Whey-administration Restores Age-dependent Atrophy and Dysfunction of Sublingual Glands

Objectives: Salivary glands in elderly individuals commonly exhibit morphological changes and dysfunction resulting in xerostomia. We investigated the effect of whey on age-dependent atrophy, gene expression alterations and dysfunction of salivary glands in animals and humans.
Methods: Young (12-week) and elderly (84-week) rats were provided water or whey from Jersey cattle ad libitum for 4 weeks. Histological analysis, DNA microarray analysis, qRT-PCR, and immunoblot analysis were performed in sublingual glands (SLGs). First-strand cDNA was synthesized from total RNA of SLGs. The resultant cDNA was hybridized to the GeneChip® Rat Gene 1.0 ST Array (Affymetrix). Data were analyzed by GeneSpring GX version 12 (Agilent). Expression change was taken as informative when FDR value was ≦0.1. Eight persons, aged 85-95, drank whey for 4 weeks. Salivary volumes and proteins were analyzed before and after whey-drinking.
Results: Whey-drinking restored age-dependent decline of salivary volume and protein concentration, and atrophy of SLGs. The transcripts of 42 genes were up-regulated and 7 genes were down-regulated by more than 1.5-fold change with FDR≦0.1 after whey-drinking. Venn diagram analysis of microarray revealed that expressions of 13 genes, including Tcfap2b and Abpa, were induced significantly by whey-drinking. Furthermore, salivary protein levels and volumes from humans were increased by whey-drinking.
Conclusions: The expression levels of genes associated with salivary proteins and tissue repair were significantly increased in Jersey whey-drinking, while those associated with lipid metabolism were decreased. Whey-administration can prevent and/or restore age-dependent atrophy and functional decline of SLGs in relation to gene expression.