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Effect of Maillard reacted peptides on human salt taste and the amiloride-insensitive salt taste receptor (TRPV1t).

Katsumata T, Nakakuki H, Tokunaga C, Fujii N, Egi M, Phan TH, Mummalaneni S, DeSimone JA, Lyall V - Chem. Senses (2008)

Bottom Line: The concentrations at which MRPs enhanced human salt taste were significantly lower than the concentrations of MRPs that produced increase in the NaCl CT response.Elevated temperature, resiniferatoxin, capsaicin, and ethanol produced additive effects on the NaCl CT responses in the presence of MRPs.The results suggest that MRPs modulate human salt taste and the NaCl + Bz CT responses by interacting with TRPV1t.

View Article: PubMed Central - PubMed

Affiliation: Food Creation Center, Kyowa Hakko Food Specialties Co., Ltd, Ibaraki, Japan.

ABSTRACT
Maillard reacted peptides (MRPs) were synthesized by conjugating a peptide fraction (1000-5000 Da) purified from soy protein hydrolyzate with galacturonic acid, glucosamine, xylose, fructose, or glucose. The effect of MRPs was investigated on human salt taste and on the chorda tympani (CT) taste nerve responses to NaCl in Sprague-Dawley rats, wild-type, and transient receptor potential vanilloid 1 (TRPV1) knockout mice. MRPs produced a biphasic effect on human salt taste perception and on the CT responses in rats and wild-type mice in the presence of NaCl + benzamil (Bz, a blocker of epithelial Na+ channels), enhancing the NaCl response at low concentrations and suppressing it at high concentrations. The effectiveness of MRPs as salt taste enhancers varied with the conjugated sugar moiety: galacturonic acid = glucosamine > xylose > fructose > glucose. The concentrations at which MRPs enhanced human salt taste were significantly lower than the concentrations of MRPs that produced increase in the NaCl CT response. Elevated temperature, resiniferatoxin, capsaicin, and ethanol produced additive effects on the NaCl CT responses in the presence of MRPs. Elevated temperature and ethanol also enhanced human salt taste perception. N-(3-methoxyphenyl)-4-chlorocinnamid (a blocker of TRPV1t) inhibited the Bz-insensitive NaCl CT responses in the absence and presence of MRPs. TRPV1 knockout mice demonstrated no Bz-insensitive NaCl CT response in the absence or presence of MRPs. The results suggest that MRPs modulate human salt taste and the NaCl + Bz CT responses by interacting with TRPV1t.

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Effect of GalA-MRP on the NaCl CT responses in the presence of SB. CT responses were monitored while the rat tongue was stimulated with R, N, N + Bz, N + Bz + SB and N + Bz + SB + 0.25% GalA-MRP (Table 1) using Stimulus Series 2 protocol (see Materials and methods). The mean ± standard error of the mean (SEM) values of the normalized phasic (A) and tonic (B) NaCl CT responses from 3 animals are shown. The hatched bars show the CT response when Bz + SB were present in both rinse and the salt stimulus. In (A), the P values for phasic response for N + Bz, N + Bz + SB, N + Bz + SB + GalA-MRP with respect to R were 0.0004, 0.0042, and 0.0011, respectively. The P value for N + Bz + SB + GalA-MRP with respect to N + Bz + SB was 0.035. In (B), the values of the tonic response for N + Bz + SB, N + Bz + SB + GalA-MRP were not different from zero (P > 0.05). (C) Shows the mean ± SEM values of the normalized tonic NaCl CT response in 3 animals as a function of GalA-MRP concentration in the presence of N + SB (Table 1).
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fig2: Effect of GalA-MRP on the NaCl CT responses in the presence of SB. CT responses were monitored while the rat tongue was stimulated with R, N, N + Bz, N + Bz + SB and N + Bz + SB + 0.25% GalA-MRP (Table 1) using Stimulus Series 2 protocol (see Materials and methods). The mean ± standard error of the mean (SEM) values of the normalized phasic (A) and tonic (B) NaCl CT responses from 3 animals are shown. The hatched bars show the CT response when Bz + SB were present in both rinse and the salt stimulus. In (A), the P values for phasic response for N + Bz, N + Bz + SB, N + Bz + SB + GalA-MRP with respect to R were 0.0004, 0.0042, and 0.0011, respectively. The P value for N + Bz + SB + GalA-MRP with respect to N + Bz + SB was 0.035. In (B), the values of the tonic response for N + Bz + SB, N + Bz + SB + GalA-MRP were not different from zero (P > 0.05). (C) Shows the mean ± SEM values of the normalized tonic NaCl CT response in 3 animals as a function of GalA-MRP concentration in the presence of N + SB (Table 1).

Mentions: Rat NaCl CT responses were monitored under control condition and in the presence of Bz alone, SB alone, or Bz + SB relative to the rinse (R; Table 1). Bz decreased the mean normalized phasic NaCl CT response (Figure 2A) by 46.8% (N + Bz). In the presence of Bz + SB, the mean normalized phasic CT response (N + Bz + SB) was further decreased to 60.4% of control, a value that was slightly bigger than the rinse artifact (R; P < 0.002). Bz decreased the mean normalized tonic NaCl CT response by 68.6% (N + Bz); and in the presence of Bz + SB, it further decreased to 98.0% of control (N + Bz + SB), a value that was not statistically different from baseline (Figure 2B; P > 0.05 with respect to zero). These results show that in the presence of Bz, SB blocks both phasic and tonic NaCl CT responses.


