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ACCGlu–innervated VTAGABA neurons mediate hyperalgesia and anxiety-like behaviors in neuropathic pain a, Left, schematic of the co-injection of CaMKII-Cre virus and the Cre-dependent anterograde trans-monosynaptic virus (rAAV-EF1α-DIO-EGFP-T2A-TK-WPRE-hGH, and H129ΔTK-ubc-tdTomato) into the ACC for the identification of ACCGlu-innervated neurons (GAD67-GFP) in the VTA. Right, representative micrograph showing the localization of anterograde virus (GFP and tdTomato) in ACCGlu neurons. Scale bar, 500 μm. b, Schematic and representative micrograph showing the specific expression of chemogenetic activation virus in ACCGlu neurons. c, Schematic of the injection of chemogenetic activation virus (VGAT1-DIO-hM3Dq) into the VTA and AAV2/1-Cre anterograde virus into the ACC. d-g, Statistics of mechanical (d) and thermal (e) pain responses, OFT (f), and EPM (g) tests following CNO application (0.5 mg/kg, i.p.) of mice receiving hM3Dq-expressing or control virus (Control, n = 8; hM3Dq, n = 8 mice). Behaviors were assessed 6 weeks after SNI. h-l, As in (c-g), except that AAV2/1-Cre anterograde virus was injected into the ACC and GAD67-DIO-hM4Di virus was injected into the VTA in SNI mice (n = 8 for each group). The data are presented as the mean ± s.e.m. Unpaired Student’s t-test, *P < 0.05, **P < 0.01. Detailed statistics information can be found in the Source Data. Source data
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The central mechanisms underlying pain chronicity remain elusive. Here, we identify a reciprocal neuronal circuit in mice between the anterior cingulate cortex (ACC) and the ventral tegmental area (VTA) that mediates mutual exacerbation between hyperalgesia and allodynia and their emotional consequences and, thereby, the chronicity of neuropathic p...
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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, a...
Neurons within the anterior cingulate cortex (ACC) orchestrate the co-occurrence of chronic pain and anxiety. The ACC hyperactivity plays a crucial role in the emotional impact of neuropathic pain. Astrocyte-mediated neuroinflammatory is responsible for regulating the balance between excitation-inhibition (E/I) in the brain. However, there is limit...
Citations
... Given that the impairment of DA release is a pathological hallmark of PD, we next performed electrochemical carbon fiber electrode (CFE) amperometric recordings [28][29][30] to monitor DA release in the striatum with a patch clamp-class super-high spatiotemporal resolution and sensitivity (Fig. 1E). Upon the application of a local electric stimulus (E-stim) to the striatal slice, a transient increase in amperometric current (I amp , with an amplitude of ~ 350 pA) occurred, followed by a decay back to the baseline, representing the release and subsequent reuptake of DA (Fig. 1F). ...
... Immunostaining was performed as previously described [19,30]. Briefly, mice were anesthetized with avertin, then perfused with 0.9% saline followed by 4% paraformaldehyde (PFA) in PBS. ...
... Previous studies have shown that ACC neurons with specific projection targets perform different functions. The ACC-PAG projection mainly modulates pain sensation [46], whereas the ACC-VTA projection modulates the emotional comorbidities of chronic pain, such as anxiety [41,47]. Thus, we injected retrograde AAV (scAAV2/2Retro-EGFP) into the PAG or VTA (Fig. 4a-b and f) on day 2 after CFA injection. ...
... Our present results revealed that anxiety mainly occurs on day 9 after intraplantar CFA injection and that direct downregulation of RAGE expression in the ACC significantly alleviated anxiety-like behavior in CFA-treated mice. The ACC is an important center for the processing of pain-related emotion [2], and our and other reports have confirmed the role of the ACC-VTA in modulating chronic pain comorbid with emotional symptoms [41,47], such as aversion and anxiety. Here, we showed that most VTA-projecting ACC neurons exhibit RAGE, which provides an anatomic basis for the ability of RAGE to regulate chronic pain comorbid with anxiety. ...
