  We present new results on line-strength gradients in a sample of 18 brightest
cluster galaxies (13 in clusters with cooling flows and 5 in clusters without).
Here we focus on the study of the Mg2 index and the 4000A break. We find that
line-strength gradients vary markedly from galaxy to galaxy, depending both on
the mass deposition rate and the presence or not of emission lines in the
nuclear regions. Gradients are found to be flat, and even positive (i.e. bluer
when going inwards), in the emission-line region of the cooling flow galaxies
with emission lines. However, outside the region where emission lines are
present, mean spectral gradients of brightest cluster galaxies, in clusters
with and without cooling flows, are consistent with those observed in giant
elliptical galaxies. In addition, and in agreement with previous studies, we
confirm a correlation between central spectral indices and the mass deposition
rates, although we find that cooling flow galaxies without emission lines do
not follow this trend.
