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Maturation of postsynaptic nicotinic structures on autonomic neurons requires innervation but not cholinergic transmission
Author(s) -
Kaiser Sergio,
Blank Martina,
Berg Darwin K.
Publication year - 2002
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2002.02050.x
Subject(s) - postsynaptic potential , ciliary ganglion , neuroscience , nicotinic agonist , neurotransmission , postsynaptic density , biology , cholinergic , inhibitory postsynaptic potential , synaptic plasticity , dendritic spine , acetylcholine receptor , excitatory postsynaptic potential , receptor , biochemistry , hippocampal formation
Postsynaptic development at the neuromuscular junction depends on nicotinic transmission and secreted components from the presynaptic motor nerve terminal. Similarly, secreted components and synaptic activity are both thought to guide development of glutamatergic synapses in the CNS. Nicotinic synapses on chick ciliary neurons are structurally complex: a large presynaptic calyx engulfs the postsynaptic neuron and overlays a series of discrete mats of receptor‐rich somatic spines tightly interwoven and folded against the soma. We used fluorescence imaging of α7‐containing nicotinic receptors and the spine constituent drebrin to monitor postsynaptic development. The results show that surgical disruption of the preganglionic input or removal of the ganglionic synaptic target tissue after synapses form in the ganglion does not disrupt the receptor‐rich spine mats. Similarly, removal of the target tissue even prior to synapse formation in the ganglion does not prevent subsequent formation of the receptor clusters and associated spine constituents. Postsynaptic development is arrested, however, if normal innervation is prevented by ablating the preganglionic neurons prior to synapse formation. In this case the neurons express reduced levels of nicotinic receptors and cytoskeletal components and organize them only into early‐stage clusters. Even low levels of residual innervation, however, can restore much of the normal postsynaptic receptor patterns. Chronic pharmacological blockade of cholinergic synaptic activity fails to replicate the effects of ablating the preganglionic nucleus. The results indicate that ciliary neurons are programmed to express postsynaptic components and can initiate clustering of α7‐containing receptors but need presynaptic guidance for maturation of the postsynaptic structure.