Increased excitatory amino acid transporter 2 levels in basolateral amygdala astrocytes mediate chronic stress-induced anxiety-like behavior

Stress-Induced Sleep Dysregulation: The Roles of Astrocytes and Microglia in Neurodegenerative and Psychiatric Disorders

Stress and sleep share a reciprocal relationship, where chronic stress often leads to sleep disturbances that worsen neurodegenerative and psychiatric conditions. Non-neuronal cells, particularly astrocytes and microglia, play critical roles in the brain's response to stress and the regulation of sleep. Astrocytes influence sleep architecture by regulating adenosine signaling and glymphatic clearance, both of which can be disrupted by chronic stress, leading to reduced restorative sleep. Microglia, activated under stress conditions, drive neuroinflammatory processes that further impair sleep and exacerbate brain dysfunction. Additionally, the gut-brain axis mediates interactions between stress, sleep, and inflammation, with microbial metabolites influencing neural pathways. Many of these effects converge on the disruption of synaptic processes, such as neurotransmitter balance, synaptic plasticity, and pruning, which in turn contribute to the pathophysiology of neurodegenerative and psychiatric disorders. This review explores how these cellular and systemic mechanisms contribute to stress-induced sleep disturbances and their implications for neurodegenerative and psychiatric disorders, offering insights into potential therapeutic strategies targeting non-neuronal cells and the gut-brain axis.

Implications of hippocampal excitatory amino acid transporter 2 in modulating anxiety and visceral pain in a mouse model of inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by chronic inflammation and significantly impairs quality of life through anxiety-like behaviors and visceral pain. Early evaluation of the risk of anxiety-like behaviors and visceral pain in IBD patients, along with targeted treatment, may benefit disease management. Visceral pain and anxiety-like behavior are often accompanied by neurological damage. Previous studies have shown that abnormal accumulation of glutamate can cause excitatory neurotoxic effects, leading to central nervous system (CNS) damage. Excitatory amino acid transporters (EAATs), particularly EAAT2, are known to regulate glutamate levels. The impact of hippocampal EAAT2 modulation on these clinical features in IBD is yet to be evaluated. Therefore, we designed this experiment to test this hypothesis. This study aimed to investigate the impact of altered levels of hippocampal EAAT2 on anxiety-like behaviors and visceral pain in mice with IBD. We observed reduced EAAT2 expression, increased glutamate levels, elevated N-methyl-d-aspartate receptors (NMDAR) expression, and obvious glutamate toxicity in the hippocampus of dextran sulfate sodium (DSS) induced IBD model mice. These mice exhibited significant visceral pain and anxiety-like behaviors. In summary, the reduced expression of EAAT2 in the hippocampus of individuals with IBD leads to elevated glutamate levels, resulting in neuronal damage and ultimately contributing to visceral pain and anxiety-like behaviors. These findings suggest that EAAT2 could serve as a therapeutic target for neurologically derived IBD symptoms.

Astrocytes in Rodent Anxiety-Related Behavior: Role of Calcium and Beyond

Anxiety is a physiological, emotional response that anticipates distal threats. When kept under control, anxiety is a beneficial response, helping animals to maintain heightened attention in environments with potential dangers. However, an overestimation of potential threats can lead to an excessive expression of anxiety that, in humans, may evolve into anxiety disorders. Pharmacological treatments show variable efficacy among patients, highlighting the need for more efforts to better understand the pathogenesis of anxiety disorders. Mounting evidence suggests that astrocytes, a type of glial cells, are active partners of neurons in brain circuits and in the regulation of behaviors under both physiological and pathological conditions. In this review, I summarize the current literature on the role of astrocytes from different brain regions in modulating anxious states, with the goal of exploring novel cerebral mechanisms to identify potential innovative therapeutic targets for the treatment of anxiety disorders.