Pathophysiology of Overactive Bladder and Pharmacologic Treatments Including β3-Adrenoceptor Agonists -Basic Research...

Area of Science:

• Urology
• Pharmacology
• Neuroscience

Background:

• Overactive bladder (OAB) is a syndrome characterized by urinary urgency, frequency, and nocturia, with diverse underlying pathologies.
• Current hypotheses for OAB generation include neurogenic, myogenic, and urothelial mechanisms.
• Autonomous myogenic contractions and afferent signals during bladder filling may contribute to urgency.

Purpose of the Study:

• To explore the mechanisms of OAB generation and the therapeutic effects of different drug classes.
• To compare the efficacy of antimuscarinics and β3-adrenergic receptor (AR) agonists in OAB treatment.
• To elucidate the specific actions of β3-AR agonists, such as mirabegron and vibegron, on nerve signaling and urothelial pathways.

Main Methods:

• Review of existing hypotheses and studies on OAB pathophysiology.
• Analysis of the mechanisms of action for antimuscarinics and β3-AR agonists.
• Examination of preclinical models, including bladder outlet obstruction (BOO)-induced detrusor overactivity.

Main Results:

• Antimuscarinics primarily block afferent nerve transmission rather than directly relaxing detrusor smooth muscle at therapeutic doses.
• β3-AR agonists inhibit afferent signals, targeting different fiber types in normal versus pathological conditions.
• Mirabegron and vibegron demonstrate potential in preventing acetylcholine release and modulating urothelial signaling.

Conclusions:

• β3-AR agonists offer a promising therapeutic avenue for OAB by targeting both efferent and afferent pathways.
• Understanding the distinct mechanisms of action is crucial for optimizing OAB treatment strategies.
• Further research into urothelial β3-AR pathways may reveal novel therapeutic targets for OAB.