LPCAT4 Knockdown Alters Barrier Integrity and Cellular Bioenergetics in Human Urothelium.

Urothelium is a transitional, stratified epithelium that lines the lower urinary tract, providing a tight barrier to urine whilst retaining the capacity to stretch and rapidly resolve damage. The role of glycerophospholipids in urothelial barrier function is largely unknown, despite their importance in membrane structural integrity, protein complex assembly, and the master regulatory role of PPARγ in urothelial differentiation. We performed lipidomic and transcriptomic characterisation of urothelial differentiation, revealing a metabolic switch signature from fatty acid synthesis to lipid remodelling, including 5-fold upregulation of LPCAT4. LPCAT4 knockdown urothelial cultures exhibited an impaired proliferation rate but developed elevated trans-epithelial electrical resistances upon differentiation, associated with a reduced and delayed capacity to restitute barrier function after wounding. Specific reduction in 18:1 PC fatty acyl chains upon knockdown was consistent with LPCAT4 specificity, but was unlikely to elicit broad barrier function changes. However, transcriptomic analysis of LPCAT4 knockdown supported an LPC-induced reduction in DAG availability, predicted to limit PKC activity, and TSPO abundance, predicted to limit endogenous ATP. These phenotypes were confirmed by PKC and TSPO inhibition. Together, these data suggest an integral role for lipid mediators in urothelial barrier function and highlight the strength of combined lipidomic and transcriptomic analyses for characterising tissue homeostasis.

EP2 and EP3 receptors as therapeutic targets for underactive bladder/detrusor underactivity due to diabetic cystopathy in a type 1 diabetic rat model.

OBJECTIVES: Diabetic cystopathy (DC) is recognized as one of the major etiologies of underactive bladder (UAB)/detrusor underactivity (DU). Although DC was first reported about three decades ago, there is a distinct lack of effective pharmacological management methods for UAB/DU due to DC with a robust certainty of evidence. In this study, we investigated whether EP2 and EP3 receptors are promising targets of pharmacological management of UAB/DU due to DC. METHODS: We used streptozotocin (STZ)-induced diabetic Sprague-Dawley rats with postvoid residual urine (PVR) greater than 0.1 mL. Sixteen weeks after induction of diabetes, we performed awake single cystometry after oral administration of the vehicle, an α-blocker (tamsulosin [TAM], 0.1 and 0.3 mg/kg), a cholinesterase inhibitor (distigmine [DIS], 0.3 and 1.0 mg/kg), or an EP2/3 dual agonist (ONO-8055, 0.01 and 0.03 mg/kg). We compared cystometric parameters after administration of the vehicle and drugs using a paired t test. P < .05 was considered to be statistically significant. RESULTS: Compared with the vehicle, TAM significantly decreased maximum intravesical pressure during voiding (Pmax), while DIS significantly increased it. However, neither drug significantly affected PVR or the residual urine rate (RUR). On the other hand, ONO-8055 significantly decreased PVR and tended to decrease RUR, although it did not significantly affect Pmax. CONCLUSION: The present study was unable to demonstrate that stimulation of EP2 and EP3 receptors caused major improvements in UAB/DU due to DC. However, this equivocal result could arise from inherent limitations of the STZ-induced diabetic rat as a UAB/DU model.

Effects of an EP2 and EP3 Receptor Dual Agonist, ONO-8055, on a Radical Hysterectomy-Induced Underactive Bladder Model in Monkeys.

OBJECTIVES: The objective was to develop an underactive bladder (UAB) model in primates and to evaluate the potential of prostanoid EP2 and EP3 receptor dual agonist ONO-8055 to become a therapeutic agent for UAB. METHODS: A surgical procedure resembling radical hysterectomy was performed on female cynomolgus monkeys. Subsequently, in vitro muscle strip studies were performed using bladder muscle strips from normal monkeys and monkeys that underwent surgery. In addition, uroflowmetric data were obtained at specified days after the surgery. To evaluate the effects of ONO-8055 and distigmine (DIS) on voiding function in the UAB monkey model, uroflowmetry was performed approximately 1 week after the surgery, before and after the cumulative intravenous administration of the compounds at 2 h intervals. RESULTS: In the bladder muscle strip studies, the responses to potassium chloride at 2 months, and carbachol and electrical field stimulation from 2 weeks decreased significantly. Voided volume (VV), maximum flow rate (Qmax), and average flow rate (Qave) decreased after surgery, while voiding time (VT) increased. In this model, ONO-8055 and DIS significantly increased VV and Qmax. DIS prolonged VT, while ONO-8055 had no effect. The results also showed that ONO-8055 increased Qave. CONCLUSIONS: We developed a neurogenic UAB model in primates. As ONO-8055 improved voiding function in this model to at least the same degree as DIS, this EP2 and EP3 receptor dual agonist has the potential to be a candidate for neurogenic UAB pharmacotherapy.

