Walker Ryan G, Foster Andrew, Randolph Chris L, Isaacson Lori G
Center for Neuroscience and Behavior, Department of Zoology, Miami University Oxford, OH 45056, USA.
Brain Res. 2009 Feb 19;1255:1-8. doi: 10.1016/j.brainres.2008.11.090. Epub 2008 Dec 9.
Mature sympathetic neurons in the superior cervical ganglion (SCG) are regulated by target-derived neurotrophins such as nerve growth factor (NGF) and neurotrophin-3 (NT-3). High molecular weight NGF species and mature NT-3 are the predominant NGF and NT-3 protein isoforms in the SCG, yet it is unknown whether the presence of these species is dependent on intact connection with the target tissues. In an attempt to determine the role of peripheral targets in regulating the neurotrophin species found in the SCG, we investigated the NGF and NT-3 protein species present in the SCG following axotomy (transection) or injury of the post-ganglionic axons. Following a 7 day axotomy, the 22-24 kDa NGF species and the mature 14 kDa NT-3 species in the SCG were significantly reduced by 99% and 66% respectively, suggesting that intact connection with the target is necessary for the expression of these protein species. As expected, tyrosine hydroxylase (TH) protein in the SCG was significantly reduced by 80% at 7 days following axotomy. In order to distinguish between the effects of injury and loss of target connectivity, the SCG was examined following compression injury to the post-ganglionic nerves. Following injury, no reduction in the 22-24 kDa NGF or 14 kDa mature NT-3 species was observed in the SCG. TH protein was slightly, yet significantly, decreased in the SCG following injury. The findings of this study suggest that the presence of the 22-24 kDa NGF and mature 14 kDa NT-3 species in the SCG is dependent on connection with peripheral targets and may influence, at least in part, TH protein expression in adult sympathetic neurons.
颈上神经节（SCG）中的成熟交感神经元受靶源性神经营养因子如神经生长因子（NGF）和神经营养因子-3（NT-3）的调节。高分子量NGF亚型和成熟的NT-3是SCG中主要的NGF和NT-3蛋白异构体，但这些异构体的存在是否依赖于与靶组织的完整连接尚不清楚。为了确定外周靶标在调节SCG中发现的神经营养因子异构体中的作用，我们研究了节后轴突切断（横断）或损伤后SCG中存在的NGF和NT-3蛋白异构体。轴突切断7天后，SCG中22 - 24 kDa的NGF异构体和成熟的14 kDa NT-3异构体分别显著减少了99%和66%，这表明与靶标的完整连接对于这些蛋白异构体的表达是必要的。正如预期的那样，轴突切断7天后，SCG中的酪氨酸羟化酶（TH）蛋白显著减少了80%。为了区分损伤和靶标连接丧失的影响，我们在节后神经受到压迫性损伤后检查了SCG。损伤后，未观察到SCG中22 - 24 kDa的NGF或14 kDa成熟NT-3异构体减少。损伤后，SCG中的TH蛋白略有但显著减少。本研究结果表明，SCG中22 - 24 kDa的NGF和成熟的14 kDa NT-3异构体的存在依赖于与外周靶标的连接，并且可能至少部分地影响成年交感神经元中TH蛋白的表达。
