Mechanistic investigation of the adrenergic induction of ventral prostate hyperplasia in mice

Inhibition of Human Prostate and Bladder Smooth Muscle Contraction, Vasoconstriction of Porcine Renal and Coronary Arteries, and Growth-Related Functions of Prostate Stromal Cells by Presumed Small Molecule Gαq/11 Inhibitor, YM-254890

Introduction: Lower urinary tract symptoms (LUTS) involve benign prostatic hyperplasia (BPH) and overactive bladder (OAB). Standard-of-care medical treatment includes α1-blockers and antimuscarinics for reduction of prostate and detrusor smooth muscle tone, respectively, and 5α-reductase inhibitors (5-ARI) to prevent prostate growth. Current medications are marked by high discontinuation rates due to unfavourable balance between efficacy and treatment-limiting side effects, ranging from dry mouth for antimuscarinics to cardiovascular dysregulation and a tendency to fall for α1-blockers, which results from hypotension, due to vasorelaxation. Agonist-induced smooth muscle contractions are caused by activation of receptor-coupled G-proteins. However, little is known about receptor- and organ-specific differences in coupling to G-proteins. With YM-254890, a small molecule inhibitor with presumed specificity for Gαq/11 became recently available. Here, we investigated effects of YM-254890 on prostate, bladder and vascular smooth muscle contraction, and on growth-related functions in prostate stromal cells.

Methods: Contractions of human prostate and detrusor tissues, porcine renal and coronary arteries were induced in an organ bath. Proliferation (EdU assay), growth (colony formation), apoptosis and cell death (flow cytometry), viability (CCK-8) and actin organization (phalloidin staining) were studied in cultured human prostate stromal cells (WPMY-1).

Results: Contractions by α1-adrenergic agonists, U46619, endothelin-1, and neurogenic contractions were nearly completely inhibited by YM-254890 (30 nM) in prostate tissues. Contractions by cholinergic agonists, U46619, endothelin-1, and neurogenic contractions were only partly inhibited in detrusor tissues. Contractions by α1-adrenergic agonists, U46619, endothelin-1, and neurogenic contractions were strongly, but not fully inhibited in renal arteries. Contractions by cholinergic agonists were completely, but by U46619 and endothelin-1 only strongly inhibited, and neurogenic contractions reduced by half in coronary arteries. YM-254890 had no effect on agonist-independent contractions induced by highmolar (80 mM) potassium chloride (KCl). Neurogenic detrusor contractions were fully sensitive to tetrodotoxin. In WPMY-1 cells, YM-254890 caused breakdown of actin polymerization and organization, and obvious, but clearly limited decreases of proliferation rate, colony formation and viability, and slightly increased apoptosis.

Conclusion: Intracellular post-receptor signaling pathways are shared by Gαq-coupled contractile receptors in multiple smooth muscle-rich organs, but to different extent. While inhibition of Gαq/11 causes actin breakdown, anti-proliferative effects were detectable but clearly limited. Together this may aid in developing future pharmaceutical targets for LUTS and antihypertensive medication.

Concentration-dependent alpha1-Adrenoceptor Antagonism and Inhibition of Neurogenic Smooth Muscle Contraction by Mirabegron in the Human Prostate

Introduction: Mirabegron is available for treatment of storage symptoms in overactive bladder, which may be improved by β₃-adrenoceptor-induced bladder smooth muscle relaxation. In addition to storage symptoms, lower urinary tract symptoms in men include obstructive symptoms attributed to benign prostatic hyperplasia, caused by increased prostate smooth muscle tone and prostate enlargement. In contrast to the bladder and storage symptoms, effects of mirabegron on prostate smooth muscle contraction and obstructive symptoms are poorly understood. Evidence from non-human smooth muscle suggested antagonism of α₁-adrenoceptors as an important off-target effect of mirabegron. As α₁-adrenergic contraction is crucial in pathophysiology and medical treatment of obstructive symptoms, we here examined effects of mirabegron on contractions of human prostate tissues and on proliferation of prostate stromal cells.

Methods: Contractions were induced in an organ bath. Effects of mirabegron on proliferation, viability, and cAMP levels in cultured stromal cells were examined by EdU assays, CCK-8 assays and enzyme-linked immunosorbent assay.

Results: Mirabegron in concentrations of 5 and 10 μM, but not 1 µM inhibited electric field stimulation-induced contractions of human prostate tissues. Mirabegron in concentrations of 5 and 10 µM shifted concentration response curves for noradrenaline-, methoxamine- and phenylephrine-induced contractions to the right, including recovery of contractions at high concentrations of α₁-adrenergic agonists, increased EC₅₀ values, but unchanged E_max values. Rightshifts of noradrenaline concentration response curves and inhibition of EFS-induced contractions were resistant to L-748,337, l-NAME, and BPIPP. 1 µM mirabegron was without effect on α₁-adrenergic contractions. Endothelin-1- and U46619-induced contractions were not affected or only inhibited to neglectable extent. Effects of mirabegron (0.5–10 µM) on proliferation and viability of stromal cells were neglectable or small, reaching maximum decreases of 8% in proliferation assays and 17% in viability assays. Mirabegron did not induce detectable increases of cAMP levels in cultured stromal cells.

Conclusion: Mirabegron inhibits neurogenic and α₁-adrenergic human prostate smooth muscle contractions. This inhibition may be based on antagonism of α₁-adrenoceptors by mirabegron, and does not include activation of β₃-adrenoceptors and requires concentrations ranging 50-100fold higher than plasma concentrations reported from normal dosing. Non-adrenergic contractions and proliferation of prostate stromal cells are not inhibited by mirabegron.

Animal models of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms are common clinical concerns that affect aging men all over the world. The underlying molecular and cellular mechanisms remain elusive. Over the past few years, a number of animal models of BPH, including spontaneous model, BPH-induction model, xenograft model, metabolic syndrome model, mechanical obstruction model, and transgenic model, have been established that may provide useful tools to fill these critical knowledge gaps. In this review, we therefore outlined the present status quo for animal models of BPH, comparing the pros and cons with respect to their ability to mimic the etiological, histological, and clinical hallmarks of BPH and discussed their applicability for future research.

A phytosterol-enriched saw palmetto supercritical CO2 extract ameliorates testosterone-induced benign prostatic hyperplasia by regulating the inflammatory and apoptotic proteins in a rat model

BACKGROUND

Benign prostatic hyperplasia (BPH) is a pathological condition affecting older men. BPH complications often lead to deterioration in the quality of life. Serenoa repens (Saw Palmetto) is used for treating lower urinary tract infections in traditional medicine.

