GLN INHIBITS INTESTINAL MUCOSAL INJURY IN YOUNG RATS WITH ACUTE HYPOXIA BY REGULATING PROINFLAMMATORY FACTORS AND AUTOPHAGY OF INTESTINAL MUCOSA CELLS

Hanzhou Guan^{1, *}, Jianbing Liu², Xinhua Zhang¹, Yingzhao Fan¹, Xiaoyu Lin²

¹Department of Neonatology, Shanxi Provincial Children’s Hospital, Taiyuan 030032, Shanxi Province, China - ²School of Basic Medical Sciences, Shanxi Medical University, Taiyuan 030001, Shanxi Province, China

Objective: To investigate the effect of glutamine (Gln) on intestinal mucosal injury in young rats with acute hypoxia by regulating inflammatory factors and autophagy. 

Methods: Sixty-four healthy SPF SD rats were divided into a model group, Gln group, Gln+6-amino-3-methyladenine (3mA) group and a 3mA group, with 15 rats in each group. The rats in the model group and the Gln group were intraperitoneally injected with 1 ml 0.9% normal saline, while the Gln+3mA group and the 3mA group were injected intraperitoneally with 20 mg mg−1 3mA. After successful modeling, rats in the model group and 3mA group were not treated. Rats in the Gln group and Gln+3mA group were given 0.3 mg mg−1 Gln by gavage. The pathological scores, pathological changes of small intestinal epithelium, serum levels of inflammatory related factors (IL-1, TNF-α, HIF-1α) and the expression levels of microtubule light chain type I protein 3-Ⅱ (LC3-II) and Beclin-1 protein were compared in each group at 0 h, 24 h and 48 h. 

Results: at 24 h and 48 h, pathological scores of rats in the Gln group were significantly lower than those in the model group (P<0.05). Pathological scores of rats in the 3mA group were significantly higher than those in the model group (P<0.05), and pathological scores of rats in Gln+3mA group were significantly higher than those in the Gln group (P<0.05). At 0 h, the structure of intestinal epithelium was basically normal, without obvious pathological changes such as swelling, degeneration, or necrosis. At 24 h, the intestinal epithelial cells were necrotic, some villi were broken and exfoliated, part of the intestinal epithelial structure disappeared, and leukocyte infiltration occurred. At 48 h later, however, the pathological changes of the small intestinal epithelium were gradually improved. The groups could be ranked by degree of pathological damage to the intestinal epithelium from most to least as the 3mA group, the Gln+3mA group, the model group, and the Gln group. No significant difference was seen in the levels of IL-1, TNF-α, and HIF-α in the serum of each group at 0 h (P>0.05). At 24 h and 48 h, the levels of IL-1, TNF-α, and HIF-α in the Gln group were significantly lower than those in the model group (P<0.05). Moreover, the levels of IL-1, TNF-α, and HIF-α in the 3mA group were significantly higher than those in the model group (P<0.05), and the levels of IL-1, TNF-α, and HIF-α in the Gln+3mA group were significantly higher than those in the Gln group (P<0.05). No significant difference was reported in the expression levels of LC3-II and Beclin-1 in the serum of rats in each group at 0 h (P>0.05). At 24 h and 48 h, the protein expression levels of LC3-II and Beclin-1 in the Gln group were significantly higher than those in the model group (P<0.05), and the protein expression levels of LC3-II and Beclin-1 in the 3mA group were significantly lower than those in the model group (P<0.05). In addition, the protein expression levels of LC3-II and Beclin-1 in the Gln+3mA group were significantly lower than those in the Gln group (P<0.05). 

Conclusion: Gln can inhibit the injury of intestinal mucosa in young rats with acute hypoxia and has protective effect. The mechanism of Gln action might be through reducing the expression of IL-1, TNF-α, HIF-α and promoting the expression of the autophagy-related proteins LC3-II and Beclin-1.