Neuronal Acetylcholine Receptors with α7 Subunits Are Concentrated on Somatic Spines for Synaptic Signaling in Embryonic Chick Ciliary Ganglia

摘要: Nicotinic acetylcholine receptors containing alpha7 subunits are widely distributed in the vertebrate nervous system. In chick ciliary ganglion such generate large synaptic currents but appear to be excluded from postsynaptic densities on cells. We show here that alpha7-containing concentrated somatic spines close proximity putative sites of presynaptic transmitter release. Intermediate voltage electron microscopy thick sections, together with tomographic reconstruction, permitted three-dimensional analysis finger-like projections emanating cell bodies. The were identified as based their morphology, cytoskeletal content, and elements. Both situ after ganglionic dissociation, grouped surface tightly folded into mats. Immunogold labeling showed them preferentially spines. Postsynaptic present vivo both soma near occasionally themselves. Synaptic vesicle-filled calyx interdigitated among Moreover, vesicles often abutted membrane sometimes included Omega profiles if caught an exocytotic event, even when no juxtaposed spine. results suggest several mechanisms for delivering receptors, they support new ideas about signaling via They also indicate neurons must have specific targeting desired locations.