Influence of fibrinogen degradation products on the action of amphetamine in the central nervous system.

Fibrinogen degradation products (FDP) in a dose dependent manner potentiated the action of amphetamine in the tests for locomotor activity (Knoll's motimeter) and stereotypy. They also antagonized the haloperidol-induced catalepsy. FDP increased the level of amphetamine 90 min after the drug administration, and depressed it 120 min after the treatment. FDP slightly depressed the level of dopamine, and increased that of homovanillic acid in the striatum. They also potentiated the accumulation of noradrenaline in the hippocampus, produced by amphetamine, but did not affect the concentrations of dopamine and serotonin. It is suggested that the change in action of amphetamine under the influence of FDP depends on the direct effect of the peptides on amphetamine level in the brain, and on the level of some neuromediators.