The transient receptor potential (TRP) superfamily of
cation channels, of which the TRP vanilloid type 1 (
TRPV1) receptor plays a critical role in inflammatory and
neuropathic pain, is expressed on nociceptors and spinal cord dorsal horn neurons. TRPV1 is also expressed on spinal astrocytes and dorsal root ganglia (DRG) satellite cells. Agonists of the
cannabinoid type 2 receptor (CB2R) suppress
allodynia, with some that can bind TRPV1. The neuroimmune C-C class chemokine-2 (CCL2) expressed on injured DRG nociceptor cell bodies, Schwann cells and spinal astrocytes, stimulates immune cell accumulation in DRG and spinal cord, a known critical
element in chronic
allodynia. The current report examined whether two CB2R agonists,
AM1710 and
AM1241, previously shown to reverse light touch
mechanical allodynia in rodent models of
sciatic neuropathy, require TRPV1 activation that leads to receptor insensitivity resulting in reversal of
allodynia. Global TRPV1 knockout (KO) mice with
sciatic neuropathy given intrathecal or intraperitoneal
AM1710 were examined for anti-
allodynia followed by immunofluorescent microscopy analysis of lumbar spinal cord and DRG of astrocyte and CCL2 markers. Additionally, immunofluorescent analysis following intrathecal
AM1710 and
AM1241 in rat was performed. Data reveal that intrathecal
AM1710 resulted in mouse anti-
allodynia, reduced spinal astrocyte activation and CCL2 expression independent of TRPV1 gene deletion. Conversely, peripheral
AM1710 in TRPV1-KO mice failed to reverse
allodynia. In rat, intrathecal
AM1710 and
AM1241 reduced spinal and DRG TRPV1 expression, with CCL2-astrocyte and -microglial co-expression. These data support that CB2R agonists can impact spinal and DRG TRPV1 expression critical for anti-
allodynia.