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Anesthesiology. 2009 Mar;110(3):487-95. doi: 10.1097/ALN.0b013e3181974f3e.

Isoflurane suppresses stress-enhanced fear learning in a rodent model of post-traumatic stress disorder.

Author information

  • 1Department of Anesthesia and Perioperative Care, University of California, San Francisco, California 94143-0464, USA. rauv@anesthesia.ucsf.edu

Abstract

BACKGROUND:

A minority of patients who experience awareness and/or pain during surgery subsequently develop post-traumatic stress disorder. In a rodent model of post-traumatic stress disorder, stress-enhanced fear learning (SEFL), rats are preexposed to a stressor of 15 foot shocks. Subsequent exposure to a single foot shock produces an enhanced fear response. This effect is akin to sensitized reactions shown by some post-traumatic stress disorder patients to cues previously associated with the traumatic event.

METHODS:

The authors studied the effect of isoflurane and nitrous oxide on SEFL. Rats were exposed to the inhaled anesthetic during or after a 15-foot shock stressor. Then, rats were given a single foot shock in a different environment. Their fear response was quantified in response to the 15-foot shock and single-foot shock environments. SEFL longevity was tested by placing a 90-day period between the 15 foot shocks and the single foot shock. In addition, the intensity of the foot shock was increased to evaluate treatment effectiveness.

RESULTS:

Increasing isoflurane concentrations decreased SEFL when given during, but not after, the stressor. At 0.40 minimum alveolar concentration (MAC), isoflurane given during the stressor blocked SEFL 90 days later. A threefold increase in the stressor intensity increased the isoflurane concentration required to block SEFL to no more than 0.67 MAC. As with isoflurane, nitrous oxide suppressed SEFL at a similar MAC fraction.

CONCLUSIONS:

These results suggest that sufficient concentrations (perhaps 0.67 MAC or less) of an inhaled anesthetic may prevent SEFL.

Comment in

PMID:
19212264
[PubMed - indexed for MEDLINE]
PMCID:
PMC2803013
Free PMC Article
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