Protective effects of oleuropein against monosodium glutamate-induced toxicity in aged rats.

The research aimed to investigate the adverse responses of the aged organism to monosodium glutamate (MSG) exposure and to evaluate the potential protective effects of oleuropein (OLE) against these responses. A total of 48 aged rats were allocated into four distinct experimental groups. Control, MSG, OLE, and MSG+OLE. Treatments were administered via oral gavage for 28 days. Biochemical markers (e.g., TAC, TOC, MDA, ALT, AST) and histopathological analyses of liver, heart and brain tissues were performed. Immunohistochemical evaluations assessed glutamate receptor (GluR) and Kir4.1 expression levels. Statistical analyses included ANOVA and post-hoc tests. MSG administration significantly increased oxidative stress markers (MDA, NO, TOC) and liver enzymes (ALT, AST), while reducing antioxidant levels (TAC, TTL). Histopathological findings revealed liver damage (hemorrhage, sinusoidal dilation) and neuronal degeneration in the prefrontal cortex. OLE co-administration mitigated these effects, reducing oxidative damage and improving liver histology. Immunohistochemical results showed MSG upregulated GluR-1, GluR-2, and mGluR-5 in heart tissue, while OLE restored Kir4.1 expression in the brainstem. OLE demonstrated hepatoprotective and neuroprotective effects against MSG-induced toxicity by reducing oxidative stress and preserving tissue integrity. These findings highlight OLE's potential as a therapeutic agent, however, additional research is required to clarify its underlying molecular pathways. The research supports the consumption of OLE-rich foods to counteract food additive-related toxicity.