Isoflurane causes neocortical but not hippocampal-dependent memory impairment in mice
Authors: FIDALGO, A. R.; CIBELLI, M.; WHITE, J. P. M.; NAGY, I.; WAN, Y.; MA, D.
Source: Acta Anaesthesiologica Scandinavica, Volume 56, Number 8, 1 September 2012 , pp. 1052-1057(6)
Abstract:<section xml:id="aas2691-sec-0001"> <title type="main">Background</title> The aim of this study is to investigate the effect of general anaesthesia induced by isoflurane with buprenorphine on hippocampus-dependent and neocortex-dependent memory, respectively, in mice, and in addition, to compare the effects of such anaesthesia on these memory processes with the effects induced by lipopolysaccharide (<fc>LPS</fc>) administration on the same memory processes. </section> <section xml:id="aas2691-sec-0002"> <title type="main">Methods</title> To assess hippocampus-dependent memory, isoflurane (for 15 min) after buprenorphine injection, or <fc>LPS</fc> 100 μg/kg (intraperitoneally) was administered 24 h before or after fear conditioning. The effect of these treatments on hippocampus-dependent memory was assessed using contextual fear-conditioning tasks at day 4. To assess neocortex-dependent memory, isoflurane anaesthesia or <fc>LPS</fc> was given 72 h after contextual fear conditioning. Neocortex-dependent memory assessment was performed at day 32. </section> <section xml:id="aas2691-sec-0003"> <title type="main">Results</title> Unlike <fc>LPS</fc> injection, isoflurane with buprenorphine-induced anaesthesia does not impair freezing responses in hippocampus-dependent fear-conditioning memory tasks. On anterograde amnesia assessment: 49.67 ± 6.87% for the anaesthesia group and 54.5 ± 4.12% for the control group. On retrograde amnesia assessment: 47.16 ± 8.71% for the anaesthesia group and 54.5 ± 4.12% for control group; P > 0.05. Thus, neither isoflurane nor buprenorphine impair hippocampus-dependent memory. However, on the neocortex-dependent memory task, both isoflurane-induced anaesthesia and <fc>LPS</fc>-induced inflammation result in reduced freezing responses: 62.13 ± 5.80% for the anaesthesia group, 74.63 ± 5.69% for the <fc>LPS</fc> group, and 81.75 ± 3.26% for the control group; P < 0.05 compared with control group. </section> <section xml:id="aas2691-sec-0004"> <title type="main">Conclusion</title> General anaesthesia induced by isoflurane with buprenorphine may result in impairment of neocortex-dependent memory in mouse. However, general anaesthesia so induced does not impair hippocampus-dependent memory in mouse in our experimental conditions. </section>
Document Type: Research article
Publication date: 2012-09-01