title: Age Differences of Salivary Alpha-Amylase Levels of Basal and Acute Responses to Citric Acid Stimulation Between Chinese Children and Adults.
abstract: It remains unclear how salivary alpha-amylase (sAA) levels respond to mechanical stimuli in different age groups. In addition, the role played by the sAA gene (AMY1) copy number and protein expression (glycosylated and non-glycosylated) in sAA activity has also been rarely reported. In this study, we analyzed saliva samples collected before and after citric acid stimulation from 47 child and 47 adult Chinese subjects. We observed that adults had higher sAA activity and sAA glycosylated levels (glycosylated sAA amount/total sAA amount) in basal and stimulated saliva when compared with children, while no differences were found in total or glycosylated sAA amount between them. Interestingly, adults showed attenuated sAA activity levels increase over those of children after stimulation. Correlation analysis showed that total sAA amount, glycosylated sAA amount, and AMY1 copy number × total sAA amount were all positively correlated with sAA activity before and after stimulation in both groups. Interestingly, correlation r between sAA levels (glycosylated sAA amount and total sAA amount) and sAA activity decreased after stimulation in children, while adults showed an increase in correlation r. In addition, the correlation r between AMY1 copy number × total sAA amount and sAA activity was higher than that between AMY1 copy number, total sAA amount, and sAA activity, respectively. Taken together, our results suggest that total sAA amount, glycosylated sAA amount, and the positive interaction between AMY1 copy number and total sAA amount are crucial in influencing sAA activity before and after stimulation in children and adults.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Courses, Guangdong Pharmaceutical University Guangzhou, China.
authors.forename: Ze-Min
authors.initials: ZM
authors.lastname: Yang
authors.affiliation: Pi-Wei Institute, Guangzhou University of Chinese Medicine Guangzhou, China.
authors.forename: Long-Hui
authors.initials: LH
authors.lastname: Chen
authors.affiliation: Pediatrics of Traditional Chinese Medicine, Haizhu Maternal and Child Health Hospital Guangzhou, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Courses, Guangdong Pharmaceutical University Guangzhou, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Lin
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Courses, Guangdong Pharmaceutical University Guangzhou, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Pi-Wei Institute, Guangzhou University of Chinese Medicine Guangzhou, China.
authors.forename: Wei-Wen
authors.initials: WW
authors.lastname: Chen
authors.affiliation: Clinical Laboratory, The First Affiliated Hospital of Guangdong Pharmaceutical University Guangzhou, China.
authors.forename: Xiao-Rong
authors.initials: XR
authors.lastname: Yang
keywords: AMY1 copy number; adults; children; citric acid stimulation; glycosylation; protein expression; salivary alpha-amylase