Collateral branching innervation of rat molar teeth from trigeminal ganglion cells shown by double labelling with fluorescent retrograde tracers

Atkinson, Martin E.; Kenyon, C.

doi:10.1016/0006-8993(90)90409-5

Cited by 15 publications

(5 citation statements)

References 13 publications

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“…As expected, autoradiography showed that 125 I‐GDNF‐labelled neuronal cell bodies were concentrated in the caudal–lateral areas of the ophthalmic–maxillary region (Atkinson & Kenyon, 1990) of the trigeminal ganglion, close to the bifurcation where the mandibular division joins the ganglion. Autoradiography confirmed that 125 I‐GDNF labelling was highly distinct and concentrated over the neuronal cell bodies as shown in bright‐field (Fig.…”

Section: Resultssupporting

confidence: 73%

Glial cell line‐derived neurotrophic factor (GDNF) from adult rat tooth serves a distinct population of large‐sized trigeminal neurons

Kvinnsland

Luukko

Fristad

et al. 2004

Eur J of Neuroscience

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Glial cell line-derived neurotrophic factor (GDNF) mediates trophic effects for specific classes of sensory neurons. The adult tooth pulp is a well-defined target of sensory trigeminal innervation. Here we investigated potential roles of GDNF in the regulation of adult trigeminal neurons and the dental pulp nerve supply of the rat maxillary first molar. Western blot analysis and radioactive 35S-UTP in situ hybridization revealed that GDNF in the dental pulp and its mRNAs were localized with Ngf in the coronal pulp periphery, in particular in the highly innervated subodontoblast layer. Retrograde neuronal transport of iodinated GDNF and Fluorogold (FG) from the dental pulp indicated that GDNF was transported in about one third of all the trigeminal dental neurons. Of the GDNF-labelled neurons, nearly all (97%) were large-sized (> or =35 microm in diameter). Analysis of FG-labelled neurons revealed that, of the trigeminal neurons supporting the adult dental pulp, approximately 20% were small-sized, lacked isolectin B4 binding and did not transport GDNF. Of the large-sized dental trigeminal neurons approximately 40% transported GDNF. About 90% of the GDNF-accumulating neurons were negative for the high-temperature nociceptive marker VRL-1. Our results show that a subclass of large adult trigeminal neurons are potentially dependent on dental pulp-derived GDNF while small dental trigeminal neurons seems not to require GDNF. This suggests that GDNF may function as a neurotrophic factor for subsets of nerves in the tooth, which apparently mediate mechanosensitive stimuli. As in dorsal root ganglia both small- and large-sized neurons are known to be GDNF-dependent; these data provide molecular evidence that the sensory supply in the adult tooth differs, in some aspects, from the cutaneous sensory system.

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Section: Resultssupporting

confidence: 73%

Glial cell line‐derived neurotrophic factor (GDNF) from adult rat tooth serves a distinct population of large‐sized trigeminal neurons

Kvinnsland

Luukko

Fristad

et al. 2004

Eur J of Neuroscience

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“…Lisney (1978) has demonstrated increased conduction velocities of pulpal afferent nerve fibers central to the root apex. Anatomical studies in the rat are consistent with the notion that many trigeminal neurons innervating tooth pulps have relatively large cell bodies, medium-large myelinated axons, and multiple peripheral branches (Sugimot0 et al, 1988;Fried et al, 1989;Atkinson and Kenyon, 1990;Sugimoto and Takemura, 1993;Johans-son et al, 1992). Of particular interest is the finding by Johannson et al (1992) that about 80% of the 2,630 axons composing the inferior dental branch of the inferior alveolar nerve (including fibers to all three molars) are myelinated fibers, and over a third of these exceed 5 pm in diameter.…”

