Excess iron disturbs intestinal stem cell homeostasis via Wnt/Notch signaling in suckling rats.

BACKGROUND: Excessive iron may adversely affect intestinal health, particularly the immature intestine of infants. The mechanism of high iron intake affecting intestine in infants remains unclear. OBJECTIVES: This study aims to investigate the effects of high iron supplementation on intestinal stem cells (ISCs) function in infant rats. METHODS: Suckling rats aged 2 days were supplemented with iron at doses of 10, 20, 30, 40, 50, and 100 mg Fe/kg body weight/day for 13 days. At the end of the treatment, jejunal tissues were harvested for histopathological evaluation, immunohistochemical staining to assess protein expression and localization, and RT-qPCR to quantify the mRNA levels of Wnt/β-catenin and Notch signaling pathway-related genes. Data were analyzed using one-way analysis of variance followed by Tukey's test. RESULTS: Histological analysis revealed that iron supplementation of 50 and 100 mg/kg significantly reduced villus height by 34.00% and 19.32%, respectively (P < 0.05), which was associated with suppressed proliferation of ISCs. Notably, with iron supplementation of 50 mg/kg, the expression of Wnt- and Notch-pathway target genes, including Hes1 and Notch1, decreased by 69.98% and 67.22% (P < 0.05), respectively, accompanied by increases of 56.57% and 13.35% in goblet and endocrine cells, respectively (P < 0.05), and a 38.54% decrease in enterocytes (P < 0.05). CONCLUSIONS: Overall, this study suggested that excessive iron intake during suckling inhibited ISCs proliferation, changed ISCs differentiation toward secretory rather than absorptive lineages, finally damaging intestine. These findings reveal the intrinsic mechanisms of iron overload-induced intestinal damage during suckling, providing an important theoretical basis for the scientific application of iron nutritional regulation for infants.