title: Isoflurane suppresses early cortical activity.
abstract: OBJECTIVE
  Isoflurane and other volatile anesthetics are widely used in children to induce deep and reversible coma, but they may also exert neurotoxic actions. The effects of volatile anesthetics on the immature brain activity remain elusive, however.
  
  
  METHODS
  The effects of isoflurane on spontaneous and sensory-evoked activity were explored using intracortical extracellular field potential and multiple unit recordings in the rat barrel cortex from birth to adulthood.
  
  
  RESULTS
  During the first postnatal week, isoflurane suppressed cortical activity in a concentration-dependent manner. At surgical anesthesia levels (1.5-2%), isoflurane completely suppressed the electroencephalogram and silenced cortical neurons. Although sensory potentials evoked by the principal whisker deflection persisted, sensory-evoked early gamma and spindle-burst oscillations were completely suppressed by isoflurane. Isoflurane-induced burst-suppression pattern emerged during the second postnatal week and matured through the first postnatal month. Bursts in adolescent and adult rats were characterized by activation of entire cortical columns with a leading firing of infragranular neurons, and were triggered by principal and adjacent whiskers stimulation, and by auditory and visual stimuli, indicating an involvement of horizontal connections in their generation and horizontal spread.
  
  
  CONCLUSIONS
  The effects of isoflurane on cortical activity shift from total suppression of activity to burst-suppression pattern at the end of the first postnatal week. Developmental emergence of bursts likely involves a development of the intracortical short-and long-range connections. We hypothesize that complete suppression of cortical activity under isoflurane anesthesia during the first postnatal week may explain neuronal apoptosis stimulated by volatile anesthetics in the neonatal rats.
authors.affiliation: INMED, INSERM U-901 Marseille, France ; Aix-Marseille University Marseille, France ; Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Guzel
authors.initials: G
authors.lastname: Sitdikova
authors.affiliation: Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Andrei
authors.initials: A
authors.lastname: Zakharov
authors.affiliation: INMED, INSERM U-901 Marseille, France ; Aix-Marseille University Marseille, France.
authors.forename: Sona
authors.initials: S
authors.lastname: Janackova
authors.affiliation: Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Gerasimova
authors.affiliation: Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Julia
authors.initials: J
authors.lastname: Lebedeva
authors.affiliation: Aix-Marseille University Marseille, France ; Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Inacio
authors.affiliation: Aix-Marseille University Marseille, France ; Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Dilyara
authors.initials: D
authors.lastname: Zaynutdinova
authors.affiliation: INMED, INSERM U-901 Marseille, France ; Aix-Marseille University Marseille, France ; Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Marat
authors.initials: M
authors.lastname: Minlebaev
authors.affiliation: Department of Neurological Sciences, University of Vermont College of Medicine Burlington, Vermont.
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Holmes
authors.affiliation: INMED, INSERM U-901 Marseille, France ; Aix-Marseille University Marseille, France ; Laboratory of Neurobiology, Kazan Federal University Kazan, Russia.
authors.forename: Roustem
authors.initials: R
authors.lastname: Khazipov