Selective Β3-adrenoceptor Agonist Research Articles

Safety and Effectiveness of Vibegron in Japanese Patients With Overactive Bladder: A Japanese Postmarketing Survey.

To evaluate the safety and effectiveness of vibegron, a highly selective β3-adrenoceptor agonist, in Japanese patients with overactive bladder (OAB) in a real-world clinical setting. This prospective survey was conducted from August 2019 to July 2023 using a central registration method. Patients newly treated with vibegron for OAB were followed for 12 weeks, and those who continued treatment were observed for up to 52 weeks. Adverse drug reactions (ADRs) and the overall improvement level were assessed, and overactive bladder symptom score (OABSS) and International Prostate Symptom Score-Quality of Life (IPSS QOL) score were collected. Of the 1848 patients in the safety analysis set, 154 ADRs were reported in 141 patients (7.63%). Common ADRs were increased residual urine volume (1.30%), constipation (1.14%), dysuria and urinary retention (0.97% each), cystitis (0.65%), and dry mouth (0.32%). The incidence of urinary retention-related adverse events (AEs) was higher in male patients, patients ≥ 65 years old, and patients with benign prostatic hyperplasia. The effectiveness rate was 88.8% among the 1561 patients in the effectiveness analysis set. Significant improvement in both OABSS and IPSS QOL scores was observed at all observation periods. The rate of achieving the minimal clinically important change in OABSS total score at the final evaluation was 75.35%. OABSS scores were also significantly reduced in all subgroup analyses. This survey found no major concerns regarding the safety and effectiveness of vibegron in Japanese OAB patients, except for urinary retention-related AEs. Vibegron is considered to represent a useful drug for treating OAB symptoms in a real-world clinical setting.

Comparative Study Between Behavior Therapy and Behavior Therapy Plus Mirabegron 50 mg in Sexually Active Men With Bothersome Overactive Bladder Symptoms - A Multicenter, Randomized Study.

We evaluated the therapeutic effects on overactive bladder (OAB) symptoms and sexual function of behavioral therapy with or without mirabegron in sexually active male patients with OAB. Mirabegron, a selective β3 adrenoceptor agonist for the treatment of OAB, has been shown to induce corpus cavernosum relaxation. In this 4-site, randomized controlled trial, 150 sexually active men with OAB were enrolled between June 2020 and May 2022. Participants were randomly allocated (1:2) into 2 treatment groups: (1) behavioral therapy alone (n = 50) and (2) a combination of mirabegron 50 mg daily and behavioral therapy (n = 100). The evaluation was based on the overactive bladder symptoms score (OABSS), the International Index of Erectile Function, the ejaculatory domain short form, the International Prostate Symptom Score, patient perception of bladder condition, quality of life, and urodynamic parameters. The therapeutic outcomes were assessed at baseline, 4 weeks, and 12 weeks. There were 65 patients (65%) in the combination subgroup and 36 patients in the behavioral therapy who completed all 12 weeks of treatment. Both groups had a statistically significant improvement in OABSS after 12 weeks of treatment. The combination therapy group achieved a statistically significant improvement in all 4 subscores of OABSS, however, the urinary frequency (P = 0.120) and urinary incontinence (P = 0.234) subscores in the behavioral therapy only group did not show a significant change. Additionally, the combination group had a significant improvement in functional bladder capacity, which was not seen in the behavioral therapy group. However, both groups did not have a significant change in erectile or ejaculatory function. Behavioral therapy combined with mirabegron had more significant impact on the improvement of OAB than behavior therapy alone. However, both groups did not have significant changes in erectile or ejaculatory function.

MTORC1 inhibition uncouples lipolysis and thermogenesis in white adipose tissue to contribute to alcoholic liver disease.

