Abstract: ObjectiveTo investigate the effects of microwave-induced synapsin I phosphoryltion on the change of synaptic vesicles cycles and amino acids neurotransmitter release.MethodsPrimary hippocampal neurons of Wistar rats were exposed to microwave radiation at the average power density of 30 mW/cm².Immunofluoresence was used to study the expression of phosphrylated synapsin I at Ser-62/67 and Ser-553 sites at 1,6,and 12 hours and 1,2,and 3 days after the microwave radiation.High performance liquid chromatography was used to detect the release of amino acid neurotransmitters and time-lapse method to observe the synaptic vesicles cycles at 6 hours after the radiation.The indexes were then detected after U0126 and roscovitine intervetion.ResultsAfter 30 mW/cm² microwave radiation,the expression of phosphorylated synapsin I at Ser-62/67 was decreased during the period of 6 hours to 2 days; Ser-553 was decreased at 12 hours; the expression of phosphorylated extracellular signal-regulated kinase(P-ERK) and cyclin-dependent kinase 5(Cdk5) reduced; the release of γ aminobutyric acid(GABA) and glycine decresed; and the speed of synaptic vesicles cycles slowered.After roscovitine intervention and radiation,the expression of phosphorylated synapsin I at Ser-553 was increased and Cdk5 was decreased; GABA release increased and the speed of synaptic vesicles cycles slowered compared to those of the group without the intervention.ConclusionMicrowave radiation at the intensity of 30 mW/cm² could induce the inhibition of synaptic vesicles cycles and docking by down-regulating ERK activity to restrain the phosphorylated synapsin I at Ser-62/67,but help to the docking of synaptic vesicles containing GABA by up-regulating Cdk5 expression to facilitate the phosphorylated synapsin I at Ser-553.