Acute selective bioactivity of grape seed proanthocyanidins on enteroendocrine secretions in the gastrointestinal tract

Figures & data

Table 1. Increase in enterohormone concentration in the medium due to grape seed proanthocyanidin extract (GSPE) or gallic acid (GA) treatment in explants from different intestinal segments.

	Duodenum		Ileum
	GIP	CCK	GLP-1	PYY
GSPE (0.2 mg/ml)	3.32 ± 2.0*	−0.46 ± 0.0*	2.37 ± 0.6*	1.10 ± 0.3*
GA (31 μg/ml)	0.16 ± 0.2	−0.53 ± 0.1*	2.17 ± 1.2	–

Results are expressed as relative units vs control.

GIP, glucose-dependent insulinotropic peptide; CCK, cholecystokinin; GLP-1, glucagon-like peptide-1; PYY, peptide tyrosine tyrosine.

*Statistically significant differences at p ≤ 0.05 (Student’s t test).

Table 2. Glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY) secretion to the medium in colon explants after 1 h treatment with digested grape seed proanthocyanidin extract (GSPE).

	GLP-1	PYY
Control	1.00 ± 0.0	1.00 ± 0.0
Digested GSPE	1.34 ± 0.1*	1.32 ± 0.2†

Results are expressed as relative units vs control.

*p < 0.05 vs control; †p < 0.05 vs control (Student’s t test).

Figure 1. Effects of flavonols on enterohormone secretion and cellular membrane potential in secretin tumour cell line (STC-1) cells. STC-1 cells were treated for 2 h with 200 µM and 1 µM of different flavanols found in grape seed proanthocyanidin extract (GSPE). (a) glucagon-like peptide-1 (GLP-1) and (b) cholecystokinin-1 (CCK1) levels were measured in the culture medium. (c) Effects of flavanols on cellular membrane potential after epicatechin stimulation expressed as % F/F₀ and relative Δ(F/F₀) (normalized to the control cells) (a), where F is fluorescence at 195 s and F₀ is basal fluorescence at 180 s. The data are displayed as the mean ± SEM. *Statistically significant differences versus controls at p < 0.05; ^a,b,c,dstatistically significant differences at p < 0.05. ECg, (–)-epicatechin gallate; B2g, procyanidin dimer B2–gallate; B2, procyanidin dimer B2.

Table 3. Gene expression of the enterohormones from fasted and fed rats.

		Condition
		Fasted	Fed
GLP-1 colon	Control	1.06 ± 0.2	1.12 ± 0.2
	1 g GSPE/kg bw	0.53 ± 0.0*	1.07 ± 0.2
PYY colon	Control	1.05 ± 0.2	1.13 ± 0.2
	1 g GSPE/kg bw	0.40 ± 0.0*	1.32 ± 0.3
CCK colon	Control	1.01 ± 0.1	1.81 ± 0.8
	1 g GSPE/kg bw	0.36 ± 0.2*	1.09 ± 0.3
CgA colon	Control	1.11 ± 0.3	1.00 ± 0.0
	1 g GSPE/kg bw	2.76 ± 0.5*	2,94 ± 0.5*

Results are expressed as relative units vs control.

GLP-1, glucagon-like peptide-1; PYY, peptide tyrosine tyrosine; CCK, cholecystokinin; CgA, chromogranin A; GSPE, grape seed proanthocyanidin extract; bw, body weight.

*Statistically significant differences at p ≤ 0.05 (Student’s t test).

Figure 2. Effects of grape seed proanthocyanidin extract (GSPE) on portal glucose. In the fasted group, overnight-fasted animals were treated with GSPE for 1 h. In the fed group, 4 h-fasted animals were treated with GSPE for 1 h, and then administered a food load. Portal glucose levels were measured 20 min after this food load. *Statistically significant differences versus respective controls at p < 0.05.

Table 4. Glucose-6-phosphatase (G6Pase) intestinal activity from fasted and fed rats.

		Condition
		Fasted	Fed
G6Pase duodenum	Control	1.00 ± 0.2	1.00 ± 0.2
	1 g GSPE/kg bw	0.31 ± 0.0*	0.24 ± 0.0*
G6Pase jejunum	Control	1.00 ± 0.2	1.00 ± 0.2
	1 g GSPE/kg bw	0.45 ± 0.1*	0.21 ± 0.0*

Results are expressed as relative units vs control.

GSPE, grape seed proanthocyanidin extract; bw, body weight.

*Statistically significant differences at p ≤ 0.05 (Student’s t test).