Adiponectin enhances calcium dependency of mouse bladder contraction mediated by protein kinase Cα expression

Adiponectin signaling regulates urinary bladder function by blunting smooth muscle purinergic contractility

Lower urinary tract symptoms (LUTS) affect approximately 50% of the population over 40 years of age and are strongly associated with obesity and metabolic syndrome. Adipose tissue plays a key role in obesity/metabolic syndrome by releasing adipokines that regulate systemic energy/lipid metabolism, insulin resistance, and inflammation. Adiponectin (ADPN), the most abundant adipokine, modulates energy/metabolism homeostasis through its insulin-sensitizing and antiinflammatory effects. Human plasma ADPN levels are inversely associated with obesity and diabetes. To the best of our knowledge, the role of adipokines such as ADPN in the LUTS associated with obesity/metabolic syndrome remains unknown. We have tested such a possible role in a global ADPN-knockout (Adpn-/-) mouse model. Adpn-/- mice exhibited increased voiding frequency, small voids, and reduced bladder smooth muscle (BSM) contractility, with absence of purinergic contraction. Molecular examination indicated significantly altered metabolic and purinergic pathways. The ADPN receptor agonist AdipoRon was found to abolish acute BSM contraction. Intriguingly, both AMPK activators and inhibitors also abolished BSM purinergic contraction. These data indicate the important contribution of what we believe is a novel ADPN signaling pathway to the regulation of BSM contractility. Dysregulation of this ADPN signaling pathway might be an important mechanism leading to LUTS associated with obesity/metabolic syndrome.

Adiponectin Signaling Regulates Urinary Bladder Function by Blunting Smooth Muscle Purinergic Contractility

Lower urinary tract symptoms (LUTS) affect ∼ 50% of the population aged >40 years and are strongly associated with obesity and metabolic syndrome. Adipose tissue plays a key role in obesity/metabolic syndrome by releasing adipokines that regulate systemic energy/lipid metabolism, insulin resistance, and inflammation. Adiponectin (ADPN), the most abundant adipokine, modulates energy/metabolism homeostasis through its insulin-sensitizing and anti-inflammatory effects. Human plasma ADPN levels are inversely associated with obesity and diabetes. The role of adipokines such as ADPN in the LUTS associated with obesity/metabolic syndrome remains unknown. We have tested such a possible role in a global ADPN knockout mouse model ( Adpn -/- ). Adpn -/- mice exhibited increased voiding frequency, small voids, and reduced bladder smooth muscle (BSM) contractility with absence of purinergic contraction. Molecular examination indicated significantly altered metabolic and purinergic pathways. The ADPN receptor agonist AdipoRon was found to abolish acute BSM contraction. Intriguingly, both AMPK activators and inhibitors also abolished BSM purinergic contraction. These data indicate the important contribution of a novel ADPN signaling pathway to the regulation of BSM contractility. Dysregulation of this ADPN signaling pathway might be an important mechanism leading to LUTS associated with obesity/metabolic syndrome.

ARTICLE HIGHLIGHTS

Lower urinary tract symptom (LUTS) is strongly associated with obesity and metabolic syndrome, however, the underlying molecular mechanisms are missing. Dysregulation of adipokine signaling could be the link for this association.Whether adiponectin, the most abundant adipokine, plays a role in regulating bladder function and dysfunction.Mice null for adiponectin exhibited increased voiding frequency, small voids, and reduced bladder smooth muscle contractility, with corresponding metabolic and purinergic pathway changes.Dysregulation of adiponectin signaling might be an important mechanism leading to LUTS associated with obesity/metabolic syndrome.

Adiponectin can be a good predictor of urodynamic detrusor underactivity: a prospective study in men with lower urinary tract symptoms

PURPOSE

To investigate whether circulating adiponectin, which is considered a possible marker of anti-atherogenic effects, is a useful predictor of bladder function, especially detrusor underactivity (DU), in men with lower urinary tract symptoms (LUTS).

METHODS

A total of 130 treatment-naïve men with non-neurogenic LUTS were prospectively stratified into two groups (the DU and non-DU groups) based on the presence or absence of DU, where DU is defined as a bladder contractility index < 100 and bladder outlet obstruction index (BOOI) < 40. The impact of serum adiponectin levels on urodynamic function, including DU, was assessed using univariate, binomial logistic regression, and receiver operating characteristic (ROC) curve analyses.

RESULTS

In total, data from 118 men were analyzed; 39 (33.0%) had DU (DU group) and 79 (67.0%) did not have DU (non-DU group). The median serum adiponectin in the DU group was significantly lower than in the non-DU group (6.2 vs 12.6 µg/mL, p < 0.001). In the binomial logistic regression analysis, lower adiponectin, smaller intravesical prostatic protrusion, and lower bladder voiding efficiency were significant factors related to DU. In the ROC analyses, serum adiponectin had the highest area under the curve value for DU diagnosis (0.849). Additionally, a cutoff value of 7.9 µg/mL for serum adiponectin level was identified for DU, which yielded a sensitivity and specificity of 79% and 90%, respectively.

