期刊
JOURNAL OF COMPARATIVE NEUROLOGY
卷 434, 期 4, 页码 445-460出版社
WILEY
DOI: 10.1002/cne.1186
关键词
acetylcholine; caudate nucleus; basal ganglia; striosome; prefrontal cortex; electron microscopy
资金
- NIMH NIH HHS [MH38546] Funding Source: Medline
- NINDS NIH HHS [NS30454, NS 07224] Funding Source: Medline
The cellular and subcellular localization of muscarinic receptor proteins mi and m2 was examined in the neostriatum of macaque monkeys by using light and electron microscopic immunocytochemical techniques. Double-labeling immunocytochemistry revealed mi receptors in calbindin-D28k-positive medium spiny projection neurons. Muscarinic mi labeling was dramatically more intense in the striatal matrix compartment in juvenile monkeys but more intense in striosomes in the adult caudate, suggesting that mi expression undergoes a developmental age-dependent change. Ultrastructurally, mi receptors were predominantly localized in asymmetric synapse-forming spines, indicating that these spines receive extrastriatal excitatory afferents. The association of m1-positive spines with lesion-induced degenerating prefronto-striatal axon terminals demonstrated that these afferents originate in part from the prefrontal cortex. The synaptic localization of m1 in these spines indicates a role of mi in the modulation of excitatory neurotransmission. To a lesser extent, mi was present in symmetric synapses, where it may also modulate inhibitory neurotransmission originating from local striatal neurons or the substantia nigra. Conversely, m2/choline acetyltransferase (ChAT) double labeling revealed that m2-positive neurons corresponded to large aspiny cholinergic interneurons and ultrastructurally, that the majority of m2 labeled axons formed symmetric synapses. The remarkable segregation of the mi and m2 receptor proteins to projection and local circuit neurons suggests a functional segregation of mi and m2 mediated cholinergic actions in the striatum: mi receptors modulate extrinsic glutamatergic and monoaminergic afferents and intrinsic GABAergic afferents onto projection neurons, whereas m2 receptors regulate acetylcholine release from axons of cholinergic interneurons. J. Comp. Neurol. 434:445-460, 2001. (C) 2001 Wiley-Liss, Inc.
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