Gene expression pattern after insertion of dexamethasone-eluting electrode into the guinea pig cochlea.

To investigate the effect of the dexamethasone-eluting electrode in the guinea pig cochlea, and compared the gene expression after 7 days insertion with that of a normal electrode or non-treated control by microarray. Male Hartley guinea pigs (SLC, Shizuoka, Japan) with an age of seven weeks were used for the study. Three were implanted with normal electrodes while three others received a dexamethasone-eluting electrode. The cochleae from two animals, which did not undergo surgery. Seven days after electrode implantation the whole temporal bone was removed and placed into RNAlater solution (Ambion, Life Technologies Co., Grand Island, NY) to stabilize and protect cellular RNA. The whole cochlea was dissected out under a microscope and total RNA were extracted.