Influence of obestatin on the histological development of the small intestine in piglets during the first week of postnatal life.

Obestatin is a gastrointestinal peptide having wide-ranging effects on cell proliferation; however, its mechanism of action remains poorly understood. Thus, the aim of the study was to elucidate the effect of exogenous obestatin on the postnatal structural development of the small intestine. Seven-day-old piglets with an average BW of 1.56 ± 0.23 kg were divided into four groups (n = 10) that received intragastrically obestatin (2, 10 or 15 µg/kg BW) or vehicle. After a 6-day experimental period, morphological analysis of gastrointestinal tract and small intestine wall (mitosis and apoptosis indexes, histomorphometry of mucosa and muscularis layers) was performed. The study revealed a seemingly incoherent pattern of the histological structure of the small intestine among the experimental groups, suggesting that the effect of obestatin is both intestinal segment specific and dose dependent. Histomorphometric analysis of the small intestine showed that higher doses of obestatin seem to promote the structural development of the duodenum while simultaneously hindering the maturation of more distal parts of the intestine. Intragastric administration of obestatin increased the crypt mitotic index in all segments of the small intestine with the strongest pro-mitotic activity following the administration of obestatin at a dose of 10 and 15 µg/kg BW. The significant differences in the number of apoptotic cells in the intestinal villi among the groups were observed only in proximal jejunum and ileum. In conclusion, it seems that obestatin shows a broad-spectrum of activity in the gastrointestinal tract of newborn piglets, being able to accelerate its structural development. However, the varied effect depending on the intestinal segment or the concentration of exogenous obestatin causes that further research is needed to clarify the exact mechanism of this phenomenon.

Influence of preterm delivery on ghrelin and obestatin concentrations in maternal plasm, milk and their expression in mammary epithelial cells.

Ghrelin and obestatin are gastrointestinal peptides with a potential role in the programming of metabolism in newborns. The present study aimed to investigate the influence of preterm delivery on ghrelin and obestatin concentrations in the maternal blood plasma and breast milk as well as their gene expressions in the mammary epithelial cells (MECs). On the 3rd day after delivery, milk and plasma samples were collected from mothers that carried to term or gave birth prematurely (< 36 weeks of gestation) and analyzed for ghrelin and obestatin concentrations. MECs isolated from the milk were analyzed for the relative expression of GHRL splice variants. In both groups ghrelin concentrations were significantly lower in milk than in blood plasma. In the preterm group obestatin concentrations were significantly higher in milk than in blood plasma but significantly lower in comparison to that of the control mothers. The expression of GHRL mRNAs was higher (P < 0.05) in MECs isolated from the preterm group as compared to those isolated from control mothers. The concentration of obestatin (but not ghrelin) in the breast milk is dependent on the term of pregnancy. Moreover, the lactating mammary gland is one of the sources of ghrelin and obestatin.