title: Propofol differentially inhibits the release of glutamate, γ-aminobutyric acid and glycine in the spinal dorsal horn of rats.
abstract: OBJECTIVE
  Propofol (2, 6-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.
  
  
  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, 400 µg/(kg·min), 600 µg/(kg·min) and 800 µg/(kg·min), with a 20 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 56.8 ± 6.0% at high-dose propofol infusion producing immobility. The inhibitory GABA and Gly efflux was also decreased about 15-20% at low-dose propofol infusion only producing sedation, but did not continue to drop with higher doses of propofol.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Anesthesiology, Chinese People Liberation Army (PLA) General Hospital, Beijing 100853, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Orthopedics, Chinese People Liberation Army (PLA) General Hospital, Beijing 100853, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, Institution of Pharmacology and Toxicology, 100039, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Yong
authors.affiliation: Department of Anesthesiology, Chinese People Liberation Army (PLA) General Hospital, Beijing 100853, China.
authors.forename: Weidong
authors.initials: W
authors.lastname: Mi
authors.affiliation: Department of Anesthesiology, Chinese People Liberation Army (PLA) General Hospital, Beijing 100853, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
keywords: Amino acids; Anesthetics; Dorsal hornm; Microdialysis; Propofol