We have previously showed that spinal high-mobility group box-1 (
HMGB1) plays an important role in the induction of central post-
stroke pain (CPSP). It has been reported that
HMGB1 exacerbates
inflammation and
pain via TLR4 or RAGE. Furthermore, the relationship between glial cells, such as microglia and astrocytes, involved in
pain exacerbation and
HMGB1 has also attracted attention. In this study, we investigated whether the interaction between spinal glial cells and
HMGB1 signaling, including its receptors TLR4 or RAGE, is directly involved in the induction of CPSP. Spinal
HMGB1 expression increased on day 3 after bilateral carotid artery occlusion (BCAO), and spinal microglia and astrocytes were clearly activated.
HMGB1 colocalized with neurons, but not with microglia and astrocytes after BCAO. Intrathecal (i.t.) injection of
lipopolysaccharides from Rhodobacter sphaeroides (LPS-RS, a TLR4 antagonist) and
low-molecular-weight heparin (
LMWH, a RAGE antagonist) significantly blocked
mechanical allodynia on day 3 after BCAO. BCAO-induced activation of spinal microglia and astrocyte were suppressed by i.t. anti-HMGB1
monoclonal antibody (mAb) and LPS-RS administration. In addition, i.t. injection of
NG-nitro-l-arginine methyl ester [a nonselective
nitric oxide synthetase (NOS) inhibitor] significantly blocked
mechanical allodynia on day 3 after BCAO and i.t. administration of anti-HMGB1 mAb, LPS-RS, and
LMWH significantly inhibited the increase of NOS activity in the spinal cord on day 3 after BCAO. These results showed that the interaction between spinal glial cells and
HMGB1/TLR4/NOS or
HMGB1/RAGE/NOS is directly involved in the induction of CPSP.