Cerebrospinal fluid contacting nucleus and its 5-HT: A new insight into the regulation mechanism of general intravenous anesthesia

Abstract

General anesthesia is one of the most common clinical anesthesia methods. Many studies have suggested that 5-HT plays an important role in the mechanism of general anesthesia, but its basic principle is still unclear. The cerebrospinal fluid (CSF)-contacting nucleus, which we identified 30 years ago, contains a large number of 5-HT neurons. In the brain, many of the nuclei involved in regulating the effects of general anesthesia send projections to the CSF-contacting nucleus.Does the CSF-contacting nucleus and its 5-HT neurons participate in regulating the effect of general anesthesia? This is a new and interesting scientific question.To answer this question, rats underwent general anesthesia by intravenous injection of propofol. During the maintenance of and recovery from general anesthesia, the protein expression of c-Fos in the CSF-contacting nucleus was significantly increased. “Knockout” of this nucleus significantly increased the of number of low-frequency δ waves, which are indicative of deep anesthesia, during general anesthesia maintenance; however, the number of high-frequency β waves, which indicate consciousness, was significantly decreased. During recovery from general anesthesia, the recovery of the righting reflex (RORR) time of rats with CSF-contacting nucleus ablation was significantly prolonged; activation of 5-HT neurons in the CSF-contacting nucleus promoted recovery from general anesthesia, while inhibition of 5-HT neurons in the CSF-contacting nucleus delayed recovery from general anesthesia.The above results suggest that the CSF-contacting nucleus and its 5-HT neurons play a key role in regulating the effect of intravenous anesthesia, especially during recovery from general anesthesia.