Electroacupuncture Attenuates CFA-Induced Inflammatory Pain by Regulating CaMKII

A moderated chain mediation model examining the relation between smartphone addiction and intolerance of uncertainty among master's and PhD students

The theories of relational regulation and compensatory Internet use suggest that intolerance of uncertainty influences smartphone addiction (SPA), which in turn is influenced by other aspects. This study used previous results to examine how intolerance of uncertainty affects SPA in PhD and master's degree programs. A convenience sample comprising 1727 master's and PhD students (99.9 %; 50.7 % female; Mage = 27.71; SD = 3.80; range = 21-43) was recruited. Using established questionnaires, we measured SPA, anxiety, positive coping style, perceived social support, and intolerance of uncertainty. The results demonstrated that intolerance of uncertainty positively affects SPA in terms of predictive power. Furthermore, anxiety and positive coping style mediate that link in a cascade fashion. A greater SPA indicates that the individual is less likely to use a positive coping style, has a higher anxiety level, and has a lower tolerance for uncertainty. While thinking about how intolerance of uncertainty affects anxiety and positive coping style, perceived social support mediates the relationship. Intolerance of uncertainty has less impact on anxiety and positive coping style when perceived social support is high. These results indicate the possibility of examining SPA prevention and intervention from several angles. Therefore, emotional regulation, which modifies anxiety and the tendency to use a positive coping style, may reduce the impact of intolerance of uncertainty on SPA. Another successful strategy for reducing smartphone addiction is to provide social support from loved ones and the community at large.

Intolerance of uncertainty affects the behavioral and neural mechanisms of higher generalization

Intolerance of uncertainty (IU) is associated with several anxiety disorders. In this study, we employed rewards and losses as unconditioned positive and negative stimuli, respectively, to explore the effects of an individual's IU level on positive and negative generalizations using magnetic resonance imaging technology. Following instrumental learning, 48 participants (24 high IU; 24 low IU) were invited to complete positive and negative generalization tasks; their behavioral responses and neural activities were recorded by functional magnetic resonance imaging. The behavior results demonstrated that participants with high IUs exhibited higher generalizations to both positive and negative cues as compared with participants having low IUs. Neuroimaging results demonstrated that they exhibited higher activation levels in the right anterior insula and the default mode network (i.e. precuneus and posterior cingulate gyrus), as well as related reward circuits (i.e. caudate and right putamen). Therefore, higher generalization scores and the related abnormal brain activation may be key markers of IU as a vulnerability factor for anxiety disorders.

Electroacupuncture may alleviate diabetic neuropathic pain by inhibiting the microglia P2X4R and neuroinflammation

Diabetic neuropathic pain (DNP) is a common and destructive complication of diabetes mellitus. The discovery of effective therapeutic methods for DNP is vitally imperative because of the lack of effective treatments. Although 2 Hz electroacupuncture (EA) was a successful approach for relieving DNP, the mechanism underlying the effect of EA on DNP is still poorly understood. Here, we established a rat model of DNP that was induced by streptozotocin (STZ) injection. P2X4R was upregulated in the spinal cord after STZ-injection. The upregulation of P2X4R was mainly expressed on activated microglia. Intrathecal injection of a P2X4R antagonist or microglia inhibitor attenuated STZ-induced nociceptive thermal hyperalgesia and reduced the overexpression of brain-derived neurotrophic factor (BDNF), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the spinal cord. We also assessed the effects of EA treatment on the pain hypersensitivities of DNP rats, and further investigated the possible mechanism underlying the analgesic effect of EA. EA relieved the hyperalgesia of DNP. In terms of mechanism, EA reduced the upregulation of P2X4R on activated microglia and decreased BDNF, IL-1β and TNF-α in the spinal cord. Mechanistic research of EA's analgesic impact would be beneficial in ensuring its prospective therapeutic effect on DNP as well as in extending EA's applicability.

