Electrical stimulation of the ventral tegmental area restores consciousness from sevoflurane-, dexmedetomidine-, and fentanyl-induced unconsciousness in rats.

BACKGROUND

Dopaminergic neurons in the ventral tegmental area (VTA) are crucially involved in regulating arousal, making them a potential target for reversing general anesthesia. Electrical deep brain stimulation (DBS) of the VTA restores consciousness in animals anesthetized with drugs that primarily enhance GABA

OBJECTIVE

To evaluate the efficacy of VTA DBS in restoring consciousness after exposure to four anesthetics with distinct receptor targets.

METHODS

Sixteen adult Sprague-Dawley rats (8 female, 8 male) with bipolar electrodes implanted in the VTA were exposed to dexmedetomidine, fentanyl, ketamine, or sevoflurane to produce loss of righting, a proxy for unconsciousness. After receiving the dopamine D1 receptor antagonist, SCH-23390, or saline (vehicle), DBS was initiated at 30 μA and increased by 10 μA until reaching a maximum of 100 μA. The current that evoked behavioral arousal and restored righting was recorded for each anesthetic and compared across drug (saline/SCH-23390) condition. Electroencephalogram, heart rate and pulse oximetry were recorded continuously.

RESULTS

VTA DBS restored righting after sevoflurane, dexmedetomidine, and fentanyl-induced unconsciousness, but not ketamine-induced unconsciousness. D1 receptor antagonism diminished the efficacy of VTA stimulation following sevoflurane and fentanyl, but not dexmedetomidine.

CONCLUSIONS

Electrical DBS of the VTA restores consciousness in animals anesthetized with mechanistically distinct drugs, excluding ketamine. The involvement of the D1 receptor in mediating this effect is anesthetic-specific.

Informations de copyright

Copyright © 2024. Published by Elsevier Inc.

Déclaration de conflit d'intérêts

Declaration of Competing Interest ☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☒ The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ken Solt reports financial support was provided by National Institutes of Health and the Department of Anesthesia, Critical Care and Pain Medicine at Massachusetts General Hospital. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.