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Immunocytochemical localization of tyrosine hydroxylase in the human striatum: A postmortem ultrastructural study
Author(s) -
Kung Lili,
Force Michelle,
Chute Dennis J.,
Roberts Rosalinda C.
Publication year - 1998
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19980105)390:1<52::aid-cne5>3.0.co;2-p
Subject(s) - dendritic spine , postsynaptic potential , synapse , striatum , biology , tyrosine hydroxylase , ultrastructure , anatomy , immunocytochemistry , neuroscience , axoplasmic transport , dopamine , endocrinology , receptor , biochemistry , hippocampal formation
An electron microscopic evaluation of tyrosine hydroxylase (TH) immunocytochemistry was used to describe the synaptic organization of dopamine innervation of the striatum in postmortem human brain tissue. TH immunoreactivity was qualitatively and quantitatively similar in the caudate and putamen. TH immunoreactivity was present mainly in unmyelinated axons and occasionally in myelinated axons. Both TH‐immunoreactive (TH‐i) varicosities (0.75–1.5 μm) and intervaricose segments (0.2–0.3 μm) formed synapses with spines and dendrites. Most synapses formed by TH‐i profiles were symmetric axospinous (57–62%) or symmetric axodendritic (33–35%). An occasional asymmetric axodendritic or asymmetric axospinous synapse was observed. Approximately 35–50% of all symmetric axospinous and axodendritic synapses were formed by TH‐i boutons. Synapses formed by TH‐i profiles were short in length (0.226 μm) and had nonperforated postsynaptic densities. TH‐i profiles formed synapses with both the head (40%) and the neck (60%) of spines. Typically, the TH‐i bouton was apposed to both a spine and a nonlabeled terminal which formed an asymmetric synapse with that spine. Direct, nonsynaptic appositions were often seen between TH‐labeled and nonlabeled boutons forming asymmetric synapses. The general pattern of TH immunoreactivity was similar to that of other species except for the presence of TH‐i myelinated axons and the observation that the majority of TH‐i synapses were formed with spines rather than with dendritic shafts. J. Comp. Neurol. 390:52–62, 1998. © 1998 Wiley‐Liss, Inc.