Jing Yang - Department of Anesthesiology, Chinese People Liberation Army (PLA) General Hospital, Beijing ۱۰۰۸۵۳, China
Wei Wang - Department of Orthopedics, Chinese People Liberation Army (PLA) General Hospital, Beijing ۱۰۰۸۵۳, China
Zheng Yong - Department of Pharmacology, Institution of Pharmacology and Toxicology, ۱۰۰۰۳۹, China
Weidong Mi - Department of Anesthesiology, Chinese People Liberation Army (PLA) General Hospital, Beijing ۱۰۰۸۵۳, China
Hong Zhang - Department of Anesthesiology, Chinese People Liberation Army (PLA) General Hospital, Beijing ۱۰۰۸۵۳, China

Objective(s): Propofol (۲, ۶-diisopropylphenol) is an intravenous anesthetic that is commonly used for the general anesthesia. It is well known that the spinal cord is one of the working targets of general anesthesia including propofol. However, there is a lack of investigation of the effects of propofol on spinal dorsal horn which is important for the sensory transmission of nociceptive signals. The objective of this study was to investigate the effects of increasing dosage of propofol on the release of glutamate (Glu), γ-aminobutyric acid (GABA) and glycine (Gly) in the spinal dorsal horn. Materials and Methods: The efflux of Glu, GABA or Gly in the spinal dorsal horn of rats was detected using transverse spinal microdialysis under an awake condition and various depths of propofol anesthesia. The infusion rates of propofol were, in order, ۴۰۰ µg/(kg·min), ۶۰۰ µg/(kg·min) and ۸۰۰ µg/(kg·min), with a ۲۰ min infusion period being maintained at each infusion rate. Results: Propofol decreased the glutamate efflux within spinal dorsal horn in a dose-dependent manner, and the maximum decrease was ۵۶.۸ ± ۶.۰% at high-dose propofol infusion producing immobility. The inhibitory GABA and Gly efflux was also decreased about ۱۵–۲۰% at low-dose propofol infusion only producing sedation, but did not continue to drop with higher doses of propofol. Conclusion: Propofol decreased both excitatory and inhibitory amino acids efflux in spinal dorsal horn, and the preferential suppression of the excitatory amino acid might be associated with the analgesic effect of propofol.

Amino acids, Anesthetics, Dorsal horn, Microdialysis, Propofol