The guanine-based purines (GBPs) have essential extracellular functions such as modulation of glutamatergic transmission and trophic effects on neurons and astrocytes. We previously showed that GBPs, such as guanosine-5′-monophosphate (GMP) or guanosine (GUO), promote the reorganization of extracellular matrix proteins in astrocytes, and increase the number of neurons in a neuron-astrocyte co-culture protocol. To delineate the molecular basis underlying these effects, we isolated cerebellar neurons in culture and treated them with a conditioned medium derived from astrocytes previously exposed to GUO or GMP (GBPs-ACM) or, directly, with GUO or GMP. Agreeing with the previous studies, there was an increase in the number of β-tubulin III-positive neurons in both conditions, compared with controls. Interestingly, the increase in the number of neurons in the neuronal cultures treated directly with GUO or GMP was more prominent, suggesting a direct interaction of GBPs on cerebellar neurons. To investigate this issue, we assessed the role of adenosine and glutamate receptors and related intracellular signaling pathways after GUO or GMP treatment. We found an involvement of A_2A adenosine receptors, ionotropic glutamate N-methyl-D-aspartate (NMDA), and non-NMDA receptors in the increased number of cerebellar neurons. The signaling pathways extracellular-regulated kinase (ERK), calcium-calmodulin-dependent kinase-II (CaMKII), protein kinase C (PKC), phosphatidilinositol-3′-kinase (PI3-K), and protein kinase A (PKA) are also potentially involved with GMP and GUO effect. Such results suggest that GMP and GUO, and molecules released in GBPs-ACM promote the survival or maturation of primary cerebellar neurons or both via interaction with adenosine and glutamate receptors.

中文翻译：

---

鸟苷和GMP会增加培养物中颗粒状小脑神经元的数量：依赖于腺苷A2A和离子型谷氨酸受体。

基于鸟嘌呤的嘌呤（GBP）具有基本的细胞外功能，例如调节谷氨酸能传递以及对神经元和星形胶质细胞的营养作用。我们先前显示，GBP，例如鸟苷5'-单磷酸酯（GMP）或鸟苷（GUO），可促进星形胶质细胞中细胞外基质蛋白的重组，并增加神经元-星形细胞共培养方案中神经元的数量。为了描述这些作用的分子基础，我们分离了培养物中的小脑神经元，并用衍生自先前暴露于GUO或GMP（GBPs-ACM）或直接用GUO或GMP的星形胶质细胞衍生的条件培养基对其进行了处理。与之前的研究一致，与对照组相比，两种情况下β-微管蛋白III阳性神经元的数量均增加。有趣的是 直接用GUO或GMP处理的神经元培养物中神经元数量的增加更为显着，表明GBPs与小脑神经元有直接相互作用。为了研究这个问题，我们评估了GUO或GMP治疗后腺苷和谷氨酸受体的作用以及相关的细胞内信号通路。我们发现A有牵连小脑神经元数量增加时，_2A腺苷受体，离子型谷氨酸N-甲基-D-天冬氨酸（NMDA）和非NMDA受体。细胞外调节激酶（ERK），钙钙调蛋白依赖性激酶II（CaMKII），蛋白激酶C（PKC），磷脂酰肌醇3'-激酶（PI3-K）和蛋白激酶A（PKA）的信号通路为也可能与GMP和GUO效应有关。这些结果表明，GMP和GUO以及在GBPs-ACM中释放的分子可通过与腺苷和谷氨酸受体的相互作用促进原代小脑神经元的存活或成熟，或两者均可。