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调节的。为了解NMDA受体亚基mrna在脊髓排尿系统发育过程中的发生变化及其功能，我们采用逆行神经元示踪和原位杂交双标记技术检测了支配膀胱肌的大鼠神经节前神经元（PGNs）发育过程中的NMDA亚基mrna。我们还检测了NMDA亚基mrna和谷氨酸转运蛋白亚型mrna在下尿路阻塞模型和脊髓损伤模型中的表达模式，这两个模型都是人类排尿系统的重要病理。在发育至成体的各个阶段，PGNs均表现出强烈的NR1亚基mRNA信号。出生后第7天，在PGNs中发现NR2B和NR2D亚基mrna的中度信号。但在发育过程中表达量逐渐下降，成虫表达量最小。这些结果表明，在发育过程中，PGNs中NR2亚基mrna的表达发生了动态变化。在发育过程中，pgn似乎通过NMDA受体改变了它们的特性。这种功能性NMDA受体在发育早期的时间表达可能通过活动依赖性突触可塑性和精细性促进成体型排尿神经回路的建立。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.