Effect of chloro-N-desmethyldiazepam on serum and brain tryptophan and serotonin in relation to the activity of central serotonergic neurons.

Chloro-N-desmethyldiazepam (CDD) significantly reduced plasma tryptophan (TRY) and increased brain TRY in mice and rats. Quipazine did not change TRY levels in mouse plasma and brain but it respectively reduced and increased these two parameters in rats, to almost the same extent as CDD. Metergoline, an antagonist of serotonergic receptors, decreased blood TRY in both mice and rats but failed to change brain TRY. CDD significantly but slightly increased brain serotonin in rats. This effect was blocked by metergoline.