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Fine structural studies of cholecystokinin‐8‐like immunoreactive neurons and axon terminals in the nucleus of tractus solitarius of the rat
Author(s) -
Takagi Hiroshi,
Kubota Yoshiyuki,
Mori Shiro,
Tateishi Kayoko,
Hamaoka Toshiyuki,
Tohyama Masaya
Publication year - 1984
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/cne.902270307
Subject(s) - biology , cholecystokinin , neuroscience , axon , nucleus , neuropeptide , solitary nucleus , anatomy , receptor , biochemistry
Cholecystokinin (CCK)‐8‐like immunoreactive structures in the nucleus of tractus solitarius (NTS) were studied by using the peroxidase‐antiperoxidase (PAP) immunohistochemical method. Immunoreactivity was localized in cell bodies and nerve fibers. The perikarya were oval or fusiform (average length 13 μm) and were mostly located in the dorsal half of the medial subnucleus of the NTS at the level of the area postrema (AP). One to three straight immunoreactive dendritelike processes emerged from the perikarya. Neurons that had first been identified under light microscopy were also studied by electron microscopy. Each neuron had a moderate amount of cytoplasm and an oval or elongated nucleus that was eccentrically located in the soma. A few synaptic inputs were found on the CCK immunoreactive perikarya, while a moderate number were seen on both proximal and distal dendrites. These neurons received both asymmetrical and symmetrical synaptic inputs. The immunoreactive dendrites were most frequently in asymmetrical synaptic contact with nonreactive boutons (max. 2.7 μm in diameter) containing fairly densely packed, small round vesicles. CCK immunoreactive boutons located in the NTS at the level of the AP were analyzed using electron microscopy; these boutons formed asymmetrical synaptic contact with other neuronal elements. Their postsynaptic targets were immunoreactive and nonreactive perikarya and dendrites. These data suggest that CCK‐containing afferents might affect the neurotransmission of heterogenous types of solitary neurons.