Postprandial PYY increase by resistant starch supplementation is independent of net portal appearance of short-chain fatty acids in pigs.

François Blachier,Anne Krog Ingerslev,Helle Nygaard Lærke,Mette Skou Hedemann,Karl-Heinz Herzig,Peter Kappel Theil,Knud Erik Bach Knudsen,Shivaprakash Jagalur Mutt,Kirstine Lykke Nielsen,Henry Jørgensen

doi:10.1371/journal.pone.0185927

Abstract

Increased dietary fiber (DF) fermentation and short-chain fatty acid (SCFA) production may stimulate peptide tyrosine-tyrosine (PYY) secretion. In this study, the effects of hindgut SCFA production on postprandial PYY plasma levels were assessed using different experimental diets in a porto-arterial catheterized pig model. The pigs were fed experimental diets varying in source and levels of DF for one week in 3×3 Latin square designs. The DF sources were whole-wheat grain, wheat aleurone, rye aleurone-rich flour, rye flakes, and resistant starch. Postprandial blood samples were collected from the catheters and analyzed for PYY levels and net portal appearance (NPA) of PYY was correlated to NPA of SCFA. No significant effects of diets on NPA of PYY were observed (P > 0.05), however, resistant starch supplementation increased postprandial NPA of PYY levels by 37 to 54% compared with rye-based and Western-style control diets (P = 0.19). This increase was caused by higher mesenteric artery and portal vein PYY plasma levels (P < 0.001) and was independent of SCFA absorption (P > 0.05). The PYY levels were higher in response to the second daily meal compared with the first daily meal (P < 0.001), but similar among diets (P > 0.10). In conclusion, the increased postprandial PYY responses in pigs fed with different levels and sources of DF are not caused by an increased SCFA absorption and suggest that other mechanisms such as neural reflexes and possibly an increased flow of digesta in the small intestine may be involved. The content of DF and SCFA production did not affect PYY levels.

Highlights

The gastrointestinal tract is a large endocrine organ releasing regulatory peptides in response to nutrient content [1]
The 5 h postprandial net portal appearance (NPA) of Peptide tyrosine-tyrosine (PYY) was 37–54% higher in response to RSD consumption compared to arabinoxylan-rich diet (AXD) and Western-style diet (WSD) intake, this difference was not statistically significant (PDiet = 0.19; Table 2)
The NPA of PYY peaked at 3.4–3.5 nmol/h 15 and 45 min after feeding in RSD and WSD-fed pigs, respectively, and at 3.2 nmol/h after 60 min in response to AXD intake (Fig 1)

Summary

Introduction

The gastrointestinal tract is a large endocrine organ releasing regulatory peptides in response to nutrient content [1]. Peptide tyrosine-tyrosine (PYY) is a hormone synthesized and released in response to food intake from the endocrine L-cells mainly in the distal part of the gastrointestinal tract, such as ileum and colon, and has several gut functions that contribute to postprandial satiety and decreased food intake [2]. These functions mediate, among others, ileal and colonic breaks to slow gastric emptying and promote digestive activities including regulation of insulin secretion and glucose homeostasis [2, 3]. Appetite regulation by SCFA is a more long-term regulation since nutrients need to reach the colon before DF fermentation and SCFA absorption can take place

Methods

Results

Conclusion