Nerve fibers in lumbar spine structures and injured spinal roots express the sensory neuron-specific sodium channels SNS/PN3 and NaN/SNS2.
METHODS
This prospective study examined the innervation of lumbar spine in tissues from patients with lower back pain and spine nerve roots from patients with traumatic brachial plexus injuries.


OBJECTIVE
To demonstrate the presence of nerve fibers in lumbar spine structures and spine nerve roots, and to determine whether they express the sensory neuron-specific sodium channels SNS/PN3 and NaN/SNS2.


BACKGROUND
The anatomic and molecular basis of low back pain and sciatica is poorly understood. Previous studies have demonstrated sensory nerves in the facet joint capsule and prolapsed intervertebral disc, but not in the ligamentum flavum. The voltage-gated sodium channels SNS/PN3 and NaN/SNS2 are expressed by sensory neurone that mediate pain, but their presence in the lumbar spine is unknown.


METHODS
Tissue samples of ligamentum flavum (n = 32), facet joint capsule (n = 20), intervertebral disc (n = 15), and spine roots (n = 8) were immunostained with specific antibodies to protein gene product 9.5 (a panneuronal marker), SNS/PN3, and NaN/SNS2.


RESULTS
Protein gene product 9.5 immunoreactive nerve fibers were detected in 72% of the ligamentum flavum specimens and 70% of the facet joint capsule specimens, but in only 20% of the intervertebral disc specimens. The study detected SNS/PN3- and NaN/SNS2-positive fibers, respectively, in 28% and 3% of the ligamentum flavum specimens and 25% and 15% of the facet joint capsule specimens. Numerous SNS/PN3- and NaN/SNS2-positive fibers were found in the acutely injured spine roots, and some were still present in the dorsal roots in the chronic state.


CONCLUSIONS
As the findings showed, SNS/PN3- and NaN/SNS2-immunoreactivity is present in a subset of nerve fibers in lumbar spine structures, including ligamentum flavum, and in injured spine roots. Selective SNS/PN3- and NaN/SNS2-blocking agents may provide new therapy for back pain and sciatica.
Bucknill
Andrew T
AT
Department of Musculoskeletal Surgery, Imperial College School of Medicine, Charing Cross Campus, London, UK.
Coward
Kevin
K
Plumpton
Christopher
C
Tate
Simon
S
Bountra
Chas
C
Birch
Rolfe
R
Sandison
Ann
A
Hughes
Sean P F
SP
Anand
Praveen
P
D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000918:Antibody Specificity; D001917:Brachial Plexus / Q000737:chemistry / Q000293:injuries / Q000473:pathology; D002648:Child; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017843:Ligamentum Flavum / Q000737:chemistry / Q000294:innervation; D017116:Low Back Pain / Q000378:metabolism; D008159:Lumbar Vertebrae / Q000294:innervation*; D008297:Male; D062559:NAV1.8 Voltage-Gated Sodium Channel; D009412:Nerve Fibers / Q000737:chemistry / Q000378:metabolism*; D009475:Neurons, Afferent / Q000737:chemistry / Q000378:metabolism*; D009479:Neuropeptides / Q000096:biosynthesis* / Q000276:immunology; D011446:Prospective Studies; D015222:Sodium Channels / Q000096:biosynthesis* / Q000276:immunology; D013119:Spinal Cord Injuries / Q000378:metabolism; D013126:Spinal Nerve Roots / Q000737:chemistry / Q000293:injuries* / Q000473:pathology*; D016707:Tissue Fixation
D000911:Antibodies, Monoclonal; D062559:NAV1.8 Voltage-Gated Sodium Channel; D009479:Neuropeptides; C568317:SCN10A protein, human; D015222:Sodium Channels