Adipose tissue thermogenic activities use fatty acids from lipolysis for heat generation. Therefore, a tight coupling between lipolysis and thermogenesis is physiologically imperative in maintaining not only body temperature but also lipids homeostasis. Adipose tissue dysfunction contributes to alcoholic liver disease (ALD). Here, studies were conducted to examine how alcohol intake affects adipose tissue thermogenic activities and whether altered adipose tissue thermogenesis contributes to ALD. Both the Lieber-DeCarli and the NIAAA mouse models of ALD were used. Denervation surgery in epididymal fat pads was performed. CL316,243, a selective β3-adrenoceptor agonist, SR59230A, a selective β3 adrenoceptor (ADRB3) antagonist, and rapamycin, a selective mechanistic target of rapamycin complex 1 (mTORC1) inhibitor, were administrated through i.p. injection. Adipocyte-specific Prdm16 knockout mice were subjected to alcohol-containing diet chronically. Chronic alcohol consumption, which enhances adipose tissue lipolysis, inhibits thermogenic activities of beige adipocytes in inguinal white adipose tissue (WAT), leading to an uncoupling status between lipolysis and thermogenesis in WAT at both basal and ADRB3 stimulation states. CL316,243 administration exacerbates liver pathologies of ALD. Alcohol intake inhibits mTORC1 activities in WAT. In mice, mTORC1 inhibition by rapamycin inhibits the thermogenesis of iWAT, whereas enhancing WAT lipolysis. Further investigations using adipocyte-specific Prdm16 knockout mice revealed that functional deficiency of beige adipocytes aggravates liver pathologies of ALD, suggesting that the inhibitory effect of alcohol on WAT browning/thermogenesis contributes to ALD pathogenesis. Chronic alcohol consumption induces an "uncoupling status" between lipolysis and browning/thermogenesis in WAT by inhibiting mTORC1 activation. Diminished WAT browning/thermogenesis, concomitant with enhanced lipolysis, contributes to ALD pathogenesis.

Development of a New Process for Tulobuterol Hydrochloride

AbstractTulobuterol is a selective β2-adrenoceptor agonist and has been widely utilized as a therapeutic agent for the treatment of asthma. Synthesis of tulobuterol has achieved many important progresses over the past decades and has gradually become one of the research hotspots in organic chemistry. This study aimed to explore a novel synthesis route to synthesize tulobuterol hydrochloride (1), an active ingredient of Chlobamolie Hydrochloride Tablets. In the study, 1 was obtained from the cost-effective, commercially available 2-chloroacetophenone through the key steps including the reactions of bromination, NaBH4 reduction, and amination. Process-related impurities were also investigated. 1 was obtained with excellent purity (99.96%) in 53% overall yield without the need for chromatographic purification. The developed method is green, facile, and cost-effective; thus, it is suitable for the industrial-scale production of 1.

β3 adrenoceptor agonist mirabegron protects against right ventricular remodeling and drives Drp1 inhibition.

The right ventricular (RV) function determines the prognosis of patients with pulmonary hypertension (PH). Metabolic disorders have been observed in the RV myocardium in PH. Activation of the β3 adrenoceptor improves cardiac function and restores cardiac metabolic efficiency in rodents with heart failure; however, its role in the RV remains uncertain. Experimental PH was induced by monocrotaline (MCT) in rats. Mirabegron, a selective β3 adrenoceptor agonist, was given to MCT rats daily from the day after MCT injection at the dose of 10 mg/kg. In vivo echocardiography and RV catheterization were performed to assess RV hemodynamics, structure, and function. RV fibrosis and hypertrophy were assessed by Sirius Red (SR) and wheat germ agglutinin (WGA) staining respectively. Western blotting was performed to examine the markers of RV fibrosis and hypertrophy, as well as the levels of the key molecules and their phosphorylated forms. The molecular changes were confirmed in the cardiac hypertrophy model of angiotensin II (Ang II) treated H9c2 cardiomyocytes using western blotting. The overloaded RV had increased β3 adrenoceptor expression, which was further increased by mirabegron. Mirabegron reduced RV pressure and reduced RV structural and functional deterioration in MCT rats. Mirabegron decreased cardiac fibrosis and hypertrophy in the overloaded RV. Mirabegron suppressed dynaminrelated protein 1 (Drp1) and promoted AMP-activated protein kinase (AMPK) signaling in the overloaded RV and Ang II treated cardiomyocytes. The β3 adrenoceptor agonist mirabegron reduced RV hypertrophy and fibrosis in PH rats. The treatment effect involved Drp1 inhibition and AMPK activation.

