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Chronic pain often leads to the development of sleep disturbances. However, the precise neural circuit mechanisms responsible for sleep disorders in chronic pain have remained largely unknown. Here, we present compelling evidence that hyperactivity of pyramidal neurons (PNs) in the anterior cingulate cortex (ACC) drives insomnia in a mouse model of nerve-injury-induced chronic pain. After nerve injury, ACC PNs displayed spontaneous hyperactivity selectively in periods of insomnia. We then show that ACC PNs were both necessary for developing chronic-pain-induced insomnia and sufficient to mimic sleep loss in naive mice. Importantly, combining optogenetics and electrophysiological recordings, we found that the ACC projection to the dorsal medial striatum (DMS) underlies chronic-pain-induced insomnia through enhanced activity and plasticity of ACC-DMS dopamine D1R neuron synapses. Our findings shed light on the pivotal role of ACC PNs in developing chronic-pain-induced sleep disorders. [Display omitted] • ACC pyramidal neurons (PNs) are selectively activated during chronic-pain-induced insomnia • Lesion of ACC PNs abolishes chronic-pain-induced insomnia • Hyperactive ACC PNs control chronic-pain-induced insomnia via the DMS pathway • Enhanced plasticity of ACC PNs to DMS D1R-MSNs mediates insomnia Over 50% of chronic pain patients experience insomnia. Li et al. reveal that heightened activity of anterior cingulate cortex excitatory neurons precisely governs chronic-pain-induced insomnia via the dorsal medial striatum pathway. This effect relies on enhanced plasticity in dopamine D1-receptor-positive medium spiny neurons. [ABSTRACT FROM AUTHOR]

Neural stem cells (NSCs) in the dentate gyrus (DG) reside in a specialized local niche that supports their neurogenic proliferation to produce adult-born neurons throughout life. How local niche cells interact at the circuit level to ensure continuous neurogenesis from NSCs remains unknown. Here we report the role of endogenous neuropeptide cholecystokinin (CCK), released from dentate CCK interneurons, in regulating neurogenic niche cells and NSCs. Specifically, stimulating CCK release supports neurogenic proliferation of NSCs through a dominant astrocyte-mediated glutamatergic signaling cascade. In contrast, reducing dentate CCK induces reactive astrocytes, which correlates with decreased neurogenic proliferation of NSCs and upregulation of genes involved in immune processes. Our findings provide novel circuit-based information on how CCK acts on local astrocytes to regulate the key behavior of adult NSCs. • Stimulating dentate CCK release promotes rNSC depolarization and proliferation • CCK modulates local astrocytes to regulate rNSCs via glutamatergic gliotransmission • CCK interneuron stimulation recruits GABAergic inputs onto excitatory neurons • Reduced CCK induces reactive astrocytes and impairs neurogenic potential of rNSCs Asrican et al. demonstrate that stimulating endogenous CCK neuropeptide release in adult dentate gyrus supports neurogenic proliferation of rNSCs through a dominant astrocyte-mediated glutamatergic signaling cascade. In contrast, reducing dentate CCK induced reactive astrocytes, decreased neurogenic proliferation of rNSCs, and upregulated genes involved in neuroinflammation. [ABSTRACT FROM AUTHOR]

Women are more vulnerable to stress and have a higher likelihood of developing mood disorders. The serotonin (5HT) system has been highly implicated in stress response and mood regulation. However, sex-dependent mechanisms underlying serotonergic regulation of stress vulnerability remain poorly understood. Here, we report that adult hippocampal neural stem cells (NSCs) of the Ascl1 lineage (Ascl1-NSCs) in female mice express functional 5HT1A receptors (5HT1ARs), and selective deletion of 5HT1ARs in Ascl1-NSCs decreases the Ascl1-NSC pool only in females. Mechanistically, 5HT1AR deletion in Ascl1-NSCs of females leads to 5HT-induced depolarization mediated by upregulation of 5HT7Rs. Furthermore, repeated restraint stress (RRS) impairs Ascl1-NSC maintenance through a 5HT1AR-mediated mechanism. By contrast, Ascl1-NSCs in males express 5HT7R receptors (5HT7Rs) that are downregulated by RRS, thus maintaining the Ascl1-NSC pool. These findings suggest that sex-specific expression of distinct 5HTRs and their differential interactions with stress may underlie sex differences in stress vulnerability., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Insomnia is often comorbid with depression, but the underlying neuronal circuit mechanism remains elusive. Recently, we reported that GABAergic ventral pallidum (VP) neurons control wakefulness associated with motivation. However, whether and how other subtypes of VP neurons regulate arousal and emotion are largely unknown. Here, we report glutamatergic VP (VP Vglut2 ) neurons control wakefulness and depressive-like behaviors. Physiologically, the calcium activity of VP Vglut2 neurons was increased during both NREM sleep-to-wake transitions and depressive/anxiety-like behaviors in mice. Functionally, activation of VP Vglut2 neurons was sufficient to increase wakefulness and induce anxiety/depressive-like behaviors, whereas inhibition attenuated both. Dissection of the circuit revealed that separated projections of VP Vglut2 neurons to the lateral hypothalamus and lateral habenula promote arousal and depressive-like behaviors, respectively. Our results demonstrate a subtype of VP neurons is responsible for wakefulness and emotion through separated projections, and may provide new lines for the intervention of insomnia and depression in patients., Competing Interests: The authors declare that they have no conflict of interest., (© 2023 The Authors.)

Patients with Alzheimer's disease (AD) exhibit progressive memory loss, depression, and anxiety, accompanied by impaired adult hippocampal neurogenesis (AHN). Whether AHN can be enhanced in impaired AD brain to restore cognitive and affective function remains elusive. Here, we report that patterned optogenetic stimulation of the hypothalamic supramammillary nucleus (SuM) enhances AHN in two distinct AD mouse models, 5×FAD and 3×Tg-AD. Strikingly, the chemogenetic activation of SuM-enhanced adult-born neurons (ABNs) rescues memory and emotion deficits in these AD mice. By contrast, SuM stimulation alone or activation of ABNs without SuM modification fails to restore behavioral deficits. Furthermore, quantitative phosphoproteomics analyses reveal activation of the canonical pathways related to synaptic plasticity and microglia phagocytosis of plaques following acute chemogenetic activation of SuM-enhanced (vs. control) ABNs. Our study establishes the activity-dependent contribution of SuM-enhanced ABNs in modulating AD-related deficits and informs signaling mechanisms mediated by the activation of SuM-enhanced ABNs., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)