Abstract

Initial nutritional stimulation is a key driving force for small intestinal maturation. In chick embryos, administration of l-glutamine (Gln) into the amniotic fluid stimulates early development of the small intestinal epithelium by promoting enterocyte differentiation. In this study, we evaluated the effects of intra-amniotic administration of Gln on enterocyte morphology and function, and elucidated a potential enteroendocrine pathway through which Gln stimulates small intestinal maturation. Our results show that Gln stimulation at embryonic day 17 significantly increased enterocyte and microvilli dimensions by 10 and 20%, respectively, within 48 h. Post-hatch, enterocytes and microvilli were 20% longer in Gln-treated chicks. Correspondingly, Gln stimulation significantly upregulated mRNA expression of brush border nutrient transporters PepT-1 and SGLT-1 and tight junction proteins TJP-1 and TJP-2, before and after hatch (P < 0.05). Since GLP-2 signaling from intestinal L-cells is associated with enterocyte growth, functionality and integrity, we examined the effects of Gln stimulation on mRNA expression of key hormones and receptors within this enteroendocrine pathway and found significant increases in GLP-2R, IGF-1 and IGF-1R expression before and after hatch (P < 0.05). In conclusion, our findings link primary nutrient stimulation in the developing small intestine with enterocyte morphological and functional maturation and enteroendocrine signaling.

Highlights

  • Initial nutritional stimulation is a key driving force for small intestinal maturation

  • intestinal sub-epithelial myofibroblasts (ISEMFs) secrete Insulin-like Growth Factor 1 (IGF-1), which binds to its receptor, IGF-1 Receptor (IGF-1R), on enterocyte basolateral membranes, and initiates subsequent ­effects[20,27]

  • We examined the effects of these treatments, compared to a non-administered control group, on pre- and post-hatch enterocyte maturation by measuring jejunal enterocyte and microvilli dimensions and quantifying mRNA expression of nutrient transporters PepT-1, Sodium Glucose Transporter1 (SGLT-1) and tight junction proteins TJP-1, TJP-2 and Occludin

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Summary

Introduction

Initial nutritional stimulation is a key driving force for small intestinal maturation. Intra-amniotic administration of l-glutamine (Gln) was found to promote proliferation and differentiation in the small intestinal epithelium of chick embryos, resulting in higher quantities of enterocytes during the first week post-hatch[19]. The objectives of this current study were to evaluate the effects of intra-amniotic administration of Gln on enterocyte morphology and function and to examine a potential mechanism by which Gln affects these parameters. These include increases in enterocyte dimensions and elongation of ­microvilli[28]; improved enterocyte

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