Department of Psychology, University of Nebraska at Omaha, Omaha, NE, USA.
Department of Psychology, University of Nebraska at Omaha, Omaha, NE, USA.
Neuroscience. 2019 Mar 15;402:66-77. doi: 10.1016/j.neuroscience.2019.01.011. Epub 2019 Jan 24.
Neural insult during development results in recovery outcomes that vary dependent upon the system under investigation. Nerve regeneration does not occur if the rat gustatory chorda tympani nerve is sectioned (CTX) during neonatal (≤P10) development. It is unclear how chorda tympani soma and terminal fields are affected after neonatal CTX. The current study determined the impact of neonatal CTX on chorda tympani neurons and brainstem gustatory terminal fields. To assess terminal field volume in the nucleus of the solitary tract (NTS), rats received CTX at P5 or P10 followed by chorda tympani label, or glossopharyngeal (GL) and greater superficial petrosal (GSP) label as adults. In another group of animals, terminal field volumes and numbers of chorda tympani neurons in the geniculate ganglion (GG) were determined by labeling the chorda tympani with DiI at the time of CTX in neonatal (P5) and adult (P50) rats. There was a greater loss of chorda tympani neurons following P5 CTX compared to adult denervation. Chorda tympani terminal field volume was dramatically reduced 50 days after P5 or P10 CTX. Lack of nerve regeneration after neonatal CTX is not caused by ganglion cell death alone, as approximately 30% of chorda tympani neurons survived into adulthood. Although the total field volume of intact gustatory nerves was not altered, the GSP volume and GSP-GL overlap increased in the dorsal NTS after CTX at P5, but not P10, demonstrating age-dependent plasticity. Our findings indicate that the developing gustatory system is highly plastic and simultaneously vulnerable to injury.
发育过程中的神经损伤会导致不同的恢复结果，这取决于所研究的系统。如果在新生儿期（≤P10）发育过程中切断大鼠味觉鼓索神经（CTX），则不会发生神经再生。目前尚不清楚新生儿 CTX 后鼓索躯体和终末场如何受到影响。本研究旨在确定新生儿 CTX 对鼓索神经神经元和脑干味觉终末场的影响。为了评估孤束核（NTS）中的终末场体积，在 P5 或 P10 时接受 CTX 的大鼠在成年后接受鼓索标记，或接受舌咽神经（GL）和较大的岩浅大神经（GSP）标记。在另一组动物中，通过在新生儿（P5）和成年（P50）大鼠的 CTX 时用 DiI 标记鼓索来确定鼓索神经元的终末场体积和数量。与成年去神经相比，P5 CTX 后鼓索神经元的丢失更大。与 P5 或 P10 CTX 后 50 天相比，鼓索终末场体积显著减少。新生儿 CTX 后缺乏神经再生不仅仅是由于神经节细胞死亡，因为大约 30%的鼓索神经元存活到成年期。尽管完整味觉神经的总场体积没有改变，但 P5 CTX 后，背侧 NTS 中的 GSP 体积和 GSP-GL 重叠增加，但 P10 CTX 后没有增加，表明存在年龄依赖性可塑性。我们的研究结果表明，发育中的味觉系统具有高度的可塑性，同时易受损伤。