Effect of Maillard reacted peptides on human salt taste and the amiloride-insensitive salt taste receptor (TRPV1t).

Katsumata T, Nakakuki H, Tokunaga C, Fujii N, Egi M, Phan TH, Mummalaneni S, DeSimone JA, Lyall V - Chem. Senses (2008)

Effect of GalA-MRP on the NaCl CT responses in the presence of SB. CT responses were monitored while the rat tongue was stimulated with R, N, N + Bz, N + Bz + SB and N + Bz + SB + 0.25% GalA-MRP (Table 1) using Stimulus Series 2 protocol (see Materials and methods). The mean ± standard error of the mean (SEM) values of the normalized phasic (A) and tonic (B) NaCl CT responses from 3 animals are shown. The hatched bars show the CT response when Bz + SB were present in both rinse and the salt stimulus. In (A), the P values for phasic response for N + Bz, N + Bz + SB, N + Bz + SB + GalA-MRP with respect to R were 0.0004, 0.0042, and 0.0011, respectively. The P value for N + Bz + SB + GalA-MRP with respect to N + Bz + SB was 0.035. In (B), the values of the tonic response for N + Bz + SB, N + Bz + SB + GalA-MRP were not different from zero (P > 0.05). (C) Shows the mean ± SEM values of the normalized tonic NaCl CT response in 3 animals as a function of GalA-MRP concentration in the presence of N + SB (Table 1).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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fig2: Effect of GalA-MRP on the NaCl CT responses in the presence of SB. CT responses were monitored while the rat tongue was stimulated with R, N, N + Bz, N + Bz + SB and N + Bz + SB + 0.25% GalA-MRP (Table 1) using Stimulus Series 2 protocol (see Materials and methods). The mean ± standard error of the mean (SEM) values of the normalized phasic (A) and tonic (B) NaCl CT responses from 3 animals are shown. The hatched bars show the CT response when Bz + SB were present in both rinse and the salt stimulus. In (A), the P values for phasic response for N + Bz, N + Bz + SB, N + Bz + SB + GalA-MRP with respect to R were 0.0004, 0.0042, and 0.0011, respectively. The P value for N + Bz + SB + GalA-MRP with respect to N + Bz + SB was 0.035. In (B), the values of the tonic response for N + Bz + SB, N + Bz + SB + GalA-MRP were not different from zero (P > 0.05). (C) Shows the mean ± SEM values of the normalized tonic NaCl CT response in 3 animals as a function of GalA-MRP concentration in the presence of N + SB (Table 1).
Mentions: Rat NaCl CT responses were monitored under control condition and in the presence of Bz alone, SB alone, or Bz + SB relative to the rinse (R; Table 1). Bz decreased the mean normalized phasic NaCl CT response (Figure 2A) by 46.8% (N + Bz). In the presence of Bz + SB, the mean normalized phasic CT response (N + Bz + SB) was further decreased to 60.4% of control, a value that was slightly bigger than the rinse artifact (R; P < 0.002). Bz decreased the mean normalized tonic NaCl CT response by 68.6% (N + Bz); and in the presence of Bz + SB, it further decreased to 98.0% of control (N + Bz + SB), a value that was not statistically different from baseline (Figure 2B; P > 0.05 with respect to zero). These results show that in the presence of Bz, SB blocks both phasic and tonic NaCl CT responses.

Bottom Line: The concentrations at which MRPs enhanced human salt taste were significantly lower than the concentrations of MRPs that produced increase in the NaCl CT response.Elevated temperature, resiniferatoxin, capsaicin, and ethanol produced additive effects on the NaCl CT responses in the presence of MRPs.The results suggest that MRPs modulate human salt taste and the NaCl + Bz CT responses by interacting with TRPV1t.

View Article: PubMed Central - PubMed

Affiliation: Food Creation Center, Kyowa Hakko Food Specialties Co., Ltd, Ibaraki, Japan.

ABSTRACT
Maillard reacted peptides (MRPs) were synthesized by conjugating a peptide fraction (1000-5000 Da) purified from soy protein hydrolyzate with galacturonic acid, glucosamine, xylose, fructose, or glucose. The effect of MRPs was investigated on human salt taste and on the chorda tympani (CT) taste nerve responses to NaCl in Sprague-Dawley rats, wild-type, and transient receptor potential vanilloid 1 (TRPV1) knockout mice. MRPs produced a biphasic effect on human salt taste perception and on the CT responses in rats and wild-type mice in the presence of NaCl + benzamil (Bz, a blocker of epithelial Na+ channels), enhancing the NaCl response at low concentrations and suppressing it at high concentrations. The effectiveness of MRPs as salt taste enhancers varied with the conjugated sugar moiety: galacturonic acid = glucosamine > xylose > fructose > glucose. The concentrations at which MRPs enhanced human salt taste were significantly lower than the concentrations of MRPs that produced increase in the NaCl CT response. Elevated temperature, resiniferatoxin, capsaicin, and ethanol produced additive effects on the NaCl CT responses in the presence of MRPs. Elevated temperature and ethanol also enhanced human salt taste perception. N-(3-methoxyphenyl)-4-chlorocinnamid (a blocker of TRPV1t) inhibited the Bz-insensitive NaCl CT responses in the absence and presence of MRPs. TRPV1 knockout mice demonstrated no Bz-insensitive NaCl CT response in the absence or presence of MRPs. The results suggest that MRPs modulate human salt taste and the NaCl + Bz CT responses by interacting with TRPV1t.

Show MeSH
Related in: MedlinePlus