School of Chinese Medicine
Enhanced excitability and down-regulated voltage-gated potassium channels in colonic DRG neurons from neonatal maternal separation rats
Irritable bowel syndrome (IBS), characterized mainly by abdominal pain, is a functional bowel disorder. The present study aimed to examine changes in the excitability and the activity of the voltage-gated K+ channel in dorsal root ganglia (DRG) neurons innervating the colon of rats subjected to neonatal maternal separation (NMS). Colonic DRG neurons from NMS rats as identified by FAST DiI™ labeling showed an increased cell size compared with those from nonhandled (NH) rats. Whole cell current-clamp recordings showed that colonic DRG neurons from NMS rats displayed: 1) depolarized resting membrane potential; 2) increased input resistance; 3) a dramatic reduction in rheobase; and 4) a significant increase in the number of action potentials evoked at twice rheobase. Whole cell voltage-clamp recordings revealed that neurons from both groups exhibited transient A-type (IA) and delayed rectifier (IK) K+ currents. Compared with NH rat neurons, the averaged density of IK was significantly reduced in NMS rat neurons. Furthermore, the Kv1.2 expression was significantly decreased in NMS rat colonic DRG neurons. These results suggest that NMS increases the excitability of colonic DRG neurons mainly by suppressing the IK current, which is likely accounted for by the downregulation of the Kv1.2 expression and somal hypertrophy. Perspective: This study demonstrates the alteration of delayed rectifier K current and Kv1.2 expression in DRG neurons from IBS model rats, representing a molecular mechanism underlying visceral pain and sensitization in IBS, suggesting the potential of Kv1.2 as a therapeutic target for the treatment of IBS. © 2011 by the American Pain Society.
dorsal root ganglia, hyperexcitability, Neonatal maternal separation, visceral pain, voltage-gated K+ channel
Source Publication Title
Journal of Pain
Luo, Jia-Lie, Hong-Yan Qin, Chun-Kit Wong, Suk-Ying Tsang, Yu Huang, and Zhao-Xiang Bian. "Enhanced excitability and down-regulated voltage-gated potassium channels in colonic DRG neurons from neonatal maternal separation rats." Journal of Pain 12.5 (2011): 600-609.