CONCLUSIONS

The serum adiponectin level was significantly associated with bladder function and may be a useful marker for predicting DU in men with LUTS.

Adiponectin levels in maternal serum and umbilical cord blood at birth by mode of delivery: relationship to anthropometric measurements and fetal sex

Background

The rate of cesarean section is increasing worldwide. Adiponectin is a hormone related to anti-inflammatory and anti-atherogenic effects; and it′s concentrations may change in response to inflammatory situations including surgical intervention. The aim of the current study was to investigate serum adiponectin levels in maternal and umbilical cord blood according to different modes of delivery and their relationship with anthropometric measurements and fetal sex.

Methods

The study population initially comprised 90 healthy pregnant women referred to the teaching hospital. Eventually, 40 participants in the vaginal delivery group and 35 subjects in the cesarean delivery group were recruited in to the study. Umbilical cord blood and maternal serum samples were analyzed according to the standard protocol from the manufacturer. The collected data were analyzed using SPSS-16 software. P-value < 0.05 was considered as the significance level for all tests.

Results

Our results indicated a significant association between maternal adiponectin and the mode of delivery, with adiponectin levels significantly higher in vaginal delivery compared to cesarean section (P < 0.001). However, no difference was found in umbilical cord blood adiponectin between the two groups (P = 0.51). A significant positive correlation was found between maternal serum adiponectin in the first day after birth and umbilical cord blood adiponectin in the vaginal delivery group (P = 0.007). Nevertheless, this correlation was not statistically significant in the cesarean delivery group (P = 0.62). There was also no significant correlation between fetal sex and anthropometric measurements with maternal adiponectin (P = 0.44) and umbilical cord blood adiponectin (P = 0.86).

Conclusions

The result of the current study revealed that maternal adiponectin concentration was significantly higher in vaginal delivery compared to cesarean section, which might be due to the increased levels of maternal adiponectin release during labor.

AdipoR-increased intracellular ROS promotes cPLA2 and COX-2 expressions via activation of PKC and p300 in adiponectin-stimulated human alveolar type II cells

Adiponectin, an adipokine, accumulated in lung system via T-cadherin after allergens/ozone challenge. However, the roles of adiponectin on lung pathologies were controversial. Here we reported that adiponectin stimulated expression of inflammatory proteins, cytosolic phospholipase A2 (cPLA2), cyclooxygenase-2 (COX-2), and production of reactive oxygen species (ROS) in human alveolar type II A549 cells. AdipoR1/2 involved in adiponectin-activated NADPH oxidase and mitochondria, which further promoted intracellular ROS accumulation. Protein kinase C (PKC) may involve an adiponectin-activated NADPH oxidase. Similarly, p300 phosphorylation and histone H4 acetylation occurred in adiponectin-challenged A549 cells. Moreover, adiponectin-upregulated cPLA2 and COX-2 expression was significantly abrogated by ROS scavenger (N-acetylcysteine) or the inhibitors of NADPH oxidase (apocynin), mitochondrial complex I (rotenone), PKC (Ro31-8220, Gö-6976, and rottlerin), and p300 (garcinol). Briefly, we reported that adiponectin stimulated cPLA2 and COX-2 expression via AdipoR1/2-dependent activation of PKC/NADPH oxidase/mitochondria resulting in ROS accumulation, p300 phosphorylation, and histone H4 acetylation. These results suggested that adiponectin promoted lung inflammation, resulting in exacerbation of pulmonary diseases via upregulating cPLA2 and COX-2 expression together with intracellular ROS production. Understanding the adiponectin signaling pathways on regulating cPLA2 and COX-2 may help develop therapeutic strategies on pulmonary diseases.

Regulation of urinary bladder function by protein kinase C in physiology and pathophysiology

BACKGROUND

Protein kinase C (PKC) is expressed in many tissues and organs including the urinary bladder, however, its role in bladder physiology and pathophysiology is still evolving. The aim of this review was to evaluate available evidence on the involvement of PKC in regulation of detrusor contractility, muscle tone of the bladder wall, spontaneous contractile activity and bladder function under physiological and pathophysiological conditions.

METHODS

This is a non-systematic review of the published literature which summarizes the available animal and human data on the role of PKC signaling in the urinary bladder under different physiological and pathophysiological conditions. A wide PubMed search was performed including the combination of the following keywords: "urinary bladder", "PKC", "detrusor contractility", "bladder smooth muscle", "detrusor relaxation", "peak force", "detrusor underactivity", "partial bladder outlet obstruction", "voltage-gated channels", "bladder nerves", "PKC inhibitors", "PKC activators". Retrieved articles were individually screened for the relevance to the topic of this review with 91 citations being selected and included in the data analysis.

