Evaluation of the effects of monosodium glutamate on the development of the cerebellum in chicken embryos

Monosodium glutamate (MSG) is a globally used food additive in the modern diet. This study aimed to search the impact of varying doses of MSG administered on embryonic development of the cerebellum. A total of 410 fertilized chicken eggs were randomly assigned to five groups: an untreated control group, a vehicle control group, and groups receiving low-dose (0.12 mg/g egg), medium-dose (0.6 mg/g egg), and high-dose (1.2 mg/g egg) MSG, respectively. The test solutions were injected into the yolk of eggs through a sterile insulin injector. On the 15th, 18th, and 21st days of incubation, the eggs from each group were randomly opened, and six live embryos were obtained. Cerebellum samples of embryos from each group were taken. The number of Purkinje cells in the cerebellum demonstrated a reduction in MSG-treated groups by the 15th, 18th, and 21st days of incubation (p < 0.05). It was noted that the organization of Purkinje cells was irregular, and degeneration and necrosis were also observed in the MSG-treated groups. A notable decrease in the thickness of both the outer and inner granular layers was observed in the MSG-treated groups on the 15th, 18th, and 21st day of incubation. While molecular layer thickness increased on day 15 and 21, decreased on day 18 (p < 0.05). Total cortex thickness decreased significantly in MSG-treated groups. PCNA-positive cells in the cerebellum were found in Purkinje cells, molecular layer cells, and outer and inner granular layer cells. However, there was a decrease in PCNA (+) cell density in MSG-treated groups (p < 0.05).