Neuroscience letters
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Neuroscience letters · Feb 2019
Orofacial operant behaviors and electrophysiological properties of trigeminal ganglion neurons following masseter muscle inflammation in rats.
Orofacial muscle pain is a significant clinical problem because it affects eating, speaking, and other orofacial functions in patients. However, mechanisms underlying orofacial muscle pain are not fully understood. In the present study we induced orofacial muscle pain by injecting Complete Freund's Adjuvant (CFA) into masseter muscle of rats and assessed pain by the orofacial operant test. ⋯ Several other membrane parameters were also different between DiI-labeled TG neurons of the CFA and control groups. Voltage-dependent currents were examined and the most significant changes following CFA were background K+ currents, which showed significantly smaller in DiI-labeled TG neurons of CFA group compared to the control group. Collectively, orofacial muscle pain in CFA model is accompanied with changes of electrophysiological properties and background K+ currents in TG neurons that innervate masseter muscles.
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Neuroscience letters · Feb 2019
Dorsal root ganglion explants derived from chemotherapy-treated mice have reduced neurite outgrowth in culture.
Chemotherapy-induced peripheral neuropathy (CIPN) is a severe and debilitating adverse effect of cancer therapy that results from treatment with neurotoxic agents. Although chemotherapy treatment has been shown to inhibit neurite outgrowth from dorsal root ganglion (DRG) neurons in vitro, evidence for this effect in vivo is lacking. In this study, we investigated whether chemotherapy treatment in mice alters the capacity for axonal outgrowth from ex vivo cultured DRG explants. ⋯ DRGs that were isolated at day 90 showed recovery of the neurite outgrowth, and no significant differences were detected in comparison to vehicle controls. These results are corroborated with an in vitro model, whereby direct application of oxaliplatin and paclitaxel dose-dependently reduced neurite outgrowth of DRG explants. In conclusion, our results show that the effect of paclitaxel and oxaliplatin on the structural plasticity of DRG is retained ex vivo (for at least 30 days) and suggest the use of DRG explants derived from chemotherapy-treated mice as an efficient method to investigate the mechanisms underlying CIPN and test for possible therapeutic targets.
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Neuroscience letters · Jan 2019
Observational StudyDiagnostic value of NT-proCNP compared to NSE and S100B in cerebrospinal fluid and plasma of patients with sepsis-associated encephalopathy.
Sepsis-associated encephalopathy (SAE) has significant impact on the neurocognitive outcome of sepsis survivors. This study was conducted to analyze the amino-terminal propeptide of the C-type natriuretic peptide (NT-proCNP) as a biomarker for SAE in comparison to neuron-specific enolase (NSE) and S100B protein. Cerebrospinal fluid (CSF) and plasma samples from twelve septic patients with SAE and nine non-septic controls without encephalopathy were analyzed. ⋯ In the sepsis cohort CSF NT-proCNP levels correlated with CSF Interleukin-6 (IL-6) levels (r = 0.616, p < 0.05) and systemic inflammation represented by high plasma procalcitonin (PCT) levels at day 3 (r = 0.727, p < 0.05). The high peak concentration of plasma NT-proCNP in the early phase of sepsis might help to predict the emergence of SAE during the further course of disease. NT-proCNP in plasma might, in contrast to CSF, indicate neurological impairment in patients with SAE.
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Neuroscience letters · Jan 2019
Randomized Controlled TrialDistinct behavioral response of primary motor cortex stimulation in itch and pain after burn injury.
It is still unclear whether chronic neuropathic pain and itch share similar neural mechanisms. They are two of the most commonly reported challenges following a burn injury and can be some of the most difficult to treat. Transcranial direct current stimulation (tDCS) has previously been studied as a method to modulate pain related neural circuits. ⋯ We did not find any treatment effects during Phase II. Based on these findings, it seems that an important placebo effect occurred during sham tDCS for itch, while active M1 tDCS seems to disrupt sensory compensatory mechanisms. We hypothesize that pain and itch are complementary but distinct mechanisms of adaptation after peripheral sensory injury following a burn injury and need to be treated differently.
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Neuroscience letters · Jan 2019
Intrathecal administration of adrenomedullin induces mechanical allodynia and neurochemical changes in spinal cord and DRG.
This study investigated the effect of adrenomedullin (AM) on mechanical pain sensitivity and its possible mechanisms. Intrathecal injection of AM receptor agonist AM1-50 (20 μg) once per day briefly reduced mechanical pain threshold on days 1 and 2 but induced prolonged mechanical allodynia on day 3. However, AM1-50 did not change mechanical pain sensation when the AM receptor antagonist AM22-52 (20 μg) was intrathecally co-administered. ⋯ These results suggest that the increased AM bioactivity induced mechanical allodynia and may contribute to the mechanical pain hypersensitivity under pathological conditions. The mechanisms may involve the activation of ERK signaling pathway and spinal glia as well as the recruitment of nNOS and TRPV1 in the spinal dorsal horn or DRG. The present study indicates that inhibition of the activation AM receptor might provide a fruitful strategy to relieving chronic pain.