Differences in Salivary Proteins as a Function of PROP Taster Status and Gender in Normal Weight and Obese Subjects

Abstract

Taste plays an important role in processes such as food choices, nutrition status and health. Salivary proteins contribute to taste sensitivity. Taste reduction has been associated with obesity. Gender influences the obesity predisposition and the genetic ability to perceive the bitterness of 6-n-propylthiouracil (PROP), oral marker for food preferences and consumption. We investigated variations in the profile of salivary proteome, analyzed by HPLC-ESI-MS, between sixty-one normal weight subjects (NW) and fifty-seven subjects with obesity (OB), based on gender and PROP sensitivity. Results showed variations of taste-related salivary proteins between NW and OB, which were differently associated with gender and PROP sensitivity. High levels of Ps-1, II-2 and IB-1 proteins belonging to basic proline rich proteins (bPRPs) and PRP-1 protein belonging to acid proline rich proteins (aPRPs) were found in OB males, who showed a lower body mass index (BMI) than OB females. High levels of Ps-1 protein and Cystatin SN (Cyst SN) were found in OB non-tasters, who had lower BMI than OB super-tasters. These new insights on the role of salivary proteins as a factor driving the specific weight gain of OB females and super-tasters, suggest the use of specific proteins as a strategic tool modifying taste responses related to eating behavior.

Keywords: gender; obesity; salivary proteins; taste sensitivity.

Figure 1

Mean values (± SEM) of body mass index (BMI) in normal weight (NW) (n = 61) and obesity (OB) (n = 57) according to gender (NW: male n = 21; female n = 40. OB: male n = 23; female n = 34) and to PROP taster status (NW: NT n = 22; MT n = 29; ST n = 10. OB: NT n = 14; MT n = 32; ST n = 11). a,b = significant difference within NW; a₁,b₁ = significant difference within OB (p ≤ 0.017; Fisher’s least significant difference (LSD) test.

Figure 2

Mean values (±SEM) of the extracted ion current (XIC) peak areas of the PRP-1, PRP-3, P-C, Hist 1, Hist 5-6, Ps-1, P-J, P-H, P-F, P-D, II-2, IB-8a, IB-1, P-Ko, Staths, Cyst S, Cyst S1, Cyst S2, Cyst SA and Cyst SN in unstimulated saliva of NW (n = 61) and OB (n = 57). Red color indicates a significant difference between NW and OB (p = 0.00079; Fisher’s test LSD).

Figure 3

Mean values (±SEM) of the XIC peak areas of the PRP-1, PRP-3, P-C, Hist 1, Hist 5-6, Ps-1, P-J, P-H, P-F, P-D, II-2, IB-8a, IB-1, P-Ko, Staths, Cyst S, Cyst S1, Cyst S2, Cyst SA and Cyst SN in unstimulated saliva of NW and OB according to gender. Males: NW n = 21, OB n = 23; females: NW n = 34, OB n = 40. Red color indicates a significant difference between NW and OB (p ≤ 0.013; Fisher’s test LSD). a₁, b₁ = significant difference between females and males with obesity; a, b = significant difference between NW females and males (p ≤ 0.013; Fisher’s test LSD).

Figure 4

Mean values (±SEM) of the XIC peak areas of the PRP-1, PRP-3, P-C, Hist 1, Hist 5-6, Ps-1, P-J, P-H, P-F, P-D, II-2, IB-8a, IB-1, P-Ko, Staths, Cyst S, Cyst S1, Cyst S2, Cyst SA and Cyst SN in unstimulated saliva of NW and OB according to PROP taster status. Non-tasters: NW n = 22, OB n = 14; medium tasters: NW n = 29, OB n = 32 and super-tasters NW n = 10, OB n = 11. Red color indicates a significant difference between NW and OB (p ≤ 0.032; Fisher’s test LSD). a₁, b₁ = significant difference between OB super-tasters and non-tasters; a, b = significant difference between NW super-tasters and non-tasters (p ≤ 0.013; Fisher’s test LSD).

Figure 5

Picture showing a summary of findings on differences between NW and OB in salivary protein levels as a function of gender and PROP taster status. The height of arrows indicates the quantified level of proteins.