磷酸化突触素在神经元囊泡循环与递质释放中作用

Effects of microwave-induced phosphorylation of synapsin Ⅰon synaptic vesicles cycles and amino acid neurotransmitter release in hippacampal neurons of rats

目的探讨磷酸化突触素I在微波辐射所致囊泡循环和氨基酸递质释放改变中的作用。方法采用30 m W/cm2微波辐射原代海马神经元,免疫荧光染色观察辐射后1、6、12 h,1、2、3 d神经元Ser-62/67及Ser-553位点突触素I磷酸化表达改变;高效液相色谱检测辐射后6 h海马神经元氨基酸递质释放量变化;time-lapse观察辐射后6 h神经元突触囊泡循环改变;给予U0126和roscovitine进行干预,观察上述指标改变。结果 30 m W/cm2微波辐射后海马磷酸化突触素I Ser-62/67、Ser-553及磷酸化细胞外调节激酶(p-ERK)、细胞周期素依赖性激酶(Cdk5)表达明显减少,γ-氨基丁酸(GABA)释放明显减少,海马神经元囊泡循环速度减慢;辐射并给予U0126后,神经元p-ERK和Ser-62/67位点突触素I磷酸化表达明显减弱,囊泡循环速度减慢;辐射并给予roscovitine后,神经元Cdk5表达减少,Ser-553位点突触素I磷酸化表达上调,GABA释放明显增加,囊泡循环速度明显减慢。结论 30 m W/cm2微波辐射通过下调海马神经元ERK活性抑制突触素I Ser-62/67位点磷酸化而使囊泡循环受抑制,囊泡锚定障碍;通过下调Cdk5促进突触素I Ser-553位点磷酸化而利于含GABA的囊泡锚定于突触前膜,但抑制囊泡循环。

Objective To investigate the effects of microwave-induced synapsin I phosphoryltion on the change of synaptic vesicles cycles and amino acids neurotransmitter release. Methods Primary 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. Results After 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-y 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. Conclusion Microwave radiation at the intensity of 30 mW/cm^2 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.