Effects of a new selective β3‐adrenoceptor agonist, vibegron, on bladder and urethral function in a rat model of Parkinson's disease

Abstract Objectives Parkinson's disease caused by the loss of dopaminergic neurons induces not only motor dysfunction but also lower urinary tract dysfunction. Patients with Parkinson's disease have recently been reported to experience both urge urinary incontinence (overactive bladder) and stress urinary incontinence, the latter of which occurs when the pressure of the bladder exceeds that of the urethra. Vibegron is a highly selective novel β3‐adrenoceptor agonist approved for the treatment of overactive bladder. However, how β3‐adrenoceptor agonists affect urethral function remains unclear. In a clinical report, the urethral function of patients with Parkinson's disease was shown to be degraded. The present study aimed to investigate the effects of vibegron on lower urinary tract activity in a rat model of Parkinson's disease. Methods In a rat model of Parkinson's disease induced by unilateral 6‐hydroxydopamine injection into the substantia nigra pars compacta, we examined the effects of vibegron on bladder and urethral activity. Results Cystometric analysis revealed that, compared with vehicle injection, intravenous injection of 3 mg/kg vibegron significantly increased the inter‐contraction interval (p < .05) and reduced voiding pressure (p < .01). However, no significant effects on urethral function were observed. Conclusions The results of the present study provide corroborating evidence that bladder dysfunction is suppressed by the administration of vibegron in Parkinson's disease model rats, confirming that vibegron is effective for treating overactive bladder without further worsening urethral function. These findings may contribute to a better understanding of the mechanisms of β3‐adrenoceptor agonists.