Effects of cold shock and cortisol on heat shock protein levels in rainbow trout

The effect of cold shock and increased levels of circulating cortisol on heat shock proteins (Hsp) levels in rainbow trout (Oncorhynchus mykiss) were examined. Cold shock: When the cultured hepatocytes were exposed to cold (at 4°C for 2 h), Hsp70 level in hepatocytes were similar to that in control. However, Hsp30 was markedly induced by cold shock. Cortisol: The high concentration of circulating cortisol (pharmacological levels) was found to reduce the Hsp70 levels in liver and gill of cortisol implanted fish (50 μ g cortisol/g body weight) exposed to heat shock (at 22°C for 2 h) compared to the sham. These results suggest that the expressions of Hsp30 and 70 in cell may be affected by cold stress response and circulating cortisol levels in fish, respectively. Furthermore, cellular stress response, such as Hsp expression, might be related with neuroendocrine/endocrine system in fish.