Electroacupuncture attenuates chronic inflammatory pain and depression comorbidity by inhibiting hippocampal neuronal apoptosis via the PI3K/Akt signaling pathway

In chronic inflammatory pain (CIP) and depression, neuroapoptosis has been identified as a contributing factor. Electroacupuncture (EA) shows promise as an alternative therapy for this comorbidity. However, the underlying mechanism remains unclear. This study aimed to investigate the effects of EA on hippocampal neuronal apoptosis in rats with CIP and depression. Rats received plantar injections of complete Freund's adjuvant (CFA) on days 0 and 14. They were then divided into groups: sham operation, model, EA, and duloxetine. EA was administered at Hegu (LI4) and Taichong (LR3) from days 15 to 28, while the duloxetine group received duloxetine and distilled water daily (0.1 mg/ml). Pain behavior was assessed using the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) tests. Depression-like behavior was evaluated through the sucrose preference test (SPT), open-field test (OFT), and forced swim test (FST). Hematoxylin and eosin (HE) staining was employed to assess pathological changes in the hippocampus. Nerve cell apoptosis was determined using TUNEL fluorescence staining. Western blot analysis was conducted to measure the protein expression of Bcl-2, Bax, p-PI3K/PI3K, and p-Akt/Akt. EA demonstrated significant pain intensity reduction and alleviation of pain-related depressive symptoms. Our findings from the HE staining confirmed that CIP induced by CFA led to morphological changes in the hippocampus, while EA effectively reversed these pathological alterations. Moreover, EA intervention remarkably reduced neuronal apoptosis and exhibited an upregulation of Bcl-2 protein expression accompanied by a decrease in Bax expression. Additionally, EA activated the PI3K/Akt signaling pathway. Overall, our study suggests that EA holds the potential to improve pain and depressive behaviors in rats with CIP and depression comorbidity, potentially mediated through the activation of the PI3K/Akt pathway, leading to a reduction in hippocampal neuronal apoptosis.

Activation of the N-methyl-D-aspartate receptor and calcium/calmodulin-dependent protein kinase IIα signal in the rostral anterior cingulate cortex is involved in pain-related aversion in rats with peripheral nerve injury

The rostral anterior cingulate cortex (rACC) of rat brain is associated with pain-related emotions. However, the underlying molecular mechanism remains unclear. Here, we investigated the effects of the N-methyl-D-aspartate (NMDA) receptor and Ca2+/Calmodulin-dependent protein kinase type II (CaMKII)α signal on pain-related aversion in the rACC of a rat model of neuropathic pain (NP). Mechanical and thermal hyperalgesia were examined using von Frey and hot plate tests in a rat model of NP induced by spared nerve injury (SNI) of the unilateral sciatic nerve. Bilateral rACC pretreatment with the CaMKII inhibitor tat-CN21 (derived from the cell-penetrating tat sequence and CaM-KIIN amino acids 43-63) or tat-Ctrl (the tat sequence and the scrambled sequence of CN21) was performed on postoperative days 29-35 in Sham rats or rats with SNI. Spatial memory performance was tested using an eight-arm radial maze on postoperative days 34-35. Pain-related negative emotions (aversions) were evaluated using the place escape/avoidance paradigm on postoperative day 35 following the spatial memory performance test. The percentage of time spent in the light area was used to assess pain-related negative emotions (i.e., aversion). The expression levels of the NMDA receptor GluN2B subunit, CaMKIIα, and CaMKII-Threonine at position 286 (Thr286) phosphorylation in contralateral rACC specimens were detected by Western blot or real time PCR following the aversion test. Our data showed that pretreatment of the rACC with tat-CN21 increased determinate behavior but did not alter hyperalgesia or spatial memory performance in rats with SNI. In addition, tat-CN21 reversed the enhanced CaMKII-Thr286 phosphorylation and had no effect on the upregulated expression of GluN2B, CaMKIIα protein, and mRNA. Our data suggested that activation of the NMDA receptor-CaMKIIα signal in rACC is associated with pain-related aversion in rats with NP. These data may provide a new approach for the development of drugs that modulate cognitive and emotional pain aspects.

