Endolymphatic hydrops by administration of vasopressin in the rat

The anti-diuretic hormone, vasopressin, has been shown to be important in r egulating inner ear fluid. We report on the involvement between Meniere's d isease and vasopressin. We designed an experiment to determine whether vaso pressin directly affects the fluid level. We chronically infused this hormo ne in rats and examined them for morphological signs of endolymphatic hydro ps. Vasopressin infusion significantly increased the scala media area by 5. 9 +/- 7.1% (P <0.01), and the length of Reissner's membrane by 5.9 +/- 3.2% (P <0.001). The results suggest that high plasma levels of vasopressin may be a principal causal factor of endolymphatic hydrops in Meniere's disease , perhaps due to down-regulating the number of vasopressin receptors.