How does dopamine change when we lose consciousness under anesthesia?

Have you ever wondered what happens in your brain when you're put under anesthesia for surgery? A recent study discovered that dopamine, a super important neurotransmitter, behaves strangely during sevoflurane anesthesia. Researchers used advanced techniques to monitor dopamine levels in the nucleus accumbens, a brain area linked to emotions and awareness. During the induction of anesthesia, dopamine levels initially increased and then gradually decreased. When the anesthesia ended, the levels returned to normal. But the most interesting part is that dopamine levels rose again when patients began to regain consciousness. This study shows that dopamine plays a key role in changes in consciousness during anesthesia. Imagine dopamine as a volume knob that goes up and down as you enter and exit a state of unconsciousness!

The study used a genetically encoded dopamine indicator called dLight1.1 to track dopamine release in the nucleus accumbens (NAc). This technique allows for precise measurement of changes in dopamine levels in real-time. Researchers combined fiber photometry with electroencephalogram (EEG) and electromyogram (EMG) recordings to monitor dopamine signal dynamics across different phases of anesthesia. During the induction phase, dopamine levels significantly increased in the first 100 seconds and then decreased in the subsequent maintenance phases of anesthesia. When sevoflurane administration ceased, dopamine levels gradually returned to baseline. Additionally, during the induction phase, dopamine signals markedly increased before the loss of consciousness (pre-LOC) and significantly declined after the loss of consciousness (post-LOC). During the emergence phase, dopamine levels rose again after the recovery of consciousness (post-ROC). These results suggest that dopamine signals in the NAc are closely correlated with changes in states of consciousness during sevoflurane anesthesia.