title: Influence of Volatile Anesthesia on the Release of Glutamate and other Amino Acids in the Nucleus Accumbens in a Rat Model of Alcohol Withdrawal: A Pilot Study.
abstract: BACKGROUND
  Alcohol withdrawal syndrome is a potentially life-threatening condition, which can occur when patients with alcohol use disorders undergo general anesthesia. Excitatory amino acids, such as glutamate, act as neurotransmitters and are known to play a key role in alcohol withdrawal syndrome. To understand this process better, we investigated the influence of isoflurane, sevoflurane, and desflurane anesthesia on the profile of excitatory and inhibitory amino acids in the nucleus accumbens (NAcc) of alcohol-withdrawn rats (AWR).
  
  
  METHODS
  Eighty Wistar rats were randomized into two groups of 40, pair-fed with alcoholic or non-alcoholic nutrition. Nutrition was withdrawn and microdialysis was performed to measure the activity of amino acids in the NAcc. The onset time of the withdrawal syndrome was first determined in an experiment with 20 rats. Sixty rats then received isoflurane, sevoflurane, or desflurane anesthesia for three hours during the withdrawal period, followed by one hour of elimination. Amino acid concentrations were measured using chromatography and results were compared to baseline levels measured prior to induction of anesthesia.
  
  
  RESULTS
  Glutamate release increased in the alcohol group at five hours after the last alcohol intake (p = 0.002). After 140 min, desflurane anesthesia led to a lower release of glutamate (p < 0.001) and aspartate (p = 0.0007) in AWR compared to controls. GABA release under and after desflurane anesthesia was also significantly lower in AWR than controls (p = 0.023). Over the course of isoflurane anesthesia, arginine release decreased in AWR compared to controls (p < 0.001), and aspartate release increased after induction relative to controls (p20min = 0.015 and p40min = 0.006). However, amino acid levels did not differ between the groups as a result of sevoflurane anesthesia.
  
  
  CONCLUSIONS
  Each of three volatile anesthetics we studied showed different effects on excitatory and inhibitory amino acid concentrations. Under desflurane anesthesia, both glutamate and aspartate showed a tendency to be lower in AWR than controls over the whole timecourse. The inhibitory amino acid arginine increased in AWR compared to controls, whereas GABA levels decreased. However, there were no significant differences in amino acid concentrations under or after sevoflurane anesthesia. Under isoflurane, aspartate release increased in AWR following induction, and from 40 min to 140 min arginine release in controls was elevated. The precise mechanisms through which each of the volatile anesthetics affected amino acid concentrations are still unclear and further experimental research is required to draw reliable conclusions.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Campus Charité Mitte and Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Seidemann
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Campus Charité Mitte and Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Spies
authors.affiliation: Institute of Pharmacology, Campus Charité Mitte, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Morgenstern
authors.affiliation: SOSTANA, Berlin, Germany.
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Wernecke
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Campus Charité Mitte and Campus Virchow-Klinikum, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Nicolai
authors.initials: N
authors.lastname: Netzhammer
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000769:Anesthesia, Inhalation; D000818:Animals; D001120:Arginine / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism; D000077335:Desflurane; D004195:Disease Models, Animal; D005247:Feeding Behavior; D018698:Glutamic Acid / Q000378:metabolism*; D007530:Isoflurane / Q000031:analogs & derivatives; D008297:Male; D017551:Microdialysis; D009714:Nucleus Accumbens / Q000378:metabolism*; D010865:Pilot Projects; D017208:Rats, Wistar; D013375:Substance Withdrawal Syndrome / Q000378:metabolism*; D013997:Time Factors; D014835:Volatilization; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D001120:Arginine; D000077335:Desflurane; D007530:Isoflurane