title: P2X3-immunoreactive primary sensory neurons innervating lumbar intervertebral disc in rats.
abstract: The P2X(3) receptor is normally localized in a sub-population of small-diameter dorsal root ganglion (DRG) neurons, and is thought to be related to pain perception. The aim of this study in rats was to examine P2X(3)-immunoreactivity in DRG neurons innervating the lumbar disc and in DRG neurons innervating cutaneous tissues. Fluoro-Gold was applied to the L5-L6 disc, the plantar skin of the hind paw (L4-L5 dermatomes), and the back skin (L1-L2 dermatomes). It has been reported that the L5-L6 disc is innervated by T13-L5 DRG neurons. We performed immunostaining using antibodies against the P2X(3) receptor of T13-L5 DRGs to examine the L5-L6 disc, L4 and L5 DRGs to examine plantar skin and L1 and L2 DRGs to examine back skin. The P2X(3)-immunoreactivity was detected in 22.0 and 22.8% of neurons, labeled by Fluoro-Gold applied to plantar and back skin, respectively. However, P2X(3)-immunoreactivity was detected in only 4.0% of the neurons projecting to the L5-L6 disc. The proportion of P2X(3)-immunoreactive neurons was significantly larger in the DRG neurons innervating the plantar or the back skin, than in the DRG neurons innervating the lumbar disc. These results suggest that the P2X(3) receptors are abundant in DRG neurons innervating cutaneous tissues, but not in neurons innervating the lumbar disc. It is likely therefore that the P2X(3) receptor is less related to the mechanism of discogenic pain, than to cutaneous tissue pain.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan. yasuaoki@h6.dion.ne.jp
authors.forename: Yasuchika
authors.initials: Y
authors.lastname: Aoki
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Ino
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Ozawa
authors.forename: Hideo
authors.initials: H
authors.lastname: Douya
authors.forename: Tanemichi
authors.initials: T
authors.lastname: Chiba
authors.forename: Hideshige
authors.initials: H
authors.lastname: Moriya
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002452:Cell Count; D002772:Cholera Toxin / Q000378:metabolism; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D005727:Ganglia, Spinal / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D007150:Immunohistochemistry; D007403:Intervertebral Disc / Q000294:innervation* / Q000378:metabolism; D008161:Lumbosacral Region / Q000294:innervation*; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058477:Receptors, Purinergic P2X3; D013266:Stilbamidines / Q000493:pharmacokinetics
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D018015:Receptors, Calcitonin Gene-Related Peptide; D018048:Receptors, Purinergic P2; D058477:Receptors, Purinergic P2X3; D013266:Stilbamidines; C052635:cholera toxin, B subunit-horseradish peroxidase; D002772:Cholera Toxin; D006735:Horseradish Peroxidase; D015740:Calcitonin Gene-Related Peptide