Induction of Salivary Proteins Modifies Measures of Both Orosensory and Postingestive Feedback during Exposure to a Tannic Acid Diet

Abstract

There are hundreds of proteins in saliva. Although it has long been hypothesized that these proteins modulate taste by interacting with taste receptors or taste stimuli, the functional impact of these proteins on feeding remains relatively unexplored. We have developed a new technique for saliva collection that does not interfere with daily behavioral testing and allows us to explore the relationship between feeding behavior and salivary protein expression. First, we monitored the alterations in salivary protein expression while simultaneously monitoring the animals' feeding behavior and meal patterns on a custom control diet or on the same diet mixed with 3% tannic acid. We demonstrated that six protein bands increased in density with dietary tannic acid exposure. Several of these bands were significantly correlated with behaviors thought to represent both orosensory and postingestive signaling. In a follow-up experiment, unconditioned licking to 0.01–3% tannic acid solutions was measured during a brief-access taste test before and after exposure to the tannic acid diet. In this experiment, rats with salivary proteins upregulated found the tannin solution less aversive (i.e., licked more) than those in the control condition. These data suggest a role for salivary proteins in mediating changes in both orosensory and postingestive feedback.

A subset of broadly responsive Type III taste cells contribute to the detection of bitter, sweet and umami stimuli

“…Mice were adapted to the test chamber and trained to drink from the sipper tubes for 5 consecutive days as previously described (Martin, Nikonova et al, 2017, Torregrossa, Nikonova et al, 2014). During training, mice were 20-h water deprived.…”

Proteomics of the Salivary Fluid

“…Several methods can be applied for collection of saliva: (1) passive droll is the simplest approach but the saliva often has a high concentration of mucins and high viscosity and (2) the Salivette ® Systems [46][47][48], the Greiner Bio-One Saliva Kit, and the recently introduced RNA-Prosal [49]. All three sample collection systems have been used in the field, and publications describing their efficacy are available [50][51][52].…”

Oral sensations and secretions

“…Additionally, composition of saliva can cause instability in emulsions (mixtures of oil and water) leading to different sensory perceptions of those emulsions among individuals (Dresselhuis, de Hoog, Stuart, Vingerhoeds, & van Aken, 2008;Vingerhoeds, Blijdenstein, Zoet, & van Aken, 2005). Furthermore, work in rats even indicates that exposure to bitterness and astringency can change saliva in ways that subsequently alter the acceptability or intensity of those bitter/astringent compounds (Martin et al, 2018;Torregrossa et al, 2014). In future years more research will hopefully confirm or clarify these linkages between diet, flavor, and saliva, and perhaps yield ways in which we could monitor or alter saliva to improve healthy dietary behaviors.…”