Objective: The purpose of this study was to immunohistochemically evaluate the effects of thyroid hormones on the olfactory epithelium (OE) in adult rats. Study design and setting Hypothyroidism was induced in rats by propylthiouracil (PTU) administration. Animals were grouped into 5 consisting of a control group, and 4 groups that had been treated with PTU for 3, 6, 9, or 12 weeks, respectively. The thickness and cell densities of the OE were examined according to the duration of PTU treatment. Changes to OE cell properties were investigated with immunohistochemical stains.
Results: No statistically significant differences were found in the thickness and cell densities of the OE among the 5 groups. The number of olfactory receptor neurons positive for neuron-specific enolase or protein gene product 9.5, however, decreased with increasing duration of PTU treatment.
Conclusion: Thyroid hormones play an important role in the maturation of olfactory receptor neurons.