Aldosterone (mineralocorticoid) equivalent to prednisolone (glucocorticoid) in reversing hearing loss in MRL/MpJ-Fas1pr autoimmune mice.
OBJECTIVE
Although the glucocorticoid prednisone is the standard therapy for autoimmune sensorineural hearing loss, what this hormone does in the ear to restore hearing is not known. MRL/MpJ-Fas(lPr) autoimmune mice consistently have shown only stria vascularis disease, implying that abnormal ion balances in the endolymph underlie cochlear dysfunction. Previously we have shown that hearing loss in these mice is reversed with prednisolone treatment. This, coupled with the complete lack of cochlear inflammation, suggests that the restoration of hearing with prednisolone is due to its sodium transport function and not to its anti-inflammatory or immune suppression effects. Therefore the hypothesis of this study was that the mineralocorticoid aldosterone, which only increases sodium transport, would be as effective as prednisolone in reversing autoimmune hearing loss.


METHODS
MRL/MpJ-Fas(lPr) autoimmune mice were treated with either prednisolone or aldosterone to compare steroid effects on auditory brainstem response (ABR) thresholds and stria morphology.


METHODS
After baseline ABR audiometry, autoimmune mice were given prednisolone (5 mg/kg per day), aldosterone (15 microg/kg per day), or water in their drinking bottles. After 2 months of treatment the ABR thresholds were remeasured, and ears collected for histological examination.


RESULTS
The untreated controls showed continued elevation of ABR thresholds and edematous stria. However, thresholds in most steroid mice were improved or unchanged and their stria morphology improved, particularly with aldosterone treatment.


CONCLUSIONS
Restoration of hearing with steroid treatment is due to increased sodium transport to re-establish cochlear ionic balances. Aldosterone therapy may offer advantages over prednisone for long-term management of not only autoimmune hearing loss, but also other forms of nonimmune-related deafness for which steroids are currently prescribed.
Trune
D R
DR
Oregon Hearing Research Center, Department of Otolaryngology--Head and Neck Surgery, Oregon Health Sciences University, Portland 97201-3998, USA.
Kempton
J B
JB
Kessi
M
M
D000450:Aldosterone / Q000627:therapeutic use*; D000818:Animals; D001327:Autoimmune Diseases / Q000188:drug therapy*; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects / Q000502:physiology; D005938:Glucocorticoids / Q000627:therapeutic use*; D006319:Hearing Loss, Sensorineural / Q000188:drug therapy*; D051379:Mice; D011239:Prednisolone / Q000627:therapeutic use*; D011897:Random Allocation
D005938:Glucocorticoids; D000450:Aldosterone; D011239:Prednisolone