Gene transfer of GLT-1, a glial glutamate transporter, into the spinal cord by recombinant adenovirus attenuates inflammatory and neuropathic pain in rats.
BACKGROUND
The glial glutamate transporter GLT-1 is abundantly expressed in astrocytes and is crucial for glutamate removal from the synaptic cleft. Decreases in glutamate uptake activity and expression of spinal glutamate transporters are reported in animal models of pathological pain. However, the lack of available specific inhibitors and/or activators for GLT-1 makes it difficult to determine the roles of spinal GLT-1 in inflammatory and neuropathic pain. In this study, we examined the effect of gene transfer of GLT-1 into the spinal cord with recombinant adenoviruses on the inflammatory and neuropathic pain in rats.


RESULTS
Intraspinal infusion of adenoviral vectors expressing the GLT-1 gene increased GLT-1 expression in the spinal cord 2-21 days after the infusion. Transgene expression was primarily localized to astrocytes. The spinal GLT-1 gene transfer had no effect on acute mechanical and thermal nociceptive responses in naive rats, whereas it significantly reduced the inflammatory mechanical hyperalgesia induced by hindlimb intraplantar injection of carrageenan/kaolin. Spinal GLT-1 gene transfer 7 days before partial sciatic nerve ligation recovered the extent of the spinal GLT-1 expression in the membrane fraction that was decreased following the nerve ligation, and prevented the induction of tactile allodynia. However, the partial sciatic nerve ligation-induced allodynia was not reversed when the adenoviruses were infused 7 or 14 days after the nerve ligation.


CONCLUSIONS
These results suggest that overexpression of GLT-1 on astrocytes in the spinal cord by recombinant adenoviruses attenuates the induction, but not maintenance, of inflammatory and neuropathic pain, probably by preventing the induction of central sensitization, without affecting acute pain sensation. Upregulation or functional enhancement of spinal GLT-1 could be a novel strategy for the prevention of pathological pain.
Maeda
Sanae
S
Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan. sanae@st.pharm.kyoto-u.ac.jp
Kawamoto
Ai
A
Yatani
Yumi
Y
Shirakawa
Hisashi
H
Nakagawa
Takayuki
T
Kaneko
Shuji
S
D000256:Adenoviridae / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D027342:Excitatory Amino Acid Transporter 2 / Q000235:genetics* / Q000378:metabolism; D018014:Gene Transfer Techniques; D006801:Humans; D006930:Hyperalgesia / Q000378:metabolism / Q000628:therapy; D007150:Immunohistochemistry; D007249:Inflammation / Q000628:therapy; D008297:Male; D009437:Neuralgia / Q000378:metabolism* / Q000628:therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism*; D019076:Transgenes
D027342:Excitatory Amino Acid Transporter 2