The same exposure was applied equally across the entire image

The same exposure was applied equally across the entire image. have been well defined. We report that ODN 2088 counteracts the SCI-elicited decrease in glial glutamate aspartate transporter (GLAST) and glutamate transporter 1 (GLT1) levels, whereas the levels of the neuronal glutamate transporter excitatory amino acid carrier 1 (EAAC1) and astroglial GABA transporter 3 (GAT3) were unaffected. The restoration of GLAST and GLT1 was neither Rabbit Polyclonal to SOX8/9/17/18 paralleled by a global effect on astrocyte and microglia activation nor by changes in the expression of cytokines and growth factors reported to regulate these transporters. We conclude that the effects of intrathecal ODN 2088 treatment extend to loci beyond the epicenter by selectively targeting glial glutamate transporters. Introduction Traumatic spinal cord injury (SCI) triggers a cascade of molecular and cellular events at the injury epicenter, including the infiltration of immune system cells, which induces an inflammatory reaction that exacerbates tissue damage caused by the initial EPZ031686 mechanical trauma1,2. Disruption of the axonal tracts that connect the brain and the spinal cord (SC) also elicits effects in SC regions that are remote from the epicenter, such as the lumbar dorsal horn (LDH)3C5. The SCI-elicited changes in the DH of remote regions have been best characterized in the context of pain EPZ031686 mechanisms, since the second-order sensory neurons which convey nociceptive information to the brain are localized to the DH. Glutamate transporters and receptors assume a central role in the hyperexcitation of these neurons following SCI. Synaptic glutamate levels are partly dependent on the extent of its release as well as the active uptake by surrounding cells through high affinity glutamate transporters6. Glutamate-aspartate transporter (GLAST)7, glutamate transporter 1 (GLT1)8, and excitatory amino acid carrier 1 (EAAC1)9 are members of the solute carrier 1 (SLC1) family of transmembrane proteins and are expressed throughout the SC; however, they are most predominantly expressed in the DH6. GLT1 accounts for approximately 40% of all spinal glutamate transporters and it is most abundant in the LDH6. Previous studies indicate that reductions in SC GLAST and GLT1 expression result in decreased glutamate uptake10C13 and lead to hyperexcitation of neurons via the overstimulation of glutamate receptors14. Whereas EAAC1 is usually primarily found in neurons15,16, both GLAST and GLT1 are predominantly expressed in astrocytes16,17. Astrocytes, microglia, and neurons express toll-like receptors (TLRs)18C21. TLRs are well known for their ability to bind components of pathogens which are referred to as pathogen-associated molecular patterns (PAMPs)22. In addition to their role in initiating innate immunity in response to contamination, TLRs bind endogenous ligands known as danger associated molecular patterns (DAMPs) that are released from damaged or necrotic cells23C25. As a result, TLRs have been implicated as mediators of sterile inflammation associated with central nervous system (CNS) injury20,21,26. Thirteen TLRs have been identified in mice. The focus of the EPZ031686 present study is usually TLR9 which is found in both humans and mice27. Earlier investigations in our laboratory have shown that intrathecal administration of ODN 2088 to mice sustaining a severe mid-thoracic contusion injury improves histopathological and functional outcomes20,26. These studies solely focused on changes occurring at the epicenter and analyzed the effects of the antagonist around the modulation of the infiltrating immune system cells, the expression of cytokines, white matter sparing and lesion volume20,26. However, treatments that target mechanisms at the epicenter could also alleviate pathology in remote regions, not only as a secondary consequence of effects at the lesion site, but through direct actions on cells at these distant regions. As the influence of the TLR9 antagonist at regions remote from the epicenter has not been adequately studied, the present investigation assessed the effects of ODN 2088 around the LDH. Results Intrathecal ODN 2088 treatment restores astroglial glutamate transporter levels in the LDH following SCI We EPZ031686 assessed the modulation of GLAST, GLT1 and EAAC1 levels in the LDH following SCI and after intrathecal treatment of injured mice with ODN 2088. Glutamate transporter levels.