Electroacupuncture Alleviates CFA-Induced Inflammatory Pain via PD-L1/PD-1-SHP-1 Pathway

Inflammatory pain is difficult to treat clinically, but electroacupuncture (EA) has been demonstrated to be effective in alleviating inflammatory pain. Programmed cell death ligand-1 (PD-L1) and its downstream signal, Src homology region two domain-containing phosphatase-1 (SHP-1) have a critical role in relieving inflammatory pain. However, whether the PD-L1/PD-1-SHP-1 pathway mediates the analgesic and anti-inflammatory effects of EA in inflammatory pain remains unclear. Here, we observed that EA reversed the complete Freund's adjuvant (CFA)-induced hyperalgesia. EA reduced the expression of IL-6, iNOS, and NF-κB pathway in dorsal root ganglia (DRG) on day 7 after CFA injection but had no effect on the expression of IL-6, iNOS, and NF-κB PP65 on day 21 after CFA injection. Moreover, EA upregulated the protein levels of the PD-L1/PD-1-SHP-1 pathway on day 7 and day 21 after CFA injection. Furthermore, EA upregulated PD-L1 expression in calcitonin gene-related peptide (CGRP)⁺ but not in isohaemagglutinin B4 (IB4)⁺ and NF200⁺ neurons on day 7 and day 21 after CFA injection. Intrathecal injection of the PD-L1/PD-1 inhibitor BMS-1 (50 or 100 µg) blocked the EA-induced analgesic effect, significantly increased IL-6 and iNOS levels, and reduced the levels of PD-L1/PD-1-SHP-1. BMS-1 (50 or 100 µg) significantly reduced the expression of PD-L1 in IB4⁺, CGRP⁺, and NF200⁺ neurons. Our results show that EA's anti-inflammatory and analgesic effects are associated with activating the PD-L1/PD-1-SHP-1 pathway and suppressing its regulated neuroinflammation. This study provides a new potential therapeutic target for treating inflammatory pain.

Mechanisms of acupuncture-electroacupuncture on inflammatory pain

Acupuncture, as a traditional treatment, has been extensively used in China for thousands of years. According to the World Health Organization (WHO), acupuncture is recommended for the treatment of 77 diseases. And 16 of these diseases are related to inflammatory pain. As a combination of traditional acupuncture and modern electrotherapy, electroacupuncture (EA) has satisfactory analgesic effects on various acute and chronic pain. Because of its good analgesic effects and no side effects, acupuncture has been widely accepted all over the world. Despite the increase in the number of studies, the mechanisms via which acupuncture exerts its analgesic effects have not been conclusively established. A literature review of related research is of great significance to elaborate on its mechanisms and to inform on further research directions. We elucidated on its mechanisms of action on inflammatory pain from two levels: peripheral and central. It includes the mechanisms of acupuncture in the periphery (immune cells and neurons, purinergic pathway, nociceptive ion channel, cannabinoid receptor and endogenous opioid peptide system) and central nervous system (TPRV1, glutamate and its receptors, glial cells, GABAergic interneurons and signaling molecules). In this review, we collected relevant recent studies to systematically explain the mechanisms of acupuncture in treating inflammatory pain, with a view to providing direction for future applications of acupuncture in inflammatory pain and promoting clinical development.

Intolerance of uncertainty and future career anxiety among Chinese undergraduate students during COVID-19 period: Fear of COVID-19 and depression as mediators

Uncertainty is mushrooming throughout COVID-19, and intolerance of uncertainty (IoU) nudges people into mental health difficulties involving fear, depression, and anxiety. The objective of this study was to investigate the role of depression and fear of COVID-19 (FoC) in the association between IoU and future career anxiety (FCA) among Chinese university students during the COVID-19 pandemic. This study involved 1,919 Chinese undergraduate students from 11 universities in eight Chinese cities with an online self-administered survey that included demographic information, IoU, FoC, depression, and FCA completed by all participants. Our study demonstrated a positive relationship between IoU and FCA and the chain mediation effect of FoC and depression. Thus, understanding how FoC affects FCA not only informs university career professionals and assists students in preparing for employment, but also motivates schools to offer career opportunities workshops and, most importantly, provides mental health support to help students effectively cope with uncertainty and overcome COVID-19-related stress.

