Morphological study about glutamate neural transmission in the micturitional center in central nervous system.

谷氨酸是哺乳动物中枢神经系统中一种主要的兴奋性神经递质。生理学研究表明，下尿路功能是通过脊髓和脊髓上水平的谷氨酸受体来调节的。为了解NMDA受体亚单位mRNAs的个体发育变化及其在脊髓排尿系统发育中的作用，采用神经元逆行追踪和原位杂交双重标记技术，对支配膀胱肌的发育中大鼠神经节前神经元(PGN)的NMDA亚单位mRNAs进行了检测。我们还检测了NMDA亚单位和谷氨酸转运体亚型在下尿路梗阻模型和脊髓损伤模型中的表达模式，这两种疾病都是人类排尿系统的重要病理组织。NR2B和NR2D亚单位的mRNAs在出生后第7天出现中等信号，但在发育过程中其表达水平逐渐下降，成体表达最低。这些结果表明，在发育过程中，PGN中NR2亚单位mRNAs的表达存在动态变化。在发育过程中，PGN似乎通过NMDA受体改变了它们的性质。这种功能性NMDA受体在发育早期的时间表达可能有助于通过活性依赖的突触可塑性和精细化来建立成人型排尿神经回路。在下尿路梗阻和脊髓损伤模型中，谷氨酸受体和转运体分子的表达均无明显变化。

Glutamate is a major excitatory neurotransmitter in the mammalian central nervous system. Physiological studies have shown that lower urinary tract function is regulated through the glutamate receptors at the level of spinal and supraspinal cord. To know the ontogenic change of NMDA receptor subunit mRNAs and function in developing spinal micturitional system, we employed double labeling technique of retrograde neuronal tracing and in situ hybridization for detecting NMDA subunit mRNAs in developing preganglionic neurons (PGNs) in the rat, which innervate bladder muscle. We also examined expression patterns of NMDA subunit mRNAs and glutamate transporter subtype mRNAs in lower urinary tract obstruction model and spinal cord injury model, which are both important human pathologies in micturition system.The PGNs showed strong signals for NR1 subunit mRNA at every stage during development to adult. Moderate signals for the NR2B and NR2D subunit mRNAs were found in PGNs at postnatal day 7. However, their expression levels decreased gradually during development, with minimal expressions in Adult. These results show that there are dynamic changes in the expression of the NR2 subunit mRNAs in the PGNs during development. PGNs seem to change their property through the NMDA receptor during development. This temporal expression of functional NMDA receptors during early development might contribute to the establishment of the adult-type micturitional neural circuit through activity-dependent synaptic plasticity and refinement. There were no significant changes in the expression of glutamate receptor and transporter molecules both in lower urinary tract obstruction and spinal cord injury models.