Acid-sensing ion channels modulate bladder nociception.

Area of Science:

• Neuroscience
• Physiology
• Pharmacology

Background:

• Neuronal sensitization and persistent afferent signaling contribute significantly to somatic and visceral pain.
• The precise mechanisms underlying afferent signaling, sensitization, and pain development remain incompletely understood.
• Acid-sensing ion channels (ASICs) are implicated in pain signaling, particularly in sensory neurons.

Purpose of the Study:

• To investigate the role of ASICs, specifically ASIC3, in bladder nociception within a chemical cystitis model.
• To determine if ASIC3 deficiency impacts the development of pelvic allodynia following cyclophosphamide (CYP) administration.
• To elucidate the contribution of ASIC3 to the excitability and sensitization of bladder afferent neurons.

Main Methods:

• Utilized a cyclophosphamide (CYP)-induced chemical cystitis mouse model.
• Compared pelvic sensitivity in wild-type and ASIC3 knockout mice post-CYP administration.
• Assessed the response of bladder sensory neurons to extracellular acidification in vitro.

Main Results:

• Mice lacking ASIC3 exhibited significant pelvic allodynia after CYP treatment, exceeding that of wild-type mice.
• This heightened sensitivity in ASIC3 knockout mice was attributed to sensitized bladder C nociceptors.
• Deletion of ASIC3 abolished the ability of bladder sensory neurons to generate action potentials upon exposure to acidic conditions.

Conclusions:

• Protons and their cognate ASIC receptors are integral to a nerve terminal mechanism controlling nociceptor excitability and sensitization.
• Loss of ASIC3 function disrupts this regulatory mechanism, leading to hyperactivation of nociceptive pathways.
• ASIC3 plays a critical role in modulating bladder afferent function and preventing pain in the context of chemical cystitis.