Estrogen-Dependent Nrf2 Expression Protects Against Reflux-Induced Esophagitis.

BACKGROUND

Gastroesophageal reflux disease is more common in males than in females. The enhanced antioxidative capacity of estrogen in females might account for the gender difference. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a pivotal role in the host defense mechanism against oxidative stress.

AIMS: This study aimed to clarify the role of Nrf2 in reflux-induced esophageal inflammation, focusing on the gender difference and nitric oxide.

METHODS

Gastroesophageal reflux was surgically induced in male and female rats. Nitrite and ascorbic acid were administered for 1 week to provoke nitric oxide in the esophageal lumen. Male rats with gastroesophageal reflux were supplemented with 17β-estradiol or tert-butylhydroquinone, an Nrf2-inducing reagent. Esophageal squamous cell carcinoma KYSE30 cells were treated with 17β-estradiol. Nrf2 expression was examined by Western blotting and quantitative real-time PCR. Antioxidant gene expression profiles were examined by a PCR array.

RESULTS

In the presence of nitric oxide, reflux-induced esophageal damage was less evident, whereas esophageal expression of Nrf2 and its target genes such as Nqo1 was more evident in female or male rats supplemented with 17β-estradiol than in male rats. 17β-Estradiol increased nuclear Nrf2 expression in KYSE30 cells. tert-Butylhydroquinone increased tissue Nqo1 mRNA expression, leading to a reduction in reflux-induced esophageal damage.

CONCLUSIONS

Estrogen-dependent Nrf2 expression might contribute to protection against the development of gastroesophageal reflux disease in females.