Metabolome analysis of masseter muscle in senescence-accelerated mouse-prone 8 (SAMP8)

Frailty is a vulnerable state that marks the transition to long-term care for the elders. Recently, the relationship between frailty and oral function has been attracting attention. By clarifying the specific metabolic changes in the masseter muscle, we aimed to contribute to maintenance of masticatory function. The purpose of this study is to clarify the changes in masseter muscle of senescence-accelerated mouse-prone 8 (SAMP8) mice metabolites and metabolic pathways due to aging. Capillary electrophoresis-mass spectrometry metabolome analysis was performed on the masseter muscle of 12-week-old, 40-week-old, and 55-week-old mice. Expression analysis was performed by reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence for the metabolome pathways extracted by metabolome analysis that considered to be related to aging. Nineteen metabolites had a significant difference in absolute quantitative values and were considered to affect the first principal component by factor loading. The extracted metabolic pathways were glycolysis, polyamine metabolome pathway, and purine metabolome pathway. RT-PCR was performed on the extracted metabolome pathways. Expression of the spermidine synthase and hypoxanthine phosphoribosyl transferase genes with significant differences by RT-PCR was confirmed by immunofluorescence. The metabolic pathways considered to be related to aging in masseter muscle were glycolysis, polyamine metabolic pathway, and purine metabolic pathway.