Stage-Specific Expression of Histone Deacetylases in the Mouse Mandibular Condylar Cartilage

ObjectiveThis study investigates the relationship between aging and histone deacetylases (HDACs) in mandibular condylar cartilage.MethodsMale C57BL/6 mice were divided into 4 age groups: postnatal day 21 (D21, postnatal development), 3 months (3M, young adulthood), 10 months (10M, middle aging), and 18 months (18M, late aging) to cover mandibular condylar cartilage aging stages. Mandibular condylar cartilage specimens were harvested and paraffin-embedded. Hematoxylin-eosin (H&E) and Safranin O-fast green staining were performed to assess morphological changes. Immunohistochemistry (IHC) was applied to map the spatiotemporal expression of the HDAC1-11 in condylar cartilage.ResultsHDAC1, HDAC6, HDAC7, and HDAC9 were undetected in the mandibular condylar cartilage. HDAC2, 3, 4, 8, and 10 were only expressed 21 days after birth, with HDAC2 showing the strongest expression. Notably, HDAC5 expression was higher at 18 months. HDAC11 had consistent intensity until 18 months when it decreased. Other HDACs peaked at 21 days and declined with age.ConclusionThis study established the spatiotemporal expression pattern of HDAC1-11 in the temporomandibular joint (TMJ) condyle during aging. It provides a foundation for further research on HDAC functions, offering insights into TMJ aging mechanisms.