PBDE-47 exposure causes gender specific effects on apoptosis and heat shock protein expression in marine medaka, Oryzias melastigma

• We fed marine medaka bioencapsulated PBDE-47 for 21 days.
• Male medaka had induced apoptosis and no heat shock protein change in liver and muscle.
• Female medaka had no induction of apoptosis but elevated heat shock protein expression in liver and muscle.
• Differences could not be explained by inherent gender heat shock response changes.
• Female marine medaka have protective mechanisms against PBDE-47 induced apoptosis.

Marine medaka (Oryzias melastigma) was fed with a low and high dose of dietary 2,2′,4,4′-tetra-bromodiphenyl ether (PBDE-47), over 21 days. Gender specific changes in caspases 3 and 8 in medaka were found as activities in male medaka were significantly increased in both liver and muscle at both low and high exposure levels whereas caspase activity in female medaka tissue remained unchanged. Results of HSP90 and HSP70 immunoassays also showed gender specific related changes as both HSP families were unchanged in liver and muscle of male medaka but significantly increased in liver and muscle of female medaka, following PBDE-47 exposure. The gender specific effects of PBDE-47 on HSP expression profiles could not be explained by inherent differences in the heat shock response of male and female marine medaka, as the HSP profiles in liver and muscle, induced by acute heat shock, were similar in both sexes. The findings from this study provide evidence that PBDE-47 can cause gender specific modulatory effects on mechanisms critical to the apoptotic cascade as well as HSP regulation and expression.