs. These results indicated that EGCG was able to exert anti-BPH activities in metabolic syndrome rats.

Association between benign prostatic hyperplasia, body mass index, and metabolic syndrome in Chinese men

Previous studies have showed that men suffering from diabetes mellitus, metabolic syndrome (MetS) and obesity have a higher risk of benign prostatic hyperplasia (BPH). The present study aimed to examine the association between BPH, obesity, and features of MetS among men of the Hunan area of China. For this cross-sectional study, 904 males (aged 50–59 years) were included. MetS parameters, International Prostate Symptom Score (IPSS), prostate-specific antigen (PSA) levels, total prostate volume (TPV), postvoid residual volume (PVR) and maximum urine flow rate (Qmax) were measured. Results showed that MetS was associated with TPV (P = 0.048), PVR (P = 0.004) and IPSS (P = 0.011), but not with other indicators of BPH progression such as PSA levels or Qmax. MetS was associated with the voiding symptoms score (P < 0.05), but not with the storage symptom score. In addition, body mass index and fasting blood glucose positively correlated with TPV (r = 0.416, P < 0.001; and r = 0.310, P= 0.011, respectively). In conclusion, results suggest that MetS is associated with higher prostatic volume, prostate symptom score and voiding symptoms, but not with other features of prostatic hyperplasia such as PSA levels or Qmax. Changes in lifestyle factors, including physical activity and prevention of MetS, might be useful to prevent BPH and its progression, but further studies are needed.

Metabolic syndrome does not impair the response to alfuzosin treatment in men with lower urinary tract symptoms: a double-blind, randomized, placebo-controlled study

OBJECTIVE

This study is a placebo-controlled comparison of the response to alfuzosin treatment for lower urinary tract symptoms (LUTS) in patients with and without metabolic syndrome (MetS).

MATERIAL AND METHODS

A total of 80 men with LUTS were included in the study. Patients had a maximum flow rate of <15 mL/sec, prostate volume of >20 mL, and International Prostate Symptom Score (IPSS) of >8. All eligible men (n=68) for evaluation were initially divided into two groups as MetS (n=34) and non-MetS (n=34) groups. Patients were further randomized to receive alfuzosin (10 mg/day) or placebo (n=17/group; a total of four groups). The outcome was measured at 12(th) week according to the changes from baseline in IPSS, quality of life (QoL) scores, maximum flow rate (Qmax), and postmictional residue.

RESULTS

Alfuzosin significantly improved LUTS in men with and without MetS compared with patients receiving placebo (p<0.05). Mean IPSS scores in treatment groups decreased significantly, whereas patients receiving placebo had no statistically significant difference (p>0.05). Similarly, alfuzosin treatment resulted in a significant increase in Qmax in patients with LUTS/benign prostatic enlargement when compared with patients in placebo group (p<0.05). Mean QoL scores measured by IPSS-QoL and QoL questionnaires also improved significantly in patients receiving alfuzosin for 3 months regardless of the presence of MetS (p<0.05).

CONCLUSION

Our results revealed that the presence of MetS in patients with LUTS did not impair the response to alfuzosin treatment.

Are blood vessels a target to treat lower urinary tract dysfunction?

Bladder dysfunction is common in the general population (Stewart et al. 2010) and even more so among patients seeing a physician for any reason (Goepel et al. 2002). It often manifests as lower urinary tract symptoms (LUTS), a term originally coined to describe voiding and storage symptoms in men with benign prostatic hyperplasia (BPH) but now more universally used to describe any type of voiding and storage symptoms in both sexes. Studies into possible causes of urinary bladder dysfunction have long focused on detrusor smooth muscle cells (Turner and Brading 1999). More recently, it became clear that several other types of cells and organs contribute to regulating detrusor smooth muscle function. These include the urothelium (Andersson and McCloskey 2014; Michel 2015), afferent nerves (Michel and Igawa 2015; Yoshimura et al. 2014b), and the central and autonomic nervous systems (Fowler and Griffiths 2010; Yoshimura et al. 2014a). Alterations in any of these may at least partly be responsible for detrusor dysfunction and, accordingly, be potential targets for the treatment of bladder dysfunction. As highlighted by an article in this issue of Naunyn-Schmiedeberg's Archives of Pharmacology (Bayrak et al. 2015), there is an additional suspect, the bladder vasculature. This article will discuss the currently available experimental and clinical evidence for a role of the vasculature in causing bladder dysfunction, and how existing and emerging treatments may modulate bladder function by acting on blood vessels. Due to a similarity in concept, data on prostate perfusion will also be discussed to some extent.

