Ghrelin in the gastrointestinal tract and blood circulation of perinatal low and normal weight piglets

Abstract

Ghrelin, the 'hunger' hormone, is an endogenous growth hormone secretagogue that exerts a wide range of physiological functions. Its perinatal presence suggests that ghrelin might be involved in growth and metabolism processes during intrauterine and postnatal life. Intrauterine growth-restricted (IUGR) neonates have altered endocrine and metabolic pathways because of malnutrition during foetal development. These changes might include an altered gastrointestinal presence of ghrelin cells (GCs). As ghrelin is mainly secreted by the stomach, this altered presence might be reflected in its serum concentrations. Smallfor-gestational age (SGA) pigs appear to be a natural occurring model for IUGR children. Therefore, the first aim of this study was to investigate the presence of gastrointestinal GCs expressing active ghrelin in normal weight (NW) foetal and postnatal piglets compared with their SGA littermates using immunohistochemical analysis in combination with stereological methods. Second, total ghrelin serum concentrations of these piglets were analysed with a porcine radioactive immunoassay. In addition, the growth of the gastric pars fundica in the NW and SGA piglets was analysed stereologically. Corresponding with humans and rats, it was shown that opened-and closed-type immunoreactive GCs are distributed along the entire gastrointestinal tract of the perinatal NW and SGA piglets. However, in contrast to the rat's stomach, the porcine GCs do not disperse from the glandular base to the glandular neck during perinatal development. Furthermore, stereological analysis demonstrated that the NW neonates have a higher amount of gastric cells expressing active ghrelin compared with the SGA piglets that could result in higher milk consumption during the neonatal period. This finding is, however, not reflected in total serum ghrelin levels, which showed no difference between the NW and SGA piglets. Moreover, the stereological volume densities of the fundic layers demonstrate a similar growth pattern in the SGA and NW piglets.

Post-natal Growth Retardation Associated With Impaired Gut Hormone Profiles, Immune and Antioxidant Function in Pigs

“…It is in accordance with the previous reports that altered 5-HT signaling resulted in both intestinal and extra-intestinal symptoms in gut disease, for example, the downregulated SERT and 5-HT4R induced functional gut disorders, such as colitis (49, 52, 53). The intestinal hormones including LEP, INS, SS, AgRP, CCK, and GHRL, play important roles in regulating appetite via controlling digestion and satiety (54, 55). The appetite-stimulating effects of AgRP are inhibited by the secretion of LEP and activated by the GHRL (56).…”

Once small always small? To what extent morphometric characteristics and post-weaning starter regime affect pig lifetime growth performance

“…Piglets weaned light appear to have an immature digestive system [ 27 , 28 ] and a higher epithelial cell turnover [ 29 ], and therefore may benefit from an increased supply of threonine [ 30 ] and methionine [ 31 ]. Their lower ghrelin expression [ 32 ] and serotonin concentrations [ 33 ] suggest that an increased supplementation of tryptophan may stimulate appetite [ 30 ].…”

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

“…In only boys and not girls, acyl ghrelin in the umbilical cord additionally correlated negatively with abdominal and thigh circumference [55]. However, there were also reports of decreased ghrelin in cord blood in SGA newborns [58] and preterm babies [48], as well as data suggesting no difference in umbilical cord concentrations ghrelin between LGA and SGA newborns [59], between AGA and SGA piglets [60], and between AGA and LGA preterm infants [61].…”