Nowadays many children receive operations with general anesthesia. Isoflurane is a commonly-used general anesthetic. Numbers of studies demonstrated that isoflurane induced neurotoxicity and neurobehavioral deficiency in young rats, however, the underlying mechanism remained unknown. Cell division cycle 42 (cdc42) played an important role in regulating synaptic vesicle trafficking and actin dynamics in neuron, which closely linked to synaptic plasticity and dendritic spine formation. Meanwhile, cdc42 also involved in many neurodegenerative diseases. However, whether cdc42 provided a protective role in isoflurane induced synaptogenesis dysfunction still unknown. As the upstream of cdc42, calcium/Calmodulin-dependent protein kinase II (CaMKII) interacts with ion channels such as VDCCs and N-methyl-D-aspartate receptors (NMDARs), which closely associated with neuroapoptosis and cognitive deficiency in developing brain. The phosphorylation of CaMKIl alpha at Thr 286 plays an important role in introduction and maintenance of long-term potentiation (LTP). Therefore, we investigated the effect of isoflurane on cdc42 and its upstream Calcium/Calmodulin-dependent protein kinase II (CaMKII) and its downstream p21 activated kinase 3 (PAK3), then determined whether CaMKII alpha/cdc42/PAK3 signaling pathway was involved in neurotoxicity and cognitive deficiency induced by isoflurane. Our study found that isoflurane induced neurotoxicity and resulted in cognitive impairment in young rats through suppressed CaMKII alpha/cdc42/PAK3 signaling pathway. Cdc42 over-expression could reverse neurotoxicity and improve cognitive impairment induced by isoflurane. (C) 2017 Published by Elsevier Inc.