Abstract
Monosodium glutamate (MSG), a commonly used flavor enhancer, has been reported to induce hepatic and renal dysfunctions. In this study, the palliative role of protocatechuic acid (PCA) in MSG-administered rats was elucidated. Adult male rats were assigned to four groups, namely control, MSG (4 mg/kg), PCA (100 mg/kg), and the last group was co-administered MSG and PCA at aforementioned doses for seven days. Results showed that MSG augmented the hepatic (AST and ALT) and renal (urea and creatinine) functions markers as well as glucose, triglycerides, total cholesterol and LDL levels. Moreover, marked increases in MDA levels accompanied by declines in GSH levels and notable decreases in the activities of SOD, CAT, GPx, and GR were observed in MSG-treated group. The MSG-mediated oxidative stress was further confirmed by down-regulation of Nfe2l2 gene expression levels in both tissues. In addition, MSG enhanced the hepatorenal inflammatory response as witnessed by increased inflammatory cytokines (IL-1b and TNF-α) and elevated NF-κB levels in both tissues. Further, significant increases in Bax (pro-apoptotic biomarker) levels together with decreases in Bcl-2 (anti-apoptotic marker) levels were observed in MSG administration. Hepatic and renal histopathological screening supported the biochemical and molecular findings. On the contrary, co-treatment of rats with PCA resulted in remarkable enhancement of the antioxidant cellular capacity, suppression of inflammatory mediators and apoptosis. These effects are possibly endorsed for activation of Nrf-2 and suppression of NF-kB signaling pathways. Collectively, addition of PCA counteracted MSG-induced hepatic and renal injurious effects through modulation of oxidative, inflammatory and apoptotic alterations.