mono-sodium glutamate is just the sodium salt of glutamate
It dissociates near instantaneously in aqueous solution
Yet many studies show MSG to be harmful — one of many citations:
Endocrinology. 1984 Jul;115(1):267-72.
Increased responsiveness of the hypothalamic-pituitary axis after neurotoxin-induced hypothalamic denervation.
Spinedi E, Johnston C, Negro-Vilar A.
Abstract
Neonatal treatment with monosodium glutamate (MSG) induces severe neuronal damage in selected brain areas, which in turn results in a number of neuroendocrine abnormalities during adult life. The present study was designed to determine what effects this partial and selective denervation of the hypothalamic-pituitary axis may have on the sensitivity of two key components of that axis, the median eminence (ME) and the anterior pituitary (AP). In order to test any changes in response that may occur after MSG treatment, the release of several peptide hormones from either the ME or the AP was evaluated in vitro, employing specific or general secretagogues....
http://www.ncbi.nlm.nih.gov/pubmed/6145582