Zhang J, El-Mas M M, Abdel-Rahman A A
Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858-4353, USA.
Eur J Pharmacol. 2001 Mar;415(2-3):117-25. doi: 10.1016/s0014-2999(01)00834-2.
In the present study, we tested the hypothesis that the activation of imidazoline I(1)-receptor, which is coupled to phosphatidylcholine-specific phospholipase C, results in downstream activation of mitogen-activated protein kinase (p42(mapk) and p44(mapk) isoforms) in PC12 cells. PC12 cells pretreated with nerve growth factor (50 ng/ml, 48 h) to initiate neuronal differentiation were incubated with [methyl-3H]choline and [3H]myristate. Activation of imidazoline I(1) receptor by rilmenidine (10 microM) caused time-dependent increases in diacylglycerol accumulation and phosphocholine release. The Western blotting analysis showed that rilmenidine (10 microM) produced a time-dependent activation of p42(mapk) and p44(mapk) that reached its maximum at 15 min and returned to control levels after 30 min. This finding was confirmed by immunofluorescence labeling of activated mitogen-activated protein kinase in the same model system. Efaroxan (imidazoline I(1)-receptor antagonist) or tricyclodecan-9-yl-xanthogenate (D609, phosphatidylcholine-specific phospholipase C inhibitor) attenuated the phosphorylation of p42(mapk) and p44(mapk) induced by rilmenidine. Nerve growth factor-induced phosphorylation of both mitogen-activated protein kinase isoforms was not affected by D609. These results support the hypothesis that the activation of the imidazoline I(1) receptor coupled phosphatidylcholine-specific phospholipase C results in the downstream activation of mitogen-activated protein kinase.
在本研究中，我们验证了以下假说：与磷脂酰胆碱特异性磷脂酶C偶联的咪唑啉I(1)受体的激活，会导致PC12细胞中丝裂原活化蛋白激酶（p42(mapk)和p44(mapk)亚型）的下游激活。用神经生长因子（50 ng/ml，48小时）预处理以启动神经元分化的PC12细胞，与[甲基-3H]胆碱和[3H]肉豆蔻酸一起孵育。利美尼定（10 microM）对咪唑啉I(1)受体的激活导致二酰基甘油积累和磷酸胆碱释放随时间增加。蛋白质印迹分析表明利美尼定（10 microM）引起p42(mapk)和p44(mapk)随时间的激活，在15分钟时达到最大值，并在30分钟后恢复到对照水平。在同一模型系统中，活化的丝裂原活化蛋白激酶的免疫荧光标记证实了这一发现。依发洛新（咪唑啉I(1)受体拮抗剂）或三环癸基黄原酸盐（D609，磷脂酰胆碱特异性磷脂酶C抑制剂）减弱了利美尼定诱导的p42(mapk)和p44(mapk)的磷酸化。D609不影响神经生长因子诱导的两种丝裂原活化蛋白激酶亚型的磷酸化。这些结果支持以下假说：与磷脂酰胆碱特异性磷脂酶C偶联的咪唑啉I(1)受体的激活导致丝裂原活化蛋白激酶的下游激活。
