Effects of ascorbate on monosodium glutamate-associated toxicities that may impact upon immunocompetence

Abstract

Excitotoxic food additives react with specialized receptors in the brain and other tissues. Unfortunately, in many instances, these reactions lead to free radical generation (resulting in oxidative stress/lipid peroxidation) and altered membrane fluidity. Ultimately, damage induced by these agents was shown to give rise to endocrine disorders and altered cell-mediated immune responses in general, and dysfunction of lymphocytes and macrophages in particular. The effects of ascorbate against some basic toxicities (that ultimately evolve into endocrine and immune system dysfunctions) induced by monosodium glutamate (MSG) was studied in rats. For 21 days, control rats received a daily placebo (4 mL distilled water) via gastric intubation; other rats were treated daily with 100 mg MSG kg−1 body weight or 100 mg MSG + 100 mg ascorbate kg−1 in 4 mL vehicle. A day after the final exposure, rats were euthanized. Serum was isolated to examine several lipid and electrolyte parameters, i.e. cholesterol, triglycerides, VLDL LDL, HDL, Na+, K+, Cl−, and . Rat spleen and thymus were also harvested for analysis. Results showed that, compared to effects from MSG alone, co-ingestion of ascorbate led to reductions in serum cholesterol, LDL, Na+, and K+. Only with serum HDL, ascorbate leads to increases compared to MSG alone. The co-treatment was also seen to block/mitigate the near three-fold rise in thymic and splenic absolute weights (and respective organ indices) produced by exposure to MSG alone. Similarly, MSG treatment also induced significant increases in blood levels of both monocytes/macrophages and eosinophils; these outcomes were again reversed by co-treatment. Data suggest that co-ingestion of ascorbate may help reduce the risk from some toxicities attributable to selective dietary constituents/additives.