Mirabegron in the Management of Overactive Bladder Syndrome.

Overactive bladder (OAB) negatively affects work productivity and quality of life in sufferers. Its overall impact is likely to increase as a result of increasing prevalence in an ageing population. The pathophysiology of OAB is not completely understood but the β3-adrenoceptor, which is highly expressed in the urinary bladder, is thought to be important for mediating human detrusor relaxation during the storage phase. Clinical trial results have demonstrated that mirabegron, a selective β3-adrenoceptor agonist offers substantial clinical efficacy and good adherence rates over 12 months. Furthermore, due to its different mechanism of action, it is likely to offer a favourable tolerability profile when compared with antimuscarinic agents, resulting in improved persistence over long-term treatment. Finally, from a health economic perspective, despite its higher drug acquisition cost, mirabegron has been found to be cost-effective, owing to the greater increase in quality-adjusted-life-years gained, when compared to antimuscarinic medications. The PubMed database was searched for English language articles published between 1 January 2005 to 31 January 2022, on the subject of mirabegron. Search terms included “mirabegron”, “overactive bladder”, “β3-adrenoceptor agonist”, “urinary incontinence”. This review summarises the evidence for mirabegron as a treatment option for the management of OAB.

β3 Relaxant Effect in Human Bladder Involves Cystathionine γ-Lyase-Derived Urothelial Hydrogen Sulfide.

It is now well established that the urothelium does not act as a passive barrier but contributes to bladder homeostasis by releasing several signaling molecules in response to physiological and chemical stimuli. Here, we investigated the potential contribution of the hydrogen sulfide (H2S) pathway in regulating human urothelium function in β3 adrenoceptor-mediated relaxation. The relaxant effect of BRL 37344 (0.1–300 µM), a selective β3 adrenoceptor agonist, was evaluated in isolated human bladder strips in the presence or absence of the urothelium. The relaxant effect of BRL 37344 was significantly reduced by urothelium removal. The inhibition of cystathionine-γ-lyase (CSE), but not cystathionine-β-synthase (CBS), significantly reduced the BRL 37344 relaxing effect to the same extent as that given by urothelium removal, suggesting a role for CSE-derived H2S. β3 adrenoceptor stimulation in the human urothelium or in T24 urothelial cells markedly increased H2S and cAMP levels that were reverted by a blockade of CSE and β3 adrenoceptor antagonism. These findings demonstrate a key role for urothelium CSE-derived H2S in the β3 effect on the human bladder through the modulation of cAMP levels. Therefore, the study establishes the relevance of urothelial β3 adrenoceptors in the regulation of bladder tone, supporting the use of β3 agonists in patients affected by an overactive bladder.

β1- and β1/β2-adrenergic receptor antagonists block 6-nitrodopamine-induced contractions of the rat isolated epididymal vas deferens.

6-Nitrodopamine (6-ND) is an endogenous modulator of the contractility in the rat isolated epididymal vas deferens (RIEVD) and considered to be the main peripheral mediator of the emission process. Use of selective and unselective β-adrenergic receptor antagonists has been associated with ejaculatory failure. Here, the effects of selective β1- and β1/β2-adrenergic receptor antagonists on RIEVD contractions induced by 6-ND, dopamine, noradrenaline, adrenaline, and electric-field stimulation (EFS) were investigated. The selective β1-adrenergic receptor antagonists atenolol (0.1 and 1µM), betaxolol (1µM), and metoprolol (1µM) and the unselective β1/β2-adrenergic receptor antagonists propranolol (1 and 10µM) and pindolol (10µM) caused significant rightward shifts of the concentration-response curve to 6-ND (pA2 6.41, 6.91, 6.75, 6.47, and 5.74; for atenolol, betaxolol, metoprolol, propranolol, and pindolol), but had no effect on dopamine-, noradrenaline-, and adrenaline-induced contractions. The effects of selective β1- and β1/β2-adrenergic receptor antagonists at a higher concentration (atenolol 1µM, betaxolol 1µM, metoprolol 1µM, propranolol 10µM, and pindolol 10µM) also reduced the EFS-induced RIEVD contractions in control, but not in RIEVD obtained from L-NAME-treated animals. The selective β1-adrenoceptor agonist RO-363, the selective β2-adrenoceptor agonist salbutamol, and the selective β3-adrenoceptor agonist mirabegron, up to 300µM, had no effect on the RIEVD tone. The results demonstrate that β1- and β1-/β2-adrenoceptor receptor antagonists act as 6-ND receptor antagonists in RIEVD, further confirming the main role of 6-ND in the RIEVD contractility.

