Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria.
Neurosci Lett. 2010 Mar 19;472(2):109-13. doi: 10.1016/j.neulet.2010.01.064. Epub 2010 Feb 2.
In the present study the time course of extracellular signal-regulated protein kinase phosphorylation (pERK1/2 appearance) in lumbar sensory dorsal root ganglia (DRG) was determined following a 5-min noxious heat or a noxious cold stimulus to the hind paw of the rat. The thermal stimuli were chosen to activate transient receptor potential (TRP) channels, but not to induce tissue damage. A quantitative analysis of phospho-ERK1/2 was performed by protein extraction and Western blot analysis. Western blot analysis showed that following the heat stimulus, phosphorylation of ERK1/2 increased 2-3-fold between 10 and 30min in the DRG on the ipsilateral side. High levels were maintained from 30min up to 16h. Following the cold stimulus to the paw, pERK1/2 immediately increased 2-fold within 2min in the DRG on the ipsilateral side, it declined within 2h and reached a second peak at 4h. In the DRGs on the contralateral side of the paw's heat or cold immersion the pERK1/2 remained low at all time points investigated. Fluorescence immunohistochemistry of the DRG following the thermal stimuli revealed an increased cytoplasmic staining for pERK1/2 in neurons. The present results show that following a 5-min nociceptive thermal stimulus sensory neurons respond with a characteristic long-lasting phosphorylation of ERK1/2.
在本研究中，通过对大鼠后爪施加 5 分钟的有害热或有害冷刺激，确定了细胞外信号调节蛋白激酶磷酸化（pERK1/2 出现）在外周感觉背根神经节（DRG）中的时间进程。选择这些热刺激是为了激活瞬时受体电位（TRP）通道，但不会引起组织损伤。通过蛋白质提取和 Western blot 分析对磷酸化 ERK1/2 进行定量分析。Western blot 分析显示，在热刺激后，DRG 中 ERK1/2 的磷酸化在同侧的 10 到 30 分钟之间增加了 2-3 倍。从 30 分钟到 16 小时保持高水平。对爪子施加冷刺激后，同侧 DRG 中的 pERK1/2 在 2 分钟内立即增加了 2 倍，在 2 小时内下降，并在 4 小时达到第二个峰值。在爪子的热或冷浸泡的对侧 DRG 中，pERK1/2 在所有研究的时间点都保持较低水平。热刺激后 DRG 的荧光免疫组织化学显示，神经元中 pERK1/2 的细胞质染色增加。本研究结果表明，在 5 分钟的伤害性热刺激后，感觉神经元对 ERK1/2 的特征性持久磷酸化做出反应。
