Marcus model-based analysis of the photo-quenching mechanism of a boronic acid fluorophore: water concentration dependence of electron transfer rate.

The photo-quenching mechanism of 2-(4-phenylboronic acid)-1-pyrenemethamide (C1-APB), which has potential application as a saccharide-recognition sensor, was investigated. By performing temperature-dependent time-resolved photoluminescence measurements, we determined the mechanism responsible for the photo-quenching properties of C1-APB to be a photoinduced electron transfer (PET). Moreover, the dependence of the electron transfer rate (kPET) on the solvent water concentration was explored in detail, and it was found that kPET increased by many orders of magnitude with increasing water concentrations. This phenomenon was analyzed using the Marcus model, in which the electron transfer can be represented by a potential diagram involving the potential barrier (ΔGa) and frequency factor (A). With the aid of temperature-dependent measurements, the contribution of ΔGa and A to the increase in kPET was successfully analyzed independently, which allowed us to discuss the effect of water molecule orientation and change in molecular structure of C1-APB. The temperature-dependence measurements performed in this study offer a powerful research tool for investigating the PET process, and will contribute to the development of molecular recognition fluorescent sensors.

[Experimental rodent models of chronic prostatitis: effect of phosphodiesterase 5 inhibitor on chronic pelvic-pain-related behavior].

Chronic prostatitis / chronic pelvic pain syndrome (CP/CPPS) is commonly diagnosed in men younger than 50 years old. It is characterized by pelvic pain, voiding symptoms and sexual dysfunction. The considerable discomfort or pain experienced has a negative impact on the quality of life of patients and is a huge economic burden because of the high recurrence rate and the low cure rate. Appropriate animal models are essential for the development of new drugs for the treatment of CP/CPPS, and several rodent models induced by different methods and over different time frames have been established. This article reviews studies of three in vivo rodent models of prostatitis, namely, chemical-induced, autoimmune-induced and hormone-associated models reported by us and other investigators. Recent clinical investigation has suggested that tadalafil improves the International Prostatic Symptom Score and the total National Institutes of Health Chronic Prostatitis Symptom Index score of patients with benign prostatic hyperplasia with CP/CPPS, which enables us to investigate the effect of tadalafil on the pelvic-pain-related behavior and prostatic inflammation in two of these prostatitis model types, experimental autoimmune prostatitis (EAP) and hormone/castration-induced prostatitis (HCP). Both models showed the pelvic-pain-related behavior and prostatic inflammation that are characteristic of chronic prostatitis. In EAP, tadalafil suppressed both the pelvic-pain-related behavior and the prostatic inflammation. In HCP, tadalafil suppressed the pelvic-pain-related behavior. These results mimic the clinical findings. Therefore EAP and HCP are suitable for the evaluation of the potency of drugs for the treatment of CP/CPPS.

Comparison of the Effects of Tadalafil and α1-Adrenoceptor Antagonists on Spontaneous Seminal Emission and Electrical Field Stimulation-Induced Seminal Vesicle Contraction in Rats.

BACKGROUND: Although numerous reports have shown that α1-adrenoceptor (α1-AR) antagonists, which are used to treat benign prostatic hyperplasia (BPH), can cause ejaculatory disorders, few studies have investigated whether the phosphodiesterase 5 (PDE5) inhibitor tadalafil has such adverse effects. In this study, we compared the effects of tadalafil and α1-AR antagonists on seminal emission and their mechanisms of action. AIM: To evaluate in normal rats the possible effects of tadalafil on spontaneous seminal emission (SSE) and seminal contraction evoked by hypogastric nerve stimulation. METHODS: Male Sprague-Dawley rats were used. To assess SSE, plastic corsets were fitted around the thorax and upper abdomen of male Sprague-Dawley rats to prevent genital autogrooming. Rats were treated orally with tadalafil or an α1-AR antagonist (silodosin, naftopidil, or tamsulosin) for 3 days and housed in wire-bottomed cages. Ejaculatory plugs dropped on the bottoms of the cages were counted and weighed. To assess the intraluminal pressure of seminal vesicles, the hypogastric nerve of urethane-anesthetized rats was isolated and electrically stimulated. After stabilization of seminal vesicle contraction, the rats were intravenously administered test drugs. The expression of PDE5, endothelial nitric oxide synthetase (eNOS), and neuronal NOS (nNOS) in the seminal vesicle and vas deferens were measured by reverse-transcription polymerase chain reaction. MAIN OUTCOME MEASURE: The number and weight of the ejaculatory plugs produced by corset-fitted rats and the intraluminal pressure of the seminal vesicle were evaluated. RESULTS: Tadalafil did not affect the number or weight of the ejaculatory plugs of corset-fitted rats, whereas all α1-AR antagonists decreased both in a dose-dependent manner. The α1-AR antagonists, but not tadalafil, inhibited the seminal vesicle contraction evoked by electrical stimulation of the hypogastric nerve. The seminal vesicle and vas deferens expressed higher levels of PDE5 and eNOS mRNA and lower levels of nNOS mRNA relative to the urethra. CLINICAL IMPLICATIONS: Tadalafil can be a treatment option in cases where there is concern about negative effects on seminal emission. STRENGTHS AND LIMITATIONS: We demonstrated different effects of tadalafil and 3 α1-AR antagonists on rat SSE and their mechanisms of action by measuring seminal vesicle contractility in vivo. A limitation is that we used normal rats, not BPH model rats, and so our results might not apply to human BPH patients. CONCLUSION: Tadalafil did not inhibit spontaneous seminal emission or electrical field stimulation-induced seminal vesicle contraction in normal rats. The NO-cyclic guanosine monophosphate pathway is unlikely to be involved in the inhibition of seminal vesicle contraction in normal rats. Yoshinaga R, Fukui T, Yoshifuji M, et al. Comparison of the Effects of Tadalafil and α1-Adrenoceptor Antagonists on Spontaneous Seminal Emission and Electrical Field Stimulation-Induced Seminal Vesicle Contraction in Rats. J Sex Med 2019;16:680-690.

