Effect of Zinc in Submandibular Salivary Gland Branching Morphogenesis

INTRODUCTION: Nerves from the parasympathetic branch are critical for the function of the glandular tissue including salivary gland. Parasympathetic innervation influences organ regeneration: tissue regrowth impaired after parasympathectomy in the salivary gland. As it is difficult to treat the damaged nerves, there is a need to develop new materials and treatment methods to treat the nerves. Zinc ions are reported to be important metal ions in the physiological functions of the nervous system and involved in neural cell proliferation and differentiation. Here, we aimed to study the influence and neuroprotective role of the extracellular zinc during submandibular salivary gland (SMG) development using ex vivo tissue culture system. Also we prepared zinc ion-containing agarose hydrogel beads (Zn+Aga) for sustained release of zinc ion. MATERIALS AND METHODS: 300~500µm size beads prepared. Different concentration of zinc were incorporated in the beads. LY294002 an antagonist of PI3Kinase pathway also incorporate as needed. Next, 0.3 wt%~4 wt% alginate hydrogel sheets prepared for ex-vivo organ culture. SMG were isolated from the pregnant ICR mouse at day 13 (E13) and culture on hydrogel sheet with or without Zn ion and LY294002 containing beads. Finally, the data analyzed histomorphometrically. RESULTS: We successfully prepare the Zn+Aga and observed the sustain release of Zn+ upto 48 hours. Histological evaluation showed that zinc ion promoted the growth of submandibular tissue. The immuno expression of AKT was promoted by the administration of zinc ion. AKT decreased by using ly294002, which is an inhibitor of PI3kinase, and it recovered after administration of zinc. This indicates that zinc administration is involved in the AKT-pathway. DISCUSSION & CONCLUSION: Collectively, these data clearly illustrate that the Zn is essential element during salivary gland organogenesis through activation of the PI3Kinase-AKT pathway. © FASEB.