Astrocytes in methylmercury, ammonia, methionine sulfoximine and alcohol-induced neurotoxicity

Astrocytes occupy ~25% of the CNS volume. Their 'foot' processes are closely associated with synapses, nodes of Ranvier, axonal tracts, and capillaries. Astrocytic functions include neurotrophic factor secretion, control of extracellular pH, inactivation of glutamate, as well as uptake and metabolism of neurotransmitters. Astrocyte-neuron interactions provide strategic sites for actions of numerous chemical compounds. In this manuscript, we discuss examples of toxins that directly affect astrocyte function (methylmercury, ammonia, methionine sulfoximine, and alcohol), leading to an altered homeostatic control of the extracellular milieu and neuronal dysfunction. In addition, the potential role of astrocytic proteins, the metallothioneins, in attenuating the neurotoxicity of methylmercury is discussed. (C) 2000 Intox Press, Inc.