Hypothalamic circuitry underlying stress-induced insomnia and peripheral immunosuppression

The neural substrates of insomnia/hyperarousal induced by stress remain unknown. Here, we show that restraint stress leads to hyperarousal associated with strong activation of corticotropin-releasing hormone neurons in the paraventricular nucleus of hypothalamus (CRHPVN) and hypocretin neurons in the lateral hypothalamus (HcrtLH). CRHPVN neurons directly innervate HcrtLH neurons and optogenetic stimulation of LH-projecting CRHPVN neurons elicits hyperarousal. CRISPR-Cas9-mediated knockdown of the crh gene in CRHPVN neurons abolishes hyperarousal induced by stimulating LH-projecting CRHPVN neurons. Genetic ablation of Hcrt neurons or crh gene knockdown significantly counteracts restraint stress-induced hyperarousal. As stress is further associated with changes in immune function, we used single-cell mass cytometry by time of flight (CyTOF) to analyze peripheral blood and found extensive changes to immune cell distribution and functional responses during wakefulness upon optogenetic stimu...