Research advances in the role of dopaminergic neurons involved in emergence from general anesthesia

Abstract

Background Dopamine plays an important role in learning and memory, arousal, emotion and motor control. Recent studies found that dopaminergic (DA) neurons are also involved in both induction and emergence of general anesthesia. But the underlying mechanism is unclear. Objective To review the potential mechanisms underlying DA regulation of the emergence from general anesthesia. Content Midbrain DA neurons are densely distributed in the ventral tegmental area(VTA) and the substantia nigra pars compacta(SNc), where mesolimbic/mesocortical and mesostriatal DA pathways respectively originate. Genetic and pharmacological enhancement of the DA pathways promotes arousal. In contrast, knock-out of dopamine receptors or ablation of VTA abolishes the arousal effect of dopamine. Recordings of the activity of VTA DA neurons show an increase or a decrease in neuronal activity when subjects are in awake or sleeping state. It is putatively accepted that general anesthesia shares similar electroencephalographic signatures with sleep, so does emergence of general anesthesia with arousal. Several optogenetic studies reveal that activating VTA DA neurons facilitates the emergence of general anesthesia. Similarly, electrical stimuli in the VTA, instead of in the SNc, shortens the delay of the emergence from general anesthesia. Therefore, VTA DA neurons may have greater impact on the recovery from general anesthesia than SNc DA neurons. Trend DA are involved in the emergence from general anesthesia, and stimulating VTA DA neurons may provide a means to accelerate the recovery of general anesthesia. Key words: Dopaminergic neuron; Anesthesia, general; Consciousness recovery; Arousal