BACKGROUND: Accumulating evidence indicates that spinal inflammatory and immune responses play an important role in the process of radicular pain caused by intervertebral disk herniation. Resolvin D1 (RvD1) has been shown to have potent antiinflammatory and antinociceptive effects. The current study was undertaken to investigate the analgesic effect of RvD1 and its underlying mechanism in rat models of noncompressive lumbar disk herniation. METHODS: Rat models of noncompressive lumber disk herniation were established, and mechanical thresholds were evaluated using the von Frey test during an observation period of 21 days (n = 8/group). Intrathecal injection of vehicle or RvD1 (10 or 100 ng) was performed for three successive postoperative days. On day 7, the ipsilateral spinal dorsal horns and L5 dorsal root ganglions (DRGs) were removed to assess the expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-10, and transforming growth factor-β1 (TGF-β1) and the activation of nuclear factor-κB (NF-κB)/p65 and phospho-extracellular signal-regulated kinase (p-ERK) signaling (n = 30/group). RESULTS: The application of nucleus pulposus to L5 DRG induced prolonged mechanical allodynia, inhibited the production of IL-10 and TGF-β1, and up-regulated the expression of TNF-α, IL-1β, NF-κB/p65, and p-ERK in the spinal dorsal horns and DRGs. Intrathecal injection of RvD1 showed a potent analgesic effect, inhibited the up-regulation of TNF-α and IL-1β, increased the release of IL-10 and TGF-β1, and attenuated the expression of NF-κB/p65 and p-ERK in a dose-dependent manner. CONCLUSIONS: The current study showed that RvD1 might alleviate neuropathic pain via regulating inflammatory mediators and NF-κB/p65 and p-ERK pathways. Its antiinflammatory and proresolution properties may offer novel therapeutic approaches for the management of neuropathic pain.
BACKGROUND: Accumulating evidence indicates that spinal inflammatory and immune responses play an important role in the process of radicular pain caused by intervertebral disk herniation. Resolvin D1 (RvD1) has been shown to have potent antiinflammatory and antinociceptive effects. The current study was undertaken to investigate the analgesic effect of RvD1 and its underlying mechanism in rat models of noncompressive lumbar disk herniation. METHODS:Rat models of noncompressive lumber disk herniation were established, and mechanical thresholds were evaluated using the von Frey test during an observation period of 21 days (n = 8/group). Intrathecal injection of vehicle or RvD1 (10 or 100 ng) was performed for three successive postoperative days. On day 7, the ipsilateral spinal dorsal horns and L5 dorsal root ganglions (DRGs) were removed to assess the expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-10, and transforming growth factor-β1 (TGF-β1) and the activation of nuclear factor-κB (NF-κB)/p65 and phospho-extracellular signal-regulated kinase (p-ERK) signaling (n = 30/group). RESULTS: The application of nucleus pulposus to L5 DRG induced prolonged mechanical allodynia, inhibited the production of IL-10 and TGF-β1, and up-regulated the expression of TNF-α, IL-1β, NF-κB/p65, and p-ERK in the spinal dorsal horns and DRGs. Intrathecal injection of RvD1 showed a potent analgesic effect, inhibited the up-regulation of TNF-α and IL-1β, increased the release of IL-10 and TGF-β1, and attenuated the expression of NF-κB/p65 and p-ERK in a dose-dependent manner. CONCLUSIONS: The current study showed that RvD1 might alleviate neuropathic pain via regulating inflammatory mediators and NF-κB/p65 and p-ERK pathways. Its antiinflammatory and proresolution properties may offer novel therapeutic approaches for the management of neuropathic pain.