Regional uptake of neurotoxic and nontoxic amino acids in vivo by the infant mouse brain

The acidic amino acids, glutamate, cysteate and homocysteate. destroy neurons in the arcuate nucleus of the hypothalamus when administered subcutaneously to infant mice. but alanine. a neutral amino acid, does not, The neurotoxicity of glutamate, cysteate and homocysteate was confirmed in this study. It was further demonstrated that glutamate accumulates in the arcuate nucleus after the administration of glutamate but not after cysteate or homocysteate administration. This rules out the possibility that the neurotoxicity of the latter two compounds is mediated by the conversion in vivo of these compounds to glutamate. It supports the thesis that the similar neurotoxic manifestations of these compounds stem from the similar molecular structure they share. Alanine accumulated in the arcuate and ventromedial nuclei of the hypothalamus and, to a lesser extent, the medial nucleus of the thalamus but had no neuropathologic effects in any brain region. The failure of alanine to damage arcuate neurons is interpreted as evidence that, because of its dissimilar molecular structure. it either does not react or reacts very differently from the acidic neuroloxic amino acids at some receptor locus on neural membranes.