Diets rich in saturated and polyunsaturated fatty acids induce morphological alterations in the rat ventral prostate

AIM

To evaluate the influence of dietary lipid quality on the body mass, carbohydrate metabolism and morphology of the rat ventral prostate.

MATERIALS AND METHODS

Wistar rats were divided into four groups: SC (standard chow), HF-S (high-fat diet rich in saturated fatty acids), HF-P (high-fat diet rich in polyunsaturated fatty acids) and HF-SP (high-fat diet rich in saturated and polyunsaturated fatty acids). We analyzed body mass, fat mass deposits, plasma blood, insulin resistance and the ventral prostate structure.

RESULTS

Groups that received high-fat diets were heavier and presented larger fat deposits than SC group. The HF-S and HF-SP groups had higher glucose, insulin and total cholesterol serum levels and insulin resistance compared with the SC. The acinar area, epithelium height and area density of the lumen were higher in the HF-SP than in the other groups. The epithelium area density and epithelial cell proliferation were greater in the HF-P and HF-SP than in the SC group. All of the groups that received high-fat diets had greater area density of the stroma, area density of smooth muscle cells and stromal cell proliferation compared with the SC group.

CONCLUSION

Diets rich in saturated and/or polyunsaturated fatty acids induced overweight. Independently of insulin resistance, polyunsaturated fatty acids increased prostate stromal and epithelial cell proliferation. Saturated fatty acids influenced only stromal cellular proliferation. These structural and morphometric alterations may be considered risk factors for the development of adverse remodeling process in the rat ventral prostate.

Increased risk of benign prostate hyperplasia in sleep apnea patients: a nationwide population-based study

Background

Sleep apnea (SA) is a common sleep disorder characterized by chronic intermittent hypoxia (IH). Chronic IH induces systemic inflammatory processes, which can cause tissue damage and contribute to prostatic enlargement. The purpose of this study was to evaluate the association between benign prostate hyperplasia (BPH) and SA in a Taiwanese population.

Methods

The study population was identified from Taiwan’s National Health Insurance Research Database (NHIRD) and contained 202 SA patients and 1010 control patients. The study cohort consisted of men aged ≥30 years who were newly diagnosed with SA between January 1997 and December 2005. Each patient was monitored for 5 years from the index date for the development of BPH. A Cox regression analysis was used to calculate the hazard ratios (HRs) for BPH in the SA and control patients.

Results

During the 5-year follow-up, 18 SA patients (8.9%) and 32 non-SA control patients (3.2%) developed BPH. The adjusted HR for BPH was 2.35-fold higher in the patients with SA than in the control patients (95% confidence interval (CI) 1.28–4.29, P<.01). We further divided the SA patients into 4 age groups. After adjusting for potential confounding factors, the highest adjusted HR for BPH in the SA patients compared with the control patients was 5.59 (95% CI = 2.19–14.31, P<.001) in the patients aged between 51 and 65 years.

Conclusion

Our study results indicate that patients with SA are associated with increased longitudinal risk of BPH development, and that the effects of SA on BPH development are age-dependent.

