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Lysosomes are important cellular structures for human health as centers for recycling, signaling, metabolism and stress adaptation. However, the potential role of lysosomes in stress‐related emotions has long been overlooked. Here, it is found that lysosomal morphology in astrocytes is altered in the medial prefrontal cortex (mPFC) of susceptible mice after chronic social defeat stress. A screen of lysosome‐related genes revealed that the expression of the mucolipin 1 gene (Mcoln1; protein: mucolipin TRP channel 1) is decreased in susceptible mice and depressed patients. Astrocyte‐specific knockout of mucolipin TRP channel 1 (TRPML1) induced depressive‐like behaviors by inhibiting lysosomal exocytosis‐mediated adenosine 5′‐triphosphate (ATP) release. Furthermore, this stress response of astrocytic lysosomes is mediated by the transcription factor EB (TFEB), and overexpression of TRPML1 rescued depressive‐like behaviors induced by astrocyte‐specific knockout of TFEB. Collectively, these findings reveal a lysosomal stress‐sensing signaling pathway contributing to the development of depression and identify the lysosome as a potential target organelle for antidepressants. [ABSTRACT FROM AUTHOR]

The mechanisms of anxiety disorders, the most common mental illness, remain incompletely characterized. The ventral hippocampus (vHPC) is critical for the expression of anxiety. However, current studies primarily focus on vHPC neurons, leaving the role for vHPC astrocytes in anxiety largely unexplored. Here, genetically encoded Ca2+ indicator GCaMP6m and in vivo fiber photometry calcium imaging are used to label vHPC astrocytes and monitor their activity, respectively, genetic and chemogenetic approaches to inhibit and activate vHPC astrocytes, respectively, patch‐clamp recordings to measure glutamate currents, and behavioral assays to assess anxiety‐like behaviors. It is found that vHPC astrocytic activity is increased in anxiogenic environments and by 3‐d subacute restraint stress (SRS), a well‐validated mouse model of anxiety disorders. Genetic inhibition of vHPC astrocytes exerts anxiolytic effects on both innate and SRS‐induced anxiety‐related behaviors, whereas hM3Dq‐mediated chemogenetic or SRS‐induced activation of vHPC astrocytes enhances anxiety‐like behaviors, which are reversed by intra‐vHPC application of the ionotropic glutamate N‐methyl‐d‐aspartate receptor antagonists. Furthermore, intra‐vHPC or systemic application of the N‐methyl‐d‐aspartate receptor antagonist memantine, a U.S. FDA‐approved drug for Alzheimer's disease, fully rescues SRS‐induced anxiety‐like behaviors. The findings highlight vHPC astrocytes as critical regulators of stress and anxiety and as potential therapeutic targets for anxiety and anxiety‐related disorders. [ABSTRACT FROM AUTHOR]

Major depressive disorder is a common and devastating psychiatric disease, and the prevalence and burden are substantially increasing worldwide. Multiple studies of depression patients have implicated glucose metabolic dysfunction in the pathophysiology of depression. However, the molecular mechanisms by which glucose and related metabolic pathways modulate depressive-like behaviors are largely uncharacterized. Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) is a glucose metabolite with pivotal functions as a donor molecule for O-GlcNAcylation. O-GlcNAc transferase (OGT), a key enzyme in protein O-GlcNAcylation, catalyzes protein posttranslational modification by O-GlcNAc and acts as a stress sensor. Here, we show that Ogt mRNA was increased in depression patients and that astroglial OGT expression was specifically upregulated in the medial prefrontal cortex (mPFC) of susceptible mice after chronic social-defeat stress. The selective deletion of astrocytic OGT resulted in antidepressant-like effects, and moreover, astrocytic OGT in the mPFC bidirectionally regulated vulnerability to social stress. Furthermore, OGT modulated glutamatergic synaptic transmission through O-GlcNAcylation of glutamate transporter-1 (GLT-1) in astrocytes. OGT astrocyte-specific knockout preserved the neuronal morphology atrophy and [Ca.sup.2+] activity deficits caused by chronic stress and resulted in antidepressant effects. Our study reveals that astrocytic OGT in the mPFC regulates depressive-like behaviors through the O-GlcNAcylation of GLT-1 and could be a potential target for antidepressants., Introduction The lifetime prevalence (~17%), disability (as a leading cause), and socioeconomic burden associated with major depressive disorder (MDD) render it one of the most common and devastating psychiatric illnesses [...]

Anxiety-related disorders can be treated by cognitive therapies and transcranial magnetic stimulation, which involve the medial prefrontal cortex (mPFC). Subregions of the mPFC have been implicated in mediating different and even opposite roles in anxiety-related behaviors. However, precise causal targets of these top-down connections among diverse possibilities have not been established. Here, we show that the lateral septum (LS) and the central nucleus of the amygdala (CeA) represent 2 direct targets of the infralimbic cortex (IL), a subregion of the mPFC that modulates anxiety and fear. Two projections were unexpectedly found to exert opposite effects on the anxious state and learned freezing: the IL-LS projection promoted anxiety-related behaviors and fear-related freezing, whereas the IL-CeA projection exerted anxiolytic and fear-releasing effects for the same features. Furthermore, selective inhibition of corresponding circuit elements showed opposing behavioral effects compared with excitation. Notably, the IL-CeA projection implemented top-down control of the stress-induced high-anxiety state. These results suggest that distinct IL outputs exert opposite effects in modulating anxiety and fear and that modulating the excitability of these projections with distinct strategies may be beneficial for the treatment of anxiety disorders., Introduction Anxiety disorders represent the most common psychiatric diseases, with a combined lifetime prevalence of over 28% (1, 2). Although the available pharmacological treatments are inadequate (3), cognitive therapies (4, [...]