Stress Hormone Sensitivity and Endolymphatic Hydrops

Abstract

Objective: Ménière’s disease is peculiar to humans, and attacks of this affliction can occur under conditions of stress. The present study aimed to assess the link between inner ear hydrops in Ménière’s disease and vasopressin, an anti-diuretic stress hormone with a potential role in inner ear fluid homeostasis.

Method: We obtained blood samples from Ménière disease patients to examine plasma vasopressin (pAVP) and obtained inner ear tissue during endolymphatic sac surgery to examine vasopressin type-2 receptor (V2R) in the endolymphatic sac. We examined pAVP and the relative V2R mRNA expression in the endolymphatic sac using real-time PCR.

Results: A significant negative correlation was revealed between pAVP and inner ear V2R (P = .014). We also examined relative cyclic AMP (cAMP) activity in the endolymphatic sac using tissue culture and cAMP assay. Both pAVP (1.6 times vs controls; P = .048) and inner ear V2R mRNA expression (41.5 times vs controls; P = .022) were significantly higher in Ménière patients. cAMP activity was basally upregulated (2.1 times vs controls) and cAMP sensitivity to vasopressin application was largely elevated (4.9 times vs controls) in Ménière patients.

Conclusion: We concluded that in the pathogenesis of inner ear hydrops resulting in Ménière attacks, pAVP elevation probably as a result of stress may present a matter of consequence, but susceptibility of the V2R-overexpressed and cAMP-hypersensitized inner ear to pAVP elevation might be essential as a basis of this disease.