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Thalamic modulation of visceral nociceptive processing in adult rats with neonatal colon irritation.
- Source :
-
Brain research [Brain Res] 2004 May 22; Vol. 1008 (2), pp. 186-92. - Publication Year :
- 2004
-
Abstract
- Visceral pain originates from visceral organs in response to a noxious stimulus which, if prolonged, may lead to chronic changes in the neural network mediating visceral nociception. For instance, colon inflammation enhances the responses of neurons in the thalamus to colorectal distension (CRD), whereas lesion in the dorsal column (DC) reverses this neuronal sensitization, suggesting that the thalamus and the DC play major roles in chronic visceral pain. In this study, we used adult rats sensitized with neonatal painful colon irritation to reveal the contribution of the thalamus and the DC to neuronal hyperexcitability in a model of chronic visceral pain. We recorded the responses of lumbosacral neurons to CRD in control rats and in rats with colon irritation following stimulation or inactivation of the thalamus, and after DC lesion. Our results show that, first, neuronal responses to CRD decreased following thalamic stimulation in control rats, whereas, in rats with colon irritation, responses either decreased or increased; second, DC lesion attenuated or enhanced these effects in the positively or in the negatively modulated group of neurons, respectively; third, lidocaine injection in the thalamus reduced the responses to CRD in some of the neurons recorded in rats with colon irritation, but had no effect on those in control rats. Therefore, it is reasonable to speculate that plasticity in rats with colon irritation that may underlie chronic pain is sustained by feedback loops ascending in the DC and engaging the thalamus.<br /> (Copyright 2004 Elsevier B.V.)
- Subjects :
- Anesthetics, Local administration & dosage
Anesthetics, Local pharmacology
Animals
Catheterization
Electrophysiology
Lidocaine administration & dosage
Lidocaine pharmacology
Male
Mechanoreceptors physiology
Microinjections
Neuronal Plasticity physiology
Physical Stimulation
Posterior Horn Cells physiology
Rats
Rats, Sprague-Dawley
Rectum physiology
Spinal Cord physiology
Animals, Newborn physiology
Colitis physiopathology
Pain physiopathology
Thalamus physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0006-8993
- Volume :
- 1008
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Brain research
- Publication Type :
- Academic Journal
- Accession number :
- 15145755
- Full Text :
- https://doi.org/10.1016/j.brainres.2004.01.083