A general response to stressors by the unicellular Tetrahymena: effect of stress on the hormone levels

Hormone (ACTH, endorphin, serotonin and T 3 ) content of the unicellular Tetrahymena was studied by using immunocytochemical and flow cytometry methods. The cells were previously treated with different concentrations of salts (NaCl or KCl for 1 h), were kept in low (+4°C) or high (+37°C) temperature for 1 h and were treated with formaldehyde or ethanol. High concentrations of salts (20 mg ml −1 medium), all levels (0.1, 0.05, 0.01%) of formaldehyde and high temperature almost doubled the hormone contents and 0.1% alcohol also significantly elevated them. The experiments call attention to the presence of a general adaptation syndrome (GAS)‐like phenomenon at a unicellular level and points to the possibility of deduction of GAS to a low level of phylogeny. Copyright © 2008 John Wiley & Sons, Ltd.