METHODS

This study was performed to compare the efficacy of β-sitosterol enriched saw palmetto oil (VISPO) and conventional saw palmetto oil (SPO) extracted using supercritical fluid extraction, in alleviating the BPH complications using testosterone-induced BPH model rats. The animals received testosterone (5 mg/kg s.c.) with or without SPO and VISPO (200 and 400 mg/kg b.w.) or Finasteride (1 mg/kg b.w.) p.o. for 28 days. At the end of the experiment, overnight fasted animals were euthanized, blood samples collected for serum analysis of testosterone. Prostate tissue histomorphology was examined by hematoxylin and eosin (H&E) staining. Western blot analysis was performed using prostate tissue homogenates.

RESULTS

VISPO exhibited superior efficacy compared to SPO as evident from the significant decrease in prostate weight to body weight ratio, serum testosterone level and increase in growth inhibition of prostate tissue compared to BPH group (p < 0.001). Histological examination of prostate tissue samples showed that VISPO treatment was comparatively better than SPO in improving the hyperplastic patterns. Further, VISPO significantly regulated the expression of inflammatory and apoptotic marker proteins in BPH rats.

CONCLUSION

Our data provide experimental evidence that β-sitosterol enriched saw palmetto oil could be higher efficacious in treating the BPH complications compared to the conventional saw palmetto oil preparations.

Outcome of Botulinum Toxin-A intraprostatic injection for benign prostatic hyperplasia induced lower urinary tract symptoms: A prospective multicenter study

INTRODUCTION

Our aim was to determine the factors predicting the outcome of intraprostatic injection of Botulinum Toxin-A (BTX-A) in the treatment of benign prostatic hyperplasia (BPH)-induced lower urinary tract symptoms (LUTS) and to evaluate its efficacy and safety.

METHODS

Between September 2016 and May 2018, 45 Egyptian patients, with BPH-induced LUTS were included; the indication was a failure of medical treatment, unfit, or refusing surgical intervention. Measurements of prostate size by TRUS, total PSA level before and 12 weeks after injection. IPSS, uroflow, and postvoiding residual urine (PVR) were measured before injection, 2, 4, 8 and 12 weeks postinjection. 100 U BTX-A vial was diluted with 10 mL of saline then injected into the transition zone at base and midzone of the prostate by TRUS.

RESULTS

The mean patients' age was 64.4 ± 6.6 years. Mean baseline IPSS 24.06 decreased to 18.75 at 2 weeks and progressively decreased to 16.37 at 12 weeks (P < 0.001), Q _max of 9.08 mL/s. increased to 10.44 at 2 weeks and 11.44 at 12 weeks (P < 0.001), mean prostate volume was 67.44cc; decreased to 66.06cc (P < 0.001) at 12 weeks and mean residual urine was 82.62 mL and decreased to 57.66 mL at 12 weeks.

DISCUSSION

Intraprostatic injection of BTX-A as modality treatment of LUTS/BPH significantly improve IPSS, Q _max , PVR, and decrease prostate volume. We can suspect better results with this line of treatment in patients with IPSS ≤ 22 and Q _max  ≤ 10 mL/min and prostate volume ≤ 56.5cc.

Botulinum toxin and benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a clinical condition where lower urinary tract symptoms are caused by both a physically obstructing prostate as well as tight smooth muscles around the bladder outlet. Treatment of this condition with botulinum toxin has been used since 2003, but this interest has somewhat died down after two large randomized controlled trials (RCTs) showing equivalence of results between their treatment and placebo arms. However, with review of animal studies and unexplained exaggerated effect of the placebo arms of the two RCTs, together with recent data of sustained benefits after 18 months of treatment, the place of botulinum toxin in the BPH field is probably still present.

Quisqualis indica Improves Benign Prostatic Hyperplasia by Regulating Prostate Cell Proliferation and Apoptosis

Quisqualis indica (QI) has been used for treating disorders such as stomach pain, constipation, and digestion problem. This study was aimed to evaluate the therapeutic efficacy of QI extract on treating benign prostatic hyperplasia (BPH) in LNCaP human prostate cancer cell line and a testosterone-induced BPH rat model. LNCaP cells were treated with QI plus testosterone propionate (TP), and androgen receptor (AR) and prostate specific antigen (PSA) expression levels were assessed by Western blotting. To induce BPH, the rats were subjected to a daily subcutaneous injection of TP (3 mg/kg) for 4 weeks. The rats in treatment group were orally gavaged with QI (150 mg/kg) together with the TP injection. In-vitro studies showed that TP-induced increases in AR and PSA expression in LNCaP cells were reduced by QI treatment. In BPH-model rats, the prostate weight, testosterone in serum, dihydrotestosterone (DHT) concentration and 5α-reductase type 2 mRNA expression in prostate tissue were significantly reduced following the treatment with QI. TP-induced prostatic hyperplasia and the expression of proliferating cell nuclear antigen (PCNA) and cyclin D1 were significantly attenuated in QI-treated rats. In addition, QI induced apoptosis by up-regulating caspase-3 and -9 activity and decreasing the B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) ratio in prostate tissues of BPH rats. Further investigation showed that TP-induced activation of AKT and glycogen synthase kinase 3β (GSK3β) was reduced by QI administration. Therefore, our findings suggest that QI attenuates the BPH state in rats through anti-proliferative and pro-apoptotic activities and might be useful in the clinical treatment of BPH.

Musulju improves benign prostatic hyperplasia by regulating inflammatory and apoptotic proteins

Alternative medicine is a widely accepted therapeutic approach for the management of various diseases. The Korean medicine, musulju (MSJ), has been traditionally used to improve vital energy in men with reduced physical strength and a weakened urinary system. The present study determined the mechanisms underlying the protective effect of MSJ against benign prostatic hyperplasia (BPH), a common disorder in elderly men that involves inflammation‑mediated imbalance between cell proliferation and death. MSJ treatment was demonstrated to decrease prostate weight, cell proliferation, and the protein expression of proliferating cell nuclear antigen in a rat model of BPH. In addition, MSJ markedly reduced serum testosterone levels, 5α‑reductase2 mRNA expression and BPH‑associated upregulation of inflammatory proteins, inducible nitric oxide synthase and cyclooxygenase 2. Furthermore, MSJ induced apoptosis by regulating B‑cell lymphoma (Bcl)‑2 protein expression and the Bcl‑2:Bax ratio, leading to caspase 3 activation. Taken together, MSJ demonstrated antiproliferative effects in BPH model rats by regulating the expression levels of proteins involved in inflammation and apoptosis. The effects of MSJ may be attributed to its alternative therapeutic properties.

