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.