Articles: hyperalgesia.
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Both local infiltration analgesia (LIA) and nerve block are common analgesic modalities for pain relief after surgery. The aim of the current study was to investigate the effects of those two modalities on pain behavior and the expression of pro-inflammatory cytokines such as interleukin (IL)-1β and IL-6 and tumor necrosis factor-α (TNF-α) in the spinal cord and dorsal root ganglion (DRG) in a rat model of perioperative fentanyl induced hyperalgesia. Rats were injected with fentanyl (60 μg/kg) 4 times and received a plantar incision after the second injection or they received pre-incision LIA and sciatic nerve block (SNB) or post-incision LIA with levobupivacaine (0.5%, 0.2 mL). ⋯ Fentanyl and an incision induced a significantly delayed mechanical hyperalgesia in the tail and thermal hyperalgesia in both hind paws and up-regulation of pro-inflammatory cytokines in the spinal cord and dorsal root ganglia. Rats treated with pre-incision LIA and SNB or post-incision LIA had alleviated hyperalgesia and significantly reduced levels of IL-1β, IL-6, and TNF-α compared to the control group. LIA and SNB partly prevented perioperative fentanyl-induced hyperalgesia and up-regulation of pro-inflammatory cytokines in the spinal cord and dorsal root ganglia.
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The experience of pain is characterized by the presence of a noxious sensory stimulus combined with negative affect, which is often treated clinically through administration of drugs such as morphine or other opioids. This study investigated the effects of morphine one and seven days after intraplantar administration of complete freund's adjuvant (CFA) in male and female rats. Hargreaves test for thermal nociception and conditioned place preference (CPP) were performed following subcutaneous administration of saline or morphine (1.0, 4.0, 8.0, 12.0 mg/kg). ⋯ Seven days after CFA treatment, both male and female rats exhibited a CPP with morphine doses of 4.0 mg/kg and higher. These results reveal sexually dimorphic properties of morphine in the paw withdrawal latencies and conditioned place preference models, representing reflexive and non-reflexive behavioral assays employed to examine inflammatory nociception. Our findings also suggest that antinociceptive effects of morphine are dynamic across early and later periods of CFA-induced inflammatory pain.
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Anesthesia and analgesia · May 2018
Neural Invasion Spreads Macrophage-Related Allodynia via Neural Root in Pancreatic Cancer.
Neural invasion (N-inv) induces the neural damage and pain in pancreatic cancer (PCa). Benign nerve injury evokes allodynia through neuroinflammation in the neural root, which might be seen in PCa. Macrophages have the potential to release excitatory cytokines after nerve injury and so may play a role in the generation of chronic neuropathic pain. The aim of this study is to represent N-inv-induced allodynia in patients with PCa and to characterize allodynia-related neuroinflammation as macrophage accumulation on dorsal root ganglion (DRG) in the N-inv animal model (N-inv model). ⋯ The present study first showed that the N-inv-induced allodynia was spread in patients with PCa and in the N-inv model. Allodynia was related to the amount of macrophages at DRG in the N-inv model. The neuroinflammation may be a target for researching the N-inv-induced pain mechanism and developing novel analgesics.