Salivary Protein Profiles and Sensitivity to the Bitter Taste of Caffeine

Abstract

The interindividual variation in the sensitivity to bitterness is attributed in part to genetic polymorphism at the taste receptor level, but other factors, such as saliva composition, might be involved. In order to investigate this, 2 groups of subjects (hyposensitive, hypersensitive) were selected from 29 healthy male volunteers based on their detection thresholds for caffeine, and their salivary proteome composition was compared. Abundance of 26 of the 255 spots detected on saliva electrophoretic patterns was significantly different between hypo- and hypersensitive subjects. Saliva of hypersensitive subjects contained higher levels of amylase fragments, immunoglobulins, and serum albumin and/or serum albumin fragments. It also contained lower levels of cystatin SN, an inhibitor of protease. The results suggest that proteolysis occurring within the oral cavity is an important perireceptor factor associated to the sensitivity to the bitter taste of caffeine.

Changes in the salivary protein profile of morbidly obese women either previously subjected to bariatric surgery or not

“…Other salivary proteins potentially associated with taste sensitivity were observed to be differently expressed in obese individuals who had been subjected to bariatric surgery: one cystatin S spot was present at higher levels, whereas CA VI protein abundance was decreased. Meanwhile, cystatin S levels were observed to be increased in individuals with low bitter taste sensitivity, in both men [15] and women (Rodrigues et al, not published). Moreover, levels of salivary CA VI have been suggested as being positively associated with bitter taste perception [6], although there is some controversy regarding this issue [16,35].…”

“…Polymorphisms in the gene coding for this salivary protein appear to contribute towards explaining some of the variation in sensitivity to the bitter compound 6-n-propylthiouracil (PROP) [33]. Moreover, support for the role of saliva in taste perception has been provided by a number of studies reporting salivary proteins as being linked to sensitivity to PROP bitterness [6,27], to the bitter compound caffeine [15], and even to the perception of fat [32]. For example, cystatins and zinc-alpha-2 glycoprotein have been observed to be present in higher or lower amounts, respectively, in saliva from children presenting higher acceptance for bitter taste.…”

“…Whereas zinc-alpha-2 glycoprotein is a protein with different functions, among which is initiation of lipid mobilisation [18], cystatins are cysteine protease inhibitors. These last are involved in the control of proteolysis within the oral cavity, and, for that reason, it was hypothesised that they could affect the accessibility of tastant molecules to taste receptors, influencing taste sensitivity [15]. Another salivary protein potentially involved in ingestion is alpha-amylase.…”

Multi-omics profiling reveals that eating difficulties developed consecutively to artificial nutrition in the neonatal period are associated to specific saliva composition

“…Underexpression of GSTP in ED patients would therefore be associated to a lesser performance in chemosensory perception. In contrast, and looking now at salivary profiles rather than at single proteins, the saliva of adult subjects hypersensitive to the bitter taste of caffeine was characterized by higher abundance of IgA, lower levels of cystatin SN and a tendency for higher proteolytic activity [46], which corresponds to the findings in ED patients. In three-month-old infants rejecting bitterness (i.e.…”

Salivary proteome and glucose levels are related with sweet taste sensitivity in young adults

“…There is growing evidence that saliva composition is related to the way in which food is perceived in the oral cavity, namely with individuals' taste responsiveness [6,7]. However, most of the studies on the influence of saliva protein composition on oral perception have been made for astringency perception [e.g.…”