[The physiological characteristics of genetic predisposition to catalepsy in rats depending on the stage of selection].

Male rats with a genetic predisposition to cataleptic reactions revealed a reduced motor activity and a diminished activation of mineralocorticoid and testosterone synthesis in response to a mild stress as compared with the Wistar rats. The reactions, however, were exactly opposite in the Wistar rats with signs of cataleptic features. The data obtained suggest that, when creating genetic animal models of human diseases, the initial stages of breeding should correspond to early stages of the disease whereas advanced stages of breeding are similar to later, chronic phases of the disease.

[The sex and corticosteroid hormones of rats selected for estrous-cycle reaction to constant illumination].

Two substrains of rats selected for the high (ESTH) and low (ESTL) ability to develop permanent oestrus under constant illumination were produced. The concentration of estradiol, testosterone in blood and 11-OCS in blood and adrenals was studied in rats of the 29 th generation under normal day (14L : 10D) and constant illumination (CL). The concentration of estradiol in blood of control rats in proestrus was 61.

[The neurohormonal characteristics of rats selected for the duration of the passive defense reaction and for the threshold of neuromuscular excitability].

Two strains of rats, "genetic catalepsy" and "low-threshold", simulating some human psychopathological symptoms, were compared. Levels of brain monoamines and blood corticosterone and testosterone showed no common features in the strains studied. The levels of dopamine in amygdala and testosterone blood levels in rats of the two strains significantly deviated in opposite directions from corresponding controls.