Acute nociceptive somatic stimulus sensitizes neurones in the spinal cord to colonic distension in the rat. J Physiol 2004 Oct 01;560(Pt 1):291-302
Date
07/31/2004Pubmed ID
15284340Pubmed Central ID
PMC1665216DOI
10.1113/jphysiol.2004.069070Scopus ID
2-s2.0-6444238582 (requires institutional sign-in at Scopus site) 39 CitationsAbstract
The common co-existence of fibromyalgia and chronic abdominal pain could be due to sensitization of spinal neurones (SNs), as a result of viscero-somatic convergence. The objective of this study is to explore the influence of acute nociceptive somatic stimulation in the form of acid injections, into the ipsilateral somatic receptive field of neurones responsive to colorectal distension (CRD), and the potential role of ionotropic glutamate receptors on sensitization. Action potentials of CRD-sensitive SNs were recorded extracellularly from the lumbar (L(2)-L(5)) spinal cord. Stimulus-response functions (SRFs) to graded CRD (10-80 mmHg, 30 s) were constructed before and 30 min after ipsilateral injection of low pH (4.0, 100 microl) saline into the somatic receptive fields. In some experiments, cervical (C(1)-C(2)) spinalization was performed to eliminate supraspinal influence. The selective NMDA receptor antagonist CGS 19755 and AMPA receptor antagonist NBQX were injected (25 micromol kg(-1), i.v.) to examine their influence on sensitization. Three types of neurones were characterized as short-latency abrupt (SLA, n = 24), short latency sustained (SLS, n = 12), and long-latency (LL, n = 6) to CRD. Ipsilateral injection of low pH (4.0) in the somatic receptive field, but not the contralateral gastrocnemius (GN) or front leg muscles, sensitized responses of these neurones to CRD. Spinalization had no influence on the development of low pH-induced sensitization. Both CGS 19755 and NBQX significantly attenuated the sensitized response to CRD in intact and spinalized animals. Acute nociceptive somatic stimulus sensitizes CRD-sensitive SNs receiving viscero-somatic convergence. The sensitization occurs at the spinal level and is independent of supraspinal influence. Ionotropic glutamate receptors in the spinal cord are involved in sensitization.
Author List
Peles S, Miranda A, Shaker R, Sengupta JNAuthors
Adrian Miranda MD Adjunct Professor in the Pediatrics department at Medical College of WisconsinJyoti N. Sengupta PhD Professor in the Medicine department at Medical College of Wisconsin
Reza Shaker MD Assoc Provost, Sr Assoc Dean, Ctr Dir, Chief, Prof in the Medicine department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
AcidsAnimals
Catheterization
Colon
Excitatory Amino Acid Antagonists
Lumbar Vertebrae
Male
Neurons, Afferent
Nociceptors
Pipecolic Acids
Quinoxalines
Rats
Rats, Sprague-Dawley
Receptors, AMPA
Receptors, N-Methyl-D-Aspartate
Spinal Cord
Spinal Cord Injuries
Stimulation, Chemical