Glutamate Neurotoxicity in Rat Cerebellar Granule Cells: A Major Role for Xanthine Oxidase in Oxygen Radical Formation

• Published in: Journal of neurochemistry Vol. 68; no. 5; pp. 2038 - 2045
• Main Authors: Atlante, A., Gagliardi, S., Minervini, G. M., Ciotti, M. T., Marra, E., Calissano, P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-05-1997; Blackwell
• Subjects: Animals; Biochemistry and metabolism; Biological and medical sciences; Central nervous system; Cerebellar granule cells; Cerebellum - cytology; Cerebellum - drug effects; Cerebellum - metabolism; Fundamental and applied biological sciences. Psychology; Glutamate; Glutamic Acid - pharmacology; Neurotoxicity; Neurotoxins - pharmacology; Oxygen radicals; Peroxides; Peroxides - metabolism; Rats; Rats, Wistar; Reactive Oxygen Species - metabolism; Vertebrates: nervous system and sense organs; Xanthine oxidase; Xanthine Oxidase - physiology; Cerebellum; Oxidative stress; Oxygen; Granule neuron; Rat; Enzyme; Toxicity; Rodentia; Central nervous system; Glutamate; Free radical; Vertebrata; Mammalia; Investigation method; Excitatory aminoacid; Neurotransmitter; Xanthine oxidase; Oxidoreductases; Photometry; Brain (vertebrata)
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.1997.68052038.x

: To gain insight into the mechanism through which the neurotransmitter glutamate causally participates in several neurological diseases, in vitro cultured cerebellar granule cells were exposed to glutamate and oxygen radical production was investigated. To this aim, a novel procedure was developed to detect oxygen radicals; the fluorescent dye 2′,7′‐dichlorofluorescein was used to detect production of peroxides, and a specific search for the possible conversion of the enzyme xanthine dehydrogenase into xanthine oxidase after the excitotoxic glutamate pulse was undertaken. A 100 µM glutamate pulse administered to 7‐day‐old cerebellar granule cells is accompanied by the onset of neuronal death, the appearance of xanthine oxidase, and production of oxygen radicals. Xanthine oxidase activation and superoxide (O2•−) production are completely inhibited by concomitant incubation of glutamate with MK‐801, a specific NMDA receptor antagonist, or by chelation of external calcium with EGTA. Partial inhibition of both cell death and parallel production of reactive oxygen species is achieved with allopurinol, a xanthine oxidase inhibitor, leupeptin, a protease inhibitor, reducing agents such as glutathione or dithiothreitol, antioxidants such as vitamin E and vitamin C, and externally added superoxide dismutase. It is concluded that glutamate‐triggered, NMDA‐mediated, massive Ca2+ influx induces rapid conversion of xanthine dehydrogenase into xanthine oxidase with subsequent production of reactive oxygen species that most probably have a causal involvement in the initial steps of the series of intracellular events leading to neuronal degeneration and death.