Metabolic syndrome and prostate abnormalities in male subjects of infertile couples

No previous study has evaluated systematically the relationship between metabolic syndrome (MetS) and prostate-related symptoms and signs in young infertile men. We studied 171 (36.5 ± 8.3-years-old) males of infertile couples. MetS was defined based on the National Cholesterol Education Program Third Adult Treatment Panel. All men underwent hormonal (including total testosterone (TT) and insulin), seminal (including interleukin-8 (IL-8), seminal plasma IL-8 (sIL-8)), scrotal and transrectal ultrasound evaluations. Because we have previously assessed correlations between MetS and scrotal parameters in a larger cohort of infertile men, here, we focused on transrectal features. Prostate-related symptoms were assessed using the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) and the International Prostate Symptom Score (IPSS). Twenty-two subjects fulfilled MetS criteria. In an age-adjusted logistic ordinal model, insulin levels increased as a function of MetS components (Wald = 29.5, P < 0.0001) and showed an inverse correlation with TT (adjusted r = -0.359, P< 0.0001). No association between MetS and NIH-CPSI or IPSS scores was observed. In an age-, TT-, insulin-adjusted logistic ordinal model, an increase in number of MetS components correlated negatively with normal sperm morphology (Wald = 5.59, P< 0.02) and positively with sIL-8 levels (Wald = 4.32, P < 0.05), which is a marker of prostate inflammation, with prostate total and transitional zone volume assessed using ultrasound (Wald = 17.6 and 12.5, both P < 0.0001), with arterial peak systolic velocity (Wald = 9.57, P = 0.002), with texture nonhomogeneity (hazard ratio (HR) = 1.87 (1.05-3.33), P < 0.05), with calcification size (Wald = 3.11, P< 0.05), but not with parameters of seminal vesicle size or function. In conclusion, in males of infertile couples, MetS is positively associated with prostate enlargement, biochemical (sIL8) and ultrasound-derived signs of prostate inflammation but not with prostate-related symptoms, which suggests that MetS is a trigger for a subclinical, early-onset form of benign prostatic hyperplasia.

Benign prostatic hyperplasia: a new metabolic disease of the aging male and its correlation with sexual dysfunctions

Metabolic syndrome (MetS) is a well-recognized cluster of cardiovascular (CV) risk factors including obesity, hypertension, dyslipidemia, and hyperglycaemia, closely associated with an increased risk of forthcoming cardiovascular disease and type 2 diabetes mellitus. Emerging evidence indicates that benign prostate hyperplasia (BPH) and its related lower urinary tract symptoms (LUTS) represent other clinical conditions frequently observed in subjects with MetS. Several modifiable factors involved in MetS determinism, such as inadequate diet, lack of physical exercise, and smoking and drinking behaviours are emerging as main contributors to the development of BPH. The pathogenetic mechanisms underlying the connection between MetS and BPH have not been completely clarified. MetS and its components, hypogonadism, and prostate inflammation probably play an important role in inducing BPH/LUTS. Although historically considered as a "normal" consequence of the aging process, BPH/LUTS should now be faced proactively, as a preventable disorder of the elderly. Type of diet and level of physical activity are now considered important factors affecting prostate health in the aging male. However, whether physical exercise, weight loss, and modifications of dietary habit can really alter the natural history of BPH/LUTS remains to be determined. Further research is advisable to better clarify these points.

Prostate volume and growth during testosterone replacement therapy is related to visceral obesity in Klinefelter syndrome

OBJECTIVE

Klinefelter syndrome (KS) is a chromosomal alteration characterized by increased risk of metabolic syndrome, mainly caused by visceral obesity. In the last years, obesity has been studied as a potential risk factor for prostate disease and recently a link has been demonstrated between visceral adiposity with prostate volume. The aim of this study was to analyze the relationship between obesity and prostate volume and growth during testosterone therapy in KS subjects.

DESIGN AND METHODS

We evaluated reproductive hormones, metabolic parameters, anthropometric measures, PSA, and prostate volume in 121 naïve non-mosaic KS patients and 60 age-matched healthy male controls. Fifty-six KS hypogonadic subjects were treated with testosterone-gel 2% and reevaluated after 18 months of treatment.