Vibegron inhibits enhanced spontaneous contractions induced by anoxia/reoxygenation in isolated whole bladder from rats

It has been recently proposed that repeated bladder ischemia/reperfusion induced by chronic pelvic ischemia may lead to detrusor overactivity, followed by lower urinary tract symptoms. Vibegron is a selective β3-adrenoceptor agonist approved for the treatment of overactive bladder. Several studies have tested β3-adrenoceptor agonists using animal models with detrusor overactivity related to bladder ischemia/reperfusion. However, whether β3-adrenoceptor agonists directly affect ischemia/reperfusion-evoked detrusor overactivity is unclear. Therefore, we examined whether bladder anoxia/reoxygenation could enhance spontaneous bladder contractions (SBCs) and investigated the effect of vibegron on enhanced SBCs. Isolated whole bladders from rats were incubated with Krebs solution aerated with 95% N2 + 5% CO2 for 5 h (anoxia). Subsequently, the bathing solution was replaced with an oxygen-saturated solution (reoxygenation). Anoxia/reoxygenation caused enhancement of the amplitude but not the frequency of SBC compared with that before reoxygenation. Vibegron (0.3–30 μM) inhibited this increase in SBC amplitude, but not the frequency, in a dose-dependent manner. The inhibitory effect of vibegron was not affected by pretreatment with the adenylyl cyclase inhibitor SQ22536 (100 μM) or protein kinase A inhibitor KT5720 (1 μM) and was not accompanied by considerable changes in cyclic adenosine monophosphate (cAMP) content in the bladder. In contrast, the large conductance potassium channel inhibitor iberiotoxin (100 nM) suppressed the inhibitory effect of vibegron. These results suggest that bladder ischemia/reperfusion induces SBC enhancement and vibegron directly inhibits detrusor overactivity via the large conductance potassium channel, which involves β3-adrenoceptor, rather than the cAMP signaling pathway.

The interaction of a β2 adrenoceptor agonist drug with biomimetic cell membrane models: The case of terbutaline sulphate

Terbutaline sulphate (TS) is a selective short-acting β2 adrenoceptor agonist used for asthma treatment. The pharmacological activity of TS depends on its binding to the transmembrane protein, β2 adrenoceptor. Thus, the interactions of this drug with biological membranes are expected, affecting its pharmacological activity. Using in vitro models to study the interaction of TS with biological membranes can provide important information about the activity of the drug. Here, liposomes with different lipid compositions were used as biomimetic models of cell membranes to evaluate the effect of composition, complexity, and physical state of membranes on TS-membrane interactions. For that, liposomes containing dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and liposomes containing DMPC and cholesterol (CHOL) were prepared. For the study of TS-membrane interactions, the TS lipophilicity was evaluated in terms of i) partition coefficient; ii) the preferential location of the drug within the membrane; iii) and the effect of TS on the membrane fluidity. The obtained data suggest that TS has an affinity for the lipid membrane, partitioning from the aqueous to the lipid phase. The affinity was dependent on the liposomes' compositions, showing a greater affinity for DMPC membranes than for DMPC:CHOL model. Dynamic light scattering (DLS) results revealed that this is due to the rigidizing effect caused by CHOL molecules. These findings provide valuable insights in the understanding of the complex interaction of TS with biomembrane models as well as the relevance of lipid compositions and membrane structure in such interactions, which may be related to its pharmacological activity and side effects.

Possible Involvement of Muscarinic Receptor Blockade in Mirabegron Therapy for Patients with Overactive Bladder.

