Recent studies indicated that G protein couple receptor 30 (GPR30), a nongenomic estrogen receptor, is widely expressed in many organ systems inducing many quick reaction of estrogen. However, there was rare report about the expression of GPR30 in the salivary gland. In the present study, we investigated the distribution of GPR30 in rat submaxillary gland by means of immunohistochemistry and in situ hybridization. GPR30 core sequences were amplified by RT-PCR with total RNA extracted from rat submaxillary gland and were analyzed by sequencing with Sanger's method. The results showed that the epithelial cells of serous alveoli and granular convoluted duct in rat submaxillary gland displayed GPR30-immunoreactivity on the plasma membrane and cytoplasm. Moreover, GPR30 mRNA hybridization signals were also detected in the cytoplasm of the above cells. GPR30 cDNA sequence cloned from rat submaxillary gland is identical to that of GPR30 from rat paraventricular and supraoptic nucleus. In conclusion, the expression of GPR30 in the serous and granular epithelial cells of submaxillary gland indicates that submaxillary gland could also be a target organ rapidly responding to estrogen stimulus, and estrogen may be involved in the functional regulation of submaxillary gland.
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