Altered Purinergic Signaling in Colorectal Dorsal Root Ganglion Neurons Contributes to Colorectal Hypersensitivity

作者：Shinoda Masamichi^*; La Jun Ho; Bielefeldt Klaus; Gebhart G F

来源：Journal of Neurophysiology, 2010, 104(6): 3113-3123.

DOI：10.1152/jn.00560.2010

Shinoda M, La JH, Bielefeldt K, Gebhart GF. Altered purinergic signaling in colorectal dorsal root ganglion neurons contributes to colorectal hypersensitivity. J Neurophysiol 104: 3113-3123, 2010. First published September 22, 2010; doi: 10.1152/jn.00560.2010. Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by pain and hypersensitivity in the relative absence of colon inflammation or structural changes. To assess the role of P2X receptors expressed in colorectal dorsal root ganglion (c-DRG) neurons and colon hypersensitivity, we studied excitability and purinergic signaling of retrogradely labeled mouse thoracolumbar (TL) and lumbosacral (LS) c-DRG neurons after intracolonic treatment with saline or zymosan (which reproduces 2 major features of IBSpersistent colorectal hypersensitivity without inflammation) using patch-clamp, immunohistochemical, and RT-PCR techniques. Although whole cell capacitances did not differ between LS and TL c-DRG neurons and were not changed after zymosan treatment, membrane excitability was increased in LS and TL c-DRG neurons from zymosan-treated mice. Purinergic agonist adenosine-5=-triphosphate (ATP) and alpha,beta-methylene ATP [alpha,beta-meATP] produced inward currents in TL c-DRG neurons were predominantly P2X 3 -like fast (similar to 70% of responsive neurons); P2X (2/3) -like slow currents were more common in LS c-DRG neurons (similar to 35% of responsive neurons). Transient currents were not produced by either agonist in c-DRG neurons from P2X(3)(-/-) mice. Neither total whole cell Kv current density nor the sustained or transient Kv components was changed in c-DRG neurons after zymosan treatment. The number of cells expressing P2X 3 protein and its mRNA and the kinetic properties of ATP-and alpha,beta-meATP-evoked currents in c-DRG neurons were not changed by zymosan treatment. However, the EC50 of alpha,beta-meATP for the fast current decreased significantly in TL c-DRG neurons. These findings suggest that colorectal hypersensitivity produced by intracolonic zymosan increases excitability and enhances purinergic signaling in c-DRG neurons.

• 出版日期2010-12