Neonatal Desflurane Exposure Induces More Robust Neuroapoptosis than Do Isoflurane and Sevoflurane and Impairs Working Memory

Abstract

Background In animal models, neonatal exposure to volatile anesthetics induces neuroapoptosis, leading to memory deficits in adulthood. However, effects of neonatal exposure to desflurane are largely unknown. Methods Six-day-old C57BL/6 mice were exposed to equivalent doses of desflurane, sevoflurane, or isoflurane for 3 or 6 h. Minimum alveolar concentration was determined by the tail-clamp method as a function of anesthesia duration. Apoptosis was evaluated by immunohistochemical staining for activated caspase-3, and by TUNEL. Western blot analysis for cleaved poly-(adenosine diphosphate-ribose) polymerase was performed to examine apoptosis comparatively. The open-field, elevated plus-maze, Y-maze, and fear conditioning tests were performed to evaluate general activity, anxiety-related behavior, working memory, and long-term memory, respectively. Results Minimum alveolar concentrations at 1 h were determined to be 11.5% for desflurane, 3.8% for sevoflurane, and 2.7% for isoflurane in 6-day-old mice. Neonatal exposure to desflurane (8%) induced neuroapoptosis with an anatomic pattern similar to that of sevoflurane or isoflurane; however, desflurane induced significantly greater levels of neuroapoptosis than almost equivalent doses of sevoflurane (3%) or isoflurane (2%). In adulthood, mice treated with these anesthetics had impaired long-term memory, whereas no significant anomalies were detected in the open-field and the elevated plus-maze tests. Although performance in a working memory task was normal in mice exposed neonatally to sevoflurane or isoflurane, mice exposed to desflurane had significantly impaired working memory. Conclusions In an animal model, neonatal desflurane exposure induced more neuroapoptosis than did sevoflurane or isoflurane and impaired working memory, suggesting that desflurane is more neurotoxic than sevoflurane or isoflurane.