title: Transient effects of anesthetics on dendritic spines and filopodia in the living mouse cortex.
abstract: BACKGROUND
  Anesthetics are widely used to induce unconsciousness, pain relief, and immobility during surgery. It remains unclear whether the use of anesthetics has significant and long-lasting effects on synapse development and plasticity in the brain. To address this question, the authors examined the formation and elimination of dendritic spines, postsynaptic sites of excitatory synapses, in the developing mouse cortex during and after anesthetics exposure.
  
  
  METHODS
  Transgenic mice expressing yellow fluorescence protein in layer 5 pyramidal neurons were used in this study. Mice at 1 month of age underwent ketamine-xylazine and isoflurane anesthesia over a period of hours. The elimination and formation rates of dendritic spines and filopodia, the precursors of spines, were followed over hours to days in the primary somatosensory cortex using transcranial two-photon microscopy. Four to five animals were examined under each experimental condition. Student t test and Mann-Whitney U test were used to analyze the data.
  
  
  RESULTS
  Administration of either ketamine-xylazine or isoflurane rapidly altered dendritic filopodial dynamics but had no significant effects on spine dynamics. Ketamine-xylazine increased filopodial formation whereas isoflurane decreased filopodial elimination during 4 h of anesthesia. Both effects were transient and disappeared within a day after the animals woke up.
  
  
  CONCLUSIONS
  Studies suggest that exposure to anesthetics transiently affects the dynamics of dendritic filopodia but has no significant effect on dendritic spine development and plasticity in the cortex of 1-month-old mice.
authors.affiliation: Department of Anesthesiology, New York University Medical Center, New York, New York, USA.
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
authors.forename: Paul C
authors.initials: PC
authors.lastname: Chang
authors.forename: Alex
authors.initials: A
authors.lastname: Bekker
authors.forename: Thomas J J
authors.initials: TJ
authors.lastname: Blanck
authors.forename: Wen-Biao
authors.initials: WB
authors.lastname: Gan
mesh_terms: D000777:Anesthetics / Q000494:pharmacology*; D000778:Anesthetics, Dissociative / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology* / Q000187:drug effects* / Q000254:growth & development; D049229:Dendritic Spines / Q000187:drug effects* / Q000648:ultrastructure; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007530:Isoflurane / Q000494:pharmacology; D007649:Ketamine / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D011554:Pseudopodia / Q000187:drug effects* / Q000648:ultrastructure; D017966:Pyramidal Cells / Q000187:drug effects / Q000648:ultrastructure; D013003:Somatosensory Cortex / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D014991:Xylazine / Q000494:pharmacology
chemical_list: D000777:Anesthetics; D000778:Anesthetics, Dissociative; D018685:Anesthetics, Inhalation; D018691:Excitatory Amino Acid Antagonists; D014991:Xylazine; D007649:Ketamine; D016291:Dizocilpine Maleate; D007530:Isoflurane