B1 and TRPV-1 receptor genes and their relationship to hyperalgesia following spinal cord injury.
METHODS
Laboratory investigation of pain behavior following spinal cord injury.


OBJECTIVE
To explore changes in the spinal cord expression of nociceptive genes following spinal cord injury (SCI) as they relate to the manifestation of pain behavior in rats.


BACKGROUND
Neuropathic pain following SCI is common, disabling, and largely untreatable. In peripheral nerve injury models, bradykinin B1 and vanilloid 1 (TRPV-1) receptor activity is associated with neuropathic pain behavior. We sought to examine the role of these gene products in SCI-mediated pain.


METHODS
Rats were subjected to SCI using the MASCIS impactor. Animals were tested preinjury and at regular intervals postinjury for the appearance of thermal hyperalgesia using a hind limb withdrawal latency test. The expression of B1 and TRPV-1 genes was assessed using real-time polymerase chain reaction. Immunohistochemistry was used to localize the B1 and TRPV-1 receptors within the spinal cord.


RESULTS
Greater than twofold increases in the expression of the B1 and TRPV-1 genes were detected in the injured region of the spinal cord in animals exhibiting hyperalgesia compared with animals with SCI that did not display hyperalgesia. Immunohistochemical staining revealed that both receptor types were largely localized to the dorsal horn. Staining for TRPV-1 receptors decreased while that for B1 receptors increased in all of the injured animals when compared with sham-operated controls.


CONCLUSIONS
B1 and TRPV-1 receptor genes are overexpressed in the injured spinal cord of animals manifesting thermal hyperalgesia following SCI compared with similarly injured animals without hyperalgesia. This finding is consistent with past work regarding the role of these receptors in nociception and indicates that ongoing modifiable processes are occurring in the spinal cord that lead to clinical pain syndromes.
DomBourian
Melkon G
MG
Department of Neurological Surgery, University of Wisconsin Medical School, Madison, WI 53792, USA.
Turner
Nicholas A
NA
Gerovac
Tiffany A
TA
Vemuganti
Raghu
R
Miranpuri
Gurwattan S
GS
Türeyen
Kudret
K
Satriotomo
Irawan
I
Miletic
Vjekoslav
V
Resnick
Daniel K
DK
D000818:Animals; D003288:Contusions / Q000150:complications / Q000503:physiopathology; D005786:Gene Expression Regulation; D006614:Hindlimb / Q000294:innervation; D006358:Hot Temperature / Q000009:adverse effects; D006930:Hyperalgesia / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology; D007249:Inflammation; D007796:Laminectomy; D008297:Male; D023421:Models, Animal; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D043783:Receptor, Bradykinin B1 / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013119:Spinal Cord Injuries / Q000150:complications* / Q000503:physiopathology; D050916:TRPV Cation Channels / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology
D009419:Nerve Tissue Proteins; D043783:Receptor, Bradykinin B1; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat