Exposing newborn mice to general anesthetic disrupts brain development
The researchers, based in The Johns Hopkins University School of Medicine , Baltimore, focused on the hippocampus, a brain region that is critical for learning and memory. The hippocampus contains a large number of neurons that develop in the early postnatal period, and which might thus vulnerable be to perturbation by anesthetic exposure. 15 day-old mice were exposed to clinically relevant doses of isoflurane and the effects on the subsequent development of the hippocampus were recorded. The structures of one class of neurons (the dentate gyrus granule cells) were found to be substantially altered. Specifically, the branches or dendrites of the neurons were almost twice the length of those in untreated animals, suggesting that the anesthetic caused an abnormal acceleration in their growth. In addition they saw a significant reduction in the number of mature dendritic spines -- structures on the dendrites where synapses are found. To see whether these changes were associated wit...