The Effect of Dietary n6:n3 Polyunsaturated Fatty Acid Ratio on Chronic Reflux Esophagitis in Rats

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Introduction: Reflux esophagitis (RE) is one of the typical lesions of gastroesophageal reflux disease (GERD). The incidence of GERD is thought related to high fat diet, while the ratio of dietary n6: n3 polyunsaturated fatty acid (PUFAs) is believed to play a role in the regulation of the inflammatory process. This study was aimed to investigate the effect of dietary n6: n3 PUFAs ratio on chronic RE in a rat model and the relationship with lipid peroxidation. Methods: Forty rats were randomly divided into 4 groups according to the n-6: n-3 PUFAs ratios in feed, including 1:1.5,10:1, 5:1 and pure n-6 PUFAs groups, and a sham operation group (10 rats, which were fed with pure n-6 PUFAs) was set up as blank control. Rat RE model (Pyloric Nylon Loop-induced Chronic Acid Reflux Esophagitis) was established by pyloric clip and section ligation. After 14 days treatment, pathological changes of the esophagus were determined, and the expression of IL-1β, IL-8, TNFα protein and mRNA in esophageal tissue homogenate were evaluated by Western blot and RT-PCR, respectively, while the MDA and SOD levels were evaluated by ELISA, respectively. Results: The food intake and body weights in the rats showed no significant difference before operation (P>0.05), while those were reduced in all groups except sham group in postoperative d7 (P<0.05) and were recovered in d14, and no intergroup differences were found (P>0.05). In PUFA1:1.5, PUFA5:1, PUFA10:1, n-6 PUFA groups and sham operation group, the postoperative d14 survival rates were 70%, 60%, 80%, 70% and 100%, respectively (P=0.306). The degree of esophagitis was lower in PUFA1:1.5 group when compared to that in the other model groups (P<0.05), but no significant difference was found among PUFA5:1, PUFA10:1 and n-6 PUFA groups(P>0.05). The protein and mRNA expression of IL-1β, IL-8 and TNFα, and the MDA levels were increased in all model groups when compared to that in sham group (P<0.05), which showed a rising tendency from PUFA1:1.5, PUFA5:1, PUFA10:1 groups to n-6 PUFA group. The SOD levels were decreased in all model groups when compared to that in sham group (P<0.05), which showed a reducing tendency from PUFA1:1.5, PUFA5:1, PUFA10:1 groups to n-6 PUFA group. Conclusion: The results indicate that the reflux related esophageal mucosal damage could be lightened by adding more n-3 PUFAs in diet, which was associated with an up-regulation of antioxidant activity and a down-regulation of lipid peroxidation in esophageal epithelium. Dietary n-6/n-3 PUFAs ratio reduction may be a beneficial strategy for gastroesophageal reflux disease management.