The selective β 3-adrenoceptor agonist mirabegron, an established alternative to antimuscarinic therapy for patients with overactive bladder, induces additional effects against receptors, transporters, and hepatic enzymes. The present study aimed to elucidate the effects of mirabegron on muscarinic receptors in the rat bladder using radioligand binding and functional assays. Mirabegron (0.1-100 μM) inhibited specific [N-methyl-3H]scopolamine methyl chloride binding in the bladder and other tissues of rats in a concentration-dependent manner. Binding affinity in the bladder was similar to that in the heart and significantly higher than those in the submaxillary gland and brain. Mirabegron induced the concentration-dependent relaxation of carbachol-induced contractions in the rat isolated bladder. Further analyses using a two-site model revealed that the relative quantities of high- and low-affinity components for mirabegron were 44.5% and 55.5%, respectively. Respective pEC50 values were 7.06 and 4.97. Based on the receptor binding affinity and pharmacokinetics of mirabegron, muscarinic receptor occupancy in the human bladder for 24 hours after the administration of a single oral dose of 50 mg mirabegron was 37%-76%. The present results demonstrate for the first time that mirabegron may relax the detrusor smooth muscle not only by β 3-adrenoceptor activation but also muscarinic receptor blockade. SIGNIFICANCE STATEMENT: Mirabegron, the first selective β 3-adrenoceptor agonist, represents an alternative to antimuscarinic agents for management of overactive bladder (OAB). The present study aimed to clarify whether mirabegron directly binds to muscarinic receptors and affects cholinergic agonist-induced contractions in rat urinary bladder and to predict muscarinic receptor occupancy in human bladder after oral administration of mirabegron. The results demonstrated that mirabegron therapy for patients with OAB may be due not only to β 3-adrenoceptor activation but also muscarinic receptor blockade.

Ruthenium red attenuates brown adipose tissue thermogenesis in rats.

Ruthenium red (RR) is a non-selective antagonist of the temperature-sensitive Transient Receptor Potential (TRP) channels and it is an important pharmacological tool in thermoregulatory research. However, the effect of RR on thermoeffector activity is not well established. Here we evaluated the effect of RR on cold-defense thermoeffectors induced by menthol, an agonist of the cold-sensitive TRPM8 channel. Adult male Wistar rats were used. Epidermal treatment with menthol raised deep body temperature due to an increase in oxygen consumption (an index of thermogenesis), a reduction in heat loss index (an index of cutaneous vasoconstriction), and an induction in warmth-seeking behavior in a two-temperature choice apparatus. Pretreatment with RR attenuated the menthol-induced increase in deep body temperature and oxygen consumption, but it did not affect heat loss index and warmth-seeking behavior. To stimulate brown adipose tissue thermogenesis, rats were treated with CL 316,243, a potent and selective β3-adrenoceptor agonist. CL 316,243 increased deep body temperature, which was attenuated by RR pretreatment. We conclude that RR reduces brown adipose tissue thermogenesis induced by menthol and CL 316,243, independent of effects at the thermal sensor level (i.e., TRPM8).

Intravesical prostatic protrusion does not compromise the therapeutic effects of Mirabegron in male patients with overactive bladder

Intravesical prostatic protrusion (IPP) is associated with the degree of benign prostatic obstruction. We evaluated the effects of Mirabegron, a selective β3 adrenoceptor agonist, on overactive bladder (OAB) in male patients with different degrees of IPP. About 185 male patients ≥40years with lower urinary tract symptoms were recruited from a tertiary referral center. OAB was defined by the overactive bladder symptom score (OABSS) urgency score of ≥2 and sum score of ≥3. IPP was measured in the midsagittal section using transrectal ultrasound and patients were divided into IPP ≤5mm and IPP >5mm groups. Outcomes were assessed at the baseline, 4, and 12weeks. About 104 patients (56.2%) were diagnosed with OAB and received Mirabegron (50mg) daily use. Both IPP groups (≤5 and >5mm) had similar baseline OABSS and International Prostate Symptom Scores (IPSS). Four-week Mirabegron usage was associated with significant decreases in both symptom score measurements, OABSS: IPP ≤5mm -27.4% and IPP >5mm -19.7% (P=.419) and IPSS: -32% and -22.5% (P=.202), respectively. Urgency, urge incontinence, and nocturia sub-scores were decreased in both groups, -26.3% and -27.4% (P=.690), 53.3% and 46.2% (P=.916), and 20.8% and 15.4% (P=.958). Effects were maintained at 12weeks. We found no significant improvement in the frequency sub-score in either group. One patient stopped medication because of intolerable hypertension. Most frequent adverse event was increased residual urine (≥50mL higher than baseline), IPP ≤5mm 9.2% and IPP >5mm 5.1% (P=.707), but no case had acute urinary retention. Mirabegron is an effective drug to treat male OAB regardless of IPP grade.

