Histopathological and histochemical changes induced by the administration of monosodium glutamate (MSG) and the Possible ameliorative effects of a natural antioxidants ( Propolis)

Abstract

Food additives are chemical substances added intentionally to food stuffs to preserve, colour, sweeten and flavor food. Monosodium glutamate (MSG) is used as a flavor enhancer and is found in most soups, salad dressing and processed meat. The use of MSG in food is growing. Irrational fear had increased in the last few years due to the adverse reactions and toxicity of MSG. Propolis, a resinous wax-like beehive product has been used as a traditional remedy for various diseases due to a variety of biological activities of this folk medicine. The present study aimed to investigate the protective and curative effects of propolis against MSG on the rat liver. Fifty male albino rats - each weighs 75-95 g- were assigned to five groups of 10 rats each: 1) rats received distilled water for 8 weeks (controls); 2) rats received 200 mg propolis /kg b. w. for 8 weeks (Propolis group); 3) rats received 1 g MSG /kg. b. w. for 8 weeks (MSG group); 4) rats received 200 mg propolis /kg. b. w. for 8 weeks + 1 g MSG /kg. b. w. during the last 4 weeks (protective group); 5) rats received 1 g MSG /kg. b. w. for 8 weeks + 200 mg propolis /kg. b. w. during the last 4 weeks (therapeutic group). Rats were received their respective doses daily by oral gavage and sacrificed 24 h after the last dose of different administrations. Histopathological studies displayed deleterious alterations in the liver tissues where MSG caused disorganization of hepatic architecture with hyaline degeneration, inflammatory reaction and leucocytic infiltration together with swollen vacuolar hyaline degeneration and even atrophy and necrosis of hepatocytes. Congestion, dilatation, damage of blood vessels and haemorrhage were met with. The portal tract showed increased fibrosis, thick walled fibrotic portal vein and inflammatory cell infiltration. Histochemical studies revealed that MSG alone decreased polysaccharides and total proteins in the liver tissue. Propolis extract in the protective group was effective in restoring MSG induced histopathological and histochemical alterations. On the contrary, propolis extract in the curative group showed mild improvement to the changes induced by MSG. The results of this study confirm the hepatotoxic effect of MSG and the ameliorative effect of propolis, especially when administrated as a prophylactic substance than therapeutic.