Aberrant Transforming Growth Factor-β Activation Recruits Mesenchymal Stem Cells During Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is the overgrowth of prostate tissues with high prevalence in older men. BPH pathogenesis is not completely understood, but it is believed to be a result of de novo overgrowth of prostatic stroma. In this study, we show that aberrant activation of transforming growth factor‐β (TGF‐β) mobilizes mesenchymal/stromal stem cells (MSCs) in circulating blood, which are recruited for the prostatic stromal hyperplasia. Elevated levels of active TGF‐β were observed in both a phenylephrine‐induced prostatic hyperplasia mouse model and human BPH tissues. Nestin lineage tracing revealed that 39.6% ± 6.3% of fibroblasts and 73.3% ± 4.2% smooth muscle cells were derived from nestin⁺ cells in Nestin‐Cre, Rosa26‐YFP^flox/+mice. Nestin⁺ MSCs were increased in the prostatic hyperplasia mice. Our parabiosis experiment demonstrate that nestin⁺ MSCs were mobilized and recruited to the prostatic stroma of wild‐type mice and gave rise to the fibroblasts. Moreover, injection of a TGF‐β neutralizing antibody (1D11) inhibits mobilization of MSCs, their recruitment to the prostatic stroma and hyperplasia. Importantly, knockout of TβRII in nestin⁺ cell lineage ameliorated stromal hyperplasia. Thus, elevated levels of TGF‐β‐induced mobilization and recruitment of MSCs to the reactive stroma resulting in overgrowth of prostate tissues in BPH and, thus, inhibition of TGF‐β activity could be a potential therapy for BPH. Stem Cells Translational Medicine2017;6:394–404

Intraprostatic Botulinum Neurotoxin Type A Injection for Benign Prostatic Hyperplasia-A Spotlight in Reality

Botulinum toxin is a neurotoxin produced by the bacterium Clostridium botulinum. It inhibits the release of acetylcholine and other neurotransmitters from the nerve terminal. Botulinum toxin, specifically toxin type A (BoNT-A) has been used since the 1970s to reduce the muscular hypercontraction disorders. The application of BoNT-A in urology field started from intra-bladder injection for overactive bladder, which has been recognized as third line therapy in many countries. Since prostate gland as well as bladder is under the influence of autonomic innervation, theorectically, injection of BoNT-A into the prostate induces chemo-denervation and modulation of prostate function, and reduces lower urinary tract symptoms (LUTS). This article reviews the application of BoNT-A in patients with LUTS/ benign prostatic hyperplasia (BPH) from mechanisms of action to clinical results. BoNT-A has been shown to induce prostate apoptosis, downregulation of alpha 1A receptors, and reduce contractile function of prostate in animal studies. Open studies of intraprostate BoNT-A injection have demonstrated promising results of reducing LUTS and improvement of voiding function in human LUTS/BPH, however, intraprostatic BoNT-A injection did not perform better than the placebo group in recent publications of placebo controlled studies. We suggested that BoNT-A prostate injection might benefit selected population of BPH/LUTS, but it is unlikely to be an effective therapy for general population of male LUTS/BPH.

D-004 ameliorates phenylephrine-induced urodynamic changes and increased prostate and bladder oxidative stress in rats

BACKGROUND

Lower urinary tract symptoms (LUTS) in patients with benign prostatic hyperplasia (BPH) mainly depend on alpha1-adrenoreceptors (α1-ADR) stimulation, but a link with oxidative stress (OS) is also involved. D-004, a lipid extract of Roystonea regia fruits, antagonizes ADR-induced responses and produces antioxidant effects. The objective of this study was to investigate whether D-004 produce antioxidant effects in rats with phenylephrine (PHE)-induced urodynamic changes.

METHODS

Rats were randomized into eight groups (ten rats/group): a negative vehicle control and seven groups injected with PHE: a positive control, three treated with D-004 (200, 400 and 800 mg/kg) and three others with tamsulosin (0.4 mg/kg), grape seed extract (GSE) (250 mg/kg) and vitamin E (VE) (250 mg/kg), respectively.

RESULTS

Effects on urinary total volume (UTV), volume voided per micturition (VM), malondialdehyde (MDA) and carbonyl groups (CG) concentrations in prostate and bladder homogenates were study outcomes. While VM and UTV lowered significantly in the positive control as compared to the negative control group, the opposite occurred with prostate and bladder MDA and CG values. D-004 (200-800 mg/kg) increased significantly both VM and UTV, lowered significantly MDA in prostate and bladder homogenates, and reduced GC levels only in the prostate. Tamsulosin increased significantly VM and UTV, but unchanged oxidative variables. GSE and VE unchanged the UTV, whereas VE, not GSE, modestly but significantly attenuated the PHE-induced decrease of VM.

CONCLUSIONS

Single oral administration of D-004 (200-800 mg/kg) was the only treatment that ameliorated the urodynamic changes and reduced increased oxidative variables in the prostate of rats with PHE-induced prostate hyperplasia.

New intraprostatic injectables and prostatic urethral lift for male LUTS

Treatment modalities for male lower urinary tract symptoms (LUTS) comprise a broad spectrum of medical and surgical options. Interest is growing in minimally invasive treatment options, which should ideally be performed in an outpatient setting and have a short recovery time, durable efficacy and a good safety profile. The preservation of all aspects of sexual function, including antegrade ejaculation, seems to be increasingly important for patients. Initial experimental data on new minimally invasive procedures-such as the intraprostatic injection of novel agents including botulinum neurotoxin A (BoNT-A), NX-1207 and PRX302-were promising, but clinical trials have not confirmed the findings. Trials of the mechanical prostatic urethral lift device-Urolift(®) (Neotract, Inc., USA)-have been positive, but further long-term results are needed to confirm its beneficial effects.

Immunomodulatory effect of red onion (Allium cepa Linn) scale extract on experimentally induced atypical prostatic hyperplasia in Wistar rats

Red onion scales (ROS) contain large amounts of flavonoids that are responsible for the reported antioxidant activity, immune enhancement, and anticancer property. Atypical prostatic hyperplasia (APH) was induced in adult castrated Wistar rats by both s.c. injection of testosterone (0.5 mg/rat/day) and by smearing citral on shaved skin once every 3 days for 30 days. Saw palmetto (100 mg/kg) as a positive control and ROS suspension at doses of 75, 150, and 300 mg/kg/day were given orally every day for 30 days. All medications were started 7 days after castration and along with testosterone and citral. The HPLC profile of ROS methanolic extract displayed two major peaks identified as quercetin and quercetin-4′-β-O-D-glucoside. Histopathological examination of APH-induced prostatic rats revealed evidence of hyperplasia and inflammation with cellular proliferation and reduced apoptosis Immunohistochemistry showed increased tissue expressions of IL-6, IL-8, TNF-α, IGF-1, and clusterin, while TGF-β1 was decreased, which correlates with the presence of inflammation. Both saw palmetto and RO scale treatment have ameliorated these changes. These ameliorative effects were more evident in RO scale groups and were dose dependent. In conclusion, methanolic extract of ROS showed a protective effect against APH induced rats that may be attributed to potential anti-inflammatory and immunomodulatory effects.