Section: Discussionsupporting

confidence: 57%

Quantitative study of the apical nerve fibers of adult and juvenile rat molars

1994

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The rat molar has become an important model for studies of interactions between nerves and the pulp-dentin complex, yet there is only limited quantitative information on the number and size distribution of axons entering the roots of this tooth. This study was undertaken to provide such a detailed characterization of the apical innervation of the rat molar. An additional objective was to compare the apical nerve composition of young, recently erupted rat molars with that of mature teeth in order to determine whether there is ongoing maturation of the innervation after the teeth have attained functional occlusion. A complete census was made of the nerve fibers entering the roots of both mature and recently erupted juvenile mandibular first molars in Sprague-Dawley rats. Each of the four roots of the first molars was processed for electron microscopy of thin sections near the apex. The majority of intradental nerve fibers entered the molar via the two larger (mesial and distal) roots. Within the apical root pulp, most, but not all, axons occurred within well-defined fascicles associated with blood vessels. Molars from adult animals (age 4 months) had a mean total of 232 (S.D. = 49, N = 7 teeth) myelinated fibers and 806 (S.D. = 143) unmyelinated axons entering the four roots. Fibers exceeding the A delta size range (circumference > or = 19 microns) accounted for only 4% of the myelinated axons at the apex. Molars from juvenile animals (age 4 weeks) had fewer myelinated fibers (mean 176, S.D. 18, N = 8), but more unmyelinated axons (mean 1,174, S.D. 160) than adults. The mean ratio of unmyelinated axons to myelinated axons was 6.6:1 for juveniles compared to 3.5:1 for adults. Juvenile teeth contained no myelinated fibers that exceeded 19 microns in circumference. These results indicate that the innervation of the rat molar resembles that of teeth of non-rodent mammals in that (1) innervation density is high, (2) there is a high ratio of unmyelinated axons, and (3) most of the myelinated fibers are of thin caliber. Furthermore, it appears that after the molar erupts, maturation of the nerve fiber composition continues with processes that include both a marked decrease in the number of unmyelinated axons and an increase in the number and size heterogeneity of myelinated fibers.

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“…The morphological structures of incisor (but not molar) are different from those of human teeth: wide apical foramen and continuous growing (Smith and Warshawsky, ). In addition, a single trigeminal ganglion cell considerably branches to the molar pulps (Atkinson and Kenyon, ). Although little information is available in terms of human S2, a functional magnetic resonance imaging (fMRI) study in human S1 demonstrates that the sensory representation of the tongue, upper incisor, and lips are located in the ventral‐to‐dorsal direction in the rostral postcentral gyrus, whereas these structures are overlapped in the rostral postcentral gyrus (Miyamoto et al, ).…”

Section: Discussionmentioning

confidence: 99%

Spatiotemporal profiles of dental pulp nociception in rat cerebral cortex: An optical imaging study

Nakamura

Kato

Shirakawa

et al. 2015

J of Comparative Neurology

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Somatosensation is topographically organized in the primary (S1) and secondary somatosensory cortex (S2), which contributes to identify the region receiving sensory inputs. However, it is still unknown how somatosensory inputs from the oral region, especially nociceptive inputs from the teeth, are processed in the somatosensory cortex. We performed in vivo optical imaging and identified the precise cortical regions responding to electrical stimulation of the maxillary and mandibular dental pulp in rats. Electrical stimulation of the mandibular incisor pulp evoked neural excitation in two areas: the most rostroventral part of S1, and the ventral part of S2 caudal to the middle cerebral artery. Maxillary incisor pulp stimulation initially evoked responses only in the ventral part of S2, although later maximum responses were also observed in S1 similar to mandibular incisor stimulation responses. The maxillary and mandibular molar pulp-responding regions were located in the most ventral S2, a part of which was histologically classified as the insular oral region (IOR). In terms of the initial responses, maxillary incisor and molar stimulation induced excitation in the S2/IOR rostral to the mandibular dental pulp-responding region. Contrary to the spatially segregated initial responses, the maximum excitatory areas responding to both incisors and molars in the mandible and maxilla overlapped in S1 and the S2/IOR. Multielectrode extracellular recording supported the characteristic localization of S2/IOR neurons responding to mandibular and maxillary molar pulp stimulation. The discrete and overlapped spatial profiles of initial and maximum responses, respectively, may characterize nociceptive information processing of dental pain in the cortex.

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Collateral branching innervation of rat molar teeth from trigeminal ganglion cells shown by double labelling with fluorescent retrograde tracers

Cited by 15 publications

References 13 publications

Glial cell line‐derived neurotrophic factor (GDNF) from adult rat tooth serves a distinct population of large‐sized trigeminal neurons

Glial cell line‐derived neurotrophic factor (GDNF) from adult rat tooth serves a distinct population of large‐sized trigeminal neurons

Quantitative study of the apical nerve fibers of adult and juvenile rat molars

Spatiotemporal profiles of dental pulp nociception in rat cerebral cortex: An optical imaging study

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