Abstract：
Differentiation of oligodendrocyte precursor cells (OPCs) into mature oligodendrocytes (OLs) is a key event for axonal myelination in the brain; this process fails during demyelinating pathologies. Adenosine is emerging as an important player in oligodendrogliogenesis, by activating its metabotropic receptors (A1R, A2AR, A2BR, and A3R). We previously demonstrated that the Gs-coupled A2BR reduced differentiation of primary OPC cultures by inhibiting delayed rectifier (IK) as well as transient (IA) outward K+ currents. To deepen the unclear role of this receptor subtype in neuron-OL interplay and in myelination process, we tested the effects of different A2BR ligands in a dorsal root ganglion neuron (DRGN)/OPC cocultures, a corroborated in vitro myelination assay. The A2BR agonist, BAY60-6583, significantly reduced myelin basic protein levels but simultaneously increased myelination index in DRGN/OPC cocultures analyzed by confocal microscopy. The last effect was prevented by the selective A2BR antagonists, PSB-603 and MRS1706. To clarify this unexpected data, we wondered whether A2BRs could play a functional role on DRGNs. We first demonstrated, by immunocytochemistry, that primary DRGN monoculture expressed A2BRs. Their selective activation by BAY60-6583 enhanced DRGN excitability, as demonstrated by increased action potential firing, decreased rheobase and depolarized resting membrane potential and were prevented by PSB-603. Throughout this A2BR-dependent enhancement of neuronal activity, DRGNs could release factors to facilitate myelination processes. Finally, silencing A2BR in DRGNs alone prevents the increased myelination induced by BAY60-6583 in cocultures. In conclusion, our data suggest a different role of A2BR during oligodendrogliogenesis and myelination, depending on their activation on neurons or oligodendroglial cells.
摘要：
少突胶质前体细胞(OPCs)分化为成熟少突胶质细胞(OLs)是脑中轴突髓鞘形成的关键事件;该过程在脱髓鞘病变期间失败。腺苷正在成为少突胶质细胞发生的重要参与者，通过激活其代谢型受体(A1R，A2AR,A2BR,和A3R）。我们先前证明了Gs偶联的A2BR通过抑制延迟整流（IK）和瞬时（IA）外向K电流来降低原代OPC培养物的分化。为了加深这种受体亚型在神经元-OL相互作用和髓鞘形成过程中的作用，我们测试了不同A2BR配体在背根神经节神经元（DRGN）/OPC共培养物中的作用，证实的体外髓鞘形成试验。A2BR激动剂，通过共聚焦显微镜分析，BAY60-6583显着降低了DRGN/OPC共培养物中的髓磷脂碱性蛋白水平，但同时增加了髓鞘形成指数。选择性A2BR拮抗剂阻止了最后一种作用，PSB-603和MRS1706。为了澄清这些意外数据，我们想知道A2BRs是否可以在DRGN上发挥功能作用。我们首先证明，通过免疫细胞化学，原始DRGN单培养表达A2BRs。它们通过BAY60-6583的选择性激活增强了DRGN的兴奋性，如动作电位射击增加所证明的那样，降低了流变酶和去极化的静息膜电位，并被PSB-603阻止。在这种依赖A2BR的神经元活动增强中，DRGN可以释放因子以促进髓鞘形成过程。最后,单独在DRGN中沉默A2BR可防止BAY60-6583在共培养物中诱导的髓鞘形成增加。总之,我们的数据表明A2BR在少突胶质细胞形成和髓鞘形成过程中的不同作用，取决于它们对神经元或少突胶质细胞的激活。
