[Effects of intratympanic injection of dexamethasone on endolymphatic hydrops and changes in guinea pigs inner ear CFTR expression].

OBJECTIVE

To observe the effect of tympanic injection of dexamethasone in the guinea pig endolymphatic hydrops and the change CFTR expression, to explore the effect of glucocorticoid treatment endolymphatic and its possible mechanism.

METHOD

Thirty guinea pigs were divided into three groups: hormone group, water group, control group. The animals(hormone group, water group) in study were injected DDAVP 4 μg/kg in the first 7 d, and will increase to 6 μg/kg in the second 3 d. The control group was given normal saline, continuous 10 d. After twelfth days, the hormone group transtympanic injection of dexamethasone (5 mg/ml, 0.5 ml), and water group, control group transtympanic given normal saline (0.5 ml), continuous injection 5 d. Using immuno- histochemistry and Western blot to detect the cystic fibrosis transmembrane conductance regulator cochlear factor (CFTR) expression.

RESULT

The water group ABR thresholds was significantly higher than that before the experiment (P < 0.01), and the water group was significantly higher than the rest of the groups (P < 0.01); Hormone group compared with the control group increased threshold value (P < 0.05). The control group had no endolym- phatic hydrops, the water group showed varying degrees of endolymphatic hydrops, cochlear duct and vestibular plus cochlear duct area ratio compared with the control group, hormone group was significantly higher (P < 0.01). hormone group area ratio was higher than the control group (P < 0.05). CFTR was primarily expressed in the stria vascularis, Corti's, spiral ligament, basilar membrane, cochlear ganglion,etc . The expression of CFTR in the water group was increased than that in the control group, and the hormone group (P < 0.01); the expression of hormone group increased compared with the control group (P < 0.05).

CONCLUSION

Tympanic injection of dexa- methasone can alleviate the desmopressin acetatein guinea pigs caused by membranous labyrinth, and the improve- ment of the hearing; Tympanic injection of dexamethasone can make the endolymphatic hydrops cochlea of guinea pigs decreased CFTR expression, indicating that the expression and possible mechanisms of CFTR intratympanic steroids reduce endolymphatic hydrops changes.