Monosodium glutamate (MSG) is a major taste enhancer that is used as a food additive. Vitamin C (Vit C) and Nigella sativa oil (NSO) are known for their potent antioxidant activities.

Objective

This study investigates the adverse effect of MSG on the thyroid gland and cerebellum of adult male albino rats and the protection against MSG-mediated toxicity provided by Vit C and NSO.

Design

Fifty rats were divided into five groups that were treated via oral gavage. Group I (control) rats received distilled water, Group II rats were treated with MSG (6 mg/gm body weight/day), Group III rats were treated with MSG and Vit C (100 mg/kg body weight /day), Group IV rats were treated with MSG and NSO (50 mg/kg body weight two times per week), and Group V rats were treated with MSG together with both Vit C and NSO with MSG. After 60 days of treatment, rats were euthanized and histological sections were prepared from the thyroid gland and the cerebellum for routine staining and immunohistochemical detection of glial fibrillar acidic protein (GFAP), Caspase-3 and proliferating cell nuclear antigen (PCNA), respectively. Cerebellar tissue was also evaluated to determine glutathione (GSH) and malondialdehyde (MDA) levels; GSH was also measured in thyroid tissue. Serum levels of fT3, fT4 and TSH (thyroid stimulating hormone) were also evaluated.

Results

Microscopic examination of cerebellar tissues revealed significant cerebellar injury and cellular apoptosis among the rats in Group II. The thyroid glands of Group II rats were notable for degenerating follicles, loss of colloid, sloughed follicular cells and congested blood vessels. The cerebellar and thyroid tissues from rats in treatment Groups III, IV and V revealed significantly less pathology. Cerebellar and thyroid tissues from Group II rats that were treated with MSG alone revealed intense GFAP and caspase-3 (cerebellar) and PCNA (thyroid) immunoreactivity. Furthermore, cerebellar tissues from rats received MSG alone (Group II) were notable for decreased levels of GSH and increased levels of MDA; thyroid tissue from rats in Group II also demonstrated decreased levels of GSH. Likewise, serum fT3 and fT4 levels were significantly decreased, while serum TSH was significantly increased among rats in Group II. Combined administration of Vit C and NSO together with MSG (Group V) revealed some variations in oxidative parameters compared to those in the Group I control rats.

Conclusions

Oral intake of MSG resulted in degenerative changes in neurons and astrocytes in cerebellum and, also degeneration of the thyroid glands of albino rats. Concomitant administration of Vit C and NSO may limit MSG-induced damage to the cerebellum and thyroid glands and thereby provide significant protection against the oxidative damage induced by MSG.

中文翻译：

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鼠尾草油和维生素C对暴露于谷氨酸钠的成年雄性白化病大鼠甲状腺和小脑的改善作用（组织学，免疫组化和生化研究）。

味精（MSG）是一种主要的增味剂，被用作食品添加剂。维生素C（Vit C）和Nigella sativa oil（NSO）以有效的抗氧化作用而闻名。

目的

这项研究调查了味精对成年雄性白化病大鼠甲状腺和小脑的不利影响，以及由Vit C和NSO提供的针对味精介导的毒性的保护作用。

设计

将五十只大鼠分为五组，通过口管法治疗。第一组（对照组）大鼠接受蒸馏水，第二组大鼠接受味精（6 mg / g体重/天），第三组大鼠接受味精和Vit C（100 mg / kg体重/天），第二组静脉内用MSG和NSO（每周两次两次，每次50 mg / kg体重）治疗，而V组大鼠用MSG以及Vit C和NSO和MSG一起治疗。治疗60天后，对大鼠实施安乐死，并从甲状腺和小脑制备组织切片，分别进行常规染色和神经胶质原纤维酸性蛋白（GFAP），Caspase-3和增殖细胞核抗原（PCNA）的免疫组织化学检测。还评估了小脑组织以确定谷胱甘肽（GSH）和丙二醛（MDA）的水平；甲状腺组织中也测定了谷胱甘肽。还评估了血清fT3，fT4和TSH（甲状腺刺激激素）水平。

结果

小脑组织的显微镜检查显示第二组大鼠中小脑损伤和细胞凋亡明显。II组大鼠的甲状腺显着变化为卵泡，胶体丢失，卵泡细胞脱落和血管充血。治疗组III，IV和V中来自大鼠的小脑和甲状腺组织显示出明显更少的病理学。仅用味精治疗的第二组大鼠的小脑和甲状腺组织显示出强烈的GFAP和caspase-3（小脑）和PCNA（甲状腺）免疫反应。此外，仅接受味精的大鼠小脑组织（II组）的GSH含量降低和MDA含量升高。第II组大鼠的甲状腺组织也显示GSH水平降低。同样，血清fT3和fT4水平也明显降低，II组大鼠血清TSH明显升高。Vit C和NSO以及MSG（V组）的联合给药显示出与I组对照组大鼠相比，氧化参数存在一些变化。

结论

口服味精会导致小脑神经元和星形胶质细胞的变性，并导致白化病大鼠的甲状腺变性。维生素C和NSO的同时给药可能会限制味精诱导的对小脑和甲状腺的损害，从而为抵抗味精诱导的氧化损伤提供了重要的保护。