Detection of mucin gene expression in normal rat middle ear mucosa by reverse transcriptase-polymerase chain reaction

Hypersecretion of mucin is a common feature of chronic and mucoid otitis me dia which may play an important role in hearing loss. The mechanisms contro lling mucin secretion in the middle ear are not completely understood. Our reverse transcriptase-polymerase chain reaction results demonstrate that mR NAs of MUC1, MUC2, MUC3; MUC4 and MUC5A C are expressed in normal rat middl e ear mucosa. Moreover, the expression of mRNA of the secretory mucins MUC2 , MUC3 and MUC5AC was threefold lower in normal middle ear mucosa than that in the intestine or trachea. In contrast, expression of the membrane-bound mucins MUC1 and MUC4 was approximately the same in both middle ear mucose and the intestine or trachea. IMUC5AC proteins were also identified immunoh istochemically in normal rat middle ear epithelium. The methodology used in this study provides useful baseline information for investigation of the m echanisms of regulation of mucin gene expression during otitis media.