Sprouting of surviving axons is one of the major reorganization mechanisms of the injured brain contributing to a partial restoration of function. Of note, sprouting is maturation as well as age-dependent and strong in juvenile brains, moderate in adult and weak in aged brains. We have established a model system of complex organotypic tissue cultures to study sprouting in the dentate gyrus following entorhinal denervation. Entorhinal denervation performed after two weeks postnatally resulted in a robust, rapid and very extensive sprouting response of commissural/associational fibers which could be visualized using calretinin as an axonal marker. In the present study we analyzed the effect of maturation on this form of sprouting and compared cultures denervated at two weeks postnatally with cultures denervated at four weeks postnatally. Calretinin immunofluorescence labeling as well as time-lapse imaging of virally-labeled (AAV2-hSyn1-GFP) commissural axons was employed to study the sprouting response in aged cultures. Compared to the young cultures commissural/associational sprouting was attenuated and showed a pattern similar to the one following entorhinal denervation in adult animals in vivo. We conclude that a maturation-dependent attenuation of sprouting occurs also in vitro, which now offers the chance to study, understand and influence maturation-dependent differences in brain repair in these culture preparations.

中文翻译：

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在内嗅皮层和海马组织型组织培养中发芽缔合和合生苔藓细胞轴突使失神经的齿状回重新支配的成熟依赖性差异

存活的轴突发芽是受伤的大脑导致部分功能恢复的主要重组机制之一。值得注意的是，发芽是成熟的，并且与年龄有关，在幼稚的大脑中很强，在成年人中适中而在老年的大脑中则很弱。我们建立了复杂器官型组织培养的模型系统，以研究内嗅神经去神经后在齿状回中的发芽。产后两周后进行的神经内神经去神经导致连合/缔合纤维的旺盛，快速和非常广泛的发芽反应，可以使用钙黄蛋白作为轴突标记物来观察。在本研究中，我们分析了成熟对这种发芽形式的影响，并将出生后两周神经支配的培养物与出生后四周神经支配的培养物进行了比较。Calretinin免疫荧光标记以及病毒标记的（AAV2-hSyn1-GFP）连合轴突的延时成像用于研究老化培养物中的发芽反应。与年轻的文化相比，合掌/协会发芽被减弱，并显示出与成年动物体内内啡肽去神经后的发芽相似的模式。我们得出的结论是，在体外也会发生成熟依赖的萌芽衰减，这现在为研究，理解和影响这些培养制剂中脑修复的成熟依赖差异提供了机会。与年轻的文化相比，合掌/协会发芽被减弱，并显示出与成年动物体内内啡肽去神经后的发芽相似的模式。我们得出的结论是，在体外也会发生成熟依赖的萌芽衰减，这现在为研究，理解和影响这些培养制剂中脑修复的成熟依赖差异提供了机会。与年轻的文化相比，合掌/协会发芽被减弱，并显示出与成年动物体内内啡肽去神经后的发芽相似的模式。我们得出的结论是，在体外也会发生成熟依赖的萌芽衰减，这现在为研究，理解和影响这些培养制剂中脑修复的成熟依赖差异提供了机会。