title: Relationship of axonal voltage-gated sodium channel 1.8 (NaV1.8) mRNA accumulation to sciatic nerve injury-induced painful neuropathy in rats.
abstract: Painful peripheral neuropathy is a significant clinical problem; however, its pathological mechanism and effective treatments remain elusive. Increased peripheral expression of tetrodotoxin-resistant voltage-gated sodium channel 1.8 (NaV1.8) has been shown to associate with chronic pain symptoms in humans and experimental animals. Sciatic nerve entrapment (SNE) injury was used to develop neuropathic pain symptoms in rats, resulting in increased NaV1.8 mRNA in the injured nerve but not in dorsal root ganglia (DRG). To study the role of NaV1.8 mRNA in the pathogenesis of SNE-induced painful neuropathy, NaV1.8 shRNA vector was delivered by subcutaneous injection of cationized gelatin/plasmid DNA polyplex into the rat hindpaw and its subsequent retrograde transport via sciatic nerve to DRG. This in vivo NaV1.8 shRNA treatment reversibly and repeatedly attenuated the SNE-induced pain symptoms, an effect that became apparent following a distinct lag period of 3-4 days and lasted for 4-6 days before returning to pretreatment levels. Surprisingly, apparent knockdown of NaV1.8 mRNA occurred only in the injured nerve, not in the DRG, during the pain alleviation period. Levels of heteronuclear NaV1.8 RNA were unaffected by SNE or shRNA treatments, suggesting that transcription of the Scn10a gene encoding NaV1.8 was unchanged. Based on these data, we postulate that increased axonal mRNA transport results in accumulation of functional NaV1.8 protein in the injured nerve and the development of painful neuropathy symptoms. Thus, targeted delivery of agents that interfere with axonal NaV1.8 mRNA may represent effective neuropathic pain treatments.
authors.affiliation: Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials, and Hospital Dentistry, School of Dentistry, UCLA, Los Angeles, California 90095, USA.
authors.forename: Supanigar
authors.initials: S
authors.lastname: Ruangsri
authors.forename: Audrey
authors.initials: A
authors.lastname: Lin
authors.forename: Yatendra
authors.initials: Y
authors.lastname: Mulpuri
authors.forename: Kyung
authors.initials: K
authors.lastname: Lee
authors.forename: Igor
authors.initials: I
authors.lastname: Spigelman
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nishimura
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000473:pathology; D059350:Chronic Pain / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005727:Ganglia, Spinal / Q000378:metabolism* / Q000473:pathology; D055785:Gene Knockdown Techniques; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000494:pharmacology; D062559:NAV1.8 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010523:Peripheral Nervous System Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000293:injuries*; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D062559:NAV1.8 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C568317:SCN10A protein, human; C568319:Scn10a protein, rat; D015222:Sodium Channels