AUTHOR=Zhou Guo-Kun , Xu Wen-Jing , Lu Yi , Zhou Yan , Feng Chen-Zhang , Zhang Jiang-Tao , Sun Shi-Yu , Wang Ruo-Meng , Liu Tong , Wu Bin 

TITLE=Acid-sensing ion channel 3 is required for agmatine-induced histamine-independent itch in mice

JOURNAL=Frontiers in Molecular Neuroscience

VOLUME=Volume 16 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2023.1086285

DOI=10.3389/fnmol.2023.1086285

ISSN=1662-5099

ABSTRACT=Itch is a common symptom of many skin and systemic diseases. Identifying novel endogenous itch mediators and the downstream signaling pathways involved will contribute to the development of new strategies for the treatment of chronic itch. In the present study, we fused a mouse model and found that an intradermal injection of agmatine (an endogenous polyamine) into the nape of the neck or cheek induced histamine-independent scratching behavior in a dose-dependent manner. In addition, the ablation of nociceptive C-fibers by resiniferatoxin (RTX) abolished agmatine-induced scratching behavior. However, agmatine-induced itch was not affected by the pharmacological inhibition of either transient receptor potential vanilloid 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1); similar results were obtained from TRPV1-/- or TRPA1-/- mice. Furthermore, agmatine-induced itch was significantly suppressed by the administration of acid-sensing ion channel 3 (ASIC3) inhibitors, APETx2 or amiloride. Agmatine also induced the upregulation of p-ERK in the spinal cord; this effect was inhibited by amiloride. Current clamp recording showed that the acute perfusion of agmatine reduced the rheobase and increased the number of evoked action potentials in acute dissociated dorsal root ganglion (DRG) neurons while amiloride reversed agmatine-induced neuronal hyperexcitability. Finally, we identified significantly higher levels of agmatine in the affected skin of a mouse model of atopic dermatitis (AD) when compared to controls, and the scratching behavior of AD mice was significantly attenuated by blocking ASIC3. Collectively, these results provide evidence that agmatine is a novel mediator of itch and induces itch via the activation of ASIC3. Targeting neuronal ASIC3 signaling may represent a novel strategy for the treatment of itch.