The Protective Effects Of Heat Shock Pretreatment On Cells

Objectives: (1)To observe variation of cells survival rate which deal with H₂O₂ after heatshock pretreatment. To see whether heat shock pretreatment can raise cells survival rate.(2)To obersve the contribution of heat shock itself to cells DNA double strands breaks. (3)To obersve the effects of heat shock pretreatment on cells which deal with hightemperatures, concluding initial DNA double strands breaks and repairments of DNAdouble strands breaks.Methods: (1) Cultured NIH3T3 and V79 cells. After heat shock pretreatment, deal withdifferent density of H₂O₂ and different recovery time. Then observe cells survival rate withMTT. (2) Cultured NIH3T3 cells, after dealing with different heat shock pretreatmenttemperatures of 37℃,39℃,42℃,43℃,45℃,After fixing with paraformaldehyde, cellswere incubated overnight with anti-γ-H2AX antibodies. Cells were then labeled withgoat-anti-mouse IgG conjugated with FITC. Variations of DNA double-strand breaks fociwere acquired on a Leica laser-scanning confocal microscope. (3) Cultured V79 cells, dealwith different high temperatures, different heat shock pretreatment temperatures anddifferent recovery time. After fixing with paraformaldehyde, cells were incubatedovernight with anti-γ-H2AX antibodies. Cells were then labeled with goat-anti-mouseIgG conjugated with FITC. Variations of DNA double-strand breaks foci were acquired ona Leica laser-scanning confocal microscope.Results: (1)To NIH3T3 cells, the best result is about 40% submlimation of cells survialrate after heat shock pretreatment. To V79 cells, the best result is about 20% submlimationof cells survial rate after heat shock pretreatment. But there are no differences on ceilssurvial rate with different recovery time .(2)Dealing cells with heat shock pretreatment and fixed immediately. Then images were acquired on confocal microscope. It showed that:Cells in control group which had foci is less than 5%. Cells dealing with 45℃,all cells hadfoci of DNA double-strand breaks. Ceils dealing with 39℃, foci in cells had no significantincreasing, but the nember of cells which had foci increased. Cells dealing with 43℃,bothfoci and the nember of cells which had foci increased. (3)Cells dealing with different hightemperatures, different heat shock temperatures and different recovery time. The resultsshowed that different heat shock temperatures can affect DNA double-strand breakssignificantly. But the result had no significant differences with different recovery time.Conclusions: Heat shock pretreatment can raise cells survival rate and decrease foci ofDNA double-strand breaks exactly. The results show that heat shock pre-treatment canreally protect cells. But heat shock pre-treatment itself can also damage cells. More data isneeded whether heat shock pre-treatment can hasten cells repairation.