# Spectroscopic Analysis of the Extracellular Matrix in Naked Mole-Rat Temporomandibular Joints

## TL;DR

This study explores the unique anti-aging properties of the temporomandibular joint in naked mole-rats, which may help understand and treat degenerative joint diseases.

## Contribution

The study identifies the molecular composition and spatial distribution of the extracellular matrix in the TMJ of naked mole-rats, linking it to their anti-aging properties.

## Key findings

- Naked mole-rats show no wear in their TMJ mandibular condyle or articular disk with age.
- The articular disk contains hyaluronic acid and collagen fibers that may relieve mechanical stress.
- Spatial distribution of the extracellular matrix is crucial for TMJ anti-aging properties.

## Abstract

Naked mole-rats are extremely long-living rodents with a maximum lifespan of 37 years, and their cellular aging and tissue aging are almost nonexistent. Therefore, in this study, we aim to analyze the extracellular matrix of the temporomandibular joint (TMJ) of naked mole-rats at the molecular level and explore the molecules involved in anti-aging and their localization. Micro-computed tomography (CT) scans revealed increased mineral density and wear of the mandibular condyle in aged mice. Conversely, CT scans did not reveal wear of the mandibular condyle in naked mole-rats, and histological analysis did not reveal wear of the articular disk. Using various spectroscopies and artificial intelligence (AI), we found that the articular disk of naked mole-rats is composed of a cartilage-like layer with hyaluronic acid and collagen fibers with varying orientations, which is thought to have relieved mechanical stress and have protected the mandibular condyle. These results suggest that not only the amount, but also the spatial distribution of the extracellular matrix is important for the anti-aging properties of the TMJ, and may contribute to elucidating the pathology of TMJ disorders and other degenerative conditions and developing therapeutic drugs.