[The effect of emotional stress and corticosterone on the activity of monoaminoxidase in the rat brain].

Dissimilar effect of emotional stress on activity of the A and B forms of brain monoamine oxidase (MAO) was found in motionless rats within 1 and 5 hrs: increase in the rate of serotonin deamination catalyzed by MAO A and decrease in the rate of catalyzed by MAO B benzylamine deamination. Preadministration of actinomycin D prevented completely these alterations in activity of MAO A and B developed after 1 hr immobilization; this suggest the regulating effect of genome on MAO activity during stress. Both low 10(-11) 10(-13) M and high 10(-5) 10(-6) M concentrations of corticosterone stimulated the MAO A deamination of serotonin, while the steroid high concentrations inhibited the MAO B deamination of benzylamine either in vitro and in vivo (after intraperitoneal administration of 5 mg/kg). Actinomycin D blocked the stimulating effect of corticosterone at low concentrations on the MAO A activity, whereas the drug did not affect both the alterations in the MAO A and B activities observed after 5 hrs stress and the inhibition of MAO B by high concentrations of corticosterone. The data obtained suggest that corticosterone is not involved in genetic regulation of the MAO A and B activities under conditions of stress, however, the hormone may be of importance in regulation of the enzymatic activity affecting the MAO conformation during the long-term stress.