[Brain catecholamines at the early stage of emotional stress].

The blood pressure (BP) dynamics and catecholamine (CA) levels in the brain regions of August and Wistar rats were studied two hours after immobilization in order to elucidate the central neurochemical mechanisms leading to the destruction of BR self-regulation under emotional stress during the experiment. The BP level did not differ from the normal. The CA concentration in the hypothalamus, midbrain, isthmus rhombencephali and medulla oblongata underwent considerable changes. It is suggested that the mechanism of the CA changes in both strains of the rats exposed to stress is similar in the hypothalamus and medulla oblongata while both strains of the rats studied showed specificity in the activity of NA-synthesizing neurons of the isthmus rhombencephali and DA-synthesizing neurons of the midbrain that might be a cause of different resistance of cardiovascular functions during the later stage of immobilization.