Previous studies have shown that astrocyte activation in the anterior cingulate cortex (ACC), accompanied by upregulation of the astrocyte marker S100 calcium binding protein B (S100B), contributes to comorbid anxiety in chronic inflammatory pain (CIP), but the exact downstream mechanism is still being explored. The receptor for advanced glycation end-products (RAGE) plays an important role in chronic pain and psychosis by recognizing ligands, including S100B. Therefore, we speculate that RAGE may be involved in astrocyte regulation of the comorbidity between CIP and anxiety by recognizing S100B. Here, we investigated the potential role of RAGE and the correlation between RAGE and astrocyte regulation in the ACC using a mouse model of complete Freund’s adjuvant (CFA)-induced inflammatory pain. We detected substantial upregulation of RAGE expression in ACC neurons when anxiety-like behaviors occurred in CFA-treated mice. The inhibition of RAGE expression decreased the hyperexcitability of ACC neurons and alleviated both hyperalgesia and anxiety in CFA-treated mice. Furthermore, we found that the ACC astrocytic S100B level increased over a similar time course. Intra-ACC application of S100B or downregulation of ACC astrocytic S100B via suppression of astrocyte activation significantly affected RAGE levels and the relative behaviors of CFA-treated mice. Taken together, these findings suggest that the upregulation of ACC neuronal RAGE results from the activation of astrocytic S100B and leads to the maintenance of pain perception and anxiety in the late phase after CFA injection, which may partly explain the mechanism by which ACC neuron‒astrocyte coupling promotes the maintenance of CIP and anxiety comorbidity.
... A small incision was made to expose the skull. The virus (150 nL/dosage) was bilaterally injected into ACC region (AP, +1.0 mm, ML, +0.3 mm, DV, −1.8 mm) at a rate of 100 nL/min using a glass pipette [42,43]. Then the micro-syringe was left in place for at least 10 min to prevent virus backflowing during the retraction. ...
Aims
The comorbidity of anxiety‐like symptoms in neuropathic pain (NP) is a significant yet often overlooked health concern. Anxiety sufferers may have a lower tolerance for pain, but which is difficult to treat. Accumulating evidence suggests a strong link between astrocytes and the manifestation of NP with concurrent anxiety‐like behaviors. And the anterior cingulate cortex (ACC) has emerged as a key player in pain modulation and related emotional processing. However, the complex mechanisms that astrocytes in ACC influence anxiety behavior in mouse models of NP remain largely unexplored.
Methods
Utilizing the traditional spared nerve injury (SNI) surgical model, we employed chemogenetic approaches, immunofluorescence, and western blot to investigate the functional significance and interactive dynamics between ACC astrocytes and excitatory neurons.
Results
Our results revealed that SNI surgery induces NP and delayed anxiety‐like behaviors, accompanied by increased astrocyte activity in the ACC. Chemogenetic manipulation demonstrated that inhibiting astrocytes alleviates anxiety symptoms, while activating them exacerbates anxiety‐like behaviors, affecting local excitatory neurons and synapse density. Direct manipulation of ACC excitatory neurons also significantly impacted anxiety‐like behaviors.
Conclusion
Our results highlight the pivotal role of ACC astrocytes in modulating anxiety‐like behavior, suggesting a novel therapeutic strategy for anxiety associated with NP by targeting astrocyte function.
... Furthermore, maintaining the E-I balance is crucial for proper neural functioning. The presence of persistent noxious stimuli during chronic pain can disturb this balance by modifying the mPFC and ACC neuronal activity [8,9]. The ongoing stress-induced aggregation and misfolding of neuronal proteins serve as key factors in the pathogenesis of synaptic dysfunction and changes in neuronal activity [10]. ...
Objectives
Endoplasmic reticulum (ER) stress‐induced protein homeostasis perturbation is a core pathological element in the pathogenesis of neurodegenerative diseases. This study aims to clarify the unique role played by C/EBP homologous protein (CHOP) as a biomarker of the unfolded protein response (UPR) in the etiology of chronic pain and related cognitive impairments following chronic constrictive nerve injury (CCI).
Methods
The memory capability following CCI was assessed utilizing the Morris water maze (MWM) and fear conditioning test (FCT). Activation of the UPR was quantified by assessing levels of CHOP and key ER stress sensors. The terminal deoxynucleotidyl transferase (TdT) dUTP nick‐end labeling (TUNEL) assay and the levels of cleaved caspase‐3 were utilized to assess apoptosis level. Synaptic plasticity was assessed via a modified Golgi‐Cox staining method, and long‐term potentiation (LTP) measurements were taken. Neuronal activity was determined by immunofluorescence and fiber photometry. Knockdown of CHOP and alleviation of ER stress were selectively induced by LV‐Ddit3‐shRNAs and the chemical chaperone 4‐phenylbutyric acid (4‐PBA), respectively.
Results
Mice subjected to CCI displayed enduring pain and cognitive impairments evident on Days 21–28 post‐surgery. Following CCI, changes in the dorsal CA1 (dCA1) manifested as ER dilation, upregulation of CHOP and upstream signaling molecules, reduced dendritic spine density, and PSD95 levels, and impaired LTP. Additionally, the co‐localization of CaMKIIα/c‐Fos and CaMKIIαdCA1‐mediated calcium signaling was significantly reduced, while the activation of CaMKIIα was found to mitigate cognitive impairments in CCI mice. Selective knockdown of CHOP enhanced synaptic plasticity and CaMKIIα neuron activity, while 4‐PBA treatment alleviated ER stress, synergistically improving cognitive deficits associated with chronic pain.
