Blood testosterone in rats: correlation of the level of individual anxiety and its impairment after "death threat".

Studies of identical groups of male Wistar rats after preliminary selection to give groups including extreme behavioral types with low and high rankings on the anxiety scale showed that blood testosterone concentrations in intact rats (controls) correlated negatively with anxiety ranking, i.e., minimal hormone concentrations (no greater than 5 nM) corresponded to high levels of anxiety - with a predominance of passive defensive behavioral components on testing. Short-term exposure to a "death threat" situation (sight of a boa attacking and eating two individuals from the group of rats) impaired this correlational relationship in a manner comparable to the sequelae of chronic neuroticization by unavoidable pain stimulation. Impairments were manifest as scatter in measures in low-anxiety animals (3-21 nM). This characteristic, reflecting the multitude of adaptive pathways in the population in threat situations, distinguishes this type of action from neuroticization by unavoidable pain stimulation, which leveled out individual differences and decreased the hormone level.

[Blood testosterone in rats: correlation with individual anxiety and its derangement after the "death threat"].

After preliminary testing on a multiparameter scale, test and experimental groups of Wistar male rats were formed on the principle of identical distribution of individuals with different anxiety levels. A negative Spearman correlation between the testosterone blood concentration and the level of anxiety was observed in intact rats: the minimum hormonal concentrations (lower than 5 nmol/l) were found in rats with high anxiety, whereas the maximum concentrations (up to 16 nmol/l) corresponded to the higher anxiety level (prevalence of passive defense reactions during testing). After a sort-term exposure to life-threatening situation (viewing of a boa's attacking and devouring two victim rats from the test group), the correlation was deranged because of appearance of a scatter in testosterone blood concentration (from 3 to 21 nmol/l) in rats with low anxiety. Neurotization with inescapable pain stimulation also deranged the initial anxiety-testosterone correlation, but, as distinct from the exposure to life-threatening situation, eliminated individual differences in testosterone concentration at its low level. The results suggest the existence of multiple ways of adaptation to life-threatening situations in a rat population.