RESULTS

Prostate volume in KS was positively related to waist circumference (WC). The KS group with WC ≥94 cm had significantly higher prostate volume, BMI, insulin plasma levels, homeostasis model assessment index, total cholesterol, triglycerides, and glycemia with respect to the KS group with WC <94 cm. After testosterone replacement therapy, only hypogonadic KS men with WC ≥94 cm had a statistically significant increase in prostate volume. Furthermore, in untreated KS subjects, prostate volume showed a statistically significant increase after 18 months of follow-up only in subjects with WC ≥94 cm.

CONCLUSIONS

This study showed that visceral obesity, insulin resistance, and lipid and glucose metabolism alterations are associated with prostate volume and growth during testosterone replacement therapy in KS, independently from androgen or estrogen levels. These latter findings might provide the basis for a better management and follow-up of KS subjects.

Decline of seminal parameters in middle-aged males is associated with lower urinary tract symptoms, prostate enlargement and bladder outlet obstruction

PURPOSE

We aimed to compare the associations between semen quality, associated reproductive indicators and the main prostate-related parameters in middle-aged men.

MATERIALS AND METHODS

This is a prospective study on 422 middle-aged men who underwent the screening for prostate health. Their reproductive function, semen quality and prostate-related pathologies were investigated.

RESULTS

Significant associations between semen quality and prostate-related parameters could be seen. Total sperm count and sperm density decreased along with the increase of the I-PSS score and total prostate volume. Also, the related lower urinary tract characteristics showed a negative correlation with main semen parameters for all investigated subjects. No significant differences in age, testicular size, and hormonal parameters were found between the subjects with or without lower urinary tract symptoms and prostate enlargement.

CONCLUSIONS

Our study suggests that altered seminal parameters in middle-aged men are associated with LUTS, prostate enlargement and/or bladder outlet obstruction. Although the assessments of prostate and lower urinary tract symptoms may not replace the semen parameters evaluating the male reproductive status, there is a need for further and more detailed investigations about the pathways behind these associations as well as possible related conditions.

PDE5 inhibitors blunt inflammation in human BPH: a potential mechanism of action for PDE5 inhibitors in LUTS

BACKGROUND

Metabolic syndrome (MetS) and benign prostate hyperplasia (BPH)/low urinary tract symptoms (LUTS) are often comorbid. Chronic inflammation is one of the putative links between these diseases. Phosphodiesterase type 5 inhibitors (PDE5i) are recognized as an effective treatment of BPH-related LUTS. One proposed mechanism of action of PDE5 is the inhibition of intraprostatic inflammation. In this study we investigate whether PDE5i could blunt inflammation in the human prostate.

METHODS

Evaluation of the effect of tadalafil and vardenafil on secretion of interleukin 8 (IL-8, a surrogate marker of prostate inflammation) by human myofibroblast prostatic cells (hBPH) exposed to different inflammatory stimuli. We preliminary evaluate histological features of prostatic inflammatory infiltrates in BPH patients enrolled in a randomized, double bind, placebo controlled study aimed at investigating the efficacy of vardenafil (10 mg/day, for 12 weeks) on BPH/LUTS.

RESULTS

In vitro treatment with tadalafil or vardenafil on hBPH reduced IL-8 secretion induced by either TNFα or metabolic factors, including oxidized low-density lipoprotein, oxLDL, to the same extent as a PDE5-insensitive PKG agonist Sp-8-Br-PET-cGMP. These effects were reverted by the PKG inhibitor KT5823, suggesting a cGMP/PKG-dependency. Treatment with tadalafil or vardenafil significantly suppressed oxLDL receptor (LOX-1) expression. Histological evaluation of anti-CD45 staining (CD45 score) in prostatectomy specimens of BPH patients showed a positive association with MetS severity. Reduced HDL-cholesterol and elevated triglycerides were the only MetS factors significantly associated with CD45 score. In the MetS cohort there was a significant lower CD45 score in the vardenafil-arm versus the placebo-one.

Fat boosts, while androgen receptor activation counteracts, BPH-associated prostate inflammation

BACKGROUND

Metabolic syndrome (MetS) and benign prostate hyperplasia (BPH) are often comorbid. Chronic inflammation, a determinant pathogenic factor for BPH, is a putative link between the two conditions.

