The effect of hyperthermia on cell viability, oxidative damage, and heat shock protein expression in hepatic cells of grass carp (Ctenopharyngodon idellus)

Abstract

The purpose of the study was to investigate the effects of mild hyperthermia on cell viability, release of lactate dehydrogenase (LDH), superoxide dismutase (SOD) activity, malondialdehyde (MDA) formation, total antioxidant capacity (T-AOC), and the relative mRNA levels of heat shock protein (HSP60, 70, and 90) in hepatic cells of grass carp (Ctenopharyngodon idellus) before and after temperature stress. Cultured cells were exposed to thermal stress (32°C) for 0.5, 1, 2, 4, and 8h. The results showed that hyperthermia stress significantly reduced cell viability (P<0.01) and increased LDH release at 0.5 and 1h (P<0.05). Additionally, hyperthermia stress led to oxidative stress as evidenced by significantly decreased T-AOC after treating cells for 0.5 and 8h (P<0.05). SOD activity also significantly decreased after 1h of stress (P<0.05), but MDA formation increased after 8h of stress (P<0.05). This may be partly responsible for the lower cell viability and higher LDH release we observed. The differences between SOD activity, MDA formation, and T-AOC between the 2h treatment group and the control were smaller than that of other groups. This indicated that cellular antioxidant enzyme systems play an important role in the defense against oxidative stress. Further tests showed that the expression of HSP60 at 1, 2, and 4h (P<0.05), HSP70 at 0.5 and 1h (P<0.01), and HSP90 at all time points after stress were higher (P<0.01) than pre-stress levels. This suggested that HSPs possess the ability to modulate cellular anti-stress responses and play key roles in protecting organisms from heat stress. In conclusion, hyperthermia inhibits cell proliferation, induces cell oxidative stress, and enhances HSP expression in hepatic cells of grass carp.