title: Isoflurane modulates glutamatergic and GABAergic neurotransmission in the amygdala.
abstract: Attempts have been made to attribute the particular features of general anaesthesia such as hypnosis, analgesia, amnesia and autonomic stability to certain brain regions. In the present study, we examined the effects of the commonplace volatile anaesthetic isoflurane on synaptic transmission in an in vitro slice preparation of the murine amygdala. Despite the established role of this limbic structure in the formation of aversive memories, conditioned fear and anxiety, as well as pain processing and regulation of sympathetic tone, the influence of volatile anaesthetics on synaptic signalling has not yet been investigated in this region of the brain. Evoked postsynaptic currents were monitored from principal neurons in the basolateral nucleus of the amygdala by means of patch-clamp recording. The mixed postsynaptic currents were mediated by non-NMDA, NMDA, GABA A and GABA B receptors. Isoflurane added to the perfusion medium reduced the strength of synaptic signalling following the activation of non-NMDA, NMDA, and GABA B receptors, whereas the GABA A receptor-mediated responses were enhanced. The overall reduction of neuronal excitability was also reflected in a reduction of field potential amplitudes. Isoflurane neither changed the membrane resting potential nor the input resistance of principal neurons in the amygdala. The present results may contribute to the understanding of how stress reactions and long-lasting neuroplastic processes are suppressed under general anaesthesia.
authors.affiliation: Department of Anaesthesiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, D-81675 Munich, Germany. a.ranft@lrz.tum.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Ranft
authors.forename: Jörg
authors.initials: J
authors.lastname: Kurz
authors.forename: Martin
authors.initials: M
authors.lastname: Deuringer
authors.forename: Rainer
authors.initials: R
authors.lastname: Haseneder
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Dodt
authors.forename: Walter
authors.initials: W
authors.lastname: Zieglgänsberger
authors.forename: Eberhard
authors.initials: E
authors.lastname: Kochs
authors.forename: Matthias
authors.initials: M
authors.lastname: Eder
authors.forename: Gerhard
authors.initials: G
authors.lastname: Hapfelmeier
mesh_terms: D000679:Amygdala / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D066298:In Vitro Techniques; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018079:Receptors, GABA / Q000502:physiology*; D017470:Receptors, Glutamate / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology
chemical_list: D018079:Receptors, GABA; D017470:Receptors, Glutamate; D007530:Isoflurane