METHODS

In a multi-center cohort of BPH patients (n = 244) who underwent prostatectomy, we evaluated whether MetS is associated with prostatic inflammation in BPH specimens. In addition, we investigated the in vitro inflammatory effects of metabolic insults on human prostatic myofibroblastic cells (hBPH).

RESULTS

Inflammatory infiltrates score (IS) in prostatectomy specimens showed a step-wise association with the number of MetS factors present (P = 0.001). After adjusting for age, reduced HDL cholesterol, and elevated triglycerides were the only factors significantly associated with IS. Increased IS was also significantly associated with hypogonadism. In an age- and testosterone (T)-adjusted model, dyslipidemia was still associated with IS. To investigate whether metabolic factors could directly trigger prostate inflammation, we performed preliminary studies in myofibroblastic hBPH. Among the different factors, oxidized low-density lipoprotein (oxLDL) showed the highest secretion of IL-8 (>10-fold)-a surrogate marker of prostate inflammation--as well as IL-6, and bFGF. Co-treatment with DHT significantly inhibited oxLDL-induced secretion of IL-8, whilst an AR-antagonist, bicalutamide, reversed DHT effects. DHT suppresses oxLDL receptor (LOX-1) expression.

CONCLUSIONS

Our data suggest that fats and insulin could have a detrimental effect on prostate health, boosting inflammation, a key pathogenic factor in BPH. Conversely, beneficial effects of DHT in counteracting lipid- and insulin-induced prostatic alterations, suggest that T-via its conversion into DHT-may have unexpected beneficial effects on prostate health.

High fat-induced obesity associated with insulin-resistance increases FGF-2 content and causes stromal hyperplasia in rat ventral prostate

Obesity affects sex hormone secretion, which can negatively influence prostatic structure, homeostasis, and disease. This investigation aimed to evaluate the repercussions of obesity induced by a high-fat diet on the rat prostate, with or without treatment with the aromatase inhibitor, Letrozole. Adult Wistar rats were fed a high-fat diet (20% saturated fat, O) for 15 weeks to induce obesity or received a balanced diet (4% fat, C). Then, a group of C and O rats were daily treated with Letrozole (1 mg/kg b.w. per day) for 2 weeks (CL and OL, respectively). Subsequently, ventral prostate was processed for analysis by transmission electron microscopy, immunohistochemistry, and Western blotting. Obesity decreased 70% of the testosterone plasma level. The prostate showed epithelial atrophy and dilated acini in the intermediate portion and epithelial wrinkling in the distal tips. The relative frequency of smooth muscle α-actin in the O group increased by 67%. Ultrastructurally, epithelial cells in obese animals presented altered secretory organelles, lipid droplets, and thicker subjacent fibromuscular layer. Letrozole treatment caused a partial restoration of the prostatic changes caused by obesity. Obesity increased the prostatic content of fibroblast growth factor-2 (FGF-2) by 150%, and Letrozole treatment increased this protein even more in the control and obese groups. This investigation shows that obesity provokes structural and ultrastructural changes in the epithelium of rat prostate; these changes might affect gland homeostasis and physiology. The epithelial and smooth muscle cell hyperplasia and increased FGF-2 expression observed in this experimental model of obesity/insulin-resistance might explain the high frequency of benign prostatic hyperplasia in insulin-resistant men.

Fraction of macroporous resin from Smilax china L. inhibits testosterone propionate-induced prostatic hyperplasia in castrated rats

The present study was conducted to evaluate the effect of a fraction of macroporous resin (FMR), a bioactive component of Smilax china L., on benign prostatic hyperplasia (BPH) in castrated rats induced by testosterone propionate. Rats were randomly divided into five groups: the negative control group (sham-operated), the model group, two FMR-treated groups (at doses of 300 mg/kg and 600 mg/kg of body weight), and the positive control group (treated with finasteride at the dose of 3 mg/kg). Drugs were administered once a day for three consecutive weeks by gastric gavage. Prostates were weighed, testosterone and dihydrotestosterone (DHT) levels in serum were determined, and histopathological examinations were carried out. FMR treatment inhibited prostatic hyperplasia, reducing the DHT level in serum and improving the prostate gland morphology compared with the model group. The overall results of this study suggest that FMR is effective at inhibiting experimentally induced prostate enlargement, and it presents a valuable resource for the treatment of human BPH.

