多巴胺对海马神经元树突和突触形态的调节作用

Effects of dopamine on morphology of the dendrites and synapses in hippocampal neurons

为探讨多巴胺(dopamine,DA)对海马神经元树突和突触形态的影响及其机制,用体外培养10 d的海马神经细胞DA(0.1μmol/L~10 mmol/L)处理1 h,用绿色荧光标记突触前Syn1,红色荧光标记树突上F-actin,分别显示突触前和突触后树突棘位点,红绿色叠加的黄色区域标示突触.结果表明:1~100μmol/L DA显著增加神经元树突棘和突触密度,该作用可被I类DA受体(DR1)拮抗剂SCH23390或ERK1/2抑制剂U0126预处理消除;10 mmol/L DA显著降低树突棘和突触密度,DR2拮抗剂Sulpride或p38抑制剂消除该抑制作用;同时,1μmol/L的DA显著上调海马神经元DR1蛋白表达,而10 mmol/L的DA上调DR2蛋白表达.以上结果提示,DA对海马神经元树突和突触密度的影响是和剂量有关的双重作用,生理范围的DA浓度经DR1介导的ERK1/2信号通路促进树突棘和突触形成,而DR2介导高剂量DA对树突棘和突触形成的抑制作用,p38信号通路可能参与这一过程.

It was aimed to investigate the effects of dopamine(DA)on the morphology of dendrites and synapses in hippocampal neurons and underlying mechanisms.The hippocampal cultured in vitro for 10 days was treated by DA(0.1μmol/L~10 mmol/L)for 1 h,respectively.Syn1 on the pre-synapse was labeled with green fluorescence,F-actin on dendrites was labeled with red fluorescence,and the sites of synapses and dendritic spines were displayed,respectively.These results showed that DA at 1~100μmol/L significantly increased the densities of dendritic spines and synapses,which could be eliminated by pretreatment with DA receptor type I(DR1)antagonist SCH23390 or ERK1/2 inhibitor U0126.DA at 10 mmol/L significantly reduced the densities of dendritic spines and synapses,which could be eliminated by DR2 antagonist Sulpride or p38 inhibitor SB203,580.Furthermore,DA at 1μmol/L significantly upregulated DR1 protein expression,while DA at 10 mmol/L upregulated DR2 protein expression in hippocampal neurons.These results suggested that DA dose-dependent bidirectionally regulated the formation of dendrites and synapses in hippocampal neurons.Physiological dose of DA promoted the formation of dendritic spines and synapses through DR1-mediated ERK1/2 signaling pathway,while DR2 mediated the inhibitory effect of high dose of DA on dendritic spines and synapses,in which p38 signaling pathway was involved.