Nutrient-intake-level-dependent regulation of intestinal development in newborn intrauterine growth-restricted piglets via glucagon-like peptide-2

Lactobacillus amylovorus Promotes Lactose Utilization in Small Intestine and Enhances Intestinal Barrier Function in Intrauterine Growth Restricted Piglets

BACKGROUND

Intrauterine growth restriction (IUGR) resulted in high mortality and many physiological defects of piglets, causing huge economic loss in the swine industry. Lactobacillus amylovorus (L. amylovorus) was identified as one of the main differential bacteria between IUGR and normal piglets. However, the effects of L. amylovorus on the growth performance and intestinal health in IUGR piglets remained unclear.

OBJECTIVES

This study aimed to investigate the promoting effects of L. amylovorus Mafic1501, a new strain isolated from normal piglets, on the growth performance and intestinal barrier functions in IUGR piglets.

METHODS

Newborn mice or piglets were assigned into 3 groups: CON (normal birth weight, control), IUGR (low birth weight), and IUGR+L. amy (low birth weight), administered with sterile saline or L. amylovorus Mafic1501, respectively. Growth performance, lactose content in the digesta, intestinal lactose transporter, and barrier function parameters were profiled. IPEC-J2 cells were cultured to verify the effects of L. amylovorus Mafic1501 on lactose utilization and intestinal barrier functions.

RESULTS

L. amylovorus Mafic1501 elevated body weight and average daily gain of IUGR mice and piglets (P < 0.05). The lactose content in the ileum was decreased, whereas gene expression of glucose transporter 2 (GLUT2) was increased by L. amylovorus Mafic1501 in IUGR piglets during suckling period (P < 0.05). Besides, L. amylovorus Mafic1501 promoted intestinal barrier functions by increasing the villus height and relative gene expressions of tight junctions (P < 0.05). L. amylovorus Mafic1501 and its culture supernatant decreased the lactose level in the medium and upregulated gene expressions of transporter GLUT2 and tight junction protein Claudin-1 of IPEC-J2 cells (P < 0.05).

CONCLUSION

L. amylovorus Mafic1501 improved the growth performance of IUGR piglets by promoting the lactose utilization in small intestine and enhancing intestinal barrier functions. Our results provided the new evidence of L. amylovorus Mafic1501 for its application in the swine industry.

Circadian rhythms of the mRNA abundances of clock genes and glucose transporters in the jejunum of weanling-growing pigs

Background

Whether abundance of glucose transporter mRNAs in the small intestine of pigs shows circadian rhythms and its regulation by clock genes was still unknown.

Objectives

We examined whether the abundance of glucose transporters and clock genes mRNAs in the small intestine of pigs shows circadian rhythms.

Methods

Twenty barrows (4 weeks old) were reared under 12 h bright and 12 h dark lighting conditions. During the 3‐week feeding trial, pigs were allowed free access to feed. The abundances of the mRNA of glucose transporters (SGLT1 and GLUT2) and clock genes (Bmal1, Per1, Per2, and Cry2) in the intestine were measured at four time points (ZT2, ZT8, ZT14, and ZT20).

Results

In the jejunum, the abundance of SGLT1 mRNA was higher at ZT20 and ZT2 and lower at ZT8 and ZT14 (p < 0.05). The abundances of GLUT2 mRNA in the jejunum at ZTs 20 and 2 were tended to be higher than those at ZTs 8 and 14 (p = 0.05). In the jejunum, the abundance of Bmal1 mRNA was higher at ZT8 and ZT14 than at ZT20 and ZT2 (p < 0.05). Further, the abundance of Per1 mRNA at ZT2 was higher than those at the other sampling times (p < 0.05). The abundance of Per1 mRNA at ZT8 was higher than that at ZT14 (p < 0.05), while that of Per2 mRNA was higher at ZT2 than those at ZTs 20 and 14 (p < 0.05).

Conclusion

We speculate that these circadian rhythms of abundances of glucose transporter mRNAs are regulated by the clock genes expressed in the jejunum.

Catch-up growth in intrauterine growth-restricted piglets associated with the restore of pancreatic and intestinal functions via porcine glucagon-like peptide-2 microspheres

Intrauterine growth restriction (IUGR) results in abnormal morphology and gastrointestinal function, such as reduced villi height and crypt depth, thinner mucosa and muscle layers, and reduced brush border enzyme activities, delayed gastric emptying, increased stress response. As a gastrointestinal growth factor, the manner by which the porcine glucagon-like peptide-2 (pGLP-2) microsphere administration restored the gastrointestinal function and growth performance of IUGR piglets was investigated. Fourteen newborn Duroc × (Yorkshire × Landrace) IUGR piglets (0.92 ± 0.113 kg) were assigned into the IUGR (negative control group) and pGLP-2 microsphere groups. The piglets in group pGLP-2 were intraperitoneally administered with 100 mg pGLP-2 microspheres on day 1 after birth. From days 15 to 26 of trial, the body weight of the pGLP-2 group was significantly higher than that of the control. IUGR piglets of group pGLP-2 showed a significantly increased pancreas weight, serum insulin content and activity of lipase and amylase. Injection of pGLP-2 microspheres restored the intestinal absorptive capacity by significantly increasing the mRNA expression of the sodium-glucose cotransporter 1 in the jejunum and the peptide transporter 1 in the jejunum. It also restored the redox balance by increasing the catalase mRNA expression and decreasing the heat shock protein 70 mRNA expression. In addition, this improvement was associated with the significant increase in gut diameter, length and weight. Therefore, it was concluded that the injection of pGLP-2 microspheres was a suitable therapeutic strategy for compensatory growth in low birth weight IUGR piglets.

A high nutrient dense diet alters hypothalamic gene expressions to influence energy intake in pigs born with low birth weight

The low birth weight (LBW) individual had greater risk of developing metabolic dysfunction in adulthood. The aim of this study was to test whether the LBW individual is more prone to glucose intolerance on a high nutrient dense (HND) diet, and to investigate the associated hypothalamic gene expressions using pigs as model. The intake of digestible energy intake, if calculated on a body weight basis, was greater in LBW pigs than that of normal birth weight (NBW) pigs. The LBW pigs fed the HND diet had greater digestible energy intake than those fed the NND diet at adulthood, which did not occur for NBW pigs. Notably, up-regulated hypothalamic toll-like receptor 4, interleukin 6 and phospho-NFκB p65 expressions, and the altered expressions of hypothalamic leptin receptor, suppressor of cytokine signaling 3, agouti-related protein and proopiomelanocortin predicted the overconsumption of energy intake and development of glucose intolerance in LBW pigs fed the HND diet. Collectively, pigs born with LBW had a distinct hypothalamic leptin signaling to a high nutrient dense diet, which contributed to greater energy intake and glucose intolerance.