A corticoamygdalar pathway controls reward devaluation and depression using dynamic inhibition code

Inhibitory gamma-aminobutyric acidergic neurons in the anterior cingulate cortex participate in the comorbidity of pain and emotion

Pain is often comorbid with emotional disorders such as anxiety and depression. Hyperexcitability of the anterior cingulate cortex has been implicated in pain and pain-related negative emotions that arise from impairments in inhibitory gamma-aminobutyric acid neurotransmission. This review primarily aims to outline the main circuitry (including the input and output connectivity) of the anterior cingulate cortex and classification and functions of different gamma-aminobutyric acidergic neurons; it also describes the neurotransmitters/neuromodulators affecting these neurons, their intercommunication with other neurons, and their importance in mental comorbidities associated with chronic pain disorders. Improving understanding on their role in pain-related mental comorbidities may facilitate the development of more effective treatments for these conditions. However, the mechanisms that regulate gamma-aminobutyric acidergic systems remain elusive. It is also unclear as to whether the mechanisms are presynaptic or postsynaptic. Further exploration of the complexities of this system may reveal new pathways for research and drug development.

The primary somatosensory sensory cortex-basolateral amygdala pathway contributes to comorbid depression in spared nerve injury-induced neuropathic pain

Comorbid depression in chronic pain is a prevalent health problem, yet the underlying neural mechanisms remain largely unexplored. This study identified a dedicated neural circuit connecting the hind limb region of the primary somatosensory cortex (S1HL) to the basolateral amygdala (BLA) that mediated neuropathic pain-induced depression. We demonstrated that depressive-like behaviors in the chronic phase of a mouse neuropathic pain model were associated with heightened activity in the S1HL and BLA. Using viral tracing and RNAscope in situ hybridization, we characterized the circuit architecture of S1HL glutamatergic projections to BLA cholecystokinin (CCK) neurons (S1HLGlu → BLACCK). In vivo fiber photometry calcium imaging revealed that both the S1HL BLA-projecting afferents and the BLA S1HL-innervating neurons exhibited hyperactivity in neuropathic pain-induced depressive states. Chemogenetic inhibition of the S1HL → BLA circuit could block neuropathic pain-induced depressive-like behaviors. In addition, specific knockdown of CCK expression in BLA S1HL-innervating neurons alleviated these depressive-like behaviors. Our findings demonstrated that the cortical-amygdala circuit S1HLGlu → BLACCK drove the transition from chronic pain to depression, thus suggesting a potential neural circuit basis for treating chronic pain-related depressive disorders.

Primary ciliary protein kinase A activity in the prefrontal cortex modulates stress in mice

Primary cilia are cellular antennae emanating from vertebrate cell surfaces to sense and transduce extracellular signals intracellularly to regulate cell behavior and function. However, their signal sensing and physiological functions in neocortical neurons remain largely unclear. Here, we show that, in response to various animal stressors, primary cilia in the mouse prefrontal cortex (PFC) exhibit consistent axonemal elongation. Selective removal of excitatory neuron primary cilia in the prefrontal but not sensory cortex leads to a reduction in animal stress sensing and response. Treatment with corticosterone, the major stress hormone, elicits an increase in primary ciliary cyclic adenosine 3',5'-monphosphate (cAMP) level in PFC excitatory neurons and a decrease in neuronal excitability dependent on primary cilia. Suppression of primary ciliary protein kinase A (PKA) activity in PFC excitatory neurons reduces animal stress. These results suggest that excitatory neurons in the PFC are involved in sensing and regulating animal stress via primary ciliary cAMP/PKA signaling.

Neural circuits mediating chronic stress: Implications for major depressive disorder

Major depressive disorder (MDD), also known as depression, is a prevalent mental disorder that leads to severe disease burden worldwide. Over the past two decades, significant progress has been made in understanding the pathogenesis and developing novel treatments for MDD. Among the complicated etiologies of MDD, chronic stress is a major risk factor. Exploring the underlying brain circuit mechanisms of chronic stress regulation has been an area of active research for recent years. A growing body of preclinical and clinical research has revealed that abnormalities in the brain circuits are closely associated with failures in coping with stress in depressed individuals. Nevertheless, neural circuit mechanisms underlying chronic stress processing and the onset of depression remain a major puzzle. Here, we review recent literature focusing on circuit- and cell-type-specific dissection of depression-like behaviors in chronic stress-related animal models of MDD and outline the key questions.

