Hyperbaric oxygen (HBO) treatment has been proven to be a promising candidate for protection of the nervous system after acute injury in animal models of neuropathic pain. The purposes of this study were to examine the antinociceptive response phase induced by HBO treatment in a model of neuropathic pain and to determine the dependence of the treatment's mechanism of alleviating neuropathic pain on the inhibition of spinal astrocyte activation. Neuropathic pain was induced in rats by chronic constriction injury of the sciatic nerve. Mechanical threshold and thermal latency were tested preoperatively and for 1 week postoperatively, four times daily at fixed time points. Methane dicarboxylic aldehyde (MDA) and superoxide dismutase (SOD) parameters were used as indices of oxidative stress response and tested before and after the treatment. The inflammatory cytokines interleukin (IL)-1β and IL-10 were assayed in the sciatic nerve were with enzyme-linked immunoassay. Glial fibrillary acidic protein activation in the spinal cord was evaluated immunohistochemically. The rats exhibited temporary allodynia immediately after HBO treatment completion. This transient allodynia was closely associated with changes in MDA and SOD levels. A single HBO treatment caused a short-acting antinociceptive response phase. Repetitive HBO treatment led to a long-acting antinociceptive response phase and inhibited astrocyte activation. These results indicated that HBO treatment played a dual role in the aggravation and alleviation of neuropathic pain, though the aggravated pain effect (transient allodynia) was far less pronounced than the antinociceptive phase. Astrocyte inhibition and anti-inflammation may contribute to the antinociceptive effect of HBO treatment after nerve injury.

Dexmedetomidine preconditioning protected against cerebral ischemic injury and was associated with upregulation of HIF-1α and VEGF expression.

Background Hip fracture is common in older adults, and can cause severe post-fracture pain. Fascia iliaca nerve block has consequently been used for preoperative analgesia. Methods We performed a randomized, controlled, double-blind clinical trial and recruited older patients with hip fractures. These patients were randomized into two groups and received ultrasound-guided fascia iliaca compartment block using either the supra-inguinal approach (group F) or the classical approach (group C). Heart rate, blood pressure, and resting and exercising visual analog scales were recorded before the procedure and at 30 min, and 6, 12, and 24 h after completion of the procedure. We recorded the duration of the procedure—as well as complications such as bleeding, hypotension, and intractable vomiting; the sleep duration in a 24 h period was also documented. Results A total of 38 patients completed the trial, and we observed no differences in the baseline characteristics or pre-procedural measurements between the two groups. Compared with the patients in group C, patients in group F exhibited significantly lower exercising VAS scores at 6 and 12 h after the procedure, faster heart rates at 6 and 24 h after the procedure, a longer procedural duration, and a longer sleep duration. There were no differences in the frequencies of complications between the two groups. The percentages of patients who took oral analgesics and the numbers of medications consumed were also not different between the two groups. Conclusions The supra-inguinal FICB provided effective analgesia and improved exercise tolerance compared with the classical approach. Trial registration The trial was registered at the Chinese Clinical Trial Registry (registration number: ChiCTR2100045644, registration date: 2021 April 20).

Local anesthetic toxicity is closely related to neuronal death and activation of the inflammatory response. Dexmedetomidine (Dex) is an adrenergic α2 receptor agonist that can reduce the neurotoxicity induced by lidocaine. It also has anti-inflammatory effects. However, the mechanism underlying the neuroprotective effects of Dex against lidocaine-induced toxicity remains to be defined. We hypothesized that Dex exerts its neural protective effect through inhibiting inflammasome activation and through anti-pyroptosis effects against local anesthetic-induced nerve injury. In a rat model of lidocaine-induced spinal cord injury, we studied the protective effect of Dex on lidocaine-induced changes in spinal cord function, inflammasome formation and pyroptosis, pro-inflammatory cytokine expression, and protein kinase C (PKC)-δ phosphorylation. Dex reduced lidocaine-induced neurotoxicity and inhibited PKC-δ phosphorylation in the spinal cord of rats. Furthermore, Dex inhibited pyroptosis and inflammasome formation (caspase-1, NLRP3, and apoptosis-associated speck-like protein (ASC)). Finally, Dex attenuated interleukin (IL)-1β and IL-18 expression, as well as microglia response. In conclusion, Dex can reduce the severity of lidocaine-induced spinal cord injury in rats by inhibiting priming and inflammasome activation and reducing pyroptosis via PKC-δ phosphorylation.

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