Localization and potential function of androgen receptor in rat salivary gland

To investigate the localization and quantity of androgen receptor (AR) in the salivary glands of rats with further analysis on the effect of castration.

Sixty male Wistar rats, aged 30-60 days, were randomly divided into three groups (castrated, sham-operated and normal controls) with 20 rats in each group. The rats in the castrated group were castrated and the submaxillary glands were removed after 1 week. The salivary glands of the rats in the sham-operated and the normal control groups were also removed. Parts of the salivary glands were fixed for immunohistochemistry and in situ hybridization assays. Other parts were used for Western blot.

AR immunoreactivity in the three groups was localized in the glandular epithelial cells of the serous acinus and the glandular duct of the salivary gland, mainly in the nuclei. AR mRNA hybridization signals in the salivary glands of the castrated group were mainly distributed in the epithelial cells of the convoluted and secretary ducts; AR mRNA in the sham-operated and the normal control groups were found in the epithelial cells of the convoluted, the secretary and the excretory ducts. The quantity of AR in the salivary glands was decreased significantly in the castrated rats compared with the sham-operated and the normal controls. Moreover, epidermal growth factor (EGF) secreted by the salivary glands was also decreased in the castrated rats.

Castration appears to affect the production of AR in the salivary gland and the distribution of the AR mRNA and could further affect the function of the salivary gland. The changes of AR and the distribution of AR mRNA may play an important role in the interactions between the testes and the salivary gland.