Mechanisms of D1/D2-like dopaminergic agonist, rotigotine, on lower urinary tract function in rat model of Parkinson's disease

Review: Lower urinary tract dysfunction in animal models of Parkinson's disease (PD): Translational aspects for the treatment of PD patients with overactive bladder

Although the loss of dopaminergic neurons in the substantia nigra and consequent motor symptoms are the hallmarks of Parkinson's disease (PD), several non-motor symptoms may appear prior to these typical motor symptoms. While a variety of non-motor symptoms have emerged as the primary predictor of PD patients' quality of life, even though motor symptoms are undoubtedly distressing. According to a study, the prevalence of lower urinary tract symptoms (LUTS) varies between 27% and 64%, suggesting that PD-related lower urinary tract dysfunction may be affected by the disease stage, the presence of concomitant conditions affecting the lower urinary tract, and other autonomic dysfunctions. Animal models can serve as a platform for research into the causes of PD-related dysfunction and the evaluation of cutting-edge therapeutic approaches although the majority of animal research have been directed toward motor symptoms of PD. At present, the cause of lower urinary tract dysfunction in PD has not been fully clarified although the increasing evidence showing the multiple mechanisms underlying PD-related LUTS has emerged. In this chapter we summarize the findings of basic research in the studies of the lower urinary tract dysfunction using with different animal PD models and we try to shed light on the translational aspects for the development of future treatment modalities in PD patients with LUTS.

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

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.