الفهرس 
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Abstract
Most food additives act either as preservatives, or enhancers of palatability. One of such these food additives is Monosodium glutamate (MSG). The safety of MSG usage has generated much controversy especially on the liver. Since ascorbic acid and Alpha-tocopherol together with MSG may be present in human diet, the present study aimed to evaluate the histological changes of the liver in rats received MSG and the possible protective role of vitamin C (ascorbic acid) and vitamin E (Alpha-tocopherol) on these effects.
To achieve this aim, twenty four adult albino rats weighting 150-250 grams each were used in the present study. The animals were divided into four groups. Each group consisted of 6 rats as follows: group A (served as control), group B (experimental group where rats received MSG for 14 days), group C (experimental group, in which the rats were fed with a diet containing MSG concomitant with ascorbic acid for 14 days), and group D (experimental group, in which the animals were fed with a diet containing MSG together with alpha-tocopherol for 14 days). The liver specimens were then subjected to normal histological procedures for paraffin embedding. Sections were cut at the thickness of 5 microns and were stained with Hematoxylin and Eosin, and histochemical staining with Masson’s Trichome and Periodic acid Schiff (P.A.S.).
In the present work, liver sections obtained from control group A served to study the basic microscopic structure of its parenchyma.
Examination of liver sections in group B revealed that the liver architecture was distorted, the majority of hepatocytes were vacuolated and some of their nuclei were small and dark. Moreover, congestion was observed at portal tracts, central veins, and in the blood sinusoids between the vacuolated hepatocytes. Sections stained with Masson’s trichrome in this group demonstrated dense collagen fibers surrounding the central veins and portal tracts. Strands of collagen fibers were seen radiating from the central veins and extending between hepatocytes. P.A.S.-stained sections showed heterogenic distribution of PAS-positive reaction.
Examination of liver sections obtained from the group C showed moderate restoration of the liver architecture. Among the liver cords, normal hepatocytes could be seen while others showed vacuolation. Central veins and portal tract showed congestion. Using Masson’s trichrome stain, collagen fibers between the cords of hepatocytes were seen almost as in the control groups with minimal increase in their deposition around the central veins, whereas sections stained by P.A.S. stain demonstrated moderately positive P.A.S. reaction in hepatocyte cytoplasm without deposition of P.A.S.-positive material in the basal lamina of the blood sinusoids.
Lastly, sections obtained from group D revealed marked improvement in histological appearance without distortion of hepatic architecture. The hepatocytes showed almost normal appearance without vacuolation and were arranged in regularly radiating liver cords around the central veins. Slight congestion of central vein was also observed. In liver sections stained by Masson’s trichrome stain, connective tissues between the cords of hepatocytes were seen almost as in the control group with minimal increase in collagen fibers deposition in the areas of portal tracts. group D liver sections stained by P.A.S. stain demonstrated mild positive P.A.S. reaction in the cytoplasm of the hepatocytes without the mosaic heterogenic appearance seen in group B.
The present work pointed out that despite the ability of MSG to cause hepatotoxicity in rats, the presence of vitamin C and vitamin E in the diet ameliorated the MSG-induced liver histopathological changes. Moreover, vitamin E hepatoprotective effect was slightly better than that of vitamin C as regards either the hepatic architecture or hepatocytes integrity.