Is a certain amount of cysteine prerequisite to produce brain damage in neonatal rats?

In this study, various manipulations were used to determine if certain amounts of cysteine are essential to damage the neonatal rat brain. The information gathered from this study indicated that concentration of free cysteine may be 0.6 mumol/g of wet brain weight or more to cause the toxicity to produce the brain damage, and the results were discussed in the light that free cysteine might itself be the cause of brain damage.