Expression of ENaC in LPS-induced inflammation of middle ear mucosa

• Published in: Acta oto-laryngologica 2012-11, Vol.132 (11), p.1145-1150
• Main Authors: Song, Jae-Jun, Kwon, Seong Keun, Cho, Chang Gun, Park, Seok-Won, Chae, Sung-Won
• Format: Article
• Language: English
• Subjects: Animals; Bacterial diseases; Biological and medical sciences; Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Ent and stomatologic bacterial diseases; epithelial sodium channel; Epithelial Sodium Channels - metabolism; Human bacterial diseases; Immunohistochemistry; Infectious diseases; Inflammation - metabolism; Inflammation - pathology; inflammatory response; lipopolysaccharide; Lipopolysaccharides; Male; Medical sciences; Mucous Membrane - metabolism; Non tumoral diseases; Otitis media; Otitis Media - etiology; Otitis Media - metabolism; Otorhinolaryngology. Stomatology; Rats; Rats, Sprague-Dawley; RNA, Messenger - metabolism
• ISSN: 0001-6489; 1651-2251
• DOI: 10.3109/00016489.2012.697640

Abstract Conclusion: The expression of all three subunits of the epithelial sodium channel (ENaC) decreased after the lipopolysaccharide (LPS) injection and normalized as the fluid collection resolved. This implies that fluid collection in acute otitis media may be caused by the inhibition of ENaC function. Objectives: We investigated the expression levels of subunits of ENaC after an injection of LPS into the middle ear cavity of rats. Methods: Seventy-two Sprague-Dawley rats were assigned randomly into the five groups that received an LPS injection and the control group. A transtympanic injection of LPS (1 mg/ml) was done and rats were sacrificed 6, 12, 24, 72, and 120 h after the procedure. Real-time RT-PCR was carried out for ENaC-α, -β, -γ, and immunohistochemistry was performed for ENaC-α and -β. Results: The level of ENaC-α expression decreased 0.50-fold and 0.55-fold at 6 and 12 h, respectively (p < 0.05), but it normalized at 24 h. It increased 3.64-fold at 72 h and 3.24-fold at 120 h (p < 0.05). At 6 and 12 h after the LPS injection into the middle ear cavity, inflammation was induced and ENaC-α immunoreactivity decreased. At 24 h, ENaC-α immunoreactivity was normalized, then at 72 and 120 h after the injection it was increased.