Regulatory effect of vitamin D on the expression of occludin in the intestinal epithelial cells of neonatal rats with necrotizing enterocolitis

Abstract

Objective To investigate the expression of occludin in the intestinal epithelial cells of neonatal rats with necrotizing enterocolitis (NEC). The influence of vitamin D on NEC and the expression of occludin was also explored. Methods Sixty neonatal Wistar rats from different litters were divided into four groups 48 hours after birth: 10 in the breast-fed+ control group, 10 in the breast-fed + vitamin D group, 20 in the NEC+ control group and 20 in the NEC+ vitamin D group.In groups with NEC, neonatal rats were separated from their mothers and treated with rat milk substitute+ hypoxia+ hypothermia.In groups with vitamin D treatment, paricalcitol was given through intraperitoneal injection 30 minutes before, one day and two days after the induction of NEC.The tissue was harvested from the ileum of the rats 72 hours after induction of NEC.Microscopically, the tissue was assessed according to the Nadler scoring system.The expression and location of occludin was observed after immunofluorescence staining.Western blotting was performed and quantified to compare the expression of occludin among groups. Results In NEC rats, the intestinal structure was destructed.Separation of the submucosal or muscular layer, discharge or disappearance of the villa was accompanied by necrosis of the intestinal cells.Vitamin D treatment could significantly alleviate those changes, with the Nadler score 1.70±0.21 compared to 2.90±0.23 without vitamin D treatment(P<0.01). The expression of occludin was decreased in NEC rats and vitamin D could partly rescue this decrease(P<0.01). The distribution of occludin was sparse and discontinuous in NEC rats while after vitamin D treatment, the distribution was maintained even and continuous. Conclusion The expression of occludin in intestinal epithelial cells is significantly reduced in NEC rat.Vitamin D treatment may inhibit the development of NEC by maintaining the expression of occludin. Key words: Occludin; Intestinal epithelial cells; Vitamin D; Necrotizing enterocolitis