The Comparative Efficacy of Unified Transdiagnostic Protocol (UP) and Mindfulness-Based Stress Reduction Protocol (MBSR) on Emotion Regulation and Uncertainty Intolerance in Infertile Women Receiving IVF

Some emotional and social aspects of infertility affect the response of the infertile women to the treatment. The purpose of this study was to compare the efficacy of unified transdiagnostic protocol (UP) and mindfulness-based stress reduction protocol (MBSR) on emotion regulation and uncertainty intolerance in infertile women receiving IVF. Forty-five infertile women with symptoms of anxiety and depression were included in the study. They were randomly assigned in two intervention groups and one control group. The UP was performed for 10 sessions and MBSR was performed for eight sessions. All participants completed emotion regulation and uncertainty intolerance questionnaires at pre-test, post-test, and follow-up stages. Both interventions had a significant effect on increasing patients' emotion regulation (p ≤ 0.05), but only unified transdiagnostic protocol had a significant effect on intolerance of uncertainty (p ≤ 0.05). Findings show that UP and MBSR have increased emotion regulation. Also UP could reduce the rate of uncertainty intolerance.

Interleukin-17 as a potential therapeutic target for chronic pain

Chronic pain remains to be a clinical challenge and is recognized as a major health problem with varying impacts on quality of life. Currently, the first-line therapy for chronic pain is opioids, which are often accompanied by unwanted psychoactive side effects. Thus, new and effective treatments for chronic pain are urgently needed and eagerly pursued. Inflammatory cytokines, especially interleukin-17 (IL-17), are reportedly potential therapeutic targets owing to their pivotal role in chronic pain from the neuroinflammation perspective. Recently, substantial evidence confirmed that IL-17 and IL-17 receptors (IL-17Rs) were increased in neuropathic, inflammatory, and cancer pain models. Notably, IL-17/IL-17R antibodies also reportedly relieve or cure inflammatory- and pain-related diseases. However, existing studies have reported controversial results regarding IL-17/IL-17Rs as potential therapeutic targets in diverse animal models of chronic pain. In this review, we present a summary of published studies and discuss the evidence, from basic to clinical to research, regarding the role and mechanism of action between IL-17 and diverse kinds of chronic pain in animal models and clinical patients. Furthermore, we evaluated IL-17-based therapy as a potential therapeutic strategy for inflammatory- and pain-related disease. Importantly, we also discussed clinical trials of IL-17/IL-17R targeting monoclonal antibodies. Overall, we found that IL-17 is a potential therapeutic target for chronic pain from the perspective of neuroinflammation.

Spinal Sirtuin 3 Contributes to Electroacupuncture Analgesia in Mice with Chronic Constriction Injury–Induced Neuropathic Pain

BACKGROUND

Electroacupuncture (EA) is a traditional Chinese therapeutic technique that has a beneficial effect on neuropathic pain; however, the specific mechanism remains unclear. In this study, we investigated whether EA inhibits spinal Ca/calmodulin-dependent protein kinase II (CaMKIIα) phosphorylation through Sirtuin 3 (SIRT3) protein, thus relieving neuropathic pain.

MATERIALS AND METHODS

We used wild-type and SIRT3 knockout (SIRT3^-/-) mice and used chronic constriction injury (CCI) as a pain model. We performed Western blotting, immunostaining, von Frey, and Hargreaves tests to gather biochemical and behavioral data. Downregulation and overexpression and spinal SIRT3 protein were achieved by intraspinal injection of SIRT3 small interfering RNA and intraspinal injection of lentivirus-SIRT3. To test the hypothesis that CaMKIIα signaling was involved in the analgesic effects of EA, we expressed CaMKIIα-specific designer receptors exclusively activated by designer drugs (DREADDs) in the spinal dorsal horn (SDH) of mice.

RESULTS

These results showed that the mechanical and thermal hyperalgesia induced by CCI was related to the decreased spinal SIRT3 expression in the SDH of mice. A significant reduction of mechanical and thermal thresholds was found in the SIRT3^-/- mice. SIRT3 overexpression or EA treatment alleviated CCI-induced neuropathic pain and prevented the spinal CaMKIIα phosphorylation. Most importantly, EA increased the expression of spinal SIRT3 protein in the SDH. Downregulation of spinal SIRT3 or CaMKIIα Gq-DREADD activation inhibited the regulatory effect of EA on neuropathic pain.

