Food for Thought: Obesity as the Major Contributing Factor for Most Urological Disorders

Efficacy of resveratrol in male urogenital tract dysfunctions: an evaluation of pre-clinical data

Resveratrol is a polyphenol found naturally in fruits and plants. Recently, studies in humans and animal models have suggested beneficial properties of this polyphenol, such as improvements to metabolic and lipid profiles, along with antioxidant, anti-inflammatory and anti-proliferative effects. In the urogenital tract (UGT), resveratrol has also been tested clinically and experimentally as a therapeutic drug in several diseases; however, the translational efficacy of resveratrol, especially in UGT, is still a matter of debate. In the present review, we address the pre-clinical efficacy of resveratrol in UGT-related dysfunctions, focusing on lower urinary tract symptoms, non-cancerous prostatic disease (benign prostatic hyperplasia and prostatitis) and erectile dysfunction. In vitro studies indicate that resveratrol reduces inflammatory markers and oxidative stress, and improves endothelial function in UGT organs and cells isolated from humans and animals. Despite displaying low oral bioavailability, in vivo administration of resveratrol largely improves erectile dysfunction, benign prostatic hyperplasia, prostatitis and voiding impairments, as evidenced in different animal models. Resveratrol also acts as a microbiota modulator, which may explain some of its beneficial effects in vivo. In contrast to the large amount of pre-clinical data, there are insufficient clinical trials to establish resveratrol treatment efficacy in human UGT-related diseases. In summary, we provide an overview of the in vivo and in vitro efficacy of resveratrol in animal and human UGT dysfunctions, which may support future clinical trials.

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.

Influence of the periprostatic adipose tissue in obesity-associated mouse urethral dysfunction and oxidative stress: Effect of resveratrol treatment

Obese mice display overactive bladder (OAB) associated with impaired urethra smooth muscle (USM) function. In this study, we evaluated the role of the adipose tissue surrounding the urethra and prostate in obese mice (here referred as periprostatic adipose tissue; PPAT) to the USM dysfunction. Male C57BL6/JUnib mice fed with either a standard-chow or high-fat diet to induce obesity were used. In PPAT, histological analysis, and qPCR analysis for gp91phox, tumor necrosis factor-α (TNF-α) and superoxide dismutase (SOD) were conducted. In USM, concentration-response curves to contractile and relaxing agents, as well as measurements of reactive-oxygen species and nitric oxide (NO) levels were performed. The higher PPAT area in obese mice was accompanied by augmented gp91phox (NOX2) and TNF-α expressions, together with decreased SOD1 expression. In USM of obese group, the contractile responses to phenylephrine and vasopressin were increased, whereas the relaxations induced with glyceryl trinitrate were reduced. The reactive-oxygen species and NO levels in USM of obese mice were increased and decreased, respectively. A higher SOD expression was also detected in obese group whilst no changes in the gp91phox levels were observed. We next evaluated the effects of the antioxidant resveratrol (100 mg/kg/day, two-weeks, PO) in the functional alterations and NO levels of obese mice. Resveratrol treatment in obese mice reversed both the functional USM dysfunction and the reduced NO production. Our data show that PPAT exerts a local inflammatory response and increases oxidative stress that lead to urethral dysfunction. Resveratrol could be an auxiliary option to prevent obesity-associated urethral dysfunction.

Oxidative stress and its possible relation to lower urinary tract functional pathology

Oxidative stress is considered to reflect an imbalance between the systemic manifestation of reactive oxygen and nitrogen species (RONS) and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. RONS are not only harmful agents that cause oxidative damage in pathologies; they also have important roles as regulatory agents in a range of biological phenomena. They are normally generated as by-products of oxygen metabolism; however, environmental stressors (i.e., ultraviolet radiation, ionizing radiations, pollutants, heavy metal, and xenobiotics) contribute to greatly increase RONS production. Several antioxidants have been exploited in recent years for their actual or supposed beneficial effect against oxidative stress, but to date, none has been approved for any indication because they have not met the criteria of efficacy for drug approval. The present review discusses the concept of oxidative stress, how to measure it, how to prevent it, and its occurrence in different organ systems with special reference to the lower urinary tract.

