[Characterisation of the gene expression profiles in the inner ear and the colliculus inferior of normal and deafened rats by gene-array-technology].

Background: The phenotype of deafness and its mechanisms are morphologically and electrophysiologically well characterised. However, the molecular mechanisms and the consequences of deafness are poorly understood.

Methods: In this study we investigated changes in gene expression profiles in subfractions of the cochlea and the colliculus inferior, a non-cochlear tissue, of normal and deafened (10 % Neomycin) rats using the gene-array-technology. RNA was prepared from modiolus (Mo) und sensorineural epithel/lateral wall (SnE/Lw) und Colliculus inferior (IC), reverse transcribed with gene specific primers, labeled with (32)P-dATP and hybridised with its complementary sequences of 1200 rat ESTs.

Results: Similar gene expression profiles were detected in Mo- and SnE/Lw in normal as well in deafened rats differing significantly from those found in IC. In deafened animals differences in mRNA levels were determined in IC for 8 genes, in Mo für 17 genes and in SnE/Lw for 25 genes in comparison to those of normal rats. By using gene-arrays many genes described in the literature previously could be detected. Otherwise most of the genes found in the cochlea are unknown.

Conclusions: The gene-array-technology is a valuable tool in otological research for gene expression analysis and, therefore, for comprehensive understanding of molecular processes in the inner ear. Furthermore gene screening for candidate genes could be a big step ahead in developing therapies of diseases of the inner ear.