Glycine plays a crucial role as a co-agonist of NMDA receptors in the neuronal circuit generating body movements in rat fetuses. (August 2015)

• Record Type: Journal Article
• Authors: Shimomura, Hideki; Ito, Mari; Nishiyama, Ayae; Tanizawa, Takakuni; Takeshima, Yasuhiro; Nishimaru, Hiroshi; Arata, Akiko
• Is Part Of: Neuroscience research. Volume 97(2015:Aug.)
• Page Start: 13
• Page End: 19
• Publication Date: 2015-08
• Subjects: Strychnine -- NMDA receptor glycine binding site -- Fetal movement -- Brainstem-spinal cord preparation; Neurosciences -- Research -- Periodicals; Neurosciences -- Research -- Japan -- Periodicals; Neurology -- Periodicals; Neurosciences -- Periodicals; Neurosciences -- Recherche -- Périodiques; Neurosciences -- Recherche -- Japon -- Périodiques; Neurosciences -- Research; Japan; Periodicals; 612.8
• DOI: 10.1016/j.neures.2015.03.004
• Languages: English
• ISSNs: 0168-0102

Abstract

Highlights: We examined the contribution of glycine to the perinatal rat spinal circuit. We used isolated brainstem-spinal cord-upper limb preparation from perinatal rat. We focused on the developmental changes of forelimb movements as a fetal movement. Glycine generated fetal movement via the glycine binding site of NMDA receptor. Fetal movement was suppressed by strychnine-sensitive glycine receptor after birth. Abstract: Neuronal circuits generating fetal movements in mammals are localized in the brainstem and the spinal cord. It has been shown that glycine plays an important role through the strychnine-sensitive glycine receptors in these circuits. However, the role of glycine as the NMDA receptor co-agonist in fetal period is not fully understood. In this study, we examined the contribution of glycine to the perinatal rat spinal circuit generating forelimb movements utilizing isolated brainstem-cervical-spinal-cord preparations. In late embryonic-days-preparations, spontaneous motor bursts related to forelimb movements (forelimb-movement-related bursts; FMRBs) and respiration-related activity were observed. In neonatal preparations, spontaneous FMRBs were not observed but periodic motor bursts resembling the FMRBs could be induced after bath application of strychnine (strychnine-induced motor bursts; SIMBs). Both FMRBs and SIMBs were blocked by either the NMDA receptor antagonist APV or the antagonists of the glycine binding site of NMDA receptors [5, 7-dichlorokynurenic acid (DCKA) or L-689560]. Furthermore, these motor bursts were facilitated by the glycine uptake blocker sarcosine. This effect of sarcosine was blocked by DCKA. The findings indicate that glycine plays a crucial role as a NMDA receptor co-agonist in generating spontaneous fetal motor activity before functioning as a classical inhibitory neurotransmitter in suppressing the fetal neuronal circuits.