Arginine vasopressin induces analgesic effects and inhibits pyramidal cells in the anterior cingulate cortex in spared nerve injured mice.

Neuropathic pain (NP) is a severe disease caused by a primary disease or lesion affecting the somatosensory nervous system. It`s reported that NP is related to the increased activity of glutamatergic pyramidal cells and changed neural oscillations in the anterior cingulate cortex (ACC). Arginine vasopressin (AVP), a neurohypophyseal hormone, has been shown to cause pain-alleviating effects when applied to peripheral system. However, the extent to which, and the mechanisms by which, AVP induces analgesic effects in the central nervous system remain unclear. In the present study, we observed that intranasal delivery of AVP inhibited mechanical pain, thermal pain and spontaneous pain sensitivity in mice with spared nerve injury. Meanwhile, AVP application exclusively reduced the FOS expression in the pyramidal cells but not interneurons in the ACC. In vivo electrophysiological recording of the ACC further showed that AVP application not only inhibited the theta oscillation in local field potential analysis, but also reduced the firing rate of spikes of pyramidal cells in the ACC in neuropathic pain mice. In summary, AVP induce analgesic effects by inhibiting neural theta oscillations and the spiking of pyramidal cells of the ACC in mice with neuropathic pain, which should provide new potential noninvasive methods for clinical treatment of chronic pain.

C-176 reduces inflammation-induced pain by blocking the cGAS-STING pathway in microglia.

OBJECTIVE: Inflammatory pain, is caused by lesions or diseases of the somatosensory tissue, is a prevalent chronic condition that profoundly impacts the quality of life. However, clinical treatment for this type of pain remains limited. Traditionally, the stimulation of microglia and subsequent inflammatory reactions are considered crucial elements to promote the worsening of inflammatory pain. Recent research has shown the crucial importance of the cGAS-STING pathway in promoting inflammation. It is still uncertain if the cGAS-STING pathway plays the role in the fundamental cause of inflammatory pain. We aim to explore the treatment of inflammatory pain by interfering with cGAS-STING signaling pathway. METHODS: In this study, we established an inflammatory pain model by CFA into the plantar of mice. Activation of microglia, various inflammatory factors and cGAS-STING protein in the spinal dorsal horn were evaluated. Immunofluorescence staining was used to observe the cellular localization of cGAS and STING. The cGAS-STING pathway proteins expression and mRNA expression of indicated microglial M1/M2 phenotypic markers in the BV2 microglia were detected. STING inhibitor C-176 was intrathecal injected into mice with inflammatory pain, and the pain behavior and microglia were observed. RESULTS: This research showed that injecting CFA into the left hind paw of mice caused mechanical allodynia and increased inflammation in the spine. Our research results suggested that the cGAS-STING pathway had a function in the inflammation mediated by microglia in the spinal cord dorsal horn. Blocking the cGAS-STING pathway using STING antagonists (C-176) led to reduced release of inflammatory factors and prevented M1 polarization of BV2 microglia in a laboratory setting. Additionally, intrathecal administration of C-176 reduced the allodynia in CFA treated mice. CONCLUSION: Our results suggest that inhibiting microglial polarization through the cGAS-STING pathway represents a potential novel therapeutic strategy for inflammatory pain.

PKCδ serves as a potential biomarker and therapeutic target for microglia-mediated neuroinflammation in Alzheimer's disease.