CONCLUSION

Our results showed that CaMKIIα phosphorylation was inhibited by spinal SIRT3 in neuropathic pain and that EA attenuated CCI-induced neuropathic pain mainly by upregulating spinal SIRT3 expression in the SDH of mice.

Optogenetic modulation of electroacupuncture analgesia in a mouse inflammatory pain model

Peripheral tissue damage and associated inflammation can trigger neuroplastic changes in somatic pain pathways, such as reduced neuronal firing thresholds and synaptic potentiation, that ultimately lead to peripheral sensitization and chronic pain. Electroacupuncture (EA) can relieve chronic inflammatory pain, but the underlying mechanisms are unknown, including the contributions of higher pain centers such as somatosensory cortex (SSC). We investigated these mechanisms using optogenetic modulation of SSC activity in a mouse inflammatory pain model. Injection of Complete Freund's Adjuvant into the hind paw reliably induced inflammation accompanied by reduced mechanical and thermal pain thresholds (hyperalgesia) within three days (mechanical: 1.54 ± 0.13 g; thermal: 3.94 ± 0.43 s). Application of EA produced significant thermal and mechanical analgesia, but these responses were reversed by optogenetic activation of SSC neurons, suggesting that EA-induced analgesia involves modulation of central pain pathways. Western blot and immunostaining revealed that EA also attenuated CaMKIIα signaling in the dorsal root ganglion, central spinal cord, SSC, and anterior cingulate cortex (ACC). In contrast, optogenetic activation of the SSC induced CaMKIIα signaling in SSC and ACC. These findings suggest that AE can relieve inflammatory pain by suppressing CaMKIIα-dependent plasticity in cortical pain pathways. The SSC and ACC CaMKIIα signaling pathways may be valuable therapeutic targets for chronic inflammatory pain treatment.

The Scaffold Protein PICK1 as a Target in Chronic Pain

Well-tolerated and effective drugs for treating chronic pain conditions are urgently needed. Most chronic pain patients are not effectively relieved from their pain and suffer from debilitating drug side effects. This has not only drastic negative consequences for the patients’ quality of life, but also constitute an enormous burden on society. It is therefore of great interest to explore new potent targets for effective pain treatment with fewer side effects and without addiction liability. A critical component of chronic pain conditions is central sensitization, which involves the reorganization and strengthening of synaptic transmission within nociceptive pathways. Such changes are considered as maladaptive and depend on changes in the surface expression and signaling of AMPA-type glutamate receptors (AMPARs). The PDZ-domain scaffold protein PICK1 binds the AMPARs and has been suggested to play a key role in these maladaptive changes. In the present paper, we review the regulation of AMPARs by PICK1 and its relation to pain pathology. Moreover, we highlight other pain-relevant PICK1 interactions, and we evaluate various compounds that target PICK1 and have been successfully tested in pain models. Finally, we evaluate the potential on-target side effects of interfering with the action of PICK1 action in CNS and beyond. We conclude that PICK1 constitutes a valid drug target for the treatment of inflammatory and neuropathic pain conditions without the side effects and abuse liability associated with current pain medication.

Intolerance of uncertainty moderates the relationship between catastrophizing, anxiety, and perceived pain in people with chronic nononcological pain

OBJECTIVE

Substantial empirical evidence has shown that intolerance of uncertainty is a central transdiagnostic feature in psychopathology and it has been suggested to be a pain-related psychological factor contributing to the experience of chronic pain. However, research in this area is virtually nonexistent. The objective of this study was to investigate associations between pain severity, catastrophizing, and anxiety in people with chronic nononcological pain, while assuming that intolerance of uncertainty moderates these relationships.

METHODS

A convenience sample of 188 individuals with nononcological chronic pain (157 women and 32 men) participated in the study. We investigated the moderated mediation of intolerance of uncertainty between anxiety and catastrophizing and between catastrophizing and pain intensity.

