Abstract | BACKGROUND: Primary sensory neurons express several types of ion channels including transient receptor potential vanilloid 1 (TRPV1) and voltage-gated Na(+) channels. Our previous studies showed an increased excitability of bladder primary sensory and spinal neurons triggered by inflammation in the distal colon as a result of pelvic organ cross-sensitization. The goal of this work was to determine the effects of TRPV1 receptor activation by potent agonists and/or colonic inflammation on voltage-gated Na(+) channels expressed in bladder sensory neurons. METHODS: Sprague-Dawley rats were treated with intracolonic saline (control), resiniferatoxin (RTX, 10(-7 ) mol L(-1)), TNBS (colonic irritant) or double treatment (RTX followed by TNBS). KEY RESULTS: TNBS-induced colitis increased the amplitude of total Na(+) current by two-fold and of tetrodotoxin resistant (TTX-R) Na(+) current by 78% (P ≤ 0.05 to control) in lumbosacral bladder neurons during acute phase (3 days post-TNBS). Instillation of RTX in the distal colon caused an enhancement in the amplitude of total Na(+) current at -20 mV from -112.1 ± 18.7 pA/pF (control) to -183.6 ± 27.8 pA/ pF (3 days post-RTX, P ≤ 0.05) without changes in TTX resistant component. The amplitude of net Na(+) current was also increased by 119% at day 3 in the group with double treatment (RTX followed by TNBS, P ≤ 0.05 to control) which was significantly higher than in either group with a single treatment. CONCLUSIONS & INFERENCES: These results provide evidence that colonic inflammation activates TRPV1 receptors at the peripheral sensory terminals leading to an up-regulation of voltage gated Na(+) channels on the cell soma of bladder sensory neurons. This mechanism may underlie the occurrence of peripheral cross-sensitization in the pelvis and functional chronic pelvic pain.
|
Authors | Q Lei, A P Malykhina |
Journal | Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society
(Neurogastroenterol Motil)
Vol. 24
Issue 6
Pg. 575-85, e257
(Jun 2012)
ISSN: 1365-2982 [Electronic] England |
PMID | 22420642
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
|
Copyright | © 2012 Blackwell Publishing Ltd. |
Chemical References |
- Diterpenes
- Sodium Channels
- TRPV Cation Channels
- TRPV1 receptor
- resiniferatoxin
|
Topics |
- Animals
- Colitis
(chemically induced, genetics, metabolism)
- Colon
(drug effects, metabolism)
- Diterpenes
(pharmacology)
- Male
- Rats
- Rats, Sprague-Dawley
- Sensory Receptor Cells
(drug effects, metabolism)
- Sodium Channels
(genetics, metabolism)
- TRPV Cation Channels
(agonists, genetics, metabolism)
- Up-Regulation
(drug effects, physiology)
|