Comparative effect of neonatal and adult exposure to monosodium glutamate

Abstract

Purpose: Exposure to monosodium glutamate (MSG) is reported to have different effects on exposed rats depending on the age of exposure, believed to be as a result of its ability to pass the blood–brain barrier and affect the level and function of neurotransmitters in the central nervous system. Aim: The present study is aimed at understanding the differential effect of MSG in rats exposed either as neonate, neonate plus adult or adult only by measuring the metabolism of selected neurotransmitters in the brain. Materials and Methods: Neonates were grouped into 2 administered 4 mg/g body weight MSG and Saline (control) on postnatal days 2, 4, 6, 8, and 10. The rats were allowed to mature for 30 weeks afterwards the MSG group were further divided into three groups (n = 6) and administered saline, 5 and 10 mg/g of MSG. Two other groups, not exposed to MSG at neonatal age, were similarly administered 5 and 10 mg/g of MSG, administration lasted for 6 weeks. Key enzymes of acetylcholine and tyrosine metabolisms as well as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured in whole brain homogenates. Results: Showed an increase in acetylcholinesterase and tyrosine hydroxylase activities which occurred similarly in both neonatal and adult administered groups. AST and ALT showed a similar activity significantly higher adult groups. Conclusion: MSG affected both neonate and adult administered groups similarly in a dose dependent manner.