Effects of Gastric Juice Exposure on Structure and Function of Rat Eustachian Tube

A rat model of reflux-induced secretory otitis media was constructed by injecting artificial gastric juice to investigate the effects of acidic reflux fluid on the structure and function of the mucosa of the rat eustachian tube (ET), and to explore the pathogenesis of reflux-induced secretory otitis media.

The ET pharyngeal orifice of Sprague-Dawley (SD) rats was exposed to the artificial gastric juice in the experimental groups. Then optical and electron microscopic examinations were performed to observe the differences in the histological structure of the rat ET, and high-speed video microscopy analysis was used to observe the beating frequency of the mucosal cilia.

After exposure to artificial gastric juice, thickened ET mucosa and an increased number of goblet cells were observed in the 3-day post-exposure group, which basically returned to normal in the 7- and 14-day post-exposure groups. In the 3-day post-exposure group, the density of mitochondria was increased, and the Golgi complex was dilated. In the 14-day post-exposure group, the structure of intracellular organelles was almost restored to normal. The ciliary beating frequency decreased in the 3- and 7-day post-exposure groups. In the 14-day post-exposure group, ciliary beating was basically restored to the level of the 3-day post-exposure group.

After gastric juice exposure, the goblet cells of the ET mucosal epithelium secreted vigorously, the structure of the organelles in the ciliated cells was damaged, the beating function was compromised, and the mucociliary clearance function was impaired. The damages were reversible, and the structural recovery occurred earlier than the functional recovery.

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