Inhibitory effects of retigabine, a Kv7 channel activator, on mechanosensitive primary bladder afferent activities and nociceptive behaviors in rats.

AIMS: Kv7 voltage-gated potassium channels have been suggested to modulate mechano-afferent transduction and nociception in the bladder. We investigated the effects of retigabine, a Kv7 channel activator, on rhythmic bladder contractions (RBCs), and single-unit afferent activities (SAAs) of the primary bladder mechanosensitive afferent nerve fibers in urethane-anesthetized rats. In addition, the effects of pretreatment with retigabine on the nociceptive behaviors provoked by an intravesical instillation of resiniferatoxin (RTX) were evaluated in the conscious condition. METHODS: Female Sprague-Dawley rats were used. Under urethane anesthesia, saline was instilled into the bladder until RBCs were induced reproducibly. Then, the effects of intravenous, cumulative administrations of retigabine (0.1-3 mg/kg) or vehicle (saline) on RBCs were assessed. In separate animals, SAAs of Aδ- and C-fibers were identified by electrical stimulation of the pelvic nerve and by bladder distention with saline. After baseline recording, vehicle or retigabine (0.01-1 mg/kg) was administered intravenously and further recordings were performed. Under pretreatment with vehicle or retigabine (3 mg/kg intraperitoneally), the frequencies of lower abdominal licking and freezing were counted and scored as the bladder nociceptive behaviors induced by intravesical RTX instillation (3 µM, 0.3 ml). RESULTS: Retigabine dose-dependently decreased both the frequency and the amplitude of RBCs and SAAs of both Aδ- and C-fibers. The effect on RBCs was more potent on the frequency than the amplitude. Retigabine inhibited the RTX-induced abdominal licking, but not freezing. CONCLUSION: Kv7 channels are likely to be implicated in inhibition of bladder mechano- and nociceptive sensory transduction. Neurourol. Urodynam. 36:280-285, 2017. © 2015 Wiley Periodicals, Inc.

Promising Effects of a Novel EP2 and EP3 Receptor Dual Agonist, ONO-8055, on Neurogenic Underactive Bladder in a Rat Lumbar Canal Stenosis Model.

PURPOSE: We investigated whether the novel EP (prostaglandin E2) receptor agonist ONO-8055 would improve the lower urinary tract dysfunction of neurogenic underactive bladder in a rat lumbar spinal canal stenosis model. MATERIALS AND METHODS: First, we studied the agonistic effect of ONO-8055 on EP receptors in EP receptor expressing CHO (Chinese hamster ovary) cells using the increase in the intracellular calcium level and intracellular cAMP (cyclic adenosine monophosphate) production as indicators of receptor activation. The effects of ONO-8055 on bladder and urethral strips from normal rats were then investigated. Finally, the effects of ONO-8055 on bladder and urethral function in rats with lumbar spinal canal stenosis were evaluated by awake cystometry and intraurethral perfusion pressure, respectively. The effects of tamsulosin and distigmine on urethral pressure were also evaluated. RESULTS: ONO-8055 is a highly potent and selective agonist for EP2 and EP3 receptors on CHO cells. While this compound contracted bladder strips, it relaxed urethral strips. Awake cystometry showed that ONO-8055 significantly decreased bladder capacity, post-void residual urine and voiding pressure. Compared with vehicle, tamsulosin and ONO-8055 significantly decreased urethral pressure. CONCLUSIONS: ONO-8055 decreased post-void residual urine, probably by decreasing bladder capacity. The decrease in voiding pressure probably resulted from the lowered urethral pressure due to relaxation of the urethra. Thus, the novel EP2 and EP3 receptor dual agonist ONO-8055 has the potential to improve neurogenic underactive bladder.