OnobotulinumtoxinA Has No Effects on Growth of LNCaP and PC3 Human Prostate Cancer Cells

OBJECTIVES

Intraprostatic injection of botulinum toxin (BTX) has been reported to have therapeutic effects on lower urinary tract symptoms related to benign prostate hyperplasia (BPH). Patients with BPH are at risk of having prostate cancer. The present study was conducted to assess the effect of onobotulinumtoxinA on prostate cancer in vitro and in vivo.

METHODS

Human prostate cancer cell lines, LNCaP and PC3 were exposed to different doses of onobotulinumtoxinA (0-10 U; Allergan, Irvine, CA, USA). Cell viability, DNA fragmentation and apoptosis assay were subsequently measured. For the in vivo study, LNCaP and PC3 xenografts were introduced into nude mice and treated with intra-tumoral onobotulinumtoxinA or saline injection. Tumor volume, histopathology and apoptosis were assessed. Presence of SNAP-25 protein, the molecular target of onobotulinumtoxinA, was studied in both cell lines by Western blot analysis.

RESULTS

OnobotulinumtoxinA did not significantly affect cell proliferation or apoptosis in LNCaP and PC3 cells. There was no significant difference in tumor size and histopathological findings between the experimental and control groups. There was no detectable SNAP-25 protein in both cell lines.

CONCLUSION

OnobotulinumtoxinA does not affect the growth of LNCaP or PC3 cells in vitro and in vivo or produce significant anti-tumor effects. Intraprostatic BTX injection for BPH might not affect the growth of prostate cancer.

Silodosin inhibits noradrenaline-activated transcription factors Elk1 and SRF in human prostate smooth muscle

Background

The transcription factors Elk1 and serum response factor (SRF) are central regulators of cell cycle and phenotype in various cell types. Elk1 is activated by phosphorylation (serine-383), while activation of SRF requires its co-factor, myocardin. Activation of Elk1 and SRF results in binding to specific DNA sequences in promoter regions, and may be induced by adrenergic receptor activation in different organs.

Objective

To examine the effects of adrenergic stimulation on Elk1 and SRF in the human prostate and the ability of the highly selective α1A-adrenoceptor antagonist, silodosin, on transcription factor activation.

Methods

Prostate tissue was obtained from patients undergoing radical prostatectomy. Expression of Elk1, SRF, and myocardin was estimated by Western blot and immunohistochemistry. Colocalizations were studied by double immunofluorescence staining. Noradrenaline- (NA-) and phenylephrine- (PE-) induced phosphorylation of Elk1 was assessed by Western blot analysis using a phospho-specific antibody. NA-induced activation of Elk1 and SRF was investigated by electrophoretic mobility shift assay (EMSA).

Results

Immunoreactivity for Elk1, SRF, and myocardin was observed in stromal cells of tissues from each patient. In fluorescence stainings, SRF colocalized with myocardin and α-smooth muscle actin (αSMA). Stimulation of prostate tissues with PE (10 µM) or NA (30 µM) increased the phosphorylation of Elk1 at serine-383. NA-induced Elk1 activation was confirmed by EMSA, where a NA-induced binding of Elk1 to the DNA sequence TTTGCAAAATGCAGGAATTGTTTTCACAGT was observed. Similarly, NA caused SRF binding to the SRF-specific DNA sequence CCATATTAGGCCATATTAGG. Application of silodosin (3 µM) to prostate tissues reduced the activity of Elk1 and SRF in NA-stimulated tissues.

Conclusions

Silodosin blocks the activation of the two transcription factors, Elk1 and SRF, which is induced by noradrenaline in the human prostate. A role of α1-adrenoceptors beyond smooth muscle contraction may be considered, which includes a function in transcriptional regulation.

Inhibition of adrenergic human prostate smooth muscle contraction by the inhibitors of c-Jun N-terminal kinase, SP600125 and BI-78D3

BACKGROUND AND PURPOSE α(1) -Adrenoceptor-induced contraction of prostate smooth muscle is mediated by calcium- and Rho kinase-dependent mechanisms. In addition, other mechanisms, such as activation of c-jun N-terminal kinase (JNK) may be involved. Here, we investigated whether JNK participates in α(1)-adrenoceptor-induced contraction of human prostate smooth muscle. EXPERIMENTAL APPROACH Prostate tissue was obtained from patients undergoing radical prostatectomy. Effects of the JNK inhibitors SP600125 (50 µM) and BI-78D3 (30 µM) on contractions induced by phenylephrine, noradrenaline and electric field stimulation (EFS) were studied in myographic measurements. JNK activation by noradrenaline (30 µM) and phenylephrine (10 µM), and the effects of JNK inhibitors of c-Jun phosphorylation were assessed by Western blot analyses with phospho-specific antibodies. Expression of JNK was studied by immunohistochemistry and fluorescence double staining. KEY RESULTS The JNK inhibitors SP600125 and BI-78D3 reduced phenylephrine- and noradrenaline-induced contractions of human prostate strips. In addition, SP600125 reduced EFS-induced contraction of prostate strips. Stimulation of prostate tissue with noradrenaline or phenylephrine in vitro resulted in activation of JNK. Incubation of prostate tissue with SP600125 or BI-78D3 reduced the phosphorylation state of c-Jun. Immunohistochemical staining demonstrated the expression of JNK in smooth muscle cells of human prostate tissue. Fluorescence staining showed that α(1A)-adrenoceptors and JNK are expressed in the same cells. CONCLUSIONS AND IMPLICATIONS Activation of JNK is involved in α(1)-adrenoceptor-induced prostate smooth muscle contraction. Models of α(1)-adrenoceptor-mediated prostate smooth muscle contraction should include this JNK-dependent mechanism.

Loss of sensory and noradrenergic innervation in benign colorectal adenomatous polyps--a putative role of semaphorins 3F and 3A

BACKGROUND

Nerve fibers can exert trophic/anti-trophic effects on epithelial cells. Substance P (SP) is a pro-proliferative neuropeptide, whereas sympathetic noradrenaline is anti-proliferative at high concentrations.

METHODS

Density of noradrenergic and sensory nerve fibers and presence of nerve repellent factors specific for noradrenergic (semaphorin 3F) and sensory nerve fibers (semaphorin 3A) were investigated in colorectal adenomas.

