Characterization of odor markers associated with aging in old ICR mice.

To identify and characterize the novel odor markers associated with aging in mice, alterations in the concentration of odorants in the urine, expression of metabolic enzymes, the histopathological structure of the sweat glands, and the expression of regulatory factors in sweat secretion were analyzed in ICR mice of four different ages (2, 6, 8 and 10-month-old). The concentrations of 15 odorants including ethylenimine and trimethylamine (TMA), and total volatile organic compounds (VOCs) were significantly higher in the urine of 8- and 10-month-old ICR mice. Among them, TMA was selected as an important odor biomarker associated with aging based on the aging-related upregulation and its odor characteristics. Also, the increase in TMA concentrations was reflected in the transcription levels of the gene encoding TMA monooxygenase in the livers and the feet as well as an age-dependent increase in the lumen area and secretory coiled portion of the sweat glands of mice. These results provide novel scientific evidence that the age-dependent changes in the volatiles in the urine are indicative of aging-related odors in ICR mice. Specifically, the study shows that TMA has potential as a novel diagnostic odor biomarker associated with aging in ICR mice to establish experimental animal platform for analyzing the efficacy and action mechanism of deodorants.