Effects of α1 antagonist and cholinesterase inhibitor on cystometric parameters in lumbar canal stenosis rats with underactive bladder.

OBJECTIVE: To examine the lower urinary tract function of a rat lumbar canal stenosis (LCS) model by in vivo cystometry before and after α1 adrenoceptor antagonist or cholinesterase inhibitor administration. MATERIALS AND METHODS: One small hole was drilled at the fifth lumbar vertebral arch, and a rectangular piece of silicone rubber was inserted into the L5-L6 epidural space. Two weeks after the surgery, awake cystometry was performed before and after the oral administration of the vehicle, tamsulosin (TAM, 0.03 and 0.1 mg/kg), or distigmine (DIS, 0.3 and 1 mg/kg). We compared the awake cystometry parameters before and after drug administration. RESULTS: The LCS rats showed a large maximum cystometric capacity (MCC) and a high residual urine rate with a lower maximum bladder pressure during micturition (Pmax). TAM and DIS significantly decreased the pressure at the onset of voiding contraction, MCC, and postvoid residual urine volume. Residual urine rate was also significantly decreased by DIS at 0.3 and 1.0 mg/kg, and TAM at 0.03 mg/kg. DIS significantly increased the frequency of nonvoiding contractions per minute. Pmax was not significantly different even after administration of DIS. CONCLUSION: The LCS rats had salient characteristics of severe infra-sacral neuropathic bladder dysfunction. TAM and DIS decreased postvoid residual urine volume, but this decrease was not accompanied by an increased Pmax or increased voided volume. Rather, decreased MCC was a possible contributing factor. Moreover, increased nonvoiding contractions after administration of DIS might participate in the decreased MCC. This novel model will be useful in studying the pharmacotherapy of the underactive bladder.

A novel animal model of underactive bladder: analysis of lower urinary tract function in a rat lumbar canal stenosis model.

AIMS: An animal model of neurogenic underactive bladder (UAB) has not been established. It was reported that a rat lumbar spinal canal stenosis (LCS) model created by cauda equina compression manifested intermittent claudication and allodynia. In this study, we examined the lower urinary tract function of the rat LCS model. METHODS: One small hole was drilled at the fifth lumbar vertebral arch (sham), and a rectangular piece of silicone rubber was inserted into the L5-L6 epidural space (LCS). Before and after surgery, a metabolic cage study was performed. After surgery, awake cystometry (CMG) and an in vitro muscle strip study were performed. Bladder morphology was evaluated by hematoxylin and eosin staining. RESULTS: The LCS rats showed a significant decrease in voided volume and a significant increase in postvoid residual volume and residual urine rate compared with Sham rats. CMG showed that the postvoid residual urine volume and numbers of non-voiding contractions significantly increased, while the voided volume, threshold pressure, and maximum intravesical pressure during voiding significantly decreased. There were no significant differences between sham and LCS rats in response to carbachol. In contrast, there was a significant increase in response to field stimulation, especially at lower frequencies, in LCS rats. LCS rats showed no obvious difference in detrusor morphology. CONCLUSIONS: This rat model requires a relatively simple surgical procedure and has characteristics of neurogenic UAB. It seems to be useful in the pathophysiological elucidation of UAB and might have potential for assessment of pharmacotherapy of UAB.

Isolation, identification, and structure of a potent alkyl-peroxyl radical scavenger in crude canola oil, canolol.

Alkylhydroperoxides in oxidized oil are undesirable components because they become alkylperoxyl radicals (ROO*) in the presence of heme, hemoglobin, or myoglobin in red meat. ROO* are biochemically reactive and damage nucleic acids and proteins, thereby harming living cells. We isolated a component, a highly potent ROO* scavenger, from crude canola oil (rapeseed), which we designated canolol, and identified its chemical structure, 4-vinyl-2,6-dimethoxyphenol. The canolol content of crude canola oil greatly increased after the seed was roasted as compared with that from unroasted seed, but it decreased in highly purified oil. This anti-ROO* activity was highest in crude oil, deceased after each refining step, and was lowest in highly purified refined oil. Canolol was thus generated during roasting. As shown previously, canolol is one of the most potent anti-ROO* components in crude canola oil and its potency is much greater than that of well-known antioxidants, including alpha-tocopherol, vitamin C, beta-carotene, rutin, and quercetin.