Effect of mirabegron on erectile function in sexually active men with bothersome overactive bladder symptoms.

To evaluate the change of erectile function (EF) in sexually active male overactive bladder (OAB) patients treated with Mirabegron. Mirabegron, a selective β3 adrenoceptor agonist, approved for the treatment of OAB, has been reported to relax human and rat corpus cavernosum and might have beneficial effect on EF. A total of 128 consecutive men with lower urinary tract symptoms attended urology outpatient clinic were evaluated for OAB and EF. Thirty-four sexually active OAB patients were prospectively enrolled in this study and received mirabegron 50 mg oral once a day. The evaluation of EF and OAB was based on a self-administered questionnaire containing International Index of Erectile Function (IIEF-5) and OAB symptom score (OABSS), respectively. Men with an OABSS urgency score of ≥2 and sum score of ≥3 were considered to have OAB. The therapeutic outcomes were assessed at baseline, 4, and 12 weeks. Mirabegron usage was associated with a statistically significant improvement of OAB symptoms (OABSS 32.1% decrease) at 4-week follow-up and the therapeutic effects were maintained at 12-week follow-up. Mirabegron usage did not improve EF (IIEF-5 4.9% decrease at 4-week; p = 0.106, and 9.1% decrease at 12-week follow-up; p = 0.077). However, the IIEF-5 was significantly decreased in the higher baseline IIEF-5 (≥17) group (11.7% decrease; p = 0.044), noncoronary artery disease (13.2%; p = 0.007), or non-DM group (13.9% decrease; p = 0.021) at 12-week follow-up. This preliminary study demonstrates that mirabegron treatment of men with OAB improved OAB symptoms, but has no beneficial effect on EF.

Mirabegron, A Selective β3-Adrenoceptor Agonist Causes an Improvement in Erectile Dysfunction in Diabetic Rats.

To investigate the possible beneficial effect of mirabegron [a selective β3-adrenoceptor (AR) agonist] treatment on erectile dysfunction (ED) in streptozotocin-induced diabetic rats. Sprague-Dawley rats (n=20) were divided into two groups: control group and streptozotocin-induced diabetic group. In vivo erectile responses were evaluated after intracavernosal injection of mirabegron (0.4 mg/kg) in rats. The relaxation responses to electrical field stimulation (EFS, 10 Hz), sodium nitroprusside (SNP, 10 nM) and sildenafil (1 μM) of corpus cavernosum (CC) strips were examined after the incubation with mirabegron (10 μM). β3-ARs expression and localization were determined by Western blot and immunohistochemical analyses in CC tissue. In vivo erectile responses of diabetic rats [intracavernasal pressure (ICP) / mean arterial pressure, 0.17±0.01] were decreased, which were restored after administration of mirabegron (0.75±0.01, P<0.001). The basal ICP (7.1±0.6 mmHg) in diabetic rats was markedly increased after mirabegron (36.1 ±5.4 mmHg, P<0.01). Mirabegron caused markedly relaxation in diabetic rat CC after phenylephrine precontraction. The relaxation responses to EFS and sildenafil were reduced in diabetic CC, which were increased in the presence of mirabegron. Mirabegron enhanced SNP-induced relaxation response in both groups. The expression and immunoreactivity of β3-ARs localized to CC smooth muscle were observed in control and diabetic rats. This is the first study to show that intracavernosal administration of mirabegron improved erectile function and neurogenic relaxation of CC in diabetic rats. These results may be supported by further studies using combinations of mirabegron and phosphodiesterase type 5 (PDE5) inhibitors for the treatment of diabetic ED, especially in patients who do not respond to PDE5 inhibitor therapy.