INTRODUCTION: To investigate the role of a novel type of protein kinase C delta (PKCδ) in the neuroinflammation of Alzheimer's disease (AD). METHODS: We analyzed PKCδ and inflammatory cytokines levels in cerebrospinal fluid (CSF) of AD and normal controls, as well as their correlations. The cellular expression pattern of PKCδ and the effects of PKCδ modulation on microglia-mediated neuroinflammation were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), western blot, RNA sequencing (RNA-seq), and immunofluorescence staining. RESULTS: PKCδ levels were increased dramatically in the CSF of AD patients and positively correlated with cytokines. PKCδ is expressed mainly in microglia in the brain. Amyloid beta (Aß) stimulation increased PKCδ expression and secretion, which led to upregulation of the nuclear factor kappa B (NF-κB) pathway and overproduction of proinflammatory cytokines. Downregulation or inhibition of PKCδ attenuated Aß-induced microglial responses and improved cognitive function in an AD mouse model. DISCUSSION: Our study identifies PKCδ as a potential biomarker and therapeutic target for microglia-mediated neuroinflammation in AD. HIGHLIGHTS: Protein kinase C delta (PKCδ) levels increase in cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD), and positively correlate with elevated inflammatory cytokines in human subjects. PKCδ is expressed mainly in microglia in vivo, whereas amyloid beta (Aß) stimulation increases PKCδ expression and secretion, causing upregulation of the nuclear factor kappa B (NF-κB) pathway and production of inflammatory cytokines. Downregulation or inhibition of PKCδ attenuates Aß-enhanced NF-κB signaling and cytokine production in microglia and improves cognitive function in AD mice. PKCδ serves as a potential biomarker and therapeutic target for microglia-mediated neuroinflammation in AD.

Simplified regimen of combined low-dose rituximab for autoimmune encephalitis with neuronal surface antibodies.

BACKGROUND: Autoimmune encephalitis (AE) with neuronal surface antibodies (NSAbs) presents pathogenesis mediated by B cell-secreting antibodies. Rituximab is a second-line choice for the treatment for AE with NSAbs, which can cause B cell depletion via targeting CD20. However, the optimal protocol and dosage of rituximab combined with first-line therapy for NSAbs-associated AE remains unclear so far. In this study, we explored the efficacy and safety of low-dose rituximab combined with first-line treatment for NSAbs-associated AE. METHODS: Fifty-nine AE patients with NSAbs were enrolled, and retrospectively divided into common first-line therapy (41 patients) and combined low-dose rituximab (100 mg induction weekly with 3 circles, followed by 100 mg reinfusion every 6 months) with first-line therapy (18 patients). Outcome measures included changes in the Clinical Assessment Scale for Autoimmune Encephalitis (CASE) score (primary endpoint), changes in the modified Rankin Scale (mRS), the Mini-mental State Examination (MMSE), the patient and caregiver Neuropsychiatric Inventory (NPI) score at each visit (baseline, discharge, 6 months, 12 months and last follow-up) between two groups (secondary endpoint), as well as oral prednisone dosage, relapse and adverse effects during follow-up. RESULTS: Compared with traditional first-line therapy group, for primary outcome, CASE scores at last follow-up were significantly improved in combined rituximab group, as well as markedly improving changes of CASE scores between baseline and each visit. While changes of mRS, MMSE and NPI scores, as secondary endpoint, were all markedly accelerating improvement between baseline and each visit, as well as both oral prednisone dosage and relapse were also greatly reduced during follow-up. Meanwhile, longitudinal analysis in combination of rituximab cohort also revealed persistently marked amelioration in a series of scales from baseline even more than 1 year. Moreover, analysis in rituximab subgroup showed no difference in any clinical outcomes between combination with single first-line and with repeated first-line treatment (≥ 2 times), while compared to delayed combination with rituximab (> 3 months), early initiation of combination (≤ 3 months) might achieve better improvements in CASE and MMSE assessment even 1 year later. No rituximab-correlated serious adverse events have been reported in our patients. CONCLUSIONS: Our simplified regimen of combined low-dose rituximab firstly showed significantly accelerating short-term recovery and long-term improvement for AE with NSAbs, in parallel with markedly reduced prednisone dosage and clinical relapses. Moreover, opportunity of protocol showed earlier initiation (≤ 3 months) with better long-term improvement.

High-frequency terahertz stimulation alleviates neuropathic pain by inhibiting the pyramidal neuron activity in the anterior cingulate cortex of mice.

