Shibata T, Watanabe M, Ichikawa R, Inoue Y, Koyanagi T
Department of Urology, Hokkaido University School of Medicine, Sapporo, Japan.
J Comp Neurol. 1999 Feb 8;404(2):172-82. doi: 10.1002/(sici)1096-9861(19990208)404:2<172::aid-cne3>3.0.co;2-u.
The glutamatergic transmission system plays a key role in afferent and efferent pathways involved in micturition. By in situ hybridization combined with retrograde Fast Blue labeling, expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor (GluR-A to -D) and N-methyl-D-aspartate (NMDA) receptor (NR1 and NR2A-D) subunit mRNAs were examined in visceromotor and somatomotor neurons of the rat lumbosacral spinal cord. Parasympathetic preganglionic neurons (PGNs) in the intermediolateral nucleus highly expressed GluR-A and GluR-B subunit mRNAs, with very low levels for GluR-C and GluR-D subunits. As for the NMDA receptor, PGNs were associated with abundant signals for NR1 subunit mRNA, but without any NR2 subunit mRNAs. On the other hand, somatomotor neurons in the ventral horn (dorsolateral nucleus) express all four AMPA receptor subunit mRNAs, showing relatively abundant expressions of GluR-C and GluR-D subunit mRNA compared with PGNs. In addition to high levels of NR1 subunit mRNA, dorsolateral nucleus neurons moderately expressed NR2A and NR2B subunit mRNAs. These results suggest that molecular organization of both AMPA and NMDA receptor channels are distinct between PGNs and dorsolateral nucleus neurons. Considering that native NMDA receptors are heteromeric channels composed of NR1 and NR2 subunits, it seems likely that dorsolateral nucleus neurons, not PGNs, are provided with functional NMDA receptors, which could induce activity-dependent changes in synaptic transmission in the efferent pathway for the lower urinary tract.
谷氨酸能传递系统在参与排尿的传入和传出通路中起关键作用。通过原位杂交结合逆行Fast Blue标记，检测了大鼠腰骶脊髓内脏运动和躯体运动神经元中α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体（GluR-A至-D）和N-甲基-D-天冬氨酸（NMDA）受体（NR1和NR2A-D）亚基mRNA的表达。中间外侧核中的副交感神经节前神经元（PGNs）高度表达GluR-A和GluR-B亚基mRNA，而GluR-C和GluR-D亚基的表达水平非常低。至于NMDA受体，PGNs与NR1亚基mRNA的丰富信号相关，但没有任何NR2亚基mRNA。另一方面，腹角（背外侧核）中的躯体运动神经元表达所有四种AMPA受体亚基mRNA，与PGNs相比，GluR-C和GluR-D亚基mRNA的表达相对丰富。除了高水平的NR1亚基mRNA外，背外侧核神经元适度表达NR2A和NR2B亚基mRNA。这些结果表明，AMPA和NMDA受体通道的分子组织在PGNs和背外侧核神经元之间是不同的。考虑到天然NMDA受体是由NR1和NR2亚基组成的异聚通道，似乎背外侧核神经元而非PGNs具有功能性NMDA受体，这可能会在下尿路传出通路中诱导突触传递的活动依赖性变化。
