TY - JOUR
T1 - μ-opioid receptors present in vagal afferents and their dendritic targets in the medial nucleus tractus solitarius
AU - Aicher, Sue A.
AU - Goldberg, Alla
AU - Sharma, Sarita
AU - Pickel, Virginia M.
PY - 2000/6/26
Y1 - 2000/6/26
N2 - Ligands of the μ-opiate receptor (MOR) are known to influence many functions that involve vagal afferent input to the nucleus tractus solitarius (NTS), including cardiopulmonary responses, gastrointestinal activity, and cortical arousal. The current study sought to determine whether a cellular substrate exists for direct modulation of vagal afferents and/or their neuronal target in the NTS by ligands of the MOR. Anterograde tracing of vagal afferents arising from the nodose ganglion was achieved with biotinylated dextran amine (BDA), and the MOR was detected by using antipeptide MOR antiserum. The medial subdivision of the intermediate NTS was examined by electron microscopy for the presence of peroxidase-labeled, BDA- containing vagal afferents and immunogold MOR labeling. MOR was present in both presynaptic axon terminals and at postsynaptic sites, primarily dendrites. In dendrites, MOR immunogold particles usually were located along extrasynaptic portions of the plasma membrane. Of 173 observed BDA-labeled vagal afferent axon terminals, 33% contained immunogold labeling for MOR within the axon terminal. Many of these BDA-labeled terminals formed asymmetric, excitatory, type synapses with dendrites, some of which contained MOR immunogold labeling. MORs were present in 19% of the dendrites contacted by BDA-labeled terminals but were present rarely in both the vagal afferent and its dendritic target. Together, these results suggest that MOR ligands modulate either the presynaptic release from or the postsynaptic responses to largely separate populations of vagal afferents in the intermediate NTS. These results provide a cellular substrate for direct actions of MOR ligands on primary visceral afferents and their second-order neuronal targets in NTS. (C) 2000 Wiley-Liss, Inc.
AB - Ligands of the μ-opiate receptor (MOR) are known to influence many functions that involve vagal afferent input to the nucleus tractus solitarius (NTS), including cardiopulmonary responses, gastrointestinal activity, and cortical arousal. The current study sought to determine whether a cellular substrate exists for direct modulation of vagal afferents and/or their neuronal target in the NTS by ligands of the MOR. Anterograde tracing of vagal afferents arising from the nodose ganglion was achieved with biotinylated dextran amine (BDA), and the MOR was detected by using antipeptide MOR antiserum. The medial subdivision of the intermediate NTS was examined by electron microscopy for the presence of peroxidase-labeled, BDA- containing vagal afferents and immunogold MOR labeling. MOR was present in both presynaptic axon terminals and at postsynaptic sites, primarily dendrites. In dendrites, MOR immunogold particles usually were located along extrasynaptic portions of the plasma membrane. Of 173 observed BDA-labeled vagal afferent axon terminals, 33% contained immunogold labeling for MOR within the axon terminal. Many of these BDA-labeled terminals formed asymmetric, excitatory, type synapses with dendrites, some of which contained MOR immunogold labeling. MORs were present in 19% of the dendrites contacted by BDA-labeled terminals but were present rarely in both the vagal afferent and its dendritic target. Together, these results suggest that MOR ligands modulate either the presynaptic release from or the postsynaptic responses to largely separate populations of vagal afferents in the intermediate NTS. These results provide a cellular substrate for direct actions of MOR ligands on primary visceral afferents and their second-order neuronal targets in NTS. (C) 2000 Wiley-Liss, Inc.
KW - Cardiovascular
KW - Electron microscopy
KW - Immunocytochemistry
KW - Nucleus of the solitary tract
KW - Opiate receptors
KW - Vagus
UR - http://www.scopus.com/inward/record.url?scp=0034717937&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034717937&partnerID=8YFLogxK
U2 - 10.1002/(SICI)1096-9861(20000626)422:2<181::AID-CNE3>3.0.CO;2-G
DO - 10.1002/(SICI)1096-9861(20000626)422:2<181::AID-CNE3>3.0.CO;2-G
M3 - Article
C2 - 10842226
AN - SCOPUS:0034717937
SN - 0021-9967
VL - 422
SP - 181
EP - 190
JO - Journal of Comparative Neurology
JF - Journal of Comparative Neurology
IS - 2
ER -