Keywords: non-lethal ionising radiation, instrumental conditioned behaviour, rats, rat behaviour, dose dependence, seasonal peculiarities, biological effects, low radiation
Effects of non-lethal doses of ionising radiation on the instrumental behaviour of rats
The dose-effect dependence of the instrumental behaviour of white rats after a single total γ-exposure (60Co) in the dosage range of 0.05 to 7.0 Gy was studied. Generalised results of seven years of our studies of post-radiation changes of operant behaviour in shuttle (active avoidance of shock ? negative reinforcement) and in Skinner (drinking reward ? positive reinforcement) boxes were evaluated weekly for a two-month period after exposure. The dose dependence, obtained using these two behavioural paradigms, displays a non-linear pattern. Three regions with different characteristic patterns of the observed effects were found: performance declines relative to control animals after exposure to doses up to 1.0 Gy; performance increases at doses in the range from 1.0 to 3.0 Gy; and again declines with dose increases up to 7.0 Gy. Possible underlying mechanisms, particularly the role of additional stress caused by animal testing, are discussed.