Aquaporins (AQPs) are central in exocrine gland function. In addition, they are most likely involved in proper saliva production. Their embryonic expression is not completely understood, nor is their role in cellular homeostasis during gland development. As a consequence of this circumstance the expression of aquaporins in mouse salivary glands were studied from embryonic day 13.5 (E13.5) to 5 days after birth (birth = E19.5).

The expression of aquaporin mRNA at E15.5, E17.5, E19.5 and postnatal day 5 was mapped using microarray methodology. Reverse transcriptase-PCR (RT-PCR) technique was used to verify and expand upon the microarray data. Microarray data generally showed a high expression of AQP1, AQP5, AQP6 and AQP11 at all dates tested. RT-PCR analysis indicated a distinct developmental expression pattern for each AQP. Aquaporin 1, 4, 5 and 11 were first detected at E13.5. AQP1 and AQP5 become more intensely expressed during the course of development, while AQP11 and AQP4 expression showed a decreasing tendency. AQP8 was first detected at E19.5, and from then on increased gradually. This study has demonstrated mRNA expression of aquaporins 1, 4, 5, 6, 8 and 11 in pre- and postnatal salivary glands from the mouse. These observations may indicate that the presence of water channels play a necessary role in the development of a functional salivary gland.