Postinjury treatment with magnesium sulfate attenuates neuropathic pains following spinal cord injury in male rats

Electroacupuncture attenuates neuropathic pain via suppressing BIP-IRE-1α-mediated endoplasmic reticulum stress in the anterior cingulate cortex

Studies have suggested that endoplasmic reticulum stress (ERS) is involved in neurological dysfunction and that electroacupuncture (EA) attenuates neuropathic pain (NP) via undefined pathways. However, the role of ERS in the anterior cingulate cortex (ACC) in NP and the effect of EA on ERS in the ACC have not yet been investigated. In this study, an NP model was established by chronic constriction injury (CCI) of the left sciatic nerve in rats, and mechanical and cold tests were used to evaluate behavioral hyperalgesia. The protein expression and distribution were evaluated using western blotting and immunofluorescence. The results showed that glucose-regulated protein 78 (BIP) and inositol-requiring enzyme 1α (IRE-1α) were co-localized in neurons in the ACC. After CCI, BIP, IRE-1α, and phosphorylation of IRE-1α were upregulated in the ACC. Intra-ACC administration of 4-PBA and Kira-6 attenuated pain hypersensitivity and downregulated phosphorylation of IRE-1α, while intraperitoneal injection of 4-PBA attenuated hyperalgesia and inhibited the activation of P38 and JNK in ACC. In contrast, ERS activation by intraperitoneal injection of tunicamycin induced behavioral hyperalgesia in naive rats. Furthermore, EA attenuated pain hypersensitivity and inhibited the CCI-induced overexpression of BIP and pIRE-1α. Taken together, these results demonstrate that EA attenuates NP by suppressing BIP- and IRE-1α-mediated ERS in the ACC. Our study presents novel evidence that ERS in the ACC is implicated in the development of NP and provides insights into the molecular mechanisms involved in the analgesic effect of EA.

Evaluation of the Concentration of Selected Elements in the Serum of Patients with Degenerative Stenosis of the Lumbosacral Spine

In humans, 23 elements have been shown to have biological activity. The purpose of this study was to evaluate the concentrations of iron (Fe), zinc (Zn), sodium (Na), potassium (K), magnesium (Mg), phosphorus (P), and calcium (Ca) in the serum of patients diagnosed with lumbar degenerative stenosis when compared to the concentrations of those elements in the serum of healthy volunteers. The study group consisted of 60 patients who were diagnosed with degenerative stenosis of the lumbosacral spine and who qualified for hemilaminectomy. The control group included 60 healthy volunteers without degenerative spinal stenosis. The clinical specimens studied had sera collected from both groups. The quantitative analysis of the selected elements revealed statistically significant (p < 0.05) lower concentrations of Zn (740 ± 110 µg/L vs. 880 ± 160 µg/L) and Mg (22,091 ± 4256 µg/L vs. 24,100 ± 4210 µg/L) in the serum of the patients from the study group when compared to the controls. By contrast, K (16,230 µg/L ± 1210 µg/L vs. 13,210 µg/L ± 1060 µg/L) and Fe (141.87 µg/L ± 11.22 µg/L vs. 109.1 µg/L ± 26.43 µg/L) levels were significantly higher in the study group compared to the controls (p < 0.05). No statistically significant changes were detected in the concentrations of the assessed micronutrients and macronutrients in both sexes in either the study group, the control group, or those based on body mass index (p > 0.05). In the serum samples from the study group, the strongest correlations were noted between the concentrations. In the study group, we showed a significant relationship between the levels of Fe/Zn (r = 0.41), Fe/Na (r = 0.41), Fe/P (r = 0.55), Zn/P (r = 0.68), Zn/K (r = 0.48), Zn/Ca (r = 0.94), Mg/Ca (r = 0.79), and Na/K (r = 0.67). We showed that only Mg concentration varied statistically significantly with the severity of pain (p < 0.05). These findings suggest that the assessment of Fe, Zn, Mg, and K concentrations can be helpful in predicting the onset of degenerative changes in the spine.

Magnesium and Pain

In terms of antinociceptive action, the main mode of action of magnesium involves its antagonist action at the N-methyl-d-aspartate (NMDA) receptor, which prevents central sensitization and attenuates preexisting pain hypersensitivity. Given the pivotal function of NMDA receptors in pain transduction, magnesium has been investigated in a variety of pain conditions. The oral and parenteral administration of magnesium via the intravenous, intrathecal, or epidural route may alleviate pain and perioperative anesthetic and analgesic requirements. These beneficial effects of magnesium therapy have also been reported in patients with neuropathic pain, such as malignancy-related neurologic symptoms, diabetic neuropathy, postherpetic neuralgia, and chemotherapy-induced peripheral neuropathy. In addition, magnesium treatment is reportedly able to alleviate fibromyalgia, dysmenorrhea, headaches, and acute migraine attacks. Although magnesium plays an evolving role in pain management, better understanding of the mechanism underlying its antinociceptive action and additional clinical studies is required to clarify its role as an adjuvant analgesic.

Effect of ketamine combined with magnesium sulfate in neuropathic pain patients (KETAPAIN): study protocol for a randomized controlled trial

Background

Neuropathic pain is difficult to treat, and the efficacy of recommended drugs remains limited. N-methyl-d-aspartate receptors are implicated, and antagonists are a pharmacological option. Ketamine is widely used in French pain clinics, but without consensus or recommendations. Furthermore, the association of ketamine with magnesium has been poorly studied. The aim of the present study is to evaluate the benefit of ketamine with or without magnesium in refractory neuropathic pain.

Methods/design

A randomized, double-blind, crossover, placebo-controlled study will be performed in Clermont-Ferrand University Hospital, Clermont-Ferrand, France. The aim is to evaluate the effect of ketamine with or without magnesium in 22 patients with neuropathic pain. Intravenous ketamine/placebo, ketamine/magnesium sulfate, or placebo/placebo will be administered consecutively to each patient, in random order, once at 5-week intervals. The primary endpoint is the AUC of pain intensity assessed on a 0–10 Numeric Pain Rating Scale for a 5-week period. Data analysis will be performed on an intention-to-treat basis, and all statistical tests (except primary analysis) will be performed with an α risk of 5% (two-sided).

Discussion

Considering the poor efficacy of the drugs available for neuropathic pain, ketamine with or without magnesium sulfate may be a valuable therapeutic option that needs to be standardized.

Trial registration

EudraCT number–2015-000142-29. Registered on April 9, 2015; version 1.4

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2254-3) contains supplementary material, which is available to authorized users.