  We present results from deep Magellan and VLT long slit optical spectroscopy
for a sample of 19 face-on low surface brightness galaxies (LSBGs) selected
from the sample of Galaz et al. (2002). In particular, we compute Lick/IDS
indices for the light emitted by the bulges hosted by these galaxies. Similar
procedure is performed for a sample of 14 face-on high surface brightness
sample from the sample of Peletier & Balcells (1996). Results indicate that
bulges of LSBGs are metal poorer, compared to those hosted by HSBGs, supporting
the hypothesis that stellar formation rates have been stable low during the
lifetime of these galaxies. We compare our results with those of Bergmann,
Jorgensen & Hill (2003).
