Endocannabinoid signaling in hypothalamic circuits regulates arousal from general anesthesia in mice

Endocannabinoid signaling in hypothalamic circuits regulates arousal from general anesthesia in mice

Abstract

Consciousness can be defined by two major attributes: awareness of environment and self, and arousal, which reflects the level of awareness. The return of arousal after general anesthesia presents an experimental tool for probing the neural mechanisms that control consciousness. Here we have identified that systemic or intracerebral injection of the cannabinoid CB1 receptor (CB1R) antagonist AM281 into the dorsomedial nucleus of the hypothalamus (DMH) – but not the adjacent perifornical area (Pef) or the ventrolateral preoptic nucleus of the hypothalamus (VLPO) – accelerates arousal in mice recovering from general anesthesia. Anesthetics selectively activated endocannabinoid (eCB) signaling at DMH glutamatergic but not GABAergic synapses, leading to suppression of both glutamatergic DMH-Pef and GABAergic DMH-VLPO projections. Deletion of CB1R from widespread cerebral cortical or prefrontal cortical (PFC) glutamatergic neurons, including those innervating the DMH, mimicked the arousal-accelerating effects of AM281. In contrast, CB1R deletion from brain GABAergic neurons or hypothalamic glutamatergic neurons did not affect recovery time from anesthesia. Inactivation of PFC-DMH, DMH-VLPO, or DMH-Pef projections blocked AM281-accelerated arousal, whereas activation of these projections mimicked the effects of AM281. We propose that decreased eCB signaling at glutamatergic terminals of the PFC-DMH projection accelerates arousal from generalanesthesia through enhancement of the excitatory DMH-Pef projection, the inhibitory DMH-VLPO projection, or both.

Authors: Zhong H1,2,3, Tong L1,4, Gu N1,2, Gao F1,2,5, Lu Y6, Xie RG3,5, Liu J3, Li X1,2,3, Bergeron R2, Pomeranz LE7, Mackie K8, Wang F1,2,3, Luo CX1, Ren Y1, Wu SX5, Xie Z9, Xu L10, Li J6, Dong H3, Xiong L3, Zhang X1,2,3.

Influence Factor: 12.574

Citation: J Clin Invest 127, 2295-2309 (2017).

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