Diet-induced hyperinsulinemia accelerates growth of androgen-independent PC-3 cells in vitro

We investigated the effect of insulin and diet-induced hyperinsulinemia on the growth of the PC-3 cells in vitro and discerned the growth promoting effect of insulin in the androgen-independent cells. Sprague-Dawley rats were kept on a high-fat diet for 4 wk for the induction of insulin resistance and hyperinsulinemia. Insulin alone or serum of the rats kept on either normal-pellet diet or high-fat diet was used to stimulate the serum-starved PC-3 cells growth in culture. S961, a high-affinity insulin-receptor antagonist, was used to confirm the insulin-mediated effects. Significant impairment in the glucose disposal rate and increase in the serum glucose and insulin levels was observed in the high-fat-diet-fed rats. The media supplemented with the serum of the high-fat-diet-fed rats accelerated the growth of the PC-3 cells in comparison to that of normal-pellet-diet-fed rats. Insulin treatment led to accelerated growth of the serum-starved PC-3 cells in a dose-dependent manner and inhibited by the S961 pretreatment. Insulin and serum of the diet-induced hyperinsulinemic rats promote the growth of androgen-independent prostate cancer PC-3 cells. Further, our results provide support for the concept that diet-associated elevation in insulin level may augment the growth of prostate cancer cells.

Prostate size correlates with fasting blood glucose in non-diabetic benign prostatic hyperplasia patients with normal testosterone levels

We evaluated the correlations between BMI, fasting glucose, insulin, testosterone level, insulin resistance, and prostate size in non-diabetic benign prostatic hyperplasia (BPH) patients with normal testosterone levels. Data from 212 non-diabetic BPH patients with normal testosterone levels, who underwent transurethral resection of the prostate (TURP) due to medical treatment failure, were evaluated retrospectively. Patients with prostate specific antigen (PSA) levels of ≥ 3 ng/mL underwent multicore transrectal prostate biopsy before TURP to rule out prostate cancer. Patients with diabetes mellitus (DM) or serum testosterone levels of < 3.50 ng/mL were excluded from analysis. Correlations between clinical and laboratory parameters were determined. Prostate size correlated positively with age (r = 0.227, P < 0.001), PSA (r = 0.510, P < 0.001), and fasting glucose level (r = 0.186, P = 0.007), but not with BMI, testosterone, insulin level, or insulin resistance (each P > 0.05). Testosterone level inversely correlated with BMI (r = -0.327, P < 0.001), insulin level (r = -0.207, P = 0.003), and insulin resistance (r = -0.221, P = 0.001), but not with age, prostate size, PSA, or fasting glucose level (each P > 0.05). Upon multiple adjusted linear regression analysis, prostate size correlated with elevated PSA (P < 0.001) and increased fasting glucose levels (P = 0.023). In non-DM BPH patients with normal testosterone levels, fasting glucose level is an independent risk factor for prostate hyperplasia.

Urological aspects of the metabolic syndrome

The metabolic syndrome is common in countries with Western lifestyles. It comprises a number of disorders-including insulin resistance, hypertension and obesity-that all act as risk factors for cardiovascular diseases. Urological diseases have also been linked to the metabolic syndrome. Most established aspects of the metabolic syndrome are linked to benign prostatic hyperplasia (BPH) and prostate cancer. Fasting plasma insulin, in particular, has been linked to BPH and incident, aggressive and lethal prostate cancer. The metabolic syndrome has also been shown to be associated with nonprostatic urological conditions such as male hypogonadism, nephrolithiasis, overactive bladder and erectile dysfunction, although data on these conditions are still sparse. Overall, the results of studies on urological aspects of the metabolic syndrome seem to indicate that BPH and prostate cancer could be regarded as two new aspects of the metabolic syndrome, and that an increased insulin level is a common underlying aberration that promotes both BPH and clinical prostate cancer. Urologists need to be aware of the effect that the metabolic syndrome has on urological disorders and should transfer this knowledge to their patients.

