Clinical Research Support Center, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8655, Japan.
Neurosci Lett. 2012 Jul 26;522(1):21-4. doi: 10.1016/j.neulet.2012.06.003. Epub 2012 Jun 9.
The survival activity of adenosine A(2A) agonist CGS21680 on motoneurons in culture through the transactivation of neurotrophin receptor TrkB has been reported previously; however, since adenosine A(2A) receptor belongs to a Gs-protein-coupled receptor, we investigated the involvement of the cAMP pathway in the survival activity of CGS21680 using purified motoneurons in culture. CGS21680 alone showed only small survival activity, but the activity was significantly enhanced by the addition of a phosphodiesterase inhibitor, IBMX. This survival activity was partially inhibited by a protein kinase A inhibitor H89 or a neurotrophin receptor tyrosine kinase inhibitor K252a, and was completely inhibited by their combination. These results indicate that the survival activity of CGS21680 on motoneurons is exerted by the mixed effect of the adenylate cyclase-cAMP-PKA pathway and transactivation of Trk neurotrophin receptor. Under conditions in which the maximum survival of motoneurons was supported by sufficient concentrations of brain-derived neurotrophic factor (BDNF), a TrkB ligand, the addition of 100μM AMPA for 3 days led to significant cell death. Treatment with CGS21680 and IBMX protected motoneurons from the toxicity of AMPA, further supporting the presence of a TrkB-independent pathway of CGS21680 activity and suggesting a novel therapeutic approach to motoneuron diseases such as amyotrophic lateral sclerosis.
先前已有报道称，腺苷 A（2A）受体激动剂 CGS21680 通过神经营养因子受体 TrkB 的转激活作用对培养中的运动神经元具有存活活性；然而，由于腺苷 A（2A）受体属于 Gs 蛋白偶联受体，我们使用纯化的培养运动神经元研究了 CGS21680 的存活活性是否涉及 cAMP 通路。CGS21680 本身仅显示出较小的存活活性，但加入磷酸二酯酶抑制剂 IBMX 后，其活性显著增强。这种存活活性被蛋白激酶 A 抑制剂 H89 或神经营养因子受体酪氨酸激酶抑制剂 K252a 部分抑制，并且当它们联合使用时被完全抑制。这些结果表明，CGS21680 对运动神经元的存活活性是通过腺苷酸环化酶-cAMP-PKA 通路的混合作用和 Trk 神经营养因子受体的转激活来发挥的。在足够浓度的脑源性神经营养因子（BDNF）支持运动神经元最大存活的条件下，添加 100μM AMPA 持续 3 天会导致明显的细胞死亡。用 CGS21680 和 IBMX 处理可保护运动神经元免受 AMPA 的毒性，进一步支持 CGS21680 活性存在独立于 TrkB 的途径，并为肌萎缩侧索硬化等运动神经元疾病提供了一种新的治疗方法。
