Abstract: Objective To explore the physiological characteristics of synaptic transmission of anterior horn early development in thoracic spinal cord mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in rats. Methods 36 Wistar rats were divided into embryonic 17 days group (E17, n=12), embryonic 20 days group (E20, n=12) and postnatal 7 days group (P7, n=12). Immunofluorescent staining of calmodulin-dependent protein kinase Ⅱ (CaMKⅡ) was used to test the distribution of AMPA receptors. Multi-electrode array technique (MED-64 system) was used to test the changes of field excitatory post-synaptic potential (fEPSP) of synaptic transmission mediated by AMPA receptor. Results There was small amount of CaMKⅡ-positive neurons existing in gray matter of spinal cord at E17, CaMKⅡ-positive neurons migrated to the center, and the number of neurons became more and more in E20 and P7 rats. The number of evoked fEPSP gradually increased in rats from E17 to P7, and could be blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). The range of synaptic connection in spinal cord gray matter significantly reduced (P<0.001). Conclusion AMPA receptors participate in the early development of spinal cord in rats and act as the main excitatory receptor of functional synaptic connection in neural network of ventricornu.

Key words: α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, spinal cord development, field excitatory postsynaptic potential, synaptic connection, rats