Plasticity of non-adrenergic non-cholinergic bladder contractions in rats after chronic spinal cord injury

H. Henry Lai; Alvaro Munoz; Christopher P. Smith; Timothy B. Boone; George T. Somogyi

doi:10.1016/j.brainresbull.2011.06.001

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Plasticity of non-adrenergic non-cholinergic bladder contractions in rats after chronic spinal cord injury

Journal article

Peer reviewed

Plasticity of non-adrenergic non-cholinergic bladder contractions in rats after chronic spinal cord injury

H. Henry Lai, Alvaro Munoz, Christopher P. Smith, Timothy B. Boone and George T. Somogyi

Brain research bulletin, Vol.86(1-2), pp.91-96

08/10/2011

DOI: 10.1016/j.brainresbull.2011.06.001

PMID: 21689735

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Abstract

► Cholinergic activation inhibits bladder NANC contractions. ► Cholinergic activation reduces purinergic contractions in normal and SCI bladders. ► Cholinergic-induced inhibition of NANC is higher in SCI than in normal bladders. ► The change in NANC may involve P2X-independent mechanisms in SCI bladders. The purpose of this study was to examine the pharmacologic plasticity of cholinergic, non-adrenergic non-cholinergic (NANC), and purinergic contractions in neurogenic bladder strips from spinal cord injured (SCI) rats. Bladder strips were harvested from female rats three to four weeks after T9–T10 spinal cord transection. The strips were electrically stimulated using two experimental protocols to compare the contribution of muscarinic and NANC/purinergic contractions in the presence and the absence of carbachol or muscarine. The endpoints of the study were: (1) percent NANC contraction that was unmasked by the muscarinic antagonist 4-DAMP, and (2) P2X purinergic contraction that was evoked by α,β-methylene ATP. NANC contraction accounted for 78.5% of the neurally evoked contraction in SCI bladders. When SCI bladder strips were treated with carbachol (10μM) prior to 4-DAMP (500nM), the percent NANC contraction decreased dramatically to only 13.1% of the neurally evoked contraction (P=0.041). This was accompanied by a substantial decrease in α,β-methylene ATP evoked P2X contraction, and desensitization of purinergic receptors (the ratio of subsequent over initial P2X contraction decreased from 97.2% to 42.1%, P=0.0017). Sequential activation of the cholinergic receptors with carbachol (or with muscarine in neurally intact bladders) and unmasking of the NANC response with 4-DAMP switched the neurally evoked bladder contraction from predominantly NANC to predominantly cholinergic. We conclude that activation of muscarinic receptors (with carbachol or muscarine) blocks NANC and purinergic contractions in neurally intact or in SCI rat bladders. The carbachol-induced inhibition of the NANC contraction is expressed more in SCI bladders compared to neurally intact bladders. Along with receptor plasticity, this change in bladder function may involve P2X-independent mechanisms.

Bladder contractility

Cholinergic receptor

Neurogenic bladder

Purinergic receptor

Spinal cord injury

Details

Title: Subtitle: Plasticity of non-adrenergic non-cholinergic bladder contractions in rats after chronic spinal cord injury
Creators: H. Henry Lai - Washington University in St. Louis
Alvaro Munoz - Baylor College of Medicine
Christopher P. Smith - Baylor College of Medicine
Timothy B. Boone - Baylor College of Medicine
George T. Somogyi - Baylor College of Medicine
Resource Type: Journal article
Publication Details: Brain research bulletin, Vol.86(1-2), pp.91-96
DOI: 10.1016/j.brainresbull.2011.06.001
PMID: 21689735
NLM abbreviation: Brain Res Bull
ISSN: 0361-9230
eISSN: 1873-2747
Publisher: Elsevier Inc
Number of pages: 6
Language: English
Date published: 08/10/2011
Academic Unit: Urology
Record Identifier: 9985244543002771

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