KEY RESULTS

The pedunculus was innervated by noradrenergic fibers, whereas the mucosa was sparsely innervated. The control submucosa compared with control mucosa demonstrated increased density of noradrenergic fibers. Control tissue was much better innervated than the polyp. This was accompanied by strong expression of semaphorin 3F in epithelial cells. Density of sensory SP+ nerve fibers was higher in control colon mucosa compared with polyp mucosa, and SP+ cell clusters and semaphorin 3A-positive cells appeared in the intercrypt space in polyps, but not in control tissue.

CONCLUSIONS & INFERENCES

This study demonstrated a marked loss of noradrenergic and sensory nerve fibers in polyp mucosa, which was associated with a strong increase of semaphorin 3F and 3A. Up-regulation of the sympathetic repellent semaphorin 3F in the polyps possibly triggers sympathetic repulsion and polyp growth due to the loss of anti-proliferative noradrenaline and presence of SP from local SP+ cells.

Anti-inflammatory and antiproliferative activities of date palm pollen (Phoenix dactylifera) on experimentally-induced atypical prostatic hyperplasia in rats

BACKGROUND

Atypical prostatic hyperplasia (APH) is a pseudoneoplastic lesion that can mimic prostate adenocarcinoma because of its cytologic and architectural features. Suspension of date palm pollen (DPP) is an herbal mixture that is widely used in folk medicine for male infertility. The aim of the present study was to evaluate the effect of DPP suspension and extract on APH-induced rats.

METHODS

APH was induced in adult castrated Wistar rats by both s.c. injection of testosterone (0.5 mg/rat/day) and smearing citral on shaved skin once every 3 days for 30 days. Saw palmetto (100mg/kg), DPP suspension (250, 500 and 1000 mg/kg), and lyophilized DPP extract (150,300 and 600 mg/kg) were given orally daily for 30 days. All medications were started 7 days after castration and along with testosterone and citral.

RESULTS

The histopathological feature in APH-induced prostate rats showed evidence of hyperplasia and inflammation. Immunohistochemical examination revealed that the expressions of IL-6, IL-8, TNF-α, IGF-1 and clusterin were increased, while the expression of TGF-β1 was decreased that correlates with presence of inflammation. Moreover, histopathological examination revealed increased cellular proliferation and reduced apoptosis in ventral prostate. Both saw palmetto and DPP treatment has ameliorated these histopathological and immunohistochemical changes in APH-induced rats. These improvements were not associated with reduction in the prostatic weight that may be attributed to the persistence of edema.

CONCLUSION

DPP may have a potential protective effect in APH-induced Wistar rats through modulation of cytokine expression and/or upregulation of their autocrine/paracrine receptors.

Correlations among cardiovascular risk factors, prostate blood flow, and prostate volume in patients with clinical benign prostatic hyperplasia

OBJECTIVE

To investigate the relationships among the cardiovascular risk factors, prostate blood flow, and prostate volume in patients with clinical benign prostatic hyperplasia (BPH).

METHODS

A total of 130 patients with the clinical diagnosis of BPH were recruited. The presence of 5 cardiovascular risk factors, including obesity, diabetes, hypertension, hyperlipidemia, and a history of cardiovascular events, was recorded. The urologic evaluation included digital rectal examination, serum prostate-specific antigen, International Prostate Symptom Score, and transrectal ultrasonography. Doppler spectrum analysis was performed with the patient in the right lateral decubitus position to measure the blood flow in the prostate capsular arteries, periurethral arteries, and neurovascular bundles. The correlations were analyzed between the resistive indexes of the prostatic branches and the cardiovascular risk factors, as well as the transrectal ultrasound findings.

RESULTS

The resistive indexes of the periurethral arteries and right neurovascular bundles showed positive correlations with the number of cardiovascular risk factors in the patients (r=.228, P=.01 and r=.225, P=.011, respectively). The periurethral artery resistive index also correlated positively with both prostate and transitional zone volumes, with the capsular artery correlating positively only with the latter. No significant correlations were noted between the resistive indexes and the International Prostate Symptom Score.

CONCLUSION

Prostate vascular resistance in patients with BPH has positive correlations with cardiovascular risk factors and prostate size. These findings suggest that prostate hypoxia might play a role in the pathogenesis of BPH.

Activation of alpha(1) -adrenergic receptors stimulate the growth of small mouse cholangiocytes via calcium-dependent activation of nuclear factor of activated T cells 2 and specificity protein 1

Small cholangiocytes proliferate via activation of calcium (Ca(2+) )-dependent signaling in response to pathological conditions that trigger the damage of large cyclic adenosine monophosphate-dependent cholangiocytes. Although our previous studies suggest that small cholangiocyte proliferation is regulated by the activation of Ca(2+) -dependent signaling, the intracellular mechanisms regulating small cholangiocyte proliferation are undefined. Therefore, we sought to address the role and mechanisms of action by which phenylephrine, an α(1) -adrenergic agonist stimulating intracellular D-myo-inositol-1,4,5-triphosphate (IP(3) )/Ca(2+) levels, regulates small cholangiocyte proliferation. Small and large bile ducts and cholangiocytes expressed all AR receptor subtypes. Small (but not large) cholangiocytes respond to phenylephrine with increased proliferation via the activation of IP(3) /Ca(2+) -dependent signaling. Phenylephrine stimulated the production of intracellular IP(3) . The Ca(2+) -dependent transcription factors, nuclear factor of activated T cells 2 (NFAT2) and NFAT4, were predominantly expressed by small bile ducts and small cholangiocytes. Phenylephrine stimulated the Ca(2+) -dependent DNA-binding activities of NFAT2, NFAT4, and Sp1 (but not Sp3) and the nuclear translocation of NFAT2 and NFAT4 in small cholangiocytes. To determine the relative roles of NFAT2, NFAT4, or Sp1, we knocked down the expression of these transcription factors with small hairpin RNA. We observed an inhibition of phenylephrine-induced proliferation in small cholangiocytes lacking the expression of NFAT2 or Sp1. Phenylephrine stimulated small cholangiocyte proliferation is regulated by Ca(2+) -dependent activation of NFAT2 and Sp1.

CONCLUSION

Selective stimulation of Ca(2+) -dependent small cholangiocyte proliferation may be key to promote the repopulation of the biliary epithelium when large bile ducts are damaged during cholestasis or by toxins.

