Histological and Ultra structural Study of the Effect of Monosodium Glutamate on the Submandibular Salivary Gland of Adult Albino Rats

Introduction: Monosodium glutamate (MSG) is used as a food flavor enhancer all over the world. However, it has adverse effects on human and experimental animals at different organs. Aim: This is study designed to evaluate the histological and the ultrastructure effect of two different doses of MSG on submandibular salivary gland (SMG) of albino rats.
Materials and Methods: Fifteen adult male albino rats (180 -200 gm). They were randomly divided into three groups (n=5). The control group I: rats were received 1 ml distilled water orally once daily for 8 weeks. The experimental groups, group II, group III: rats were received 15 mg/kg and 30 mg/kg b. wt. respectively of MSG dissolved in 0.2 ml of distilled water orally once daily for 8 weeks. Animals were sacrificed and two pairs of (SMG) were dissected out, left side was processed for light microscopic examination LM and the right one for transmission electron microscopic examination TEM.
Results: LM examination of group II revealed some serous acini lost their normal arrangement. The acini were distended, their cytoplasm was vacuolated and some of them were degenerated. Nuclear changes appeared in form of large, hyperchromatic, pleomorphic and some pyknotic nuclei. Dilated intercalated and striated ducts with ill-defined cell borders. Enlarged blood vessels that engorged with red blood cells RBCs found between the acini and the striated ducts. Mucous acini has irregular arrangement with vacuolated cytoplasm and nuclear changes. Group III revealed loss of normal glandular architecture, abnormal shape of serous and mucous acini, obvious nuclear changes. The ductal cells were dilat­ed and blood vessels engorged with RBCs with inflammatory cell infiltration in connec­tive tissue. TEM examination of group II revealed mild changes as irregular outline of electron dense nucleus, occasional confluence of secretory granules. Marked dilatation of ruff endoplasmic reticulum, few number of lysosomes and mild dilatation of intracellular canaliculi. These changes were more obvious at group III.
Conclusion: From the present study we concluded that MSG has degenerative changes at acini and ductal cells of (SMG). Therefore, we recommended that excessive consumption of food containing this salt should be avoided.