Besides neurotoxic effects, inhaled anesthetics might have other adverse effects on the developing brain. Ribosomal protein S6 (rpS6), the first identified ribosomal protein undergoing phosphorylation, has important physiological functions in regulating protein synthesis, cell proliferation, and glucose homeostasis. To date, the function of sevoflurane on rpS6 phosphorylation is unclear. In our present study, we showed that sevoflurane anesthesia inhibited rpS6 phosphorylation in cerebral cortex and CA1 region of the hippocampus. The activity of Akt was detected to be reduced within both cortical and hippocampal regions in the brain with the treatment of sevoflurane. However, the treatment seemed to have no effect on the phosphorylation of mammalian target of rapamycin (mTOR), a downstream effector of Akt. Sevoflurane had a paradoxical effect on ERK activity in the hippocampus and cerebral cortex. Last but not the least, Sevoflurane increased PP1 activity in the cerebral cortex and hippocampus. Thus, the exposure to sevoflurane inhibited dramatically the phosphorylation of rpS6 in neonatal rat brains. The inhibitory effect of sevoflurane on rpS6 phosphorylation might be mediated by the suppression on AKT activity at an mTOR-independent manner and the enhancement of PP1 activity.
Keywords: Sevoflurane; cerebral cortex; hippocampus; ribosomal protein S6.