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Background: Submandibular salivary glands are responsible for secretion of major amount of saliva which is important for normal oral environment of the oral cavity. Aim: to evaluate the effect of the Immunosuppressive drug Sirolimus on structure and immunohistochemistry of the submandibular salivary glands of the rats. Material and Methods Forty healthy adult male albino rats (body weight 150 -180 gram) were divided into two equal groups 20 animals each. Group 1 served as controls while group 2 were treated with the immunosuppressive drug sirolimus (rapamycin). Control group were subdivided into two subgroups subgroup 1.1: received ethanol and saline in comparable volume to group 2 and same route of administration while subgroup 1.2 were left untreated. After 3 months, rats were sacrificed and specimens of the right side of submandibular salivary glands were stained with H & E and Immunoperoxidase. While specimens of the left side were examined with transmission electron microscope. Results: Histologically, by H & E, both control subgroups showed normal structure of submandibular salivary gland. While, rats administrated sirolimus showed altered structure. Using TEM, the ultrastructural of submandibular salivary glands of both control subgroups showed normal architecture. While, sirolimus treatedgroup revealed degeneration in the glands acinar and ductal cells. Immunohistochemical findings showed normal staining reactivity of submandibular salivary gland of the control group while, sirolimus-treated group showed marked reduction in their staining reaction. Conclusion: Sirolimus administration cause structural and ultrastructural alterations in the parenchymal and stromal elements of the submandibular salivary gland that affect the salivary secretion and may lead to detrimental effect on oral health.

Introduction:With the growing interest in the applications of gold nanoparticles (AuNPs) in biotechnology and their physiological effects, possible toxicity of gold nanoparticles is becoming an increasingly important issue. It was shown that the toxicity is both dose-and size-dependent, and the AuNPs of higher concentration would cause more cytotoxicity. Aim: Aim of this work was to study the toxic effect of intraperitoneal administration of gold nanoparticles -if any-on the mucous membrane of the tongues of albino rats and the possibility of one-month recovery period. Material and Methods: Forty-six male albino rats were used in the present investigation. They were divided into the following groups: Group (1) (16 rats) served as controls, they received the solvent of AuNPs intraperitoneally daily for 21 days. Group (2) (15 rats) received 10mg/kg body weight of AuNP solution intraperitoneally daily for 21 days. Group (3) (15 rats) were treated the same way as Group 2 for 21 days and then left for one-month as a recovery period. Results: Examination of the tongue of the rats which were exposed to gold nanoparticles solution revealed atrophic and degenerative changes of both the dorsal and ventral surfaces of the tongue as well as the lingual salivary glands. The examined tongues of the rats which were allowed a recovery period showed improvement in the histological picture. Conclusion: Exposure to over dose of AuNPs causes atrophic and degenerative changes. A recovery period of one-month can lead to regeneration and improvement in the histological picture.Properties of gold nanoparticles such as shape, size, surface chemistry, targeting ligand, elasticity, and composition largely influence

Introduction: Tacrolimus is a macrolide calcineurin inhibitor which has been shown to decrease acute and chronic rejection, improved renal function over the longterm post-transplant. Tacrolimus is considered the drug of choice in immunosuppressive therapy for chronic diseases irresponsive to corticosteroids, autoimmune diseases and organ transplantation system. Aim: The aim of the investigation was to study the effect of the immunosuppressive drug Tacrolimus on the lingual mucous membrane and salivary glands of treated rats through hematoxylin and eosin stained sections to detect any microscopic changes in the structure of the mucous membrane and salivary glands of the tongues & Masson's trichrome stained sections for detection of the integrity of collagen. Material and Methods: Thirty healthy adult male albino rats with body weight ranging from 150 to 180 gm were used in this investigation. The animals were divided into two groups 15 animals each. Group 1: served as control, group 2: animals were treated with the immunosuppressive drug tacrolimus dissolved in distilled water in a daily oral dose of 0.5 mg/kg body weight. At the end of the experiment the rats of different groups were euthanized by cervical dislocation. The tongues were dissected out, fixed, processed, embedded in paraffin, sectioned and stained with hematoxylin and eosin for histological evaluation & Masson's trichrome stain for demonstration of collagen fibers. Results: The light microscopic examination of group I showed the normal histological features of both surface epithelium and underlying lamina propria, while group II Treated with tacrolimus revealed atrophic and degenerative changes that involved the surface epithelium and lamina propria of both the dorsal and ventral surfaces of the tongue as well as the lingual salivary glands. Conclusion: Tacrolimus administration showed structural alterations in the lingual mucous membrane and the lingual salivary glands which will certainly affect the taste sensation.