Effects of Hyaluronic Acid on Salivary Glands of Adult and Aged Mice



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Xerostomia, commonly known as dry mouth, is caused by a decrease in the amount of saliva (hyposalivation) that the body produces, that results from damaged or senescing salivary glands. Unfortunately, there is yet to be a definitive cure for xerostomia. Hyaluronan (HA) is a macromolecule that is abundantly expressed during salivary gland organogenesis. HA is synthesized by HA synthases (HASs), of which three isoforms exists, HAS1, HAS2, and HAS3. In this current study, we investigated the effects HA has on the salivary gland using Has1ï¾–/ï¾–; Has3ï¾–/ï¾– and wild-type (wt) adult and aged mice. Salivary glands (SGs) were stained with Hematoxylin and Eosin (H&E) and Alcian Blue. For immunohistochemistry, slides were stained with biotinylated binding protein (HABP), anti-K14, and DAPI. RNA was extracted from the SGs of all mice for RT-PCR. Both H&E and Alcian Blue stains showed morphological differences in adult and aged wt and Has1-/-;Has3-/- mice. Immunostaining revealed that in the SG, HA is expressed at high levels within the capsules and septae, and forms a surrounding structure at each acini and collecting duct. Has1-/-;Has3-/- adult mice presented a decrease in HA throughout the SG compared to the wt mice. RT-PCR revealed a significant decrease in the expression of AQP5 and ?-amylase adult Has1-/-;Has3-/- compared to wt mice, however, in the aged samples, Has1-/-;Has3-/- mice presented an increase in ?-amylase compared to wt mice. Has1-/-;Has3-/- mice are possibly more effective in preserving SG stem cells which could prevent the loss of mucous acini as mice age.