PPARγ: a molecular link between systemic metabolic disease and benign prostate hyperplasia

The emergent epidemic of metabolic syndrome and its complex list of sequelae mandate a more thorough understanding of benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) in the context of systemic metabolic disease. Here we discuss the nature and origins of BPH, examine its role as a component of LUTS and review retrospective clinical studies that have drawn associations between BPH/LUTS and type II diabetes, inflammation and dyslipidemia. PPARγ signaling, which sits at the nexus of systemic metabolic disease and BPH/LUTS through its regulation of inflammation and insulin resistance, is proposed as a candidate for molecular manipulation in regard to BPH/LUTS. Finally, we introduce new cell and animal models that are being used to study the consequences of obesity, diabetes and inflammation on benign prostatic growth.

The illusion of prostate-specific antigen decline in patients with metabolic syndrome and insulin resistance

What's known on the subject? and What does the study add? Studies have shown that PSA is negatively associated with obesity as a result of hemodilution or metabolic effect. Hemodilution could be the main reason for low PSA levels in obese men. However, the intrinsic metabolic effects such as insulin resistance (IR) or metabolic syndrome (MS) on PSA level have not been clearly evaluated although obesity is closely tied to MS and IR. We regarded MS and IR as the pathophysiological cornerstone of metabolic disorder in obesity and analyzed the relationships among MS, IR, and PSA levels, and plasma volume by using the concept of PSA mass, the total circulating PSA protein. PSA mass did not change depending on the severity of the obesity, MS or IR. Even the group with both MS and IR, which could be the most metabolically disturbed in this study, did not have different PSA mass, comparing with the group without any MS or IR. Thus, the decline in PSA level in men with MS or IR can be also explained by increased plasma volume other than any intrinsic metabolic effects.

OBJECTIVE

• To investigate the detailed mechanism of prostate-specific antigen (PSA) decline in metabolic syndrome (MS) and insulin resistance (IR), which lowers the predictive value of the PSA test, we examined the effect of haemodilution and the possibility of an intrinsic metabolic effect.

PATIENTS AND METHODS

• We analysed 28,315 men who underwent routine check-ups. We compared the age-adjusted mean PSA levels in subjects with and without MS before and after adjusting or stratifying the plasma volume. We analysed changes in PSA level, plasma volume and PSA mass according to obesity grade, number of MS components, IR severity and diagnosis of MS, IR or both using an analysis of covariance.

RESULTS

• The PSA levels were lower in the group with MS than in the group without MS (P= 0.001), but this difference disappeared after adjusting or stratifying the plasma volume (P > 0.05 for all). The PSA levels decreased, plasma volume increased, and PSA mass did not change as the number of MS components increased (P= 0.002, P < 0.001, P= 0.55, respectively) or the IR severity increased (P= 0.001, P < 0.001, P= 0.34, respectively). • Similarly, PSA levels were lower, plasma volumes were higher and PSA masses were the same in subjects with MS (P= 0.002, P < 0.001, P= 0.10, respectively), IR (P= 0.018, P < 0.001, P= 0.94, respectively), or both (P= 0.003, P < 0.001, P= 0.86, respectively) than in subjects without those conditions.

CONCLUSION

• The PSA decline in MS and IR may result simply from a haemodilution effect and be unrelated to intrinsic metabolic disturbances. For this reason, PSA levels could be underestimated in patients with MS or IR because of haemodilution.

Pioglitazone attenuates prostatic enlargement in diet-induced insulin-resistant rats by altering lipid distribution and hyperinsulinaemia

BACKGROUND AND PURPOSE

Increased incidence of benign prostatic hyperplasia among insulin-resistant individuals suggests a role for hyperinsulinaemia in prostatic enlargement. We have already reported increased cell proliferation and enlargement of prostate gland in insulin-resistant rats. The present study aimed to elucidate the molecular mechanisms underlying the reversal of prostatic enlargement in insulin-resistant rats by the peroxisome proliferator-activated receptor γ agonist pioglitazone.

