RT Journal Article SR Electronic T1 The Development of Excitatory Synapses in Cultured Spinal Neurons JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 7339 OP 7350 DO 10.1523/JNEUROSCI.17-19-07339.1997 VO 17 IS 19 A1 Richard J. O’Brien A1 Andrew L. Mammen A1 Seth Blackshaw A1 Michael D. Ehlers A1 Jeffrey D. Rothstein A1 Richard L. Huganir YR 1997 UL http://www.jneurosci.org/content/17/19/7339.abstract AB Immunohistochemical studies of synapses in the CNS have demonstrated that glutamate receptors (GluRs) are concentrated at postsynaptic sites in vivo and in vitro(Baude et al., 1995). The mechanisms leading to receptor clustering at excitatory synapses are far less understood than those governing acetylcholine receptor accumulation at the neuromuscular junction (Hall and Sanes,1993) or glycine receptor aggregation at central inhibitory synapses (Kirsch et al., 1993). Using cultured rat spinal cord neurons, we demonstrate that clustering of the AMPA receptor subunit GluR1 is among the earliest events in excitatory synapse formation in vitro, coincident with the onset of miniature EPSCs and in many cases preceding presynaptic vesicle accumulation. Postsynaptic receptor clustering is induced in a highly specific and reiterative pattern, independent of receptor activation, by contact with a subset of axons capable of inducing receptor clusters. The subunit composition of AMPA receptor clusters varied significantly between neurons but was invariant within a given neuron. The presence of either GluR2 or GluR3 was common to all receptor clusters. Neither high-affinity glutamate transporters nor NMDA receptors appeared to be concentrated with AMPA receptor subunits at these excitatory synapses.