title: Administration of epinephrine does not increase learning of fear to tone in rats anesthetized with isoflurane or desflurane.
abstract: Previous reports suggest that the administration of epinephrine increases learning during deep barbiturate-chloral hydrate anesthesia in rats but not during anesthesia with 0.4% isoflurane in rabbits. We revisited this issue, using fear conditioning to a tone in rats as our experimental model for learning and memory and isoflurane and desflurane as our anesthetics. Expressed as a fraction of the minimum alveolar anesthetic concentration (MAC) preventing movement in 50% of rats, the amnestic 50% effective dose (ED(50)) for fear to tone in control rats inhaling isoflurane and injected with saline intraperitoneally (i.p.) was 0.32 +/- 0.03 MAC (mean +/- se) compared with 0.37 +/- 0.06 MAC in rats injected with 0.01 mg/kg of epinephrine i.p. and 0.38 +/- 0.03 MAC in rats injected with 0.1 mg/kg of epinephrine i.p. For desflurane, the amnestic ED(50) were 0.32 +/- 0.05 MAC in control rats receiving a saline injection i.p. versus 0.36 +/- 0.04 MAC in rats injected with 0.1 mg/kg of epinephrine i.p. We conclude that exogenous epinephrine does not decrease amnesia produced by inhaled isoflurane or desflurane, as assessed by fear conditioning to a tone in rats.
authors.affiliation: *Department of Anesthesia and Perioperative Care, University of California, San Francisco; and †Department of Psychology, University of California, Los Angeles.
authors.forename: James M
authors.initials: JM
authors.lastname: Sonner
authors.forename: Yilei
authors.initials: Y
authors.lastname: Xing
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Anya
authors.initials: A
authors.lastname: Maurer
authors.forename: Michael S
authors.initials: MS
authors.lastname: Fanselow
authors.forename: Robert C
authors.initials: RC
authors.lastname: Dutton
authors.forename: Edmond I
authors.initials: EI
authors.lastname: Eger
mesh_terms: D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D000077335:Desflurane; D004837:Epinephrine / Q000494:pharmacology*; D005239:Fear; D007530:Isoflurane / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology*; D007858:Learning / Q000187:drug effects*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane; D004837:Epinephrine