title: Sevoflurane Inhalation Accelerates the Long-Term Memory Consolidation via Small GTPase Overexpression in the Hippocampus of Mice in Adolescence.
abstract: Sevoflurane exposure impairs the long-term memory in neonates. Whether the exposure to animals in adolescence affects the memory, however, has been unclear. A small hydrolase enzyme of guanosine triphosphate (GTPase) rac1 plays a role in the F-actin dynamics related to the synaptic plasticity, as well as superoxide production via reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. The current study was designed to examine whether sevoflurane exposure to mice in early adolescence modifies the long-term learning ability concomitantly with the changes in F-actin constitution as well as superoxide production in the hippocampus according to the levels of rac1 protein expression. Four-week-old mice were subjected to the evaluation of long-term learning ability for three days. On day one, each mouse was allowed to enter a dark chamber for five min to acclimatization. On day two, the procedure was repeated with the addition of an electric shock as soon as a mouse entered the dark chamber. All mice subsequently inhaled 2 L/min air with (Sevoflurane group) and without (Control group) 2.5% sevoflurane for three hours. On day three, each mouse was placed on the platform and retention time, which is the latency to enter the dark chamber, was examined. The brain removed after the behavior test, was used for analyses of immunofluorescence, Western immunoblotting and intracellular levels of superoxide. Sevoflurane exposure significantly prolonged retention time, indicating the enhanced long-term memory. Sevoflurane inhalation augmented F-actin constitution coexisting with the rac1 protein overexpression in the hippocampus whereas it did not alter the levels of superoxide. Sevoflurane exposure to 4-week-old mice accelerates the long-term memory concomitantly with the enhanced F-actin constitution coexisting with the small GTPase rac1 overexpression in the hippocampus. These results suggest that sevoflurane inhalation may amplify long-term memory consolidation via the increased cytoskeleton constitution in the hippocampus of animals in early adolescence.
authors.affiliation: Department of Anesthesiology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Nakamura
authors.affiliation: Department of Anesthesiology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan.
authors.forename: Hiroyuki
authors.identifier: http://orcid.org/0000-0001-6298-0663
authors.initials: H
authors.lastname: Kinoshita
authors.affiliation: Department of Pharmacology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan.
authors.forename: Guo-Gang
authors.initials: GG
authors.lastname: Feng
authors.affiliation: Department of Physiology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan.
authors.forename: Hisaki
authors.initials: H
authors.lastname: Hayashi
authors.affiliation: Department of Anesthesiology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
authors.forename: Maiko
authors.initials: M
authors.lastname: Satomoto
authors.affiliation: Department of Physiology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan.
authors.forename: Motohiko
authors.initials: M
authors.lastname: Sato
authors.affiliation: Department of Anesthesiology, Aichi Medical University School of Medicine, Nagakute, Aichi, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujiwara
mesh_terms: D000367:Age Factors; D018685:Anesthetics, Inhalation / Q000008:administration & dosage* / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D056547:CA1 Region, Hippocampal / Q000187:drug effects* / Q000201:enzymology; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D057567:Memory, Long-Term / Q000187:drug effects*; D008738:Methyl Ethers / Q000008:administration & dosage* / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D000077149:Sevoflurane; D013481:Superoxides / Q000378:metabolism
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D013481:Superoxides; D000077149:Sevoflurane; D020558:GTP Phosphohydrolases