Comparison of the Neuroapoptotic Properties of Equipotent Anesthetic Concentrations of Desflurane, Isoflurane, or Sevoflurane in Neonatal Mice

ArticleinAnesthesiology 114(3):578-87 · March 2011with28 Reads
DOI: 10.1097/ALN.0b013e3182084a70 · Source: PubMed
Abstract
Volatile anesthetics facilitate surgical procedures and imaging studies in millions of children every year. Neuronal cell death after prolonged exposure to isoflurane in developing animals has raised serious concerns regarding its safe use in children. Although sevoflurane and desflurane are becoming more popular for pediatric anesthesia, their cytotoxic effects have not been compared with those of isoflurane. Accordingly, using newborn mice, the current study established the respective potencies of desflurane, isoflurane, and sevoflurane and then compared equipotent doses of these anesthetics regarding their effects on cortical neuroapoptosis. Minimum alveolar concentrations were determined in littermates (aged 7-8 days, n = 42) using tail-clamp stimulation in a bracketing study design. By using equipotent doses of approximately 0.6 minimum alveolar concentration, another group of littermates was randomly assigned to receive desflurane, isoflurane, or sevoflurane or to fast in room air for 6 h. After exposure, animals (n = 47) were euthanized, neocortical apoptotic neuronal cell death was quantified, and caspase 3 activity was compared between the four groups. The minimum alveolar concentration was determined to be 12.2% for desflurane, 2.7% for isoflurane, and 5.4% for sevoflurane. After a 6-h exposure to approximately 0.6 minimum alveolar concentration of desflurane, isoflurane, or sevoflurane, neuronal cell death and apoptotic activity were significantly increased, irrespective of the specific anesthetic used. In neonatal mice, equipotent doses of the three commonly used inhaled anesthetics demonstrated similar neurotoxic profiles, suggesting that developmental neurotoxicity is a common feature of all three drugs and cannot be avoided by switching to newer agents.
    • "This time-sequence profile of apoptosis induced by propofol has not been previously reported. Previous studies have shown that prolonged inhalational and intravenous anesthetic exposure causes altered dendritic spine morphology and synaptic loss in the developing brains of several animal species (Creeley et al., 2013; Istaphanous et al., 2011; Satomoto et al., 2009; Yang et al., 2014; Zou et al., 2011). Since these reports were in vitro studies, however, the time-sequence profile could not be confirmed. "
    [Show abstract] [Hide abstract] ABSTRACT: The neurotoxicity of anesthetics on the developing brain has drawn the attention of anesthesiologists. Several studies have shown that apoptosis is enhanced by exposure to anesthesia during brain development. Although apoptosis is a physiological developmental step occurring before the maturation of neural networks and the integration of brain function, pathological damage also involves apoptosis. Previous studies have shown that prolonged exposure to anesthetics causes apoptosis. Exactly when the apoptotic cascade starts in the brain remains uncertain. If it starts during the early stage of anesthesia, even short-term anesthesia could harm the brain. Therefore, apoptogenesis should be continuously monitored to elucidate when the apoptotic cascade is triggered by anesthesia. Here, we describe the development of a continuous monitoring system to detect caspase-3 activation using an in vivo model. Brain slices from postnatal days 0–4 SCAT3 transgenic mice with a heterozygous genotype (n = 20) were used for the monitoring of caspase-3 cleavage. SCAT3 is a fusion protein of ECFP and Venus connected by a caspase-3 cleavable peptide, DEVD. A specimen from the hippocampal CA1 sector was mounted on a confocal laser microscope and was continuously superfused with artificial cerebrospinal fluid, propofol (2,6-diisopropylphenol, 1 μM or 10 μM), and dimethyl sulfoxide. Images were obtained every hour for five hours. A pixel analysis of the ECFP/Venus ratio images was performed using a histogram showing the number of pixels with each ratio. In the histogram of the ECFP/Venus ratio, an area with a ratio > 1 indicated the number of pixels from caspase-3-activated CA1 neurons. We observed a shift in the histogram toward the right over time, indicating caspase-3 activation. This right-ward shift dramatically changed at five hours in the propofol 1 μM and 10 μM groups and was obviously different from that in the control group. Thus, real-time fluorescence energy transfer (FRET) imaging was capable of identifying the onset of apoptosis triggered by propofol in neonatal brain slices. This model may be a useful tool for monitoring apoptogenesis in the developing brain.