EXPERIMENTAL APPROACH

Sprague-Dawley rats were fed a normal pellet or a high-fat diet for 12 weeks with or without pioglitazone (20 mg·kg(-1)). Subgroups of animals fed different diets were castrated. Effects of dietary manipulation and pioglitazone were measured on insulin sensitivity, lipid distribution, cell proliferation and apoptosis.

KEY RESULTS

A high-fat diet led to the accumulation of fat in non-adipose tissues, insulin resistance, compensatory hyperinsulinaemia and prostatic enlargement in rats. Pioglitazone treatment altered fat distribution, improved insulin sensitivity and normalized lipid and insulin level in rats on the high-fat diet. The improved metabolic parameters led to decreased cellular proliferation and increased apoptosis in the prostate gland. High-fat diet feeding and pioglitazone treatment did not change plasma testosterone levels. However, significant prostatic atrophy was observed in castrated rats irrespective of dietary intervention.

CONCLUSIONS AND IMPLICATIONS

Our results show a previously unexplored therapeutic potential of pioglitazone for prostatic enlargement under insulin-resistant condition and further suggest that targeting distribution of lipid from non-adipose tissue to adipose tissue and insulin signalling could be new strategies for the treatment of benign prostatic hyperplasia.

Relative influence of testosterone and insulin in the regulation of prostatic cell proliferation and growth

Prostatic hyperplasia is a common problem of the aged men population. Recent experimental and clinical studies provide sufficient evidence that apart from androgens, insulin also plays an important role in the pathogenesis of prostatic hyperplasia. The present study was aimed to investigate the relative influence of testosterone and insulin on the cellular proliferation and prostatic growth. Effect of testosterone on the prostate of hypoinsulinemic, and glandular injection of insulin-receptor antagonist S961 on the prostate of castrated Sprague-Dawley rat (220±10 g) was examined. Significant decrease in the weight of the ventral prostate was observed in the streptozotocin-induced hypoinsulinemic rats (~6 fold), which is restored by the intervention of testosterone. Although, glandular injection of S961 did not led to any change in the frequency of proliferating cell nuclear antigen (PCNA) positive cells in normal rats, significant decrease was observed in the castrated rats. Castration led to increase in the frequency of the caspase-3 and the TUNEL positive cells in the ventral prostate. Further, long-term (6 weeks) administration of S961 induced significant decrease in the weight of the ventral prostate. Results of the present study provide that both testosterone and insulin promote prostatic cell proliferation and change in the level of either of the hormone results in the destabilization of cellular equilibrium, and modulation of the insulin-receptor signaling in the prostate may provide an alternative strategy for the treatment of prostatic enlargement. Further, studies are required to better understand the interplay between these hormones in the regulation of prostatic growth.

Role of insulin and testosterone in prostatic growth: who is doing what?

Previous studies have demonstrated increased incidence of benign prostatic hyperplasia in insulin-resistant individuals. In addition to androgens, prostatic growth is sensitive to the peptide growth factors including insulin. Experimental studies employing intervention of selective β-cell toxin streptozotocin and castration suggest that depletion of either insulin or testosterone results in the severe prostatic atrophy (>80%). Exogenous testosterone and diet-induced experimental hyperinsulinemia induces prostatic enlargement in rats. Further, hyperinsulinemia sensitizes prostate towards the growth promoting effect of testosterone, and testosterone augments prostatic growth even in the hypoinsulinemic rats. However, in castrated rats diet-induced hyperinsulinemia fails to promote prostatic growth. Based on these evidences it is hypothesized that in the presence of testosterone insulin plays an important role in the prostatic growth. The epidemiological reports witnessing increased incidences of prostatic enlargement in men with metabolic syndrome, which are known to have increased level of insulin, provides a validating clue to the hypothesis. Further, the hypothesis suggests that targeting insulin signaling pathway could be a new objective for the treatment of prostatic enlargement.