Effects of the phosphodiesterase 5 inhibitor Tadalafil on bladder function in a rat model of partial bladder outlet obstruction.

AIMS: To investigate the effect of the phosphodiesterase 5 (PDE5) inhibitor Tadalafil on bladder blood flow and bladder function in a rat model of partial bladder outlet obstruction (BOO). METHODS: Female 14-15-week-old Sprague-Dawley rats were divided into three groups. BOO was surgically induced in rats by placing a rubber ring around the urethra. BOO rats were administered daily oral Tadalafil (BOO-Tadalafil) or vehicle (BOO-Vehicle), while sham-operated animals were treated with vehicle (Sham). On the 14th day after surgery, micturition behavior was recorded for 24 hr by using a metabolic cage. On the 15th day after surgery, bladder blood flow and bladder weight were measured. The expression of PDE5 mRNA in the vesical and iliac arteries of intact rats was measured by reverse transcriptase-polymerase chain reaction. RESULTS: BOO led to a significant decrease in bladder blood flow and a significant increase in bladder weight. These changes were partially suppressed by Tadalafil treatment. The number of micturitions in the BOO group was significantly increased and the average micturition volume was significantly decreased, without affecting the total micturition volume. Repeated Tadalafil treatment markedly inhibited the increase in micturition frequency and the decrease in average micturition volume. PDE5 mRNA was expressed in the vesical and iliac arteries. CONCLUSION: Tadalafil suppressed the reduction in bladder blood flow caused by BOO in rats and improved urinary function. This action of Tadalafil may contribute to its amelioration of bladder function. Neurourol. Urodynam. 35:444-449, 2016. © 2015 Wiley Periodicals, Inc.

Effect of a single treatment with tadalafil on blood flow in lower urinary tract tissues in rat models of bladder overdistension/emptying and abdominal aorta clamping/release.

Impaired blood flow in lower urinary tract (LUT) tissues is a pathophysiological cause of LUT symptoms. We investigated the effects of the phosphodiesterase 5 (PDE5) inhibitor tadalafil on the sustained decrease in bladder blood flow (BBF) and time-dependent changes in BBF and prostate blood flow (PBF) resulting from ischemia/reperfusion in two rat models. In a rat model of bladder overdistension/emptying (O/E), the bladder was overdistended by saline infusion and emptied after 2h. Tadalafil was administered intraduodenally immediately after emptying. In a rat model of clamping/release (C/R), the abdominal aorta was clamped for 2h after a single oral dose of tadalafil and then the clamp was released. BBF in O/E and C/R rats and PBF in C/R rats were measured by laser Doppler flow imaging. BBF decreased on overdistension and partially recovered after emptying. A progressive decrease in BBF was observed after O/E, and this was prevented by tadalafil treatment. Both BBF and PBF decreased during clamping of the abdominal aorta and partially recovered after clamp removal. Oral pretreatment with tadalafil partially or completely prevented the decreases in BBF and PBF not only after clamp removal but also during clamping. PDE5 mRNA was highly expressed in the bladder and the supporting vasculature. Tadalafil inhibited the O/E-induced decrease in BBF and the C/R-induced time-dependent decreases in BBF and PBF. PDE5 inhibition by tadalafil may improve both BBF and PBF.

Transcription factor IRF5 drives P2X4R+-reactive microglia gating neuropathic pain.

In response to neuronal injury or disease, microglia adopt distinct reactive phenotypes via the expression of different sets of genes. Spinal microglia expressing the purinergic P2X4 receptor (P2X4R) after peripheral nerve injury (PNI) are implicated in neuropathic pain. Here we show that interferon regulatory factor-5 (IRF5), which is induced in spinal microglia after PNI, is responsible for direct transcriptional control of P2X4R. Upon stimulation of microglia by fibronectin, IRF5 induced de novo expression of P2X4R by directly binding to the promoter region of the P2rx4 gene. Mice lacking Irf5 did not upregulate spinal P2X4R after PNI, and also exhibited substantial resistance to pain hypersensitivity. Furthermore, we found that expression of IRF5 in microglia is regulated by IRF8. Thus, an IRF8-IRF5 transcriptional axis may contribute to shifting spinal microglia toward a P2X4R-expressing reactive state after PNI. These results may provide a new target for treating neuropathic pain.

IRF8 is a critical transcription factor for transforming microglia into a reactive phenotype.

Microglia become activated by multiple types of damage in the nervous system and play essential roles in neuronal pathologies. However, how microglia transform into reactive phenotypes is poorly understood. Here, we identify the transcription factor interferon regulatory factor 8 (IRF8) as a critical regulator of reactive microglia. Within the spinal cord, IRF8 expression was normally low; however, the expression was markedly upregulated in microglia, but not in neurons or astrocytes, after peripheral nerve injury (PNI). IRF8 overexpression in cultured microglia promoted the transcription of genes associated with reactive states; conversely, IRF8 deficiency prevented these gene expressions in the spinal cord following PNI. Furthermore, IRF8-deficient mice were resistant to neuropathic pain, a common sequela of PNI, and transferring IRF8-overexpressing microglia spinally to normal mice produced pain. Therefore, IRF8 may activate a program of gene expression that transforms microglia into a reactive phenotype. Our findings provide a newly observed mechanism for microglial activation.