Kimpinski K, Campenot R B, Mearow K
Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada.
J Neurobiol. 1997 Oct;33(4):395-410. doi: 10.1002/(sici)1097-4695(199710)33:4<395::aid-neu5>3.0.co;2-5.
We used compartmented cultures to study the regulation of adult sensory neurite growth by neurotrophins. We examined the effects of the neurotrophins nerve growth factor (NGF), neurotrophin-3 (NT3), and BDNF on distal neurite elongation from adult rat dorsal root ganglion (DRG) neurons. Neurons were plated in the center compartments of three-chambered dishes in the absence of neurotrophin, and neurite extension into the distal (side) compartments containing NGF, BDNF, or NT3 was quantitated. Initial proximal neurite growth did not require any of the neurotrophins, while subsequent elongation into distal compartments required NGF. After neurites had extended into NGF-containing distal compartments, removal of NGF by treatment with anti-NGF resulted in the cessation of growth with minimal neurite retraction. In contrast to the effects of NGF, no distal neurite elongation was observed into compartments with BDNF or NT3. To examine possible additive influences, neurite extension into compartments containing BDNF plus NGF or NT3 plus NGF was quantitated. There was no increased neurite extension into NGF plus NT3 compartments, while the combination of BDNF plus NGF resulted in an inhibition of neurite extension compared with NGF alone. We then investigated whether the regrowth of neurites that had originally grown into NGF subsequent to in vitro axotomy still required NGF. The results demonstrated that unlike adult sensory nerve regeneration in vivo, the in vitro regrowth did require NGF, and neither BDNF nor NT3 was able to substitute for NGF. Since the initial growth from neurons after dissociation (which is also a regenerative response) did not require NGF, it would appear that neuritic growth and regrowth of adult DRG neurons in vitro includes both NGF-independent and NGF-dependent components. The compartmented culture system provides a unique model to further study aspects of this differential regulation of neurite growth.
我们使用分隔培养法来研究神经营养因子对成年感觉神经元轴突生长的调节作用。我们检测了神经营养因子神经生长因子（NGF）、神经营养因子-3（NT3）和脑源性神经营养因子（BDNF）对成年大鼠背根神经节（DRG）神经元远端轴突伸长的影响。将神经元接种在三室培养皿的中央隔室中，在无神经生长因子的情况下培养，然后对延伸至含有NGF、BDNF或NT3的远端（侧）隔室中的轴突进行定量分析。最初的近端轴突生长不需要任何神经营养因子，而随后向远端隔室的伸长则需要NGF。当轴突延伸至含有NGF的远端隔室后，用抗NGF处理去除NGF会导致生长停止，且轴突回缩极少。与NGF的作用相反，未观察到轴突向含有BDNF或NT3的隔室中伸长。为了检测可能的叠加影响，对延伸至含有BDNF加NGF或NT3加NGF的隔室中的轴突进行了定量分析。轴突向NGF加NT3隔室中的延伸没有增加，而BDNF加NGF的组合与单独使用NGF相比，导致轴突延伸受到抑制。然后我们研究了最初生长至NGF中的轴突在体外切断后再生是否仍需要NGF。结果表明，与成年感觉神经在体内的再生不同，体外再生确实需要NGF，BDNF和NT3都不能替代NGF。由于神经元解离后的初始生长（这也是一种再生反应）不需要NGF，因此成年DRG神经元在体外的轴突生长和再生似乎包括不依赖NGF和依赖NGF的成分。分隔培养系统提供了一个独特的模型，可进一步研究轴突生长这种差异调节的各个方面。
