title: Anesthetic Sevoflurane Causes Rho-Dependent Filopodial Shortening in Mouse Neurons.
abstract: Early postnatal anesthesia causes long-lasting learning and memory impairment in rodents, however, evidence for a specific neurotoxic effect on early synaptogenesis has not been demonstrated. Drebrin A is an actin binding protein whose localization in dendritic protrusions serves an important role in dendritic spine morphogenesis, and is a marker for early synaptogenesis. We therefore set out to investigate whether clinically-relevant concentrations of anesthetic sevoflurane, widely- used in infants and children, alters dendritic morphology in cultured fetal day 16 mouse hippocampal neurons. After 7 days in vitro, mouse hippocampal neurons were exposed to four hours of 3% sevoflurane in 95% air/5% CO2 or control condition (95% air/5% CO2). Neurons were fixed in 4% paraformaldehyde and stained with Alexa Fluor555-Phalloidin, and/or rabbit anti-mouse drebrin A/E antibodies which permitted subcellular localization of filamentous (F)-actin and/or drebrin immunoreactivity, respectively. Sevoflurane caused acute significant length-shortening in filopodia and thin dendritic spines in days-in-vitro 7 neurons, an effect which was completely rescued by co-incubating neurons with ten micromolar concentrations of the selective Rho kinase inhibitor Y27632. Filopodia and thin spine recovered in length two days after sevoflurane exposure. Yet cluster-type filopodia (a precursor to synaptic filopodia) were persistently significantly decreased in number on day-in-vitro 9, in part owing to preferential localization of drebrin immunoreactivity to dendritic shafts versus filopodial stalks. These data suggest that sevoflurane induces F-actin depolymerization leading to acute, reversible length-shortening in dendritic protrusions through a mechanism involving (in part) activation of RhoA/Rho kinase signaling and impairs localization of drebrin A to filopodia required for early excitatory synapse formation.
authors.affiliation: University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America.|Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Zimering
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America.
authors.forename: Yuanlin
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America.
authors.forename: Lining
authors.initials: L
authors.lastname: Huang
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America.
authors.forename: Yiying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, United States of America.
authors.forename: Zhongcong
authors.initials: Z
authors.lastname: Xie
mesh_terms: D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D049229:Dendritic Spines / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006624:Hippocampus / Q000166:cytology; D008738:Methyl Ethers / Q000494:pharmacology*; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D009479:Neuropeptides / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D000077149:Sevoflurane; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D000199:Actins; D000577:Amides; D000777:Anesthetics; D008738:Methyl Ethers; D009479:Neuropeptides; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C053386:drebrins; C108830:Y 27632; D000077149:Sevoflurane; D020741:rho GTP-Binding Proteins