Child and Adolescent Health Programs in Obesity and Depression: A Systematic Review and Meta-Analysis

Obesity and depression are public health issues of increasing concern worldwide. This study aims to evaluate programs that address obesity and their impact on depressive symptoms in children and adolescents. Obesity and depression share a bidirectional relationship, where each can serve as both a cause and a consequence of the other.

METHODS

A systematic review and meta-analysis were conducted following PRISMA criteria, with the registration recorded under PROSPERO code (CRD42024550644). The selected publications report on intervention programs for obesity and depression in children and adolescents aged 6 to 18 years. The selection was from databases including PUBMED, SCOPUS, LILACS, COCHRANE, WOS, SciELO, and ScienceDirect, using PICOS criteria to define inclusion. ROB-2 and ROBINS-1 were applied to assess bias.

RESULTS

Out of 3376 articles reviewed, eight met the inclusion criteria, some including several programs. These programs varied in duration and type, demonstrating changes in reducing Body Mass Index (BMI) and depressive symptoms. However, evidence supporting the effectiveness of programs that address both conditions is limited, particularly in developing countries. Additionally, the results exhibit high heterogeneity due to the diversity of evaluation criteria and methodological approaches, highlighting considerable risks of bias.

CONCLUSIONS

Intervention programs for obesity management show statistically significant effects on depressive symptoms, although there is heterogeneity in the designs for their standardization and long-term follow-up strategies; however, the evaluations consider DSM-5 and ICD-11 criteria, which contributes to homogeneity. It is vital to address these closely related issues from a multidimensional perspective, considering socio-emotional and psychological factors, and to promote early intervention to maximize effectiveness and enhance quality of life at various stages of development.

Selective activation of SIGMAR1 in anterior cingulate cortex glutamatergic neurons facilitates comorbid pain in depression in male mice

Depression and comorbid pain are frequently encountered clinically, and the comorbidity complicates the overall medical management. However, the mechanism whereby depression triggers development of pain needs to be further elucidated. Here, by using the chronic restraint stress (CRS) mouse model of depression and comorbid pain, we showed that CRS hyperactivated the glutamatergic neurons in the anterior cingulate cortex (ACC), as well as increasing the dendrite complexity and number. Chemogenetic activation of these neurons can induce depression and pain, while chemogenetic blockade can reverse such depression-induced pain. Moreover, we utilized translating ribosome affinity purification (TRAP) in combination with c-Fos-tTA strategy and pharmacological approaches and identified SIGMAR1 as a potential therapeutic molecular target. These results revealed a previously unknown neural mechanism for depression and pain comorbidity and provided new mechanistic insights into the antidepressive and analgesic effects of the disease.

Distinct circuits and molecular targets of the paraventricular hypothalamus decode visceral and somatic pain

Visceral and somatic pain serve as protective mechanisms against external threats. Accumulated evidence has confirmed that the paraventricular hypothalamus (PVH) plays an important role in the perception of visceral and somatic pain, whereas the exact neural pathways and molecules distinguishing them remain unclear. Here, we report distinct neuronal ensembles within the PVH dedicated to processing visceral and somatic pain signals. An essential discovery is the distinct expression of P2X3R and VIPR2 in visceral and somatic pain-activated PVH neuronal ensembles. Furthermore, visceral pain- and somatic pain-responsive PVH neuronal ensembles project to specific downstream regions, the ventral part of the lateral septal nucleus (LSV) and the caudal part of the zona incerta (ZIC), respectively. These findings unveil that the PVH acts as a pain sorting center that distinctly processes visceral and somatic pain, identifying potential molecular targets for specific pain processing and providing a new framework for comprehending how the brain processes nociceptive information.

The secondary visual cortex mediated the enhancement of associative learning on methamphetamine self-administration behaviors

RATIONALE

Methamphetamine addiction is a persistent and intractable pathological learning and memory, whereas no approved therapeutics is available. However, few attentions have been paid to how associative learning participates in the formation of intractable memory related to drug addiction OBJECTIVES AND METHODS: To investigate the role of associative learning in methamphetamine addiction and the underlying neurobiological mechanism, methamphetamine self-administration, oral sucrose self-administration, chemogenetic neuromanipulation, and fiber photometry in mice were performed in this study.

