title: The Effects of Monosodium Glutamate and Tannic Acid on Adult Rats.
abstract: BACKGROUND
  Monosodium glutamate (MSG) is a widely-used flavor enhancer and stabilizer in ready-made or packaged foods. The excessive use of MSG has been shown to increase oxidative stress in different organ systems and causes glucose metabolism disorders, obesity, and coronary diseases.
  
  
  OBJECTIVE
  In this study, the antioxidant activity of tannic acid was investigated experimentally with respect to its protective effects against overdosed MSG-induced oxidative stress in rats. The study took place in Turkey in August 2013.
  
  
  METHODS
  Four groups (n = 7) of three- to four-month-old Sprague-Dawley female rats were used in this study. The first group was the control, who were administered saline. The second group received tannic acid (50 mg/kg, 3 days) intraperitoneally (i.p.). The third group received MSG (2 g/kg, 7 days) i.p., and the fourth group received both tannic acid (50 mg/kg, 3 days, pretreatment) and MSG (2 g/kg, 7 days) i.p. The animals were euthanized ten days later. Blood was collected for determining the hematological values and blood glucose levels. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels were determined in the brain, liver, and kidney homogenates, and in the erythrocyte hemolysate. Histopathological examination of the brain, liver, and kidneys was conducted through hematoxylin-eosin staining.
  
  
  RESULTS
  The data showed that the tannic acid treatment statistically decreased the MDA levels in the brain tissues of the group administered MSG and tannic acid (P < 0.001) when compared to the corresponding values of the control group. The SOD activities in the blood hemolysates of the MSG and tannic acid group increased when compared to the corresponding values for the MSG group (P < 0.01). Additionally, we found that pretreatment with tannic acid reduced blood glucose levels in comparison to the levels of the MSG group (P = 0.029). The results of our study show that tannic acid pretreatment in adult rats decreased blood glucose levels and oxidative stress.
  
  
  CONCLUSIONS
  In the literature, it was observed that short-term MSG exposure does not cause significant histological changes in the kidneys, liver, or brain cortex. These findings should be re-evaluated in additional long-term studies.
authors.affiliation: Department of Medical Biology, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Ugur Calis
authors.affiliation: Department of Medical Biology, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Didem
authors.initials: D
authors.lastname: Turgut Cosan
authors.affiliation: Department of Medical Biology, Recep Tayyip Erdogan University, Faculty of Medicine, Rize, Turkey.
authors.forename: Faruk
authors.initials: F
authors.lastname: Saydam
authors.affiliation: Department of Medical Biology, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Umut
authors.initials: U
authors.lastname: Kerem Kolac
authors.affiliation: Department of Medical Biology, Istanbul Aydin University, Faculty of Medicine, Istanbul, Turkey.
authors.forename: Ahu
authors.initials: A
authors.lastname: Soyocak
authors.affiliation: Department of Medical Biology, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Hulyam
authors.initials: H
authors.lastname: Kurt
authors.affiliation: Department of Medical Biology, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Hasan
authors.initials: H
authors.lastname: Veysi Gunes
authors.affiliation: Department of Histology and Embryology, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Varol
authors.initials: V
authors.lastname: Sahinturk
authors.affiliation: Department of Biostatistics, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Fezan
authors.initials: F
authors.lastname: Sahin Mutlu
authors.affiliation: Vocational School of Health Services, Eskisehir Osmangazi University, Eskisehir, Turkey.
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Ozdemir Koroglu
authors.affiliation: Department of Medical Biology, Eskisehir Osmangazi University, Faculty of Medicine, Eskisehir, Turkey.
authors.forename: Irfan
authors.initials: I
authors.lastname: Degirmenci
keywords: Antioxidant; Monosodium Glutamate; Oxidative Stress; Tannic Acid