Tadalafil for the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia: pathophysiology and mechanism(s) of action

BACKGROUND

The PDE5 inhibitor tadalafil is investigation for the treatment of lower urinary tract symptoms (LUTS) in men with benign prostatic hyperplasia (BPH). Several clinical studies of tadalafil and other PDE5 inhibitors have reported significant symptom reduction but limited urinary flow rate improvement. This manuscript reviews the published literature describing the pathophysiology of male LUTS, with an emphasis on mechanisms that may be modulated or improved by phosphodiesterase type 5 (PDE5) inhibition.

METHODS

Literature (through March 2010) was obtained via Medline searches and from the individual reviewers files. Articles were selected for review based on describing in vitro, preclinical, or clinical studies of pathological processes contributing to LUTS, or possible effects of PDE5 inhibition in the lower urinary tract.

RESULTS

Major mechanisms contributing to LUTS include: reduced nitric oxide/cyclic guanosine monophosphate signaling; increased RhoA kinase pathway activity; autonomic overactivity; increased bladder afferent activity; and pelvic ischemia. Tadalafil and other PDE5 inhibitors have demonstrated beneficial effects on smooth muscle relaxation, smooth muscle and endothelial cell proliferation, nerve activity, and tissue perfusion that may impact LUTS in men.

CONCLUSIONS

The pathophysiology of male LUTS is complex and not completely understood. LUTS may occur independently of BPH or secondary to BPH but in both cases involve obstructive or irritative mechanisms with substantial pathophysiological overlap. While the precise mechanism remains unclear, inhibition of PDE5 seems to have an effect on several pathways that may impact LUTS.

Botulinum neurotoxin A for benign prostatic hyperplasia

PURPOSE OF REVIEW

The injection of botulinum neurotoxin A (BoNT-A) into the prostate represents an alternative, minimal invasive treatment for lower urinary tract symptoms suggestive of benign prostatic hyperplasia (BPH), which gained the interest of urologists during the last years, although it is not yet licensed. The purpose of this review is to summarize the mechanisms through which BoNT-A could inhibit the progression of BPH and eliminate the lower urinary tract symptoms according to the findings of animal studies. Furthermore, we review clinical studies to report the efficacy and safety of intraprostatic BoNT-A injection according to various injection protocols.

RECENT FINDINGS

The experimental studies report induced relaxation of the prostate, atrophy, and reduction in its size through inhibition of the trophic effect of the autonomic system on the prostate gland. Also, a possible mechanism of reduction in lower urinary tract symptoms might take place through inhibition of sensory afferents from the prostate to the spinal cord. Clinical studies report symptomatic relief and improvement in the measured parameters during the follow-up period, whereas local or systematic side-effects are rare.

SUMMARY

We should recognize that, at present, this therapy is still experimental. Although the results of the clinical studies are encouraging, the level of evidence is low. Clearly, we need large-scale, clinical, placebo-controlled, randomized studies, including long-term surveillance to document the evidence of this therapy and, eventually, to register BoNT-A for this indication.

A signaling network in phenylephrine-induced benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is an age-related disease of unknown etiology characterized by prostatic enlargement and coinciding with distinctive alterations in tissue histomorphology. To identify the molecular mechanisms underlying the development of BPH, we conducted a DNA microarray study using a previously described animal model in which chronic alpha(1)-adrenergic stimulation by repeated administration of phenylephrine evokes histomorphological changes in the rat prostate that resemble human BPH. Bioinformatic tools were applied to microarray data obtained from prostate tissue to construct a network model of potentially relevant signal transduction pathways. Significant involvement of inflammatory pathways was demonstrable, including evidence for activation of a TGF-beta signaling cascade. The heterodimeric protein clusterin (apolipoprotein J) was also identified as a prominent node in the network. Responsiveness of TGF-beta signaling and clusterin gene and protein expression were confirmed independently of the microarray data, verifying some components of the model. This is the first attempt to develop a comprehensive molecular network for histological BPH induced by adrenergic activation. The study also implicated clusterin as a novel biochemical target for therapy.

Stromal growth and epithelial cell proliferation in ventral prostates of liver X receptor knockout mice

With specific liver X receptor alpha and beta (LXRalpha and LXRbeta) antibodies, we found that LXRalpha is strongly expressed in the luminal and basal cells of prostatic epithelium. The ventral prostates (VP) of LXRalpha(-/-) mice are characterized by the presence of smooth-muscle actin-positive stromal overgrowth around the prostatic ducts and by numerous fibrous nodules pushing into the ducts and causing obstruction, so that most of the ducts were extremely dilated. BrdU labeling and Ki67 staining revealed epithelial and stromal proliferation in the fibrous nodules. However, the dense stroma surrounding the ducts was not positive for proliferation markers. There was no detectable difference between WT and LXRalpha(-/-) mice VP in the expression of the androgen receptor, but there was an increase in nuclear expression of Snail and Smad 2/3, indicating enhanced TGF-beta signaling. Upon treatment of WT mice for 3 months with the LXR agonist T2320 or for 3 weeks with beta-sitosterol, LXRalpha was downregulated, and a VP phenotype similar to that of LXRalpha(-/-) mice resulted. We conclude that in rodents, LXRalpha seems to control VP stromal growth and that LXRalpha(-/-) mice may be a useful model to study prostatic stromal hyperplasia. Because LXRalpha is expressed in the epithelium, the excessive stromal growth in LXRalpha(-/-) mice indicates that LXRalpha is essential for epithelial stromal communication.

The alpha1A-adrenoceptor gene is required for the alpha1L-adrenoceptor-mediated response in isolated preparations of the mouse prostate

BACKGROUND AND PURPOSE

This study investigated whether deletion of the alpha1A-adrenoceptor gene influences contractile responses of mouse prostate to noradrenaline. Responses of mouse prostate to noradrenaline are known to be mediated by alpha1L-adrenoceptors, which are thought to be a functional phenotype of alpha1A-adrenoceptor.

EXPERIMENTAL APPROACH

Prostate tissues from alpha1A-adrenoceptor knockout mice which were homozygous (alpha1A -/-) and heterozygous (alpha1A +/-) for the disrupted alpha1A-adrenoceptor gene, as well as wild-type (alpha1A +/+) littermates were mounted in glass-isolated organ baths. Electrical field stimulation of nerves and exogenous application of noradrenaline were used to investigate the effects of alpha1A-adrenoceptor disruption on prostate contractility.

KEY RESULTS

Frequency-response curves to electrical field stimulation (0.5 ms pulse duration, 60 V, 0.1-20 Hz) yielded frequency-dependent contractions. At frequencies of 10 and 20 Hz, prostates from alpha1A -/- mice elicited an approximately 30% decreased response compared with prostates from alpha(1A)+/+ mice. Prazosin (0.3 muM) attenuated responses to electrical field stimulation in prostates from alpha1A +/+ and alpha1A +/- mice but not from alpha1A -/- mice. Increasing concentrations of exogenously administered noradrenaline (10 nM-1 mM) produced mean concentration-response curves in prostates from alpha1A +/+ and alpha1A +/- mice, which were not different. Maximum responses to noradrenaline were decreased by approximately 80% in prostates from alpha1A -/- mice compared with alpha1A +/+ mice. Prazosin attenuated responses to noradrenaline in all genotypes.