RESULTS

We reported that associative learning increased methamphetamine-induced self-administration, but not oral sucrose self-administration. In addition, the enhancement of methamphetamine-induced self-administration was independent of more methamphetamine consumption, and remained with higher drug-taking and motivation in the absence of visual cues, suggesting the direct effects of the associative learning that enhanced methamphetamine-induced self-administration. Moreover, chemogenetic inactivation of the secondary visual cortex (V2) reduced the enhancement of the drug-taking induced by associative learning but did not alter sucrose-taking. Further fiber photometry of V2 neurons demonstrated that methamphetamine-associative learning elicits V2 neuron excitation, and sucrose-associative learning elicits V2 neuron inhibition.

CONCLUSIONS

Therefore, this study reveals the neurobiological mechanism of V2 excitability underlying how associative learning participates in the formation of intractable memory related to drug addiction, and gives evidence to support V2 as a promising target for stimulation therapy for methamphetamine addiction.

Chronic Neuropathic Pain and Comorbid Depression Syndrome: From Neural Circuit Mechanisms to Treatment

Chronic neuropathic pain and comorbid depression syndrome (CDS) is a major worldwide health problem that affects the quality of life of patients and imposes a tremendous socioeconomic burden. More than half of patients with chronic neuropathic pain also suffer from moderate or severe depression. Due to the complex pathogenesis of CDS, there are no effective therapeutic drugs available. The lack of research on the neural circuit mechanisms of CDS limits the development of treatments. The purpose of this article is to provide an overview of the various circuits involved in CDS. Notably, activating some neural circuits can alleviate pain and/or depression, while activating other circuits can exacerbate these conditions. Moreover, we discuss current and emerging pharmacotherapies for CDS, such as ketamine. Understanding the circuit mechanisms of CDS may provide clues for the development of novel drug treatments for improved CDS management.

Dynamic prefrontal inhibition code mediates reward devaluation

Repeated reward intake decreases its subjective pleasantness, which is a common phenomenon called reward devaluation. In this issue of Neuron, Yuan et al.1 unravel that blunted inhibitory response of anterior cingulate cortex (ACC) encodes this process, whose hypersensitization leads to anhedonia.

Dose-dependent action of cordycepin on the microbiome-gut-brain-adipose axis in mice exposed to stress

The high risk for anxiety and depression among individuals with stress has become a growing concern globally. Stress-related mental disorders are often accompanied by symptoms of metabolic dysfunction. Cordycepin is a Chinese herbal medicine commonly used for its metabolism-enhancing effects. We aimed to investigate the dose-dependent effects of cordycepin on psycho-metabolic disorders induced by stress. Our behavioral tests revealed that 12.5 mg/kg cordycepin by oral gavage significantly attenuated the anxiety- and depression-like behaviors induced by stress in mice. At 25 mg/kg, cordycepin restored the reduced weight and cell size of adipose tissues caused by stress. Besides ameliorating the metabolic dysbiosis of gut microbiota due to stress, cordycepin significantly reduced the elevated contents of 5-hydroxyindoleacetic acid in the serum and prefrontal cortex at 12.5 mg/kg and reversed the decrease in adipose induced by stress at 25 mg/kg. Correlation analyses further revealed that 12.5 mg/kg cordycepin reversed stress-induced changes in the intestinal microbiome of NK4A214_group and decreased serum Myristic acid and PC(15:0/18:1(11Z)) and cytokines, such as IFN-γ and IL-1β. 25 mg/kg cordycepin reversed stress-induced changes in the abundances of Prevoteaceae_UCG-001 and Desulfovibrio, increased serum L-alanine level, and decreased serum Inosine-5'-monophosphate level. Cordycepin thereby ameliorated the anxiety- and depression-like behaviors as well as disturbances in the adipose metabolism of mice exposed to stress. Overall, these findings offer evidence indicating that the prominent effects of cordycepin in the brain and adipose tissues are dose dependent, thus highlight the importance of evaluating the precise therapeutic effects of different cordycepin doses on psycho-metabolic diseases.