Brain serotonin and epileptic seizures in mice: a pharmacological and biochemical study.

5-Hydroxytryptophan (5-HTP) reduced the intensity of both audiogenic and pentylenetrazol seizures. p-Chlorophenylalanine reduced audiogenic seizure (AGS) susceptibility but failed to change the pentylenetetrazol seizure (PTS). Drugs blocking brain serotonin (5-HT) receptors suppressed AGS but caused no clear effects upon PTS. Pentylenetetraziol-induced shock increased brain 5-hydroxyindoleacetic acid (5hiaa) concentrations and decreased 5-HT levels. Single audiogenic shock decreased the acumulation of 5-HT and 5-HIAA in the brains of mice pretreated with 5-HTP. On the other hand PTS increased the accumulation of 5-HT and 5-HIAA in the brains of mice pretreated with 5-HTP. It is suggested that AGS decrease brain 5-HT turnover whilst PTS cause an opposite effect.