Age-related changes on MAO in Bl/C57 mouse tissues: a quantitative radioautographic study.

The distribution of MAO-A and -B in brain and peripheral tissues of Bl/C57 mice and their changes during ageing were studied by quantitative enzyme radioautography with [3H]Ro41-1049 and [3H]Ro19-6327. In the brain, MAO-A decreased between weeks 4 and 8 and then remained unchanged until 25 months, whereas MAO-B increased for the whole period studied. Heart also showed a continuous increase in MAO-B, but not MAO-A, with ageing, and liver showed a decrease in MAO-B in the older animals. These results show marked species differences in the distribution and age-related changes of MAO and might help to elucidate the high sensitivity of Bl/C57 mouse of MPTP, which increases with age.