TY - JOUR
T1 - Subcellular localization of α-2A-adrenergic receptors in the rat medial nucleus tractus solitarius
T2 - Regional targeting and relationship with catecholamine neurons
AU - Glass, Michael J.
AU - Huang, Jie
AU - Aicher, Sue A.
AU - Milner, Teresa A.
AU - Pickel, Virginia M.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 2001/4/30
Y1 - 2001/4/30
N2 - α-2A-adrenergic receptor (α2A-AR) agonists modulate diverse autonomic functions. These actions are believed to involve functionally specialized, second-order neurons in catecholamine-containing portions of the medial nucleus tractus solitarius (mNTS) at both intermediate (NTSi) and caudal (NTSc) levels. However, the cellular mechanisms subserving α2A-AR-mediated actions within the mNTS have yet to be established. Immunocytochemistry was employed to examine the subcellular distribution of α2A-AR in both the intermediate and caudal mNTS and its association with cells containing the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH). Quantitative regional comparison using immunogold showed that this receptor was distributed differentially to dendrites (NTSi, 46%; NTSc, 31%) and glia (NTSi, 29%; NTSc, 48%) at different levels of the NTS. Somata, axons, and terminals less frequently contained α2A-AR. The subcellular distribution of α2A-AR relative to catecholaminergic neurons also was similar within both subregions. Approximately 50% of α2A-AR-labeled somata also contained TH. In somatic profiles, α2A-AR labeling was often found in the cytosol and in association with endoplasmic reticulum and Golgi complexes, sites of receptor synthesis and trafficking. Approximately 20% of α2A-AR-immunoreactive dendrites also contained TH, where the receptor was often found on extrasynaptic portions of the plasma membrane near unlabeled terminals, some of which made symmetric contacts. However, TH-labeled terminals and dendrites usually were detected in the neuropil at a short distance (<10 μm) from α2A-AR-labeled neurons. α2A-AR-labeled glia frequently apposed unlabeled dendrites and terminals and were often located near TH-immunoreactive dendrites. These results indicate that, within the mNTS, α2A-AR is involved in a variety of autonomic processes, including postsynaptic modulation of mostly noncatecholaminergic dendrites, as well as influencing glia functions.
AB - α-2A-adrenergic receptor (α2A-AR) agonists modulate diverse autonomic functions. These actions are believed to involve functionally specialized, second-order neurons in catecholamine-containing portions of the medial nucleus tractus solitarius (mNTS) at both intermediate (NTSi) and caudal (NTSc) levels. However, the cellular mechanisms subserving α2A-AR-mediated actions within the mNTS have yet to be established. Immunocytochemistry was employed to examine the subcellular distribution of α2A-AR in both the intermediate and caudal mNTS and its association with cells containing the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH). Quantitative regional comparison using immunogold showed that this receptor was distributed differentially to dendrites (NTSi, 46%; NTSc, 31%) and glia (NTSi, 29%; NTSc, 48%) at different levels of the NTS. Somata, axons, and terminals less frequently contained α2A-AR. The subcellular distribution of α2A-AR relative to catecholaminergic neurons also was similar within both subregions. Approximately 50% of α2A-AR-labeled somata also contained TH. In somatic profiles, α2A-AR labeling was often found in the cytosol and in association with endoplasmic reticulum and Golgi complexes, sites of receptor synthesis and trafficking. Approximately 20% of α2A-AR-immunoreactive dendrites also contained TH, where the receptor was often found on extrasynaptic portions of the plasma membrane near unlabeled terminals, some of which made symmetric contacts. However, TH-labeled terminals and dendrites usually were detected in the neuropil at a short distance (<10 μm) from α2A-AR-labeled neurons. α2A-AR-labeled glia frequently apposed unlabeled dendrites and terminals and were often located near TH-immunoreactive dendrites. These results indicate that, within the mNTS, α2A-AR is involved in a variety of autonomic processes, including postsynaptic modulation of mostly noncatecholaminergic dendrites, as well as influencing glia functions.
KW - Autonomic nervous system
KW - Clonidine
KW - Glia
KW - Immunocytochemistry
KW - Withdrawal
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U2 - 10.1002/cne.1135
DO - 10.1002/cne.1135
M3 - Article
C2 - 11283959
AN - SCOPUS:0035972113
SN - 0021-9967
VL - 433
SP - 193
EP - 207
JO - Journal of Comparative Neurology
JF - Journal of Comparative Neurology
IS - 2
ER -