DGAVP、Org2766对海马突触体蛋白质合成的影响与Ca~(2+)水平的相关性

我们过去的工作表明:DGAVP(脱甘氨酰胺精氨酸加压素)和 Org2766(ACTH_(4-9)的改构物)易化记忆巩固过程与海马突触体蛋白质合成有关.本实验以~3H-亮氨酸为标记物,以 ANI(茴香霉素)/为工具药,在突触体水平上观察了 DGAVP.Org2766对蛋白质合成的影响与 Ca~(2 )浓度的相关性。结果表明:(1)突触体正常的蛋白质合成依赖于合适的 Ca~(2 )浓度,加入螯合剂 EGTA 将 Ca2 螫合或加入异搏定将 Ca~(2 )通道阻断以后,~3H-Leu 对突触体蛋白质的掺入量都显著下降(p<0.05)(2)蛋白质合成抑制剂 ANI 的抑制作用与温育环境中 Ca~(2 )浓度无关,无论在正常 Ca~(2 )或是 Ca~(2 )被螯合的条件下都有同样的抑制效应(3)只有在正常 Ca~(2 )浓度下,DGAVP 或 Org2766才能对抗 ANTI 的抑制效应,当加入 EGTA 或异搏定以后即失去对抗效应;在后两种情况下~3H-Leu 向突触体的掺入量均显著降低。看来 Ca~(2 )不仅是突触传递的重要信使,而且也是突触体蛋白质合成过程以及上述两种神经肽干预该过程不可缺少的因素,同时也提示,这两种神经肽的中枢效应的神经化学机理在突触体水平上有其相似之处.

THE DEPENDENCE OF PROTEIN SYNTHESIS IN HIPPOCAMPAL SYNAPTOSOMES ON Ca~(2+)LEVEL IN THE PRESENCE OF DGAVP AND Org2766'

By the use of ~3H-Leu and a protein synthesis inhibitor,the rela- tion between the changes in protein synthesis by DGAVP or Org2766 and Ca~(2 )concentration in the synaptosomal level was in'vestigated.The results showed that:(1)The synaptosomal protein synthesis depended on optimal Ca~(2 )concentra- tion.After Ca~(2 )was chelated by EGTA or the Ca~(2 )-channels were blocked by verapamil,the incorporation of ~3H-Leu into hippocampal synaptosomal pro- teins decreased obviously.(2)There was no dependence of the protein synthesis inhibition by ANI on Ca~(2 )level,since the ANI-induced inhibition occurred significantly,no matter whether Ca~(2 )concentration in medium was normal or low.(3)DGAVP and Org2766 may go against the inhibition by ANI,only if Ca~(2 )must be in normal concentration.When EGTA or verapamil was added,this antagonism disappeared,and the incorporation of ~3H-Leu into synaptosomal proteins was significantly decreased under conditions of the Ca~(2 )deficiency.