CONCLUSIONS AND IMPLICATIONS

alpha1L-Adrenoceptor-mediated responses in mouse prostate are abolished in alpha1A -/- mice, demonstrating that the alpha1A-adrenoceptor gene is essential to the manifestation of the prostatic alpha1L-adrenoceptor phenotype. This implies that alpha1L-adrenoceptors are indeed a functional phenotype of alpha1A-adrenoceptor.

Intraprostatic Botulinum Toxin Type A Injection in Patients Unfit for Surgery Presenting with Refractory Urinary Retention and Benign Prostatic Enlargement. Effect on Prostate Volume and Micturition Resumption

OBJECTIVES

To evaluate the effect of intraprostatic injection of botulinum toxin A (BoNTA) on prostate volume and refractory urinary retention in patients with benign prostatic enlargement.

METHODS

Twenty-one men with benign prostatic enlargement on chronic indwelling catheter for at least 3 mo who were not candidates for surgery because of poor general condition received 200 U BoNTA in the transition zone by transrectal approach under ultrasound guidance. Patients were reevaluated at 1 and 3 mo posttreatment.

RESULTS

Patients had a mean age of 80+/-2 yr. Injections were done without anaesthetic support as an outpatient procedure. No significant local effects occurred. Baseline prostate volume of 70+/-10 ml decreased to 57+/-10 ml (p<0.0006) at 1 mo and to 47+/-7 ml (p=0.03 against 1 mo) at 3 mo. At 1 mo, 16 patients (76%) could resume voiding with a mean Qmax of 9.0+/-1.2 ml/s. At 3 mo, 17 patients (81%) voided with a mean Qmax of 10.3+/-1.4 ml/s. Residual urine was 80+/-19 ml and 92+/-24 ml at the two time points, respectively. Mean serum total PSA decreased from 6.0+/-1.1 ng/ml at baseline to 5.0+/-0.9 ng/ml at 3 mo (p=0.04).

CONCLUSIONS

BoNTA injection into the prostate swiftly reduces prostate volume and may be a promising treatment for refractory urinary retention in patients with benign prostatic enlargement who are unfit for surgery. Future studies will determine the duration of BoNTA effect.

Alpha1-, alpha2- and beta-adrenoceptors in the urinary bladder, urethra and prostate

1 We have systematically reviewed the presence, functional responses and regulation of alpha(1)-, alpha(2)- and beta-adrenoceptors in the bladder, urethra and prostate, with special emphasis on human tissues and receptor subtypes. 2 Alpha(1)-adrenoceptors are only poorly expressed and play a limited functional role in the detrusor. Alpha(1)-adrenoceptors, particularly their alpha(1A)-subtype, show a more pronounced expression and promote contraction of the bladder neck, urethra and prostate to enhance bladder outlet resistance, particularly in elderly men with enlarged prostates. Alpha(1)-adrenoceptor agonists are important in the treatment of symptoms of benign prostatic hyperplasia, but their beneficial effects may involve receptors within and outside the prostate. 3 Alpha(2)-adrenoceptors, mainly their alpha(2A)-subtype, are expressed in bladder, urethra and prostate. They mediate pre-junctional inhibition of neurotransmitter release and also a weak contractile effect in the urethra of some species, but not humans. Their overall post-junctional function in the lower urinary tract remains largely unclear. 4 Beta-adrenoceptors mediate relaxation of smooth muscle in the bladder, urethra and prostate. The available tools have limited the unequivocal identification of receptor subtypes at the protein and functional levels, but it appears that the beta(3)- and beta(2)-subtypes are important in the human bladder and urethra, respectively. Beta(3)-adrenoceptor agonists are promising drug candidates for the treatment of the overactive bladder. 5 We propose that the overall function of adrenoceptors in the lower urinary tract is to promote urinary continence. Further elucidation of the functional roles of their subtypes will help a better understanding of voiding dysfunction and its treatment.

The application of botulinum toxin in the prostate

PURPOSE

Botulinum neurotoxin is the most potent naturally occurring toxin known to inhibit various neurotransmitters. Injection of botulinum neurotoxin into the bladder and urethral sphincter has been used to treat bladder hyperactivity and sphincter dyssynergia. Recently botulinum neurotoxin application was extended to prostate disorders. Why would a urologist want to target the prostate?

MATERIALS AND METHODS

We reviewed the literature on the mechanisms of action and clinical efficacy of botulinum neurotoxin treatment of the prostate. In addition to our personal clinical experience and basic research, information was gathered from MEDLINE and published abstracts from international meetings. We also present basic research and discuss the potential mechanism of action of botulinum neurotoxin on the prostate.

RESULTS

There are 8 current peer reviewed publications on the injection of botulinum neurotoxin in the prostate. Cystoscopic transurethral or transperineal/transrectal ultrasound guided techniques have been used. Outcome improvement reported includes decreases in prostate size, prostate specific antigen and residual urine volume, and improvement in the flow rate and symptom score lasting 6 months or longer.

CONCLUSIONS

Botulinum toxin has demonstrated exciting and promising preliminary results for male lower urinary tract symptoms. Translational research suggests novel mechanism of action of botulinum toxin in the prostate for benign prostatic hyperplasia and chronic nonbacterial prostatitis. It may even be considered as adjuvant treatment for prostate cancer. The use of botulinum neurotoxin in the prostate is currently Food and Drug Administration off label and in support of evidence based medicine practices caution should be applied until larger, randomized clinical studies are completed. More basic research is needed to identify the mechanisms by which botulinum toxin affects the prostate.

The potential and promise of using botulinum toxin in the prostate gland

Botulinum neurotoxin (BoNT) has been called the 'most poisonous poison' and a potential bioterrorist weapon. However, it is possible to use the elegant and specific activity of this toxin to treat various medical conditions. Recently, the application of BoNT was extended to prostate disorders, and we review published reports on the mechanisms of action and clinical efficacy of BoNT in the prostate. The information was gathered from Medline, abstracts from recent urological meetings, and from personal experience. BoNT has shown promising preliminary results for male lower urinary tract symptoms, and translational research suggests a novel mechanism of action of BoNT in the prostate. Importantly, the application of BoNT in the prostate is not approved by the regulatory agencies and caution should be used until larger randomized clinical studies are completed.

