Mineralocorticoid receptors in the mammalian olfactory mucosa

Mineralocorticoid hormones regulate secretion and absorption in a wide vari ety of epithelial tissues, although specific mechanisms in the olfactory mu cosa are currently unknown. Utilizing reverse transcription-polymerase chai n reaction (RT-PCR) analysis, we have demonstrated the expression of minera locorticoid (type I) receptor messenger RNA in the rodent olfactory mucosa. Ampli fication products of predicted size were obtained with nucleotide se quences corresponding to respective mineralocorticoid receptor (MR) kidney transcripts. Immunocytochemistry, using an antibody with known specificity for MRs, was then utilized in order to localize the cellular site(s) of MR protein expression in the olfactory mucosa. The highest levels of MR immuno reactivity were localized to the supranuclear region of sustentacular cells , as well as the acinar cells of the Bowman's glands. The respiratory regio ns of the nasal cavity were devoid of appreciable MR immunoreactivity. This study demonstrates both MR transcript and protein expression in the olfact ory mucose. We hypothesize that the mineralocorticoid hormones may have a r ole in modulation of olfactory secretion and/or sensory transduction in the peripheral olfactory system.