The Effect of Monosodium Glutamate on Neuronal Signaling Molecules in the Hippocampus and the Neuroprotective Effects of Omega-3 Fatty Acids

Abstract

Monosodium glutamate (MSG) is a flavoring substance added to many ready-to-eat foods and has known neurotoxic effects. This study was performed in order to examine the potential toxic effect of MSG on neurons in various regions of the hippocampus in prepubertal rats. It also investigated the protective effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on brain-derived neurotropic factor (BDNF), n-methyl-D-aspartate receptor (NMDA-R), and neuropeptide-Y (NPY) expression in the brain, using immunohistochemical and biochemical methods. Six female prepubertal Wistar albino rats were used in each group. Group 1, the control group, received 0.9% saline solution subcutaneously (sc) on days 1, 3, 5, 7, and 9. Group 2 received 4 mg/g MSG sc on days 1, 3, 5, 7, and 9. Group 3 received MSG + EPA (4 mg/g sc on days 1, 3, 5, 7, and 9. Oral 300 mg/kg for 9 d), while Group 4 received MSG + DHA (4 mg/g sc on days 1, 3, 5, 7, and 9 and 300 mg/kg orally for 9 d, respectively). At the end of the ninth day the hippocampal regions of the brain were removed and either fixed for immunohistochemical staining or stored at −80 °C for biochemical parameter investigation. BDNF, NMDA-R, and NPY expression results were evaluated using immunohistochemistry and an enzyme-linked immunosorbent assay. According to our findings, neurons in the control group hippocampal CA1 and DG regions exhibited strong BDNF, NPY, and NMDA-R reactions, while an expression in both regions decreased in the MSG group (p < 0.00). However, in the MSG-EPA and MSG-DHA groups, BDNF, NPY, and NMDA-R immunoreactions in neurons in the same region were similar to those of the control group (p = 0.00). No significant difference was observed in terms of expression in hippocampal neurons between the MSG-EPA and MSG-DHA groups (p > 0.00). In conclusion, since MSG caused a decrease in BDNF, NMDA-R, and NPY neural signaling molecules in the CA1 and DG regions of the hippocampus of prepubertal rats compared to the control group, care is required over the consumption of MSG, since it may affect memory-related neurons in these age groups. In addition, we concluded that the use of omega-3 fatty acids such as EPA and DHA in addition to MSG may protect against the neurotoxic effects of MSG.

The Influence of Sodium Glutamate on the Microstructure of the Thyroid Gland of Mature White Rats

“…Харчова добавка глутамат натрію (MSG) може стимулювати чутливі рецептори, покращувати смак страв та збільшувати апетит, тому MSG вважається однією з основних причин збільшення ваги [9]. Деякі дослідження відзначали набір ваги у новонароджених мишей після прийому MSG, що призводило до уражень в дугоподібному ядрі гіпоталамуса (ARCN) [10].…”

Targeting Glutamate Neurotoxicity through Dietary Manipulation: Potential Treatment for Migraine

“…Therefore, substitution of omega-3 fatty acids for omega-6 could offer beneficial effects on excitotoxic brain damage. Additionally, eicosapentaenoic acid (EPA) and DHA (long-chain omega-3s) also showed promising benefits for protecting against monosodium glutamate (MSG) neurotoxicity in the hippocampus of prepubertal rats [ 110 ]. This neuroprotective effect of omega-3s could be attributed to their role in enhancing the plasticity, communication, and function of astrocytes [ 111 ].…”

Investigation of the Protective Effect of Omega-3 Fatty Acids on Monosodium Glutamate-Induced Hippocampal Injury

“…Bu iki boyama arasında ve son inkübasyondan sonra kesitler üç defa 5 dakika PBS ile yıkandı. İmmunohistokimyasal reaksiyonun görünürlüğünü saptamak amacıyla kesitler 3-Amino-9-Ethylcarbazole (AEC) ile 5 dakika boyanarak, Çekirdek boyası olarak Mayer'in hematoksilen'i kullanılıp, boyanan camlar lamlar ultramount ile lamelle kapatılıp, Olympus CX31 mikroskobuyla incelenerek fotoğraflandı (20). Fotoğraflarda Leica Q Win Plus analiz sistemi kullanılarak sayımlar yapıldı.…”