TOXICITY OF MONOSODIUM GLUTAMATE ON ARTICULAR CARTILAGE IN YOUNG MALE AND FEMALE ALBINO RATS: OXIDATIVE STRESS, PRO-INFLAMMATORY CYTOKINES AND FREE AMINO ACIDS

Abstract

Monosodium glutamate (MSG) is a widely used flavor enhancer with a number of adverse effects such as cartilage inflammation. In the current study, we have tested the inflammation in articularcartilages following MSG administration, which might be a contributor to the changes in the markers of oxidative stress and alteration in articular cartilage free amino acids observed in the animals. Thirty two young male and female albino rats divided into two main groups. Rats of the first group, served as male and female control groups received distilled water orally. The second group, male and female groups of eight rats received monosodium glutamate orally at a high dose of 8g/kg b.wt. forlong duration (three months) daily. Monosodium glutamate-treated rats showed significant alterations in serumproinflammatory cytokines, interleukin1- β (IL-1β) and tumor necrosis factoralpha (TNFα)with an increment incartilage homogenatenitric oxide concentration. Also, significant differences in number of oxidative stress parameters likemalondialdehyde (MDA), glutathione (GSH), and total antioxidant activity. In addition, there was significant increases in some free amino acids (Glu, GABA, Asp) contents and significant decreases recorded in the others (Ala, Gly, Tau) in cartilage homogenate following MSG administration at (P<0.05). Moreover, significant increases in serum calcium and phosphorus levels followed the increment of glutamic acidwere shownin MSG-treated rats as compared to control animals. The pattern of induction of oxidative stress and activity of pro-inflammatory cytokines in the animals is an indicatedas that oxidative stress induced by MSG in the cartilage tissues of rats, which might be contributed tocartilage matrix degradation, inflammation and may be osteoarthritis.