James B. Rogers

Observations of Chemical Changes in the Palate of Guinea Pigs with Relation to Aging

V 00 similar dietary and environmental conditions. The exact purpose of this study was to detect chemical differences, if any, between sexes in the 1and 4year-old age groups, as well as differences between the two age groups of 1and 4-year-old animals. Twenty animals in equal numbers of both sexes were used. The experimental animals, sex, and age (ranging in days) were: Group 1 (female), 230 days; Group 1 (male), 265-346 days; Group 2 (female), 1,429-1,450 days; and Group 2 (male), 1,421-1,581 days. Group 1 constituted the 1-yearold animals, and Group 2 was composed of the 4year-old animals. After sacrificing the animals, specimens weighing approximately 25 mg. were removed surgically from the palate. All specimens were immersed in liquid nitrogen, pulverized, and homogenized in 1.6 M perchloric acid at 40 C. The initial sediment was subjected to 0.1 N sodium hydroxide at 370 C. for 12 hours and centrifuged. The supernatant solution was designated as the cold alkali-soluble fraction (non-collagenous). The remaining sediment was subjected to 0.1 N sodium hydroxide at 100° C. for 30 minutes and centrifuged. This supernatant solution was designated as the hot alkali-soluble fraction (collagenous). Both fractions were analyzed for nitrogen (K. J. OBRINK, Biochem. J., 59:134, 1955) and protein-bound hexoses (R. J. WINZLER, Methods of Biochemical Analysis, 2:279, 1955). Absorbence measurements were performed with the spectrophotometer.* Four ratios were constructed, using both nitrogen and hexoses as parameters, to note any differences with aging. The statistical results of this study are presented in the table. This study showed no significant differences (p > 0.02) in the palatal tissues with aging between sexes of the same age groups and in palatal tissues of 1-year-old and 4-year-old animals in non-collagenous to collagenous ratios. However, some changes with aging were observed in the hexose ratios between the 1-year-old and 4-year-old groups. These changes suggest a decrease in the carbohydrate content of the non-collagenous fraction of palatal tissue with aging and an increase of the carbohydrate content of the collagenous fraction of palatal tissue with aging. The reduction in hexose with age tends to agree with a previous report (D. E. FLIEDER, J. dent. Res., 41:112, 1962) on human oral mucosa. The noted similarity between Group 1 and Group 2 females of the cold soluble hexose to cold soluble nitrogen ratio is not explainable at this time.