Effect of NaCl and sucrose tastants on protein composition of oral fluid analysed by SELDI-TOF-MS.

During eating, human saliva is secreted into the oral cavity by salivary glands. The relative contribution of different glands to total salivary flow rate depends, among other factors, on the tastants in the food. Few reports indicated that also the salivary protein composition depends on the tastant make-up of the food. We studied the influence of sodium-chloride- and sucrose solutions on the presence of proteins in the M(r) range 2-20kDa in whole saliva. Upon oral stimulation with a sodium chloride solution, a sucrose solution or water, we collected whole saliva from 14 volunteers after t=1 min, t=11 min and t=20 min. Saliva protein profiles were analysed by SELDI-TOF-MS. SELDI-TOF-MS intensities of m/z values representing different protein masses were compared between subjects, tastants and time conditions. For subsets of the 33 detected masses, significant effects were observed for all factors, with most masses involved in the Subjects effect: m/z(Subjects)>m/z(Time×Stimulus)>m/z(Stimulus)>m/z(Time). Most effects on saliva protein composition were observed at t=1 min, whilst almost no effects were observed at t=11 min and t=20 min. When considering the Stimulus×Time interaction, we identified four different stimulus-response patterns. Proteins identified in the present study, and attributed to specific glands or tissues in literature, were used to associate stimulus-response patterns with tissue provenances. Observed stimulus-response patterns were not uniquely associated to particular glands and tissues. Hence, there was no evidence of the involvement of particular tissues or glands in tastant-specific protein responses. In conclusion, oral stimulation with different tastants affects salivary protein composition in a protein- and stimuli dependent way, which seems not be associated with any specific tissues or glands of origin.