DISCUSSION

Urinary bladder function includes the ability to store urine at low intravesical pressure followed by a subsequent release of bladder contents due to a rapid phasic contraction that is maintained long enough to ensure complete emptying. This review summarizes the current concepts regarding the potential contribution of PKC to contractility, physiological voiding, and related signaling mechanisms involved in the control of both the storage and emptying phases of the micturition cycle, and in dysfunctional voiding. Previous studies linked PKC activation exclusively with an increase in generation of the peak force of smooth muscle contraction, and maximum force generation in the lower urinary tract. More recent data suggests that PKC presents a broader range of effects on urinary bladder function including regulation of storage, emptying, excitability of the detrusor, and bladder innervation. In this review, we evaluated the mechanisms of peripheral and local regulation of PKC signaling in the urinary bladder, and their impact on different phases of the micturition cycle under physiological and pathophysiological conditions.

Effects of Moderate Alcohol Intake in the Bladder of the Otsuka Long Evans Tokushima Fatty Diabetic Rats

Diabetes is related with a number of cystopathic complications. However, there have been no studies about the influence of alcohol consumption in the bladder of type 2 diabetes. Thus, we investigated the effect of moderate alcohol intake in the bladder of the Otsuka Long Evans Tokushima Fatty (OLETF) diabetic rat. The non-diabetic Long-Evans Tokushima Otsuka (LETO, n=14) and the OLETF control group (n=14) were fed an isocaloric diet; the LETO (n=14) and the OLETF ethanol group (n=14) were fed 36% ethanol 7 g/kg/day. After ten weeks, muscarinic receptors, RhoGEFs, myogenic change, and the level of oxidative stress were evaluated. Moderate alcohol intake significantly decreased excessive muscarinic receptor and Rho kinase expressions in the OLETF rats compared with the LETO rats. In addition, iNOS and collagen expression were not changed in the OLETF rats in spite of alcohol consumption. Superoxide dismutase levels, which is involved in antioxidant defense, in the LETO rats were significantly decreased after alcohol consumption, however those in the OLETF rats were similar. Moderate alcohol consumption reduces the oxidative stress, and may prevent molecular and pathologic changes of the bladder of rats with type 2 diabetes.

A short review of adipokines, smooth muscle and uterine contractility

Obesity is a major health problem worldwide. The prevalence of obesity is increasing in both developed and developing countries. In the UK, for example, 60% of adults are overweight and 25% are obese. Obesity is associated with many pathological complications including respiratory, cardiovascular and endocrine, but it also affects fertility and is associated with many reproductive complications. This has led us and others to investigate links between women with high BMI, pregnancy outcome and uterine function. These studies in turn have led investigators to ask how obesity can have such an impact on reproduction and, as part of this, to consider the role of the adipokines released from adipose tissues. Our focus in this short review is on adipokines and myometrial activity, and for completeness we overview their effects on other smooth muscles. To date four adipokines (leptin, visfatin, apelin and ghrelin) have been investigated and all affect myometrial contractility, but some more potently than others. We consider the possible mechanisms involved in how adipokines may modify uterine contractility, and discuss the potential impact on labor and delivery.

Two types of overcontraction are involved in intrarenal artery dysfunction in type II diabetic mouse

Contractile responses in small intrarenal arteries are associated with diabetic nephropathy. However, the mechanisms that induce and maintain altered small vessel contraction are not clearly understood. To further understand intrarenal artery dysfunction in diabetes, phenylephrine (PE)-induced force development was assessed in the intrarenal artery [interlobar artery (ILA)] in control (lean) and type II diabetic (ob/ob) mice. PE-induced dose-dependent force development in the ILA was significantly greater in ob/ob mice than in lean mice (592.8 ± 5.2 and 770.1 ± 12.1 µ/mm tissue, respectively, following administration of 30 µM PE, n = 5). Under high-glucose conditions (twice the normal concentration of glucose), PE-induced force development in the ILA was only enhanced in ob/ob mice (946.0 ± 18.2 µN/mm tissue; n = 5). ILA dysfunction reduces blood flow to the glomerulus and may induce diabetic nephropathy. Basal overcontraction of the ILA in ob/ob mice under normal-glucose conditions was reduced by pretreatment with rottlerin, a calcium-independent protein kinase C (PKCδ) inhibitor. Total PKC activity was also reduced by rottlerin. Under high-glucose conditions, the enhanced ILA contraction in diabetic mice was suppressed by rho A and rho kinase inhibitors. Our results indicate two types of ILA dysfunction in diabetes, as follows: 1) a basal increase in PE-induced contraction under normal-glucose conditions, and 2) extracellular glucose-dependent enhancement of PE-induced contraction. We believe that these dysfunctions are mediated by the activation of the PKCδ and rho A-rho kinase pathways, respectively.