In vitro study of hormonal regulation of heat shock protein 70 expression in sea bream

The effects of hormones on Hsp70 expression in silver sea bream Sparus sarba have been assessed in vivo, but data on Hsp70 expression in vitro are still not available. For this purpose, it is necessary to develop fish cell lines for the study of Hsp expression. The aim of the present study is to develop in vitro systems from sea bream tissue to investigate the regulatory pattern of hormones on Hsp70 expression in these models.;Hsp70 levels increased after heat shock or cold shock. Hsp70 was induced by both heat shock and cold shock treatment in the primary cultures of silver sea bream and black sea bream. The heat shock treatment was performed at 32° and 37°C, and the cold shock at 4°C. The primary cultures of silver sea bream and black sea bream are sensitive systems for Hsp70 synthesis induced by thermal stress. Cell lines of silver sea bream and black sea bream responded to elevated temperature at 37°C with elevated Hsp70 expression suggesting cell lines preserved the features of Hsp70 induction. Macrophages of silver sea bream also synthesized Hsp70 on exposure to heat stress at 30°C.;The present work studied the direct action of four different kinds of hormones, cortisol, rbGH, rbIGF-I and oPRL on Hsp70 expression in fish cells in absence of stress and results obtained are different from those previously reported. In the present study, in vitro exposure to cortisol has various effects on the Hsp70 levels in three cell types. It increased the expression of Hsp70 in both fibroblasts, SSF and BSF, from 0.1 to 100 ng/ml concentration and reduced the Hsp70 levels significantly in SSM from 1 to 500ng/ml, moreover, these effects of cortisol can be blocked by cortisol receptor blocker RU486. In vitro exposure to rbGH did not affect the Hsp70 levels in SSF and BSF but reduced the Hsp70 levels in SSM at 10 ng/ml. Hsp70 expression was not changed by rbIGF-I in SSF and BSF but was significantly decreased in SSM from 1 to 10 ng/ml. oPRL has downregulatory effect on Hsp70 levels in both SSF and SSM but did not affect the Hsp70 levels in BSF. (Abstract shortened by UMI.).