027 Mirabegron elicits recovery of erectile function in a rat model of streptozotocin-induced diabetes

Erectile dysfunction (ED) is a growing problem among men with diabetes. Phosphodiesterase type 5 inhibitors (PDE5i) are not effective in the management of diabetes-associated ED. Mirabegron, a selective β3-adrenoceptor agonist, has been approved for the treatment of overactive bladder. This study is focused on the possible beneficial effect of intracavernosal injection of mirabegron on ED in streptozotocin-induced diabetic rats. Adult Sprague-Dawley (n=20) rats were equally divided into two groups: control and diabetic rats subjected to streptozotocin (45 mg/kg, intraperitoneal). In vivo erectile responses were also repeated after intracavernosal injection of mirabegron (dose of 0.4 mg/kg). The relaxant responses of corpus cavernosum (CC) strips were evaluated in the presence or absence of mirabegron (10 μM). Expression and localization of β3-adrenoceptors in penile tissue were determined by Western blot analysis and immunohistochemistry. Diabetic rats demonstrated significantly decreased ratio of intracavernosal pressure to mean arterial pressure (0.17± 0.02; P < .001) and total intracavernosal pressure (2057 ± 199 mmHg; P < .001) which were restored by intracavernosal administration of mirabegron (0.75± 0.01; 3888 ± 295 mmHg). The basal intracavernosal pressure in diabetic rats was markedly increased after mirabegron. In in vitro studies, the nitrergic relaxation response to electrical field stimulation (10 Hz) in diabetic CC was enhanced almost 7-fold after the presence of mirabegron. Mirabegron increased sodium nitroprusside-induced (10nM) relaxation in CC of diabetic rats. The relaxant response to sildenafil (1μM) in the diabetic group was lower than the control group, which was augmented after incubation with mirabegron. The protein expression and localization of β3-adrenoceptors in the CC did not differ between diabetic and control rats.

Recent advances and current trend in the pharmacotherapy of obesity

Nonpharmacological approach to the prevention and treatment of obesity includes considerable lifestyle changes such as adequate physical exercise, smoking cessation, limiting alcohol intake, avoiding sedentary lifestyles, intensive behavioral counseling (psychotherapy), proper nutritional (dietary) programs, and bariatric surgery. For a pharmacotherapeutic substance to be regarded as an anti-obesity drug, it has to demonstrate a reduction of at least 5%–10% in the baseline body weight within a year of commencing treatment. Pharmacotherapeutic agents used to treat obesity include sympathomimetic appetite suppressant drugs, pancreatic lipase inhibitors, antidiabetic drugs, serotonin 5-HT2Cagonists, anticonvulsant drugs, atypical antidepressants, hormones, selective β3adrenoceptor agonists, and various combination preparations. The choice of agent should be individualized and dictated by patient comorbidities, relative contraindications, available clinical trial evidence, and clinical expertise. In addition to pharmacological therapy, all anti-obesity drugs should be prescribed with the premise of dietary caloric restriction and exercise. Bariatric surgery is the most effective treatment for obesity when the other forms of intervention have failed to produce a clinically significant weight loss in individuals with a body mass index of ≥35 kg/m2. Finally, concerning the prospective future research directions on the pharmacotherapy of obesity, a number of initiatives have been put forward to develop a peripherally restricted CB1receptor antagonist (such as TM38837 compound) that targets only the peripheral CB1receptors by restricting their ability to cross the blood–brain barrier in order to avoid the serious and severe psychiatric adverse effects found to be associated with the unrestricted CB1receptor antagonists such as rimonabant.

Identification of Uridine 5'-Diphosphate-Glucuronosyltransferases Responsible for the Glucuronidation of Mirabegron, a Potent and Selective β3-Adrenoceptor Agonist, in Human Liver Microsomes.

