Korean J Anat.  2002 Oct;35(5):439-452.

Quantitative and Ultrastructural Analysis of Afferent Terminals from Tooth Pulp in the Trigeminal Principal Sensory Nucleus

• Nam HK
• Choi KS
• Park KP
• Bae YC

Abstract

To analyze the synaptic characteristics of axon terminals originated from tooth pulp in the trigeminal principal sensory nucleus, and find morphological evidence that p-endings on these terminals use GABA as neurotransmitter, labeling of tooth pulp afferents with wheat -germ agglutinin conjugated horseradish peroxidase, postembedding immunocytochemistry and morphometric analysis were performed. The results obtained were as follows. The labeled boutons contained clear and round synaptic vesicles, and the mean number of synaptic contacts was 4.21 +/- 2.58. The postsynaptic profiles were usually middle or distal dendrites and dendritic spines rather than soma or proximal dendrites. The mean number of synaptic contacts with p -endings was 2.62 +/- 2.01. The volume of labeled bouton was 4.39 +/- 3.08 micro meter 3 and highly correlated (P<.01) with surface area (r = 0.96), total apposed surface area (r = 0.84), total active zone area (r = 0.84), mitochondrial volume (r = 0.95), the number of synaptic vesicles (r = 0.92), the number of synaptic profiles (r = 0.76) and the number of synaptic p -endings (r = 0.67). The p -endings contained pleomorphic synaptic vesicles. The volume of p -ending was 0.91 +/- 0.47 micro meter 3 and highly correlated (P<.01) with surface area (r = 0.94), total apposed surface area (r = 0.76), total active zone area (r = 0.62), mitochondrial volume (r = 0.70) and the number of synaptic vesicles (r = 0.94). P -endings were GABA immunoreactive. These results suggest that tooth pulp afferent terminals in trigeminal principal sensory nucleus may be related to complex processing of sensory information and presynaptic p -endings using GABA as neurotransmitter, are important in this sensory processing. The "size principle" of Pierce and Mendel (1993) is also applicable to tooth pulp afferent terminals and presynaptic p -endings.

Keyword

Trigeminal principal sensory nucleus; Afferent terminal; Tooth pulp; GABA

MeSH Terms

Carisoprodol
Dendrites
Dendritic Spines
gamma-Aminobutyric Acid
Horseradish Peroxidase
Immunohistochemistry
Mitochondrial Size
Neurotransmitter Agents
Presynaptic Terminals
Synaptic Vesicles
Tooth*
Triticum
Carisoprodol
Horseradish Peroxidase
Neurotransmitter Agents
gamma-Aminobutyric Acid