Optogenetic activation of dopaminergic neurons in the ventral tegmental area facilitates general anesthesia via projections to the parabrachial nucleus in Rats
Objectives In this study,we specifically activated the dopaminergic pathway from the ventral tegmental nucleus projecting to the parabrachial nucleus(VTADA-PBN)in the midbrain of male Sprague-Dawley rats by optogenetic techniques to investigate the role of the pathway in the emergence from propofol anesthesia.Methods 32 male SD rats were randomly divided into ChR2+Light on group,ChR2+Light off group,mCherry+Light on group and mCherry+Light off group,with 8 rats in each group.Rats in each group were induced with propofol anesthesia at a dose of 11 mg·kg-1 via the tail vein,and anesthesia was maintained at a dose of 48 mg·kg-1·h-1 for 30 min,and the time of loss of righting reflex and recovery of the righting reflex were recorded.Immunofluorescence verified viral injection sites.The electroencepha-logram(EEG)was used to record the changes of during induction and recovery of anesthesia.Results Optogenetic activation of the VTADA-PBN pathway showed no statistically significant difference in LORR time(P>0.05)and a shortened RORR time(P<0.001).Compared with the mCherry group,c-Fos expression was significantly higher in the VTA of the ChR2 group(P<0.001);The EEG results showed that the percentage of β-wave power was higher in the light-activated group than in the light-control group during RORR(P<0.05),while the per-centage of δ-wave power was lower than in the light-control group(P<0.01).Conclusion The VTADA-PBN pathway are involved in the reg-ulation of the emergence stage of propofol anesthesia,and activation of this pathway may play a pro-arousal role.
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