[Reverse absorption of serotonin by synaptosomes and its level in the rat cerebral cortex in acute and chronic stress].

Acute stress was simulated in Wistar rats by means of uncontrolled electric shock within 6 hrs; chronic stress, after the first 6-hr course, was developed within 9 days using 1-h daily treatment. Within 18 hrs of the acute stress occurring concentration of serotonin was decreased 2-fold in tissues of brain cortex, while reverse absorption of the neurotransmitter in synaptosomes was increased 3-fold. Under conditions of chronic stress concentration of serotonin tend to increase, whereas reverse absorption by nerve endings was decreased, which appear to occur due to brain adaptation to chronic stress.