Mirabegron is cleared by multiple mechanisms, including drug-metabolizing enzymes. One of the most important clearance pathways is direct glucuronidation. In humans, M11 (O-glucuronide), M13 (carbamoyl-glucuronide), and M14 (N-glucuronide) have been identified, of which M11 is one of the major metabolites in human plasma. The objective of this study was to identify the uridine 5'-diphosphate (UDP)-glucuronosyltransferase (UGT) isoform responsible for the direct glucuronidation of mirabegron using human liver microsomes (HLMs) and recombinant human UGTs (rhUGTs). Reaction mixtures contained 1-1000μM mirabegron, 8mM MgCl2, alamethicin (25μg/mL), 50mM Tris-HCl buffer (pH 7.5), human liver microsome(HLM) or rhUGT (1.0mg protein/mL), and 2mM UDP-glucuronic acid in a total volume of 200μL for 120min at 37°C. HLMs from 16 individuals were used for the correlation study, and mefenamic acid and propofol were used for the inhibition study. Regarding M11 formation, rhUGT2B7 showed high activity among the rhUGTs tested (11.3pmol/min/mg protein). This result was supported by the correlation between M11 formation activity and UGT2B7 marker enzyme activity (3-glucuronidation of morphine, r 2=0.330, p=0.020) in individual HLMs; inhibition by mefenamic acid in pooled HLMs (IC50=22.8μM); and relatively similar K m values between pooled HLMs and rhUGT2B7 (1260 vs. 486μM). Regarding M13 and M14 formation, rhUGT1A3 and rhUGT1A8 showed high activity among the rhUGTs tested, respectively. UGT2B7 is the main catalyst of M11 formation in HLMs. Regarding M13 and M14 formation, UGT1A3 and UGT1A8 are strong candidates for glucuronidation, respectively.

β₂-Adrenoceptor Blockade Deteriorates Systemic Anaphylaxis by Enhancing Hyperpermeability in Anesthetized Mice.

PurposePatients treated with propranolol, a nonselective β-adrenoceptor antagonist, develop severe anaphylaxis, but the mechanism remains unknown. We determined effects of β1- and β2-adrenoceptor antagonists on the anaphylaxis-induced increase in vascular permeability in mice.MethodsIn anesthetized ovalbumin-sensitized C57BL mice, mean arterial blood pressure (MBP) was measured, and Evans blue dye extravasation and hematocrit (Hct) were assessed at 20 minutes after antigen injection. The following pretreatment groups (n=7/group) were studied: (1) sensitized control (non-pretreatment), (2) propranolol, (3) the selective β2-adrenoceptor antagonist ICI 118,551, (4) the selective β1-adrenoceptor antagonist atenolol, (5) adrenalectomy, (6) the selective β2-adrenoceptor agonist terbutaline, and (7) non-sensitized groups.ResultsThe antigen injection decreased MBP, and increased Hct and vascular permeability in the kidney, lung, mesentery, and intestine, but not in the liver or spleen. Pretreatment with ICI 118,551, propranolol and adrenalectomy, but not atenolol, reduced the survival rate and augmented the increases in Hct and vascular permeability in the kidney, intestine, and lung as compared with the sensitized control group. Pretreatment with terbutaline abolished the antigen-induced alterations. Plasma epinephrine levels were increased significantly in the sensitize control mice.ConclusionsBlockade of β2-adrenoceptor can deteriorate systemic anaphylaxis by augmenting hyperpermeability-induced increase in plasma extravasation by inhibiting beneficial effects of epinephrine released from the adrenal glands in anesthetized mice.

Clenbuterol Induces Cell Cycle Arrest in C2C12 Myoblasts by Delaying p27 Degradation through β-arrestin 2 Signaling.

β2-Adrenoceptor (β2-AR) agonists promote muscle growth. The aim of this study was to elucidate some effects of the selective β2-adrenoceptor agonist clenbuterol (CLB) on myoblast proliferation. We found that CLB induces cell cycle arrest in C2C12 myoblasts. This effect is partly due to the enhanced stability of p27, rather than the increased gene transcription via cAMP response element-binding protein (CREB). Specifically, CLB treatment enhanced the accumulation of p27 in the nucleus while depleting it from the cytosol via a mechanism that requires β2-AR. Surprisingly, p27 accumulation was not reversed by the protein kinase A (PKA) inhibitor H-89, but interestingly, was alleviated by the knockdown of β-arrestin 2. Thus, our work provides a basis for β2-AR agonists inhibit myoblasts proliferation through signaling via β2-AR, β-arrestin 2, and p27.