Background: Dexmedetomidine has repeatedly shown to improve anxiety but the precise neural mechanisms underlying this effect remain incompletely understood. Here, we aim to explore the role of corticotropin-releasing hormone-producing hypothalamic paraventricular (CRHPVN) neurons in mediating the anxiolytic effects of dexmedetomidine.
Methods: A social defeat stress mouse model was employed to evaluate the anxiolytic effects induced by dexmedetomidine through the elevated plus-maze, open-field test, and measurement of serum stress hormone levels. In vivo Ca2+ signal fibre photometry and ex vivo patch-clamp recordings were utilized to determine the excitability of CRHPVN neurons and investigate the specific mechanism involved. CRHPVN neuron modulation was achieved through chemogenetic activation or inhibition.
Results: Compared with saline, dexmedetomidine (40 µg/kg) alleviated anxiety-like behaviors. Additionally, dexmedetomidine reduced CRHPVN neuronal excitability. Chemogenetic activation of CRHPVN neurons decreased the time spent in the open arms of the elevated plus-maze and in the central area of the open-field test. Conversely, chemogenetic inhibition of CRHPVN neurons had the opposite effect. Moreover, the suppressive impact of dexmedetomidine on CRHPVN neurons was attenuated by the α2 receptor antagonist yohimbine.
Conclusions: Our results indicate that the anxiety-like effects of dexmedetomidine are mediated via α2 adrenergic receptor-triggered inhibition of CRHPVN neuronal excitability in the hypothalamus.
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