Sahar Abdel-Nasser Mohammed, Tarik Essawy And Saher Sayed Mohammed,

ABSTRACT
Background: Titanium Dioxide Nanoparticles(TiO2 NPs) Have Been Used In A Wide Variety Of Applications In Our Daily Life. However, The Safety Of Their Exposure Remains Unclear. Objective: Investigating TiO2NPs-induced Alterations In The Rat Submandibular Salivary Gland (SMSG) Using Masson?s Trichrome Stain (MT) & Alpha Smooth Muscle Actin (?-SMA). Methodology: 50 Adult Rats Weighing About ?200-250 Gm Were Divided Into 4 Groups: Group I (control Group), Group II Divided Into 2 Subgroups: Subgroup IIA Received TiO2 NPs A Daily Dose Of 10 Mg/kg/day For 14 Days And Subgroup IIB Received TiO2 NPs A Daily Dose Of 50 Mg/kg/day For 14 Days, Group III Divided Into 2 Subgroups: Subgroup IIIA Received TiO2 NPs A Daily Dose Of 10 Mg/kg/day For One Month And Subgroup IIIB Received TiO2 NPs A Daily Dose Of 50 Mg/kg/day For One Month & Group IV (recovery Group) Received TiO2 NPs A Daily Dose Of 10 Mg/kg/day For One Month & Allowed For One Month Of Recovery After TiO2 NPs Withdrawal. All Animals Were Sac-rificed,SMSG Were Dissected, Specimens Were Prepared And Sections Were Stained With Masson?s Trichrome. Immunohistochemical Detection Of Alpha Smooth Muscle Actin Was Done.

Results: Masson?s Trichrome Sections Of SMSG Of The Current Study Revealed A Dramatically Increasing Of The Amount Of Blue-stained Collagen Fibersfrom Group II To Group III In Compared To Control Group. The Collagen Fibersin Recovery Group Exhibited Degree Of Hyaline Degeneration. Immunohistochemical Results Revealed A Statistically High Significantincrease In ?-SMA Positive Cytoplasmic Immunoreaction Of Myoepithelial Cells In A Time-dependent Manner From Group II To Group IV. Conclusion: TiO2 NPs Could Produce Changes To The Structure Of SMSG. These Changes Were Both Time And Dose Dependent. Also They Were Persistent, Which Did Not Regress After One Month Following Cessation Of Tio2 NPs Intake.