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Synaptic organization of tooth pulp afferent terminals in the rat trigeminal sensory nuclei
Author(s) -
Bae Yong Chul,
Kim Jong Pil,
Choi Byung Ju,
Park Kuk Pil,
Choi Min Ki,
Moritani Masayuki,
Yoshida Atsushi,
Shigenaga Yoshio
Publication year - 2003
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.10741
Subject(s) - horseradish peroxidase , axon , postsynaptic potential , biology , sensory system , synaptic vesicle , wheat germ agglutinin , anatomy , nucleus , ultrastructure , trigeminal ganglion , axoplasmic transport , vesicle , free nerve ending , neuroscience , afferent , biochemistry , lectin , receptor , membrane , enzyme
Abstract Previous studies provide evidence that a structure/function correlation exists in the distinct zones of the trigeminal sensory nuclei. To evaluate this relationship, we examined the ultrastructure of afferent terminals from the tooth pulp in the rat trigeminal sensory nuclei: the principalis (Vp), the dorsomedial part of oral nucleus (Vdm), and the superficial layers of caudalis (Vc), by using transganglionic transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). A total of 93 labeled boutons were serially sectioned, in which some sections were incubated with γ‐aminobutyric acid (GABA) antiserum. Almost all labeled boutons formed asymmetric contact with nonprimary dendrites, in which more than half of labeled boutons in the Vc made synapses with their spines. The labeled boutons could be divided into two types on the basis of numbers of dense‐cored vesicles (DCVs) in a boutons: S‐type and DCV‐type. Almost all labeled boutons in the Vp and Vdm were S‐type, whereas two types were distributed evenly in the Vc. In contrast to DCV‐type boutons, the S‐type was frequently postsynaptic to unlabeled axon terminals containing a mixture of round, oval, and flattened vesicles (p‐endings) and forming symmetrical synapses. Most p‐endings examined were immunoreactive to GABA. The frequency of axoaxonic contacts was higher for labeled boutons in the Vp than in the Vdm and Vc. These results suggest that the three structures of trigeminal sensory nuclei serve distinct functions in nociceptive processing. J. Comp. Neurol. 463:13–24, 2003. © 2003 Wiley‐Liss, Inc.