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.

A special case of learning disorder in isolant rats as a model of disintegration.

The combination of two factors - isolation and ontogenesis (starting from 21 days) and subsequent training of rats to a cyclical habit - could in some animals (30%) lead to the formation of unusual behavioral strategies consisting of maintenance of the cyclical habit without reinforcement with food. This dissociation from the vital motivation is regarded as an analog of the disintegration phenomenon, a key step in psychoneurotic disorders. The most common type of disturbance in isolated animals was suppression of searching activity, with extreme learning difficulty, though a training process including a two-month break led to a significant increase in motor-searching activity in this situation. These behavioral abnormalities were accompanied by morphological changes in the sensorimotor cortex of the brain, with a relative thinning of layer 5 and selective decreases in the density of satellite glial cells and deviations from the normal correlational relationships between behavioral and neuroglial measures.