Influence of radiation on survivability, behavior and neurochemical correlates of rats

The aim of the work was to study the dependence of individual radiosensitivity of white and black rats on radiation. The rats under study were derived from a cross between black and white rats and called Ratus Ratus-Georgia. Comparative radiosensitivity of white (Wistar) and black rats was studied at a total exposure with sublethal and lethal doses (5, 7 and 9 Gy). Cumulative survival functions of rats, a spectrum of changes in some ethological parameters and content of serotonin and catecholamines in their brain structures were given as criteria of radiosensitivity. Survival rate of black and white rats is connected with changes in the composition and distribution of biogenic amines in the various brain structures, as well as with a decrease of locomotor and orienting-exploratory activity, on the one hand, and with increase of emotionality, stereotyped activity, passive defensive behavior of the rats, on another. Regression coefficients of dependence of survival functions on irradiation doses of black rats were rather higher than those of white rats after irradiation with doses in 5, 7 and 9 Gy. A change in the intensity of mortality with changes in radiation dose per unit depends on the synthesis of serotonin and on the number of sulfhydryl groups, deficiency of which is one of the important factors for white rats. Results of the study allow us to suppose that changes in the radiation sensitivity of rats after irradiation with sublethal and lethal doses are caused by consequences of radiation damage and by activation of the serotonergic system at the process of restitution after radiation injury. On the other hand, a higher radiation sensitivity of white rats in comparison with that of black rats is caused by low content of serotonin, thiols, melanin and other biologically active substances which are endogenous radioprotectors defining individual radioresistance.