Aim: 

of this study was to find the dose-effect relationship of ionizing radiation effects at nonlethal dose range upon conditioned instrumental behaviour of rats.

Methods: 

The instrumental activity in shuttle box of white rats was studied after single total exposure to gamma-radiation (⁶⁰Co) in the dose range of 0.05 to 7 Gy. The rats' performance was evaluated with negative painful enforcement (414 animals) weekly during two months after the exposure.

Results: 

The results of instrumental behaviour studies showed complicated non-linear dose dependence with three characteristic intervals. The first of them (0.05 to 1.0 Gy), according to the shuttle box behaviour, is characterized by a decrease of the number of conditioned responses, accompanied by their latency increase; a decrease of acquired learning skills stability. The second dose-dependence interval obtained in the shuttle boxes corresponds to the dosage range from 1.0 to approximately 3.0-4.0 Gy. It is characterized by an elevated level of conditioned activity of the rats: increase in the number of conditioned responses, their latency shortening, and increase in stereotyped behaviour stability. The third interval of the dose-dependence function is characterized by a decrease of all behaviour indices, and it corresponds to doses above 4.0-5.0 Gy. Statistical model of dose-effect relations of conditioned responses numbers changes may be presented as function: Y = 1.3401*X³-18.546X²+65.252X+69.291.

Conclusions: 

Studies of the instrumental activity of the rats after exposure to ionizing radiation showed complicated nonlinear dependence of the behavioural indices on the exposure dose.