Neuropathic pain (NP) is caused by a lesion or disease of the somatosensory system and is characterized by abnormal hypersensitivity to stimuli and nociceptive responses to non-noxious stimuli, affecting approximately 7-10% of the general population. However, current first-line drugs like non-steroidal anti-inflammatory agents and opioids have limitations, including dose-limiting side effects, dependence, and tolerability issues. Therefore, developing new interventions for the management of NP is urgent. In this study, we discovered that the high-frequency terahertz stimulation (HFTS) at approximately 36 THz effectively alleviates NP symptoms in mice with spared nerve injury. Computational simulation suggests that the frequency resonates with the carbonyl group in the filter region of Kv1.2 channels, facilitating the translocation of potassium ions. In vivo and in vitro results demonstrate that HFTS reduces the excitability of pyramidal neurons in the anterior cingulate cortex likely through enhancing the voltage-gated K+ and also the leak K+ conductance. This research presents a novel optical intervention strategy with terahertz waves for the treatment of NP and holds promising applications in other nervous system diseases.

Up to 1 in 10 people are estimated to experience neuropathic pain, a particularly challenging form of chronic pain where nerve damage causes extreme sensitivity to everyday stimuli. Current treatments often rely on painkiller drugs that can lead to serious side effects as well as dependency issues. New and effective interventions are therefore necessary. One radically different approach is the use of 'terahertz' waves, a type of electromagnetic radiation that has the ability to affect the chemical bonds holding molecules together. In fact, previous research has shown that specific frequencies of terahertz waves can modify the activity of certain proteins. With this technique, it may therefore be possible to disrupt voltage-dependent potassium channels, a type of proteins which help to regulate nerve cell activity and is a possible target for pain therapy. To explore this approach, Peng, Wang, Tan et al. investigated whether high-frequency terahertz stimulation that targets potassium ion channels could reduce neuropathic pain in mice. The animals, which had undergone surgery recreating nerve damage, were implanted with a device that allowed the delivery of terahertz waves into a brain region vital for regulating pain sensations. Experiments showed that delivering 36 terahertz radiations changed important ion channel properties (such as how easily they would allow ions to pass through), decreasing neuron activity and raising the pain threshold of the mice. This finding indicates that, with further development, terahertz frequency stimulation could become a new, non-drug method to manage neuropathic pain. Additional research will be needed to see if terahertz waves could also be applied to other neurological disorders influenced by ion channel activity.

Proanthocyanidins induce analgesic and anxiolytic effects in spared nerve injured mice by decreasing in vivo firing rate of pyramidal cells in the insular cortex.

Neuropathic pain is one of the most common symptoms of clinical pain that often accompanied by severe emotional changes such as anxiety. However, the treatment for comorbidity of chronic pain and anxiety is limited. Proanthocyanidins (PACs), a group of polyphenols enriched in plants and foods, have been reported to cause pain-alleviating effects. However, whether and how PACs induce analgesic and anxiolytic effects in the central nervous system remain obscure. In the present study, we observed that microinjection of PACs into the insular cortex (IC) inhibited mechanical and spontaneous pain sensitivity and anxiety-like behaviors in mice with spared nerve injury. Meanwhile, PACs application exclusively reduced the FOS expression in the pyramidal cells but not interneurons in the IC. In vivo electrophysiological recording of the IC further showed that PACS application inhibited the firing rate of spikes of pyramidal cells of IC in neuropathic pain mice. In summary, PACs induce analgesic and anxiolytic effects by inhibiting the spiking of pyramidal cells of the IC in mice with neuropathic pain, which should provide new evidence of PACs as the potential clinical treatment of chronic pain and anxiety comorbidity.

Photoredox/copper cocatalyzed domino cyclization of oxime esters with TMSCN: access to antifungal active tetrasubstituted pyrazines.

A photoredox/copper cocatalyzed domino cyclization of oxime esters with TMSCN has been developed. A range of structurally novel tetrasubstituted pyrazines have been obtained. This method features high bond-forming efficiency, high step economy, broad substrate scope, and gram-scale synthesis. Moreover, preliminary bioactivity evaluation of pyrazine products shows their promising antifungal activities.