Conclusion
CCI‐induced CHOP upregulation impairs dCA1 synaptic plasticity and neuronal activity, leading to chronic pain‐related cognitive deficits.
... Although tonic versus phasic firing patterns of VTA DA neurons have been reported to be functionally involved in motivation behavior and reward prediction (58)(59)(60)(61), how the firingpattern alteration determines social decisionmaking remains to be fully elucidated. To determine whether the altered DA release is underlying sex preference governed by different firing patterns, we performed electrochemical carbon-fiber electrode (CFE)-based amperometric recordings (62)(63)(64) in response to phasic or tonic optogenetic stimuli and found that repetitive phasic stimulation induced the release of larger DA transients, characterized by (Fig. 8H and fig. S11I). ...
... Stereotaxic surgery was performed as previously described (14,62,63). The mice were anesthetized with avertin (1.5% tribromoethanol, 2.5% tertiary butanol, and 0.9% NaCl; 0.1 ml/ 5 g body weight). ...
... The general methods for preparing NAc slices were similar to those described previously (62,70). Mice were anaesthetized with tribromoethanol via intraperitoneal injection (0.2 ml/ 10 g). ...
Sociosexual preference is critical for reproduction and survival. However, neural mechanisms encoding social decisions on sex preference remain unclear. In this study, we show that both male and female mice exhibit female preference but shift to male preference when facing survival threats; their preference is mediated by the dimorphic changes in the excitability of ventral tegmental area dopaminergic (VTA DA ) neurons. In males, VTA DA projections to the nucleus accumbens (NAc) mediate female preference, and those to the medial preoptic area mediate male preference. In females, firing-pattern (phasic-like versus tonic-like) alteration of the VTA DA -NAc projection determines sociosexual preferences. These findings define VTA DA neurons as a key node for social decision-making and reveal the sexually dimorphic DA circuit mechanisms underlying sociosexual preference.
... Forming a positive feedback loop that mediates the mutual promotion of chronic pain comorbidity [53] BLA-ACC / / / Overactive in pain comorbidity [54] ACC-STN / / / Overactive in chronic pain [55] mPFC Glu -NAc Glu / Excitatory ...
... Simultaneously, VTA DA neurons project back to ACC Glu neurons to mediate the feedback regulation of negative emotions on pain abnormalities. Thus, the ACC Glu -VTA GABA -VTA DA -ACC Glu circuit serves as a positive feedback neural circuit between the pain processing center and the emotional center, functioning as a core mechanism for the interaction between pain perception and emotional states, as well as an essential central mechanism for the long-term maintenance and progression of chronic pain [53]. Additionally, the ACC is closely connected to other brain regions that regulate emotional states, such as the amygdala [75]. ...
Chronic pain is a multidimensional experience that not only involves persistent nociception but is also frequently accompanied by significant emotional disorders, such as anxiety and depression, which complicate its management and amplify its impact. This review provides an in-depth exploration of the neurobiological mechanisms underlying the comorbidity of chronic pain and emotional disturbances. Key areas of focus include the dysregulation of major neurotransmitter systems (serotonin, gamma-aminobutyric acid, and glutamate) and the resulting functional remodeling of critical neural circuits implicated in pain processing, emotional regulation, and reward. Given the contribution of neuroimmune mechanisms to pain chronicity and mood disorders, we further conducted an in-depth investigation into the role of neuroimmune factors, including resident immune cells, infiltrating immune cells, and the release of inflammatory mediators. This review further discusses current therapeutic strategies, encompassing pharmacological interventions, neuromodulation, and integrative approaches, and emphasizes the necessity of targeted treatments that address both pain and emotional components. Finally, it identifies gaps in the current understanding and outlines future research directions aimed at elucidating the complex interplay between chronic pain and emotional disorders, thereby laying the foundation for more effective and holistic treatment paradigms.
... Next, we sought to establish connections between biochemical findings with behavioral consequences. As VTA DA activity is deeply involved in the neural circuit that mediates inflammatory and neuropathic pain [9,10,57], we hypothesized that the acute and chronic pain responses might be altered in Jmjd3 cKO mice. To test this, 4-6 mo WT and cKO mice of both sexes underwent CFA-induced mechanical hyperalgesia and their acute and chronic pain responses were measured at various time points for 18 days by Von Frey's hairs (Fig. 5A). ...