Novel action of botulinum toxin on the stromal and epithelial components of the prostate gland

PURPOSE

Intraprostatic injection of BTX-A has demonstrated clinical improvement in men with bladder outlet obstruction. We investigated the mechanisms of action of BTX-A on the prostate.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were injected with varying doses of BTX-A into the prostate and the prostates were harvested after 1 or 2 weeks. The effects of BTX-A on prostate histology, and the proliferative and apoptotic indexes were determined using hematoxylin and eosin staining, proliferative cell nuclear antigen staining and TUNEL staining, respectively. Changes in alpha(1A) adrenergic receptor and androgen receptor were evaluated by Western blotting.

RESULTS

One week after BTX-A injection generalized prostate atrophy was observed. There was a significant increase in apoptotic cells (12, 16 and 22-fold), and decrease in proliferative cells (38%, 77% and 80%) and alpha(1A) adrenergic receptor (13%, 80% and 81%) for 5, 10 and 20 U, respectively. There was no significant change in androgen receptors. The effects were decreased 2 weeks after BTX-A treatment.

CONCLUSIONS

BTX-A injection into the prostate alters cellular dynamics by inducing apoptosis, inhibiting proliferation and down-regulating alpha(1A) adrenergic receptors. BTX-A may potentially be the drug that has dual actions on the static and dynamic components of benign prostatic hyperplasia.

Effect of D-004, a Lipid Extract from the Cuban Royal Palm Fruit, on Atypical Prostate Hyperplasia Induced by Phenylephrine in Rats

BACKGROUND AND OBJECTIVE

Benign prostatic hyperplasia (BPH) is a non-malignant enlargement of the prostate that results in obstructive lower urinary tract symptoms. Saw palmetto (Serenoa repens), the dwarf American palm (Arecaceae family), is commonly used to treat BPH. The Cuban royal palm (Roystonea regia) also belongs to the Arecaceae family, and 200-400mg of D-004, a lipid extract from its fruits, administered orally for 14 days has been shown to prevent testosterone- but not dihydrotestosterone-induced prostatic hyperplasia in rats. D-004 (125-250 microg/mL) added to preparations of rat vas deferens caused a marked, dose-dependent and significant inhibition of noradrenaline-induced smooth muscle contraction, a response mediated through alpha(1)-adrenoceptors, and was more effective in these respects than Saw palmetto. However, the in vivo effects of D-004 and Saw palmetto on the hypertensive response induced by noradrenaline were modest (albeit significant), and neither treatment affected resting blood pressure or heart rate in rats. The differential effects of D-004 in in vitro and in vivo models could be related to a differential affinity for adrenoceptor subtypes or to different bioavailabilities in vascular and urogenital targets. Phenylephrine injected into rodents induces prostatic hyperplasia with all the characteristic morphological changes of the condition but does not result in enlargement of the prostate. Therefore, this phenylephrine-induced change in rat prostate tissue is called atypical prostatic hyperplasia. It serves as an in vivo model of prostatic hyperplasia induced by stimulation of alpha(1)-adrenoceptors. The objective of this study was to determine whether D-004 can inhibit induction of atypical prostatic hyperplasia by phenylephrine in rats.

METHODS

Rats were randomly distributed into five groups (ten rats/group). One group was a negative control and received oral vehicle only. The other four groups were injected subcutaneously with phenylephrine (2 mg/kg): of these groups, one was a positive control receiving the vehicle, and the other three groups were treated with D-004 or Saw palmetto (both 400 mg/kg) or tamsulosin 0.4 mg/kg. All active treatments were given orally for 28 days. After completion of treatment, rats were placed unrestrained in metabolic cages and micturition studies were performed. The rats were later killed and their prostates removed and weighed. Prostate samples were processed for histological study, with histological changes being assessed according to a scoring system. Bodyweight was measured at baseline and at weekly intervals.

RESULTS

Histological examination of positive control rats revealed features of atypical prostatic hyperplasia, with piling-up, papillary and cribiform patterns and budding-out of epithelial cells. Micturition assessment revealed that phenylephrine significantly lowered both the total volume of urine in 1 hour and the volume per micturition; the latter was considered the main efficacy variable. D-004 and Saw palmetto extracts significantly prevented this reduction in volume per micturition by 70.5% and 68.6%, respectively, while tamsulosin totally abolished the reduction in micturition induced by phenylephrine (100% inhibition). Tamsulosin, D-004 and Saw palmetto significantly reduced the histological changes of atypical prostatic hyperplasia induced by phenylephrine by 73.1%, 61.2% and 50.0%, respectively.

CONCLUSIONS

Administration of D-004 resulted in marked and significant prevention of phenylephrine-induced impairment of micturition and histological changes in rat prostate. These findings indicate that, in vivo, D-004 effectively opposes these responses to phenylephrine, which are mediated through urogenital alpha(1)-adrenoceptors. In this respect, D-004 was moderately more effective than Saw palmetto, a phytotherapeutic standard used to treat BPH, but less effective than tamsulosin, a selective alpha(1A)-adrenoceptor antagonist.

Effect of neurokinins on canine prostate cell physiology

BACKGROUND

Sensory peptide neurotransmitters have been implicated as significant regulators of prostate growth. This study was designed to evaluate the role of neurokinins in proliferation, differentiation, and contraction of canine prostate cells in culture.

METHODS

NK1, NK2, and NK3 receptor subtypes were localized in canine prostate tissue by immunocytochemistry and ligand binding studies. Functional effects of neurokinin agonists were tested on cell differentiation (expression of smooth muscle actin (SMA)), proliferation (MTS assay), and contraction of canine prostate cells in culture.

RESULTS

Immunocytochemical staining of canine prostate sections revealed strong stromal staining for NK1 together with weak stromal staining for NK2 and even weaker staining for NK3. Furthermore, there was overlapping localization of NK1 receptors, substance P (SP), and calcitonin gene-regulated peptide (CGRP) in prostate tissue sections. SP caused concentration-dependent increase in SMA expression that was attenuated in a concentration-dependent manner by YM-44778, a non-selective antagonist for neurokinin receptors, but not by either the NK2 antagonist (SR-48968) nor by the NK3 antagonist (SB-223412). SP and neurokinin A (NKA) also caused a modest contraction of stromal cells in collagen gels. NKA stimulated proliferation of prostate epithelial cells without any apoptotic effect, which was attenuated by SR-48968. Surprisingly, in binding studies NK3 appeared to be the most abundant neurokinin receptor subtype, although functional studies failed to reveal significant coupling of this receptor.

CONCLUSIONS

Our results suggest that, at least in vitro, neurokinins have modest effects on canine prostate epithelial cell proliferation, stromal differentiation, and contraction.