Nonetheless, the increased percentage of dead
cells (calcein -/ PI +) after 72 hours of treatment with
melatonin, although moderated, was statistically significant
(p < 0.001) in cells with a more oxidative metabolism. In
these cells, cultured in the galactose medium, more than 50% of the cellular mass was lost after 72 hours of treatment with
melatonin. Due to this, the measurement of the percentage
of live/dead cells in the remaining population probably
represents early (or other) events of cell death as well as
processes of selection of the more resistant subpopulations.
In fact, we cannot exclude divergent effects of melatonin
in the different cell subpopulations. In accordance to
this hypothesis, we observed a different pattern of AIF
expression in some cells which may indicate the presence of
different cell subpopulations with dissimilar susceptibility to
activate this pathway (Supplementary Figure S2).