Glutamate mobilizes [Zn2+] through Ca2+ -dependent reactive oxygen species accumulation.

Liberation of zinc from intracellular stores contributes to oxidant-induced neuronal injury. However, little is known regarding how endogenous oxidant systems regulate intracellular free zinc (Zn(2+)). Here we simultaneously imaged Ca(2+) and Zn(2+) to study acute Zn(2+) changes in cultured rat forebrain neurons after glutamate receptor activation. Neurons were loaded with fura-2FF and FluoZin-3 to follow Ca(2+) and Zn(2+), respectively. Neurons treated with glutamate (100 microM) for 10 min gave large Ca(2+) responses that did not recover after termination of the glutamate stimulus. Glutamate also increased Zn(2+), however glutamate-induced Zn(2+) changes were completely dependent on Ca(2+) entry, appeared to arise entirely from internal stores, and were substantially reduced by co-application of the membrane-permeant chelator TPEN during the glutamate treatment. Pharmacological maneuvers revealed that a number of endogenous oxidant producing systems, including nitric oxide synthase, phospholipase A(2), and mitochondria all contributed to glutamate-induced Zn(2+) changes. We found no evidence that mitochondria buffered Zn(2+) during acute glutamate receptor activation. We conclude that glutamate-induced Zn(2+) transients are caused in part by Ca(2+)-induced reactive oxygen species that arises from both cytosolic and mitochondrial sources.