    Article · Jun 2016
    • "Most anesthetics produce apoptosis and other neurodegenerative changes when administered to young animals [1][2][3][4]. These histological findings have been described in several species, including nonhuman primates, and can be associated with deficits in learning, memory, attention , and other aspects of behavior [5][6][7]in both rodents and primates. "
    [Show abstract] [Hide abstract] ABSTRACT: Exposure to general anesthesia at an early age has been associated with adverse neurodevelopmental outcomes in both animal and human studies, but some of these studies employed anesthetic agents that are no longer in clinical use. In this manuscript, we describe the methods used to construct a new population-based study cohort to study the association between early anesthetic exposure and subsequent neurodevelopmental outcomes. A birth cohort of all children born in Olmsted County, MN from January 1, 1996 to December 31, 2000 was identified. For each, school enrollment status in the Independent School District (ISD) 535 at age 5 or 6 and all episodes of anesthetic exposure before age 3 were identified. A study cohort was created by matching children enrolled in ISD 535 based on the propensity of receiving general anesthesia. Three analyses were performed to characterize the study cohort by comparing the birth and parental information, comorbidities, and socioeconomic status. The first analysis compared the characteristics of birth cohort children who were and were not enrolled in ISD 535. The second analysis evaluated the success of the propensity matching schemes in creating groups of children that were similar in measured characteristics except for anesthesia exposure. The third analysis compared the characteristics of children with anesthesia exposures who were and were not included in the final cohort based on propensity matching. Results of these analyses demonstrate only slight differences among the comparison groups, and therefore these are unlikely to compromise our future analysis of anesthetic exposure and neurodevelopmental outcomes.
    Full-text · Article · May 2016
    • "Isoflurane is a commonly used clinical anesthetic, and millions of children worldwide that undergo surgery are anesthetized with isoflurane for prolonged time periods that may induce subsequent learning and memory deficits [1, 4, 5]. Thus, we used 7-day-old mice to model clinical anesthesia in young children to explore how isoflurane can affect brain development together with learning and memory. "
    [Show abstract] [Hide abstract] ABSTRACT: . Isoflurane disrupts brain development of neonatal mice, but its mechanism is unclear. We explored whether isoflurane damaged developing hippocampi through FASL-FAS signaling pathway, which is a well-known pathway of apoptosis. Method . Wild type and FAS- or FASL-gene-knockout mice aged 7 days were exposed to either isoflurane or pure oxygen. We used western blotting to study expressions of caspase-3, FAS (CD95), and FAS ligand (FASL or CD95L) proteins, TUNEL staining to count apoptotic cells in hippocampus, and Morris water maze (MWM) to evaluate learning and memory. Result . Isoflurane increased expression of FAS and FASL proteins in wild type mice. Compared to isoflurane-treated FAS- and FASL-knockout mice, isoflurane-treated wild type mice had higher expression of caspase-3 and more TUNEL-positive hippocampal cells. Expression of caspase-3 in wild isoflurane group, wild control group, FAS/FASL-gene-knockout control group, and FAS/FASL-gene-knockout isoflurane group showed FAS or FASL gene knockout might attenuate increase of caspase-3 caused by isoflurane. MWM showed isoflurane treatment of wild type mice significantly prolonged escape latency and reduced platform crossing times compared with gene-knockout isoflurane-treated groups. Conclusion . Isoflurane induces apoptosis in developing hippocampi of wild type mice but not in FAS- and FASL-knockout mice and damages brain development through FASL-FAS signaling.
    Full-text · Article · Nov 2015
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