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Reactive Oxygen Species Influence Nerve Growth Factor Synthesis in Primary Rat Astrocytes
Author(s) -
Naveilhan Philippe,
Neveu Isabelle,
Jehan Frédéric,
Baudet Christel,
Wion Didier,
Brachet Philippe
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.62062178.x
Subject(s) - nerve growth factor , anisomycin , microbiology and biotechnology , xanthine , protein biosynthesis , chemistry , xanthine oxidase , reactive oxygen species , trichloroacetic acid , biochemistry , biology , enzyme , receptor
Newborn rat brain astrocytes, cultured in a serum‐free medium, were exposed for 30 min to two types of reactive oxygen species. Cells were either treated with the xanthine/xanthine oxidase (X/XOD) system, which generates both H 2 O 2 and the O 2 βradical, or to H 2 O 2 alone. Both treatments induced a dose‐dependent accumulation of nerve growth factor (NGF) transcripts, 6 h after the exposure. Maximal effect was obtained with 6 mU/ml XOD, or 10– 4 M H 2 O 2 . A rapid expression of protooncogenes of the jun and fos families was also noticed in X/XOD‐or H 2 O 2 ‐treated cells. This phenomenon was transient in cells exposed to X/XOD. However, in the case of H 2 O 2 ‐treated cells, the accumulation of c‐fos or c‐jun mRNAs was still pronounced 6 h after the end of the treatment and the levels of cell‐secreted NGF appeared relatively reduced, when compared with those obtained after a shock with the X/XOD system. This raised the possibility that H 2 O 2 at 10– 4 M could depress protein synthesis. Measurements of the incorporation of radiolabeled amino acids into trichloroacetic acid‐precipitable material supported this assumption. Level of radioactivity associated with cellular material was dramatically reduced in H 2 O 2 ‐treated cells, when it was compared with control or XI XOD‐trreated cells. Furthermore, treatment of cells with the protein synthesis inhibitor anisomycin had an effect similar to that of H 2 O 2 because it caused an accumulation of c‐fos, c‐jun , and NGF transcripts after 6 h of treatment. It is concluded that the effect of H 2 O 2 results from an impairment of protein synthesis, which is accompanied by the “superinduction” of c‐fos, c‐jun , or NGF genes. To understand better the effect of X/XOD, the reaction was conducted in the presence of a large excess of catalase, which removes H 2 O 2 . The presence of catalase reduced the amplitude of the response of the NGF gene to the X/XOD treatment. Conversely, low doses of H 2 O 2 and X/ XOD were more efficient for the production of NGF than each treatment alone. These results suggest that both O 2 β and H 2 O 2 are important metabolites in the process of activation of the NGF gene, possibly via the formation of the OH* radical or other reactive products, which could constitute active regulatory molecules.