RESULTS

The full moderated mediation model accounted for significant variance in pain intensity (R2 = .148, P< .001). Intolerance of uncertainty significantly moderated the interaction between anxiety and catastrophizing (B = 0.039, SE = 0.012, CI [0.015, 0.063]) and between catastrophizing and pain intensity (B = -0.034, SE = 0.010, CI [-0.054, -0.014]). Anxiety and intolerance of uncertainty did not interact in predicting catastrophizing, although an interaction effect was found between intolerance of uncertainty and catastrophizing in predicting pain intensity.

CONCLUSION

This study is the first to address the interrelationship of intolerance of uncertainty, catastrophizing, and anxiety in relation to perceived pain intensity. The current findings support intolerance of uncertainty as a relevant psychological variable that is distinct from other relevant constructs in the setting of pain research and treatment.

Experiences of international medical students enrolled in Chinese medical institutions towards online teaching during the COVID-19 pandemic

Introduction

. The COVID-19 pandemic has forced the world to pause. One hundred and eighty-eight countries have imposed countrywide school closures, affecting more than 1.5 billion children and youths. The majority of academic leaders are currently encouraging online education to resolve this crisis. This study aimed to investigate international medical students' (IMS) experiences of online teaching during the COVID-19 pandemic.

Methods

Data were collected online using a validated questionnaire and one open-ended question, presented on the Google forms platform. The study attracted responses from 1,107 IMS volunteer participants. IBM SPSS v. 25, GraphPad Prism v. 9, and MindManager v. 2018 were used for data analysis. All variables were subjected to descriptive statistical analysis. The Mann-Whitney U test was used in subgroup analysis and the Kruskal-Wallis test was also applied for year-wise comparisons. Open-ended text responses were analyzed qualitatively, extracting themes by which responses were classified.

Results

Among 1,107 respondents, a total of 67.8% were males, and the majority (63.1%) of the IMS were in the age group of 21-23 years. The results show that more than half of the respondents reported their Internet connection quality as poor to average. Poor Internet connection severely affected IMS online learning experience. Persistent and recurrent issues with Internet access became a significant concern for IMS. Lack of electricity is one of the factors that can contribute to poor learning output and dissatisfaction with online teaching. IMS perceive online medical education as unhelpful in several phases of the training, such as improving their clinical skills, knowledge, and discussion skills.

Conclusions

During these unprecedented periods, online teaching has allowed medical education to continue. However, IMS are generally dissatisfied with online teaching. Medical students must visualize the human body, so supportive technologies are important to compensate for the lack of clinical practices. Medical institutions may need to invest in faculty training programs and continually adjust to enhance the content of online training and international partnerships. A switch from conventional face-to-face teaching to a fully functional virtual education framework in the medical education field will take time and experience.

Electroacupuncture Regulates Pain Transition Through Inhibiting PKCε and TRPV1 Expression in Dorsal Root Ganglion

Many cases of acute pain can be resolved with few side effects. However, some cases of acute pain may persist beyond the time required for tissue injury recovery and transit to chronic pain, which is hard to treat. The mechanisms underlying pain transition are not entirely understood, and treatment strategies are lacking. In this study, the hyperalgesic priming model was established on rats to study pain transition by injection of carrageenan (Car) and prostaglandin E2 (PGE2). The expression levels of protein kinase C epsilon (PKCε) and transient receptor potential vanilloid 1 (TRPV1) in the L4–L6 dorsal root ganglion (DRG) were investigated. Electroacupuncture (EA) is a form of acupuncture in which a small electric current is passed between a pair of acupuncture needles. EA was administrated, and its effect on hyperalgesia and PKCε and TRPV1 expression was investigated. The PKCε–TRPV1 signaling pathway in DRG was implicated in the pain transition. EA increased the pain threshold of model animals and regulated the high expression of PKCε and TRPV1. Moreover, EA also regulated hyperalgesia and high TRPV1 expression induced by selective PKCε activation. We also found that EA partly increased chronic pain threshold, even though it was only administered between the Car and PGE2 injections. These findings suggested that EA could prevent the transition from acute to chronic pain by inhibiting the PKCε and TRPV1 expression in the peripheral nervous system.