Midbrain dopamine (mDA) neurons participate in a wide range of brain functions through an intricate regulation of DA biosynthesis. The epigenetic factors and mechanisms in this process are not well understood. Here we report that histone demethylase JMJD3 is a critical regulator for DA biosynthesis in adult mouse mDA neurons. Mice carrying Jmjd3 conditional knockout or undergoing pharmaceutical inhibition of JMJD3 showed consistent reduction of DA content in midbrain and striatum. Histological examination of both mice confirmed that TH and NURR1, two key molecules in DA biosynthesis pathway, were decreased in mDA neurons. Mechanistic experiments in vivo and in vitro further demonstrated that the transcriptions of Th and Nurr1 in mDA neurons were suppressed by JMJD3 deficiency, because of increased repressive H3K27me3 and attenuated bindings of JMJD3 and NURR1 on the promoters of both genes. On behavioral level, a significant prolonged inflammation-induced mechanical hyperalgesia was found in conditional knockout mice regardless of sex and age, whereas motor function appeared to be intact. Our findings establish a novel link between DA level in mDA neurons with intrinsic JMJD3 activity, and suggest prolonged chronic inflammatory pain as a major loss-of-function consequence.
Supplementary Information
The online version contains supplementary material available at 10.1186/s40478-024-01912-x.
... Professor Wang Changhe's [92] long-term research on the interaction between pain and emotion revealed that the anterior cingulate cortex (ACC) and the ventral tegmental area (VTA) form a positive feedback loop that not only mediates the interaction between pain and emotion but also plays a critical role in the progression and maintenance of chronic pain. This suggests that targeting the ACC-VTA-ACC feedback loop may provide new therapeutic avenues for chronic pain management. ...
Animal models play a crucial role in translational pain research. They provide a means to understand the underlying mechanisms of pain, test potential therapeutic approaches, and simulate various pain conditions. This chapter explores the significance and application of different animal models in this field. Rodent models, such as mice and rats, are commonly used due to their genetic manipulability and ease of handling. For instance, neuropathic pain models can be induced by nerve injury to study the changes in neuronal circuitry and molecular pathways. Moreover, primate models offer closer similarities to human physiology and behavior, allowing for more accurate assessment of pain perception and responses. However, each model has its limitations, and careful consideration must be given to the selection and interpretation of results. Future research should focus on developing more refined and clinically relevant animal models to accelerate the translation of findings from bench to bedside and improve pain management strategies for patients.
... 100,103,104 The ACC receives a wide range of projections from other brain regions, forming neural circuits crucial for the modulation of chronic pain, including visceral pain. 84,100,105,106 Recent findings have revealed that glutamatergic neurons in the claustrum (CL) project to the ACC and mediate visceral pain behavior, although these neurons may not regulate inflammatory pain. 100,107 Xu et al. 100 identified positive responses from glutamatergic neurons in both the CL and ACC to visceral pain, and viral tracing confirmed anatomical connections between the two regions. ...
Chronic visceral pain stems from internal organs and is frequently associated with functional gastrointestinal disorders, like irritable bowel syndrome (IBS). Since the underlying mechanisms of visceral pain remain largely unclear, clinical management is often limited and ineffective. Comprehensive research into the pathogenesis of visceral pain, along with the development of personalized therapeutic strategies, is crucial for advancing treatment options. Studies suggest that imbalances in purinergic receptors and neural circuit function are closely linked to the onset of visceral pain. In this review, we will explore the etiology and pathological mechanisms underlying visceral pain, with a focus on ion channels, epigenetic factors, and neural circuits, using functional gastrointestinal disorders as case studies. Finally, we will summarize and evaluate emerging treatments and potential initiatives aimed at managing visceral pain.
... 25,26 In the brainstem, an ACC Glu -VTA GABA -VTA DA -ACC Glu positive-feedback loopmediated the progression and maintenance of neuropathic pain and comorbid anxiodepressive-like behavior. 48 Noradrenergic projections from the LC innervated the ACC, which facilitated brain responses to pain and itch. 8,49 However, in our present study, only weak staining was observed in the brainstem. ...
The anterior cingulate cortex (ACC) is critical for pain perception, emotion and cognition. Previous studies showed that the ACC has a complex network architecture, which can receive some projection fibers from many brain regions, including the thalamus, the cerebral cortex and other brain regions. However, there was still a lack of whole-brain mapping of the ACC in adult mice. In the present study, we utilized a rabies virus-based retrograde trans-monosynaptic tracing system to map whole-brain afferents to the unilateral ACC in adult mice. We also combined with a new high-throughput, high-speed and high-resolution VISoR imaging technique to generate a three-dimensional whole-brain reconstruction. Our results showed that several principal groups of brain structures send direct monosynaptic inputs to the ACC, including the cerebral cortex, amygdala, striatum, the thalamus, and the brainstem. We also found that cortical neurons in the ACC mainly receive ipsilateral monosynaptic projections. Some cortical areas and forebrain regions also bilaterally projected to the ACC. These findings provide a complete analysis of the afferents to the ACC in adult mice, and whole-brain mapping of ACC afferents would provide important anatomic evidence for the study of pain, memory, and cognition.