Evidence of increased oxidative stress in hippocampal primary cultures of trisomy 16 mouse. Studies on metallothionein-I/II

In the trisomy 16 mouse che increased gene dosage of SOD-1 increases H2O2 p roduction that results in increased oxidative stress. We report here that i n hippocampal primary cultures, metallothionein (MT)-I/II immunoreactivity was present mainly in glial fibrillary acidic protein-immunolabeled cells. Western blot analysis showed a two-fold higher level of MT-I/II in trisomy 16 mice then in euploid Littermates. In contrast, the immunoreactivity of g lutamine synthetase, another glia-expressed protein, was similar in hippoca mpal cultures of trisomy 16 mouse and euploid littermates. Oxyblot analysis of hippocampal cultures showed that the carbonyl content in several protei n bands was higher in trisomy 16 mice than in euploid littermates giving ev idence for increased oxidative stress in trisomy 16 mouse cultures. To eval uate the responsiveness of MT-I/II to agents that increase the level of rea ctive oxygen species in cells we measured the effect of H2O2, kainic acid, (+/-)ACPD, and beta-amyloid peptide 1-42. Western blot analysis documented that in hippocampal cultures of euploid littermates MT-I/II was maximally i ncreased by 50 mu M H2O2, 100 mu M kainic acid, 10 mu M (+/-)ACPD, or 1.0 m M beta-amyloid peptide 1-42, whereas in those of trisomy 16 mice no further increase above the elevated level was observed. Our data suggest that in t he trisomy 16 mouse the production of reactive oxygen species may have shif ted the intracellular redox environment that could have altered the suscept ibility of MT-I/II transcription. The possibility that transcription factor s whose activation may be essential to initiate MT-I/II transcription get o xidized has yet to be examined.