Chronic treatment with resveratrol improves overactive bladder in obese mice via antioxidant activity

The objective of the present work was to evaluate whether oral intake with resveratrol ameliorates overactive bladder in high-fat fed mice. Male C57BL6 mice fed with standard chow or high-fat diet to induce obesity received a two-week therapy with resveratrol (100mg/kg, given as a daily gavage). Weight and metabolic profile, together with cystometry and in vitro bladder contractions were evaluated. Measurements of gp91phox and SOD1 mRNA expressions and reactive-oxygen species (ROS) in bladder tissues, and serum TBARS were performed. Obese mice exhibited increases in body weight and epididymal fat mass, which were significantly reduced by oral treatment with resveratrol. Cystometric study in obese mice showed increases in non-voiding contractions, post-voiding pressure and voiding frequency that were reversed by resveratrol treatment. Likewise, the in vitro bladder overactivity in response to electrical-field stimulation (80V, 1-32Hz) or carbachol (1nM to 10mM) were normalized by resveratrol. The gp91phox and SOD1 mRNA expressions in bladder tissues were markedly higher in obese mice compared with lean group. In addition, ROS levels in bladder tissues and serum lipid peroxidation (TBARS assay) were markedly higher in obese compared with lean mice, all of which were reduced by resveratrol treatment. In lean group, resveratrol had no effect in any parameter evaluated. Our results show that two-week therapy of obese mice with resveratrol reduces the systemic and bladder oxidative stress, and greatly ameliorated the cystometry alterations and in vitro bladder overactivity. Resveratrol treatment could be an option to prevent obesity-associated overactive bladder.

Soluble guanylyl cyclase (sGC) degradation and impairment of nitric oxide-mediated responses in urethra from obese mice: reversal by the sGC activator BAY 60-2770

Obesity has emerged as a major contributing risk factor for overactive bladder (OAB), but no study examined urethral smooth muscle (USM) dysfunction as a predisposing factor to obesity-induced OAB. This study investigated the USM relaxant machinery in obese mice and whether soluble guanylyl cyclase (sGC) activation with BAY 60-2770 [acid 4-({(4-carboxybutyl) [2-(5-fluoro-2-{[4-(trifluoromethyl) biphenyl-4-yl] methoxy} phenyl) ethyl] amino} methyl) benzoic] rescues the urethral reactivity through improvement of sGC-cGMP (cyclic guanosine monophosphate) signaling. Male C57BL/6 mice were fed for 12 weeks with a high-fat diet to induce obesity. Separate groups of animals were treated with BAY 60-2770 (1 mg/kg per day for 2 weeks). Functional assays and measurements of cGMP, reactive-oxygen species (ROS), and sGC protein expression in USM were determined. USM relaxations induced by NO (acidified sodium nitrite), NO donors (S-nitrosoglutathione and glyceryl trinitrate), and BAY 41-2272 [5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-pyrimidin-4-ylamine] (sGC stimulator) were markedly reduced in obese compared with lean mice. In contrast, USM relaxations induced by BAY 60-2770 (sGC activator) were 43% greater in obese mice (P < 0.05), which was accompanied by increases in cGMP levels. Oxidation of sGC with ODQ [1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one] (10 μM) potentiated BAY 60-2770-induced USM responses in the lean group. Long-term oral BAY 60-2770 administration fully prevented the impairment of USM relaxations in obese mice. Reactive-oxygen species (ROS) production was enhanced, but protein expression of β1 second guanylate cyclase subunit was reduced in USM from obese mice, both of which were restored by BAY 60-2770 treatment. In conclusion, impaired USM relaxation in obese mice is associated with ROS generation and down-regulation of sGC-cGMP signaling. Prevention of sGC degradation by BAY 60-2770 ameliorates the impairment of urethral relaxations in obese mice.