Influence of low protein diets on gene expression of digestive enzymes and hormone secretion in the gastrointestinal tract of young weaned piglets

Abstract

Abstract:To investigate dietary protein level effects on digestive mechanisms, weaned piglets were fed for 45 d with diets containing 20%, 17%, or 14% crude protein (CP) supplemented to meet requirements for essential amino acids. This article describes the influence of dietary protein on gastrointestinal hormones and expression of an array of digestive enzymes in the gastrointestinal tract and pancreas. Results indicated that there were no significant differences in expression of enzymes involved in carbohydrate digestion, except for maltase in the duodenum. In the jejunum, amylase expression in pigs fed 20% CP was much higher than that in pigs fed other diets (P<0.05) and maltase expression in those fed 17% CP was higher than that in other treatments (P<0.05). Although there were no remarkable differences in expression of aminopeptidase in the small intestine or carboxypeptidase in the pancreas (P>0.05), there was a trend towards higher expression of various proteases in pigs fed 17% CP. The duodenal expression of enteropeptidase in diets with 14% and 17% CP was significantly higher than that with 20% CP (P<0.05), but treatment differences did not existed in jejunum (P>0.05). The expression of GPR93 as a nutrient-responsive G protein-coupled receptor in 14% and 17% CP diets was significantly higher than that in 20% CP diet in the small intestine (P<0.05). The expressions of genes for pancreatic enzymes, lipase and elastase, were significantly higher in pigs fed diets with low CP, while similar trends occurred for carboxypeptidase, chymotrypsin and amylase. Conversely, the gastric expressions of pepsinogen A and progastricsin were lower with the 17% CP diet. Differences between treatments were found in the gastric antral contents of cholecystokinin and somatostatin: both increased in pigs fed 17% CP, accompanied by decreased content of motilin, which was also seen in plasma concentrations. These patterns were not reflected in duodenal contents. In general, 17% dietary CP was beneficial to the digestion of nutrient substance in the gastrointestinal tract.

Chronic feeding with protein-restricted diets affect ileal amino acid digestibility and the expression of nutrient-sensing, hormone secretion, gastrointestinal digestive enzyme, and nutrient transporter genes in young weaned pigs

“…There was no significant difference (P > 0.05) between the 17% and 20% CP diet groups (Figure 3). This result is consistent with previous results showing that a protein-restricted diet can affect the expression of chymotrypsin, aminopeptidase, amylase, and carboxypeptidase [50,60]; however, it is not consistent with previous results indicating that a proteinrestricted diet cannot affect the expression of pepsinogen and trypsinogen in pigs [4,50,60]. Therefore, in the present study, the 17% CP-restricted diet can increase the expression of genes encoding pepsinogen in the stomach but induced a trend toward higher mRNA levels of trypsinogen, chymotrypsin, CPA, and α-amylase than those in other groups, although there were no significant differences.…”

“…The nutrient sensing of CaSR is expressed in a number of tissues and is involved in calcium homeostasis and the regulation of a variety of cellular processes, including proliferation, differentiation, expression, ion channel function and hormone secretion, as well as fluid absorption [23]. CCK can stimulate gallbladder contraction and pancreatic growth [50], and L-phenylalanine L-tryptophan can stimulate the release of CCK from isolated CCK cells [51]. The diets AAs with higher affinity for CaSR are the aromatic AAs L-tryptophan, L-phenylalanine, L-tyrosine and L-histidine, where basic and branch-chain AAs are the least effective [52].…”

The effect of dietary high energy density and carbohydrate energy ratio on digestive enzymes activity, nutrient digestibility, amino acid utilization and intestinal morphology of weaned piglets

“…The intestinal sucrase and lactase activities had increased expression in piglets fed dietary high carbohydrate‐fed piglets, which could suggest increased carbohydrate metabolism (Tian et al, ). However, this does not seem to be overtly utilized for improved body weight gain.…”

Proteomic Quantification of Lysine Acetylation and their Essential Role in Response to Pig Fed Different Protein Levels

“…Animals and management were described in Tian et al (2016). In this experiment, we just select small intestinal samples of young pigs from two groups: pigs fed with 20% and 17% CP based on NRC (2012) recommendations (Supplemental Table 1).…”

“…Li et al (2017) also found that there were no differences on growth performance of piglets between 17% CP 20% CP group. Our previous research (Tian et al, 2016) showed that 17% CP diet was in favor of digestion and absorption of the nutrient in the intestine of piglets, and the mRNA abundance of many kinds proteases in piglets fed diets containing 17% CP tended to be higher than those of piglets fed diets containing 20% CP, which implied that reducing dietary CP content and supplementing with free AA meeting specific requirements improves the nitrogen utilization efficiency without affecting the growth performance of piglets. Proteomics profiles analysis result (Ma et al, 2015) showed that compared with 20% CP group, some signal pathways such as protein digestion and absorption pathway, PI3K-Akt signaling pathway, focal adhesion pathway and coagulation cascades pathway were up-regulated in 17% CP group.…”