Monosodium glutamate (MSG), a commonly used food additive and preservative, was reported to be toxic, especially to nervous tissues. It caused cellular death through oxidative stress. Antioxidants, preferably natural ones, were recommended to be used to guard against oxidative stress.
The aim of this study was to evaluate and compare the possible protective effects of natural antioxidants vitamin C and piperine (black pepper extract) on MSG-induced cerebellar damage in rats.
Materials and methods
Forty adult male Wistar rats were divided equally into four groups: control (I), MSG (II), vitamin C (III), and black pepper (IV) groups. The MSG group received 3 g/kg/ day MSG orally, whereas groups III and IV received, simultaneously with MSG, oral vitamin C (100 mg/kg/day) and oral piperine (10 mg/kg/day), respectively. After 2 weeks, reduced glutathione (GSH) was measured in all animals and then all rats were sacrificed. Cerebellar sections from all groups were subjected to H&E and immunohistochemical staining for glial fibrillary acidic protein (GFAP) and caspase-3. The area percentage of positive reactions was measured and statistically analyzed.
Cerebellar neuronal damage and decreased GSH levels were detected in the MSG group. Preservation of cerebellar structure was detected in groups III and IV; however, more potent protection and nearly normal GSH were observed with piperine. Studying the MSG group immunohistochemically revealed marked decrease in caspase-3-positive reactions versus groups III and IV. However, there was nearly normal caspase-3-positive reaction and significant decrease in GFAP-positive immunoreaction with piperine than with vitamin C.
Both vitamin C and black pepper could preserve the cerebellum histologically in the MSG rat model. However, black pepper was more protective.