Involvement of the NO synthase system in stress-mediated brain reactions.

The neurosis-like state developing as a result of chronic stress in animals and accompanied by transient cerebral hypoxia can lead to significant impairments to many brain structures. The effects of the humoral components of the stress reaction on the brain are mediated by both extra- and intracellular signal pathways, among which nitric oxide (NO) is of great importance. We report here immunohistochemical studies of the expression of the constitutive neuronal (nNOS) and inducible (iNOS) isoforms of NO synthase in neurons in the brains of white rats in conditions of chronic stress leading to the development of a neurosis- like state.

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.

Effects of chronic neuroticization on the monoaminergic systems of different structures in the brains of rats with different typological characteristics.

The levels of monoamines and their metabolites were studied by HPLC with electrochemical detection in homogenates of hypothalamus, hippocampus, prefrontal cortex, and amygdala in intact and neuroticized Wistar rats with different types of behavior in the open field and forced swimming tests. Intact rats with intermediate levels of activity and depressivity had higher serotonin concentrations in the hypothalamus and lower noradrenaline and hydroxyindoleacetic acid levels in the hippocampus than rats characterized by low activity and high depressivity. In neuroticization, the levels of study monoamines and their metabolites decreased in all the brain structures investigated with the exceptions of an increase in the dopamine concentration in the hippocampus and the dihydroxyphenylacetic acid concentration in the prefrontal cortex.

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.