In vitro effects of sera from stressed rats on growth parameters of normal and transformed rat cells

摘要

We compared the effects of serum from either unstressed, chronically stressed, or acutely stressed rats on selected growth parameters of three types of rat cells in culture: chemically transformed mammary adenocarcinoma (AC 33) cells; virally transformed rat kidney (B77) cells; and non-transformed normal rat kidney (NRK) cells.;The cells used in these experiments can be grown using rat serum as their growth supplement. Serum from chronically stressed rats reduced the growth of AC 33 cells, but had no effect on the growth of B77 or NRK cells. Thymidine incorporation was reduced when any of these cells were fed with serum from chronically stressed rats. Cellular protein content increased when any of these cells were adapted to serum from chronically stressed rats.;Serum from acutely stressed rats inhibited the growth of AC 33 cells, had no effect on the growth of NRK cells, and increased the growth of B77 cells. Feeding AC 33 or NRK cells with serum from acutely stressed rats decreased thymidine incorporation; adapting these cells to this serum increased cellular protein. Thymidine incorporation and protein content of B77 cells were significantly increased after these cells had adapted to serum from acutely stressed rats.;Because chronic stress reduced tumor growth in vivo and because serum from chronically stressed rats decreased thymidine incorporation by all three cell types tested, attempts were made to characterize the factor(s) responsible for this effect. Sera from unstressed and chronically stressed rats were dialyzed using two molecular weight exclusion membranes and heating to 56$spcirc$ for 30 min. Thymidine incorporation and cellular protein content were compared using these sera.;Dialyzing serum from unstressed rats uniformly reduced thymidine incorporation. The effect of dialysis on the reduction of thymidine incorporation caused by serum from chronically stressed rats varied with the concentration of serum used; there was no effect at low serum concentrations, but dialysis reduced thymidine incorporation at higher serum concentrations. Dialyzates from these two sera also reduced thymidine incorporation whether the rats had been stressed or not. Heating serum from unstressed rats reduced thymidine incorporation; serum from chronically stressed rats was unaffected by this treatment. (Abstract shortened with permission of author.).