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Updated: Jun 5, 2025
Murine Model of Advanced Periodontitis Induced by Nylon Ligature in the Second Upper Molar
Published on: May 30, 2025
The cortical areas processing periodontal ligament nociception in mice
Risako Okuma1, Shutaro Kobayashi2, Satomi Kobayashi3
1Department of Orthodontics, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan; Department of Biology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan; Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan; Department of Oral Structural and Functional Biology, Nihon University Graduate School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
Researchers studied how the brain processes periodontal ligament (PDL) pain in mice. Findings suggest the insular cortex, not the primary somatosensory cortex, plays a key role in localizing dental pain.
Area of Science:
- Neuroscience
- Pain Research
- Somatosensation
Background:
- Toothaches are often difficult to pinpoint, despite periodontal ligament (PDL) pain being more localized.
- The cerebral cortex processes pain (nociception), potentially using somatotopic organization for localization, but the specific cortical areas for PDL pain are not well understood.
Purpose of the Study:
- To investigate the cortical processing and localization of periodontal ligament (PDL) pain.
- To identify the specific brain regions involved in sensing dental pain originating from the PDL.
Main Methods:
- Electrical stimulation of the molar PDL in anesthetized mice.
- In vivo optical imaging using voltage-sensitive dyes and flavin fluorescence.
- Immunohistochemistry to detect c-Fos protein expression as a marker for neural activity.
Main Results:
- Cortical responses to PDL stimulation were observed in the primary somatosensory cortex (S1) and a region extending from the insular cortex (IC) to the secondary somatosensory cortex (S2), termed the C-area.
- Responses in S1 were weak, while the C-area showed consistent activation, with similar initial locations regardless of the stimulated PDL.
- Bilateral neural activation was detected in the cingulate gyrus, auditory cortex, temporal association cortex, ectorhinal cortex, and IC, but not in S1 or S2.
Conclusions:
- The somatotopic organization of S1, S2, and IC does not fully explain PDL pain localization.
- The prominent contralateral responses in the insular cortex (IC) may be crucial for understanding the laterality of dental pain perception.
