title: Assessment of general anaesthetic cytotoxicity in murine cortical neurones in dissociated culture.
abstract: General anaesthetics are proposed to cause unconsciousness by modulating neuronal excitability in the mammalian brain through mechanisms that include enhancement of inhibitory GABA(A) receptor currents and suppression of excitatory glutamate receptor responses. Both intravenous and volatile agents may produce neurotoxic effects during early postnatal rodent brain development through similar mechanisms. In the following study, we investigated anaesthetic cytotoxicity in primary cortical neurones and glia from postnatal day 2-8 mice. Cultures at 4-20 days in vitro were exposed to combinations of ketamine (100 μM to 3 mM), nitrous oxide (75%, v/v) and/or isoflurane (1.5-5%, v/v) for 6-12 h. Neuronal survival and cell death were measured via microtubule associated protein 2 immunoassay and lactate dehydrogenase release assays, respectively. Clinically relevant anaesthetic concentrations of ketamine, nitrous oxide and isoflurane had no significant neurotoxic effects individually or when given as anaesthetic cocktails, even with up to 12 h exposure. This lack of neurotoxicity was observed regardless of whether cultures were prepared from postnatal day 0-2 or day 8 mice, and was also unaffected by number of days in vitro (DIV 4-20). Significant neurotoxic effects were only observed at supraclinical concentrations (e.g. 1-3 mM ketamine). Our study suggests that neurotoxicity previously reported in vivo is not due to direct cytotoxicity of anaesthetic agents, but results from other impacts of the anaesthetised state during early brain development.
authors.affiliation: Neuroscience & Biochemistry Programs, Smith College, Northampton, MA 01063, USA.
authors.forename: Laura L
authors.initials: LL
authors.lastname: Campbell
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Tyson
authors.forename: Emily E
authors.initials: EE
authors.lastname: Stackpole
authors.forename: Kristen E
authors.initials: KE
authors.lastname: Hokenson
authors.forename: Hanna
authors.initials: H
authors.lastname: Sherrill
authors.forename: Jeanne E
authors.initials: JE
authors.lastname: McKeon
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Kim
authors.forename: Scott D
authors.initials: SD
authors.lastname: Edmands
authors.forename: Cristina
authors.initials: C
authors.lastname: Suarez
authors.forename: Adam C
authors.initials: AC
authors.lastname: Hall
mesh_terms: D018681:Anesthetics, General / Q000633:toxicity*; D000818:Animals; D000831:Animals, Newborn; D002470:Cell Survival / Q000187:drug effects; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007530:Isoflurane / Q000633:toxicity*; D007649:Ketamine / Q000633:toxicity*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D016202:N-Methylaspartate / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009609:Nitrous Oxide / Q000633:toxicity*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D018681:Anesthetics, General; D008869:Microtubule-Associated Proteins; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D007649:Ketamine; D007530:Isoflurane; D007770:L-Lactate Dehydrogenase; D009609:Nitrous Oxide