Changes in the convulsion threshold and in the level of brain biogenic amines in rats chronically treated with phenobarbital or diazepam.

In experiments on 72 male Wistar rats, chronically treated with phenobarbital and diazepam, studies are made of the change in the convulsion threshold after sound stimulation during treatment and after withdrawal of the drugs. The level of biogenic amines in the brain at the end of the treatment (60th day) and after withdrawal of the drugs (3rd day) was also determined. The convulsion threshold was found to be considerably lower on the 3rd day after drug withdrawal in rats treated with phenobarbital and to a lesser extent (also on the 3rd day) in rats treated with diazepam. Serotonin level is considerably lower in both groups of animals. The significance of the disturbed correlation between serotonin and noradrenaline and particularly the sharp decrease of the serotonin level for the appearance of intensified convulsion activity is discussed.