Effects of 3-methyl-1-(5-oxohexyl)-7-propylxanthine on the in vivo release of monoamines studied by intracerebral dialysis.

The effect of a xanthine derivative, 3-methyl-1-(5-oxohexyl)-7-propylxanthine (HWA 285, 10 mg/kg i.p.), on the release of endogenous monoamines and their metabolites from the rat striatum and hippocampus are examined in vivo by intracerebral dialysis technique. Using this method, which is based on the dialysis principle, a small-calibered (0.5 mm) dialysis tube is inserted into the striatum or hippocampus transversally and is perfused with Ringer solution. The amounts of dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in the perfusates are measured by high performance liquid chromatography system with electrochemical detection. HWA 285 (10 mg/kg) decreased monoamine levels in hippocampal perfusates after its i.p. administration. However, there were no consistent changes in monoamine release in striatal perfusates after the drug administration. These findings suggest that HWA 285 exerts an inhibitory influence on hippocampal dopaminergic and serotonergic systems.