Thippeswamy Thimmasettappa, Howard Mark R, Cosgrave Anna Siobhan, Arora Daleep Kumar, McKay Jennifer S, Quinn John P
Department of Veterinary Preclinical Sciences, University of Liverpool, Brownlowhill Street, Liverpool, L69 7ZJ, UK.
J Mol Neurosci. 2007;33(3):268-77. doi: 10.1007/s12031-007-0066-8. Epub 2007 Sep 11.
Nerve growth factor (NGF)-deprivation or axotomy of dorsal root ganglion (DRG) neurons causes stress, which they cope by triggering various mechanisms. Among several molecular changes, in the present study, we demonstrate preprotachykinin-A-substance P (PPTA-SP) and activity-dependent neuroprotective protein-vasoactive intestinal peptide (ADNP-VIP) expression pattern using DRG neurons-Schwann cells coculture and axotomy model. In the presence of NGF, DRG cultures showed high levels of PPTA and ADNP mRNA expression, which were significantly suppressed in the absence of NGF and/or nitric oxide synthase (NOS) inhibition by NG-nitro-L-arginine methyl ester (L-NAME), suggesting that both NGF and nitric oxide (NO) can regulate PPTA and ADNP expression. However, treating coculture with NO donor, diethylenetriamine nitric oxide (DETA-NO) did not increase PPTA and ADNP expression in the presence or absence of NGF, although there was a marginal increase in ADNP expression in the absence of NGF. NGF-deprivation increases endogenous NO; thus, DETA-NO had no further effect on PPTA and ADNP expression. Alternatively, NGF produced from NO-stimulated Schwann cells influence gene expression. In addition, interestingly, DETA-NO treatment of Schwann cells alone suppresses both PPTA and ADNP, suggesting differential response of DRG neurons-Schwann cells coculture to DETA-NO. SP and ADNP immunostaining of axotomized DRGs revealed significant reduction in SP and ADNP compared to intact DRG, which was partially recovered in neuronal NOS blocker, 7-nitroindazole (7-NI)-treated DRGs, particularly intense ADNP staining in satellite glia. As ADNP is VIP-responsive gene, we further explored VIP expression in DRGs. Axotomy increased VIP in DRG neurons, but 7-NI treatment caused intense VIP staining in satellite glia. These observations suggest a complex interaction of NO-NGF with PPTA/SP and ADNP-VIP in neuron-glial communication when neurons are stressed.
神经生长因子（NGF）剥夺或背根神经节（DRG）神经元轴突切断会引发应激，神经元通过触发各种机制来应对。在本研究中，在多种分子变化之中，我们利用DRG神经元 - 雪旺细胞共培养和轴突切断模型展示了前速激肽原A - 物质P（PPTA - SP）和活性依赖的神经保护蛋白 - 血管活性肠肽（ADNP - VIP）的表达模式。在NGF存在的情况下，DRG培养物显示出高水平的PPTA和ADNP mRNA表达，而在缺乏NGF和/或用NG - 硝基 - L - 精氨酸甲酯（L - NAME）抑制一氧化氮合酶（NOS）时，这些表达被显著抑制，这表明NGF和一氧化氮（NO）都可以调节PPTA和ADNP的表达。然而，在用NO供体二乙三胺一氧化氮（DETA - NO）处理共培养物时，无论有无NGF，PPTA和ADNP的表达均未增加，尽管在缺乏NGF时ADNP表达有少量增加。NGF剥夺会增加内源性NO；因此，DETA - NO对PPTA和ADNP的表达没有进一步影响。另外，由NO刺激的雪旺细胞产生的NGF会影响基因表达。此外，有趣的是，单独用DETA - NO处理雪旺细胞会抑制PPTA和ADNP，这表明DRG神经元 - 雪旺细胞共培养对DETA - NO有不同的反应。对轴突切断的DRG进行SP和ADNP免疫染色显示，与完整的DRG相比，SP和ADNP显著减少，在用神经元型NOS阻滞剂7 - 硝基吲唑（7 - NI）处理的DRG中部分恢复，特别是卫星胶质细胞中ADNP染色强烈。由于ADNP是VIP反应性基因，我们进一步探究了DRG中VIP的表达。轴突切断增加了DRG神经元中的VIP，但7 - NI处理导致卫星胶质细胞中VIP染色强烈。这些观察结果表明，当神经元受到应激时，在神经元 - 胶质细胞通讯中，NO - NGF与PPTA/SP和ADNP - VIP之间存在复杂的相互作用。
