Distribution of aquaporin-5, transforming growth factor-β₁ and laminin during regeneration of atrophic rat submandibular glands after duct ligation

Abstract

The aim of this study was to determine the localization of aquaporin-5 (AQP5), transforming growth factor-β 1 (TGF-β 1) and laminin during regeneration of the rat submandibular gland. After duct ligation for 7 days, the regenerating glands were collected on days 0, 1, 3, 7, and 14 after ligation release to study the process of regeneration. Immunohistochemical staining revealed apical expression of AQP5 in many acinar cells, strong expression in intercalated ducts (ICDs) of the normal submandibular gland at Day 14, and strong expression in duct-like structures (DLSs) during regeneration from Day 0 to 7. However, a few AQP5-negative acinar cells were detected during regeneration. At Day 0, immunopositivity for TGF-β 1 was detected in connective tissue. At Days 3 and 7 during regeneration, TGF-β 1 immunostaining was observed in DLSs, which were surrounded by α-smooth muscle actin-positive thickened myoepithelial cells. Laminin staining was strong in the thickened basement membrane of DLSs at Day 3 during regeneration, but weak around acinar cells at Day 14. These findings suggest that TGF-β 1 is involved in the environment around DLSs, myoepithelial cells and laminin, that DLSs have the same functional properties as ICDs, and that AQP5-negative acinar cells may be mucous cells.

Dynamics of Salivary Gland AQP5 under Normal and Pathologic Conditions

“…After reopening of the ligated duct, restoration of the acinar structure was observed depending on the recovery period. The localization of AQP5 was also detected in the apical membrane of the acinar cells in accordance with the restoration of acinar cells, and in intercalated duct cells [28]. Recently, Aure et al [29,30] showed that the mouse salivary gland homeostasis is regulated predominantly based on the self-duplication of the differentiated acinar cells rather than differentiation of the stem cells under normal and abnormal condition.…”

Insight into Salivary Gland Aquaporins

“…The remaining AQP5 expression was still localized at the apical membranes of the remaining shrunken acinar cells [ 172 ]. After reopening of the ligated duct, there was a gradual restoration of the expression of AQP5 with localization to the apical membrane of the acinar cells and in intercalated ductal cells [ 173 ]. Another study reported a transient reduction in AQP5 expression after ligation removal followed by restoration of the normal expression and localization at the apical, basal and lateral membranes of the SG cells [ 171 ].…”

Aquaporins in the nervous structures supplying the digestive organs – a review

“…and Wang, 2017; Patel et al, 2017;Tie et al, 2017;Xu et al, 2017Tanski et al, 2020). Apart from participation in the transport of water and other substances, AQPs are involved in many regulatory processes, such as the proliferation and migration of cells, phagocytosis, tissue regeneration, apoptosis and many others (Szpilbarg et al, 2016;Pelagalli et al, 2018;Yasumitsu et al, 2018;Guo et al, 2019). Because the digestive system is the place where water transport is very intensive, high levels of almost all isoforms of aquaporins (AQP1-AQP11) have been found in the gastrointestinal (GI) tract and other digestive organs, such as salivary glands, pancreas, liver, gallbladder and bile duct (Zhu et al, 2016(Zhu et al, , 2019Zhang et al, 2019).…”