Inhibition of bladder sensory afferents via intrabladder injection of adenoassociated viruses-retro–mediated Gi-DREADDs alleviates bladder overactivity and pain in mice

Increased afferent sensitivity is a key pathophysiological mechanism of overactive bladder (OAB) and interstitial cystitis/bladder pain syndrome. Gi-DREADDs-based chemogenetic offers a novel approach for silencing neuronal activity. This study investigates the translational potential of Gi-DREADDs in suppressing OAB and pain by selectively silencing bladder primary sensory neurons. All mice were female. The transduction efficiency and specificity of 3 adeno-associated virus (AAV) serotypes (AAV9, PHP.S, and AAV-retro) delivered via bladder injection or intrathecal injection were compared. Bladder-injected AAV-retro demonstrated the highest specificity, transducing 70% of dorsal root ganglion (DRG) neurons labeled with retrograde tracer DiI. It did not transduce DRG neurons innervating organs outside bladder, the autonomic neurons in major pelvic ganglion and the motor neurons in spinal cord. Unexpectedly, bladder-injected PHP.S failed to transduce bladder sensory neurons. Using AAV-retro to deliver hM4D(Gi) to bladder DRG neurons, and activation with clozapine-N-oxide (CNO), significantly inhibited DRG neuron responses to high K+ and capsaicin in vitro. In vivo, activation of AAV-retro-mediated hM4D(Gi) with CNO significantly alleviated OAB and pain behaviors in both acute (capsaicin) and chronic (cyclophosphamide) pain models without affecting voiding pressure or causing urinary retention. These findings indicate that selectively silencing bladder sensory neurons with chemogenetic has translational potential for treatment of OAB or chronic bladder pain.