Di-n-butyl phtalate (DBP) and 4-tert-octylphenol (OP) are environmental pollutants with estrogenic
activity that have been shown to have endocrine disruptive actions in reproduction of several fish
species. However, their impact in bone and scale metabolism, which are estrogen-responsive tissues,
remains unknown. In this study, we evaluated the impact of these compounds on mineral metabolism
in fish scales that, like bone, are a dynamic tissue maintained by continuous cycles of formation and
resorption mediated, respectively, by osteoblasts (OSB) and osteoclasts (OSC). Using an in vitro
bioassay, Atlantic sea bass (a marine species) and Mozambique tilapia (a freshwater species) scales
were incubated with a range of concentrations of OP and DBP in culture media for a short (30
minutes) or long (24 hours) incubation time. Effects on the activity of tartrate resistant acid
phosphatase (TRAP) and alkaline phosphatase (ALP), markers for OSC and OSB activities,
respectively, were assessed using a colorimetric enzymatic assay. DBP (10-6 M) affected TRAP
activity in both species. While in sea bass, TRAP activity increased with DBP after 30 min incubation
but was unaffected after 24 h, in tilapia no alterations were observed at the short term but a significant
decrease was observed after 24 h incubation with this compound. None of the tested concentrations
(10-10 to 10-6 M) affected ALP activity in both species. On the contrary, OP effects were only observed
on the activity of ALP, which was significantly decreased after a 24 h incubation with 10-8 M of OP
in the scales of both species. These results suggest that the exposure to these compounds may have
disruptive effects on the metabolism of mineralized tissues in both marine and freshwater species.
Future studies will investigate the mechanisms involved in these responses and the consequences for
fish health.Foundation for Science and Technology of Portugal (FCT), through projects PTDC/AAG-GLO/4003/2012 and PEst-C/MAR/LA0015/2011 and fellowship to PP (SFRH/BPD/84033/2012).info:eu-repo/semantics/publishedVersio
