Effect of citalopram (Lu 10-171) on tranylcypromine and tryptophan-induced wet-dog shakes in rats.

It has been found that citalopram (Lu 10-171) has profound effects on serotonin (5-HT) metabolism by increasing the 5-HT levels in the cerebellum, medulla, and the whole brain with a corresponding decrease of the 5-HIAA levels in all parts of the brain except the brain stem. On the other hand, the drug does not appear to have any influence on the wet-dog shakes response induced by the combination of a monoamine oxidase inhibitor (MAOI) and L-tryptophan. It is suggested that by increasing the neuronal levels of 5-HT, citalopram decreases the turnover of 5-HT and firing rate of serotonin neurons. It has also been observed that citalopram could be an agonist of a certain type of 5-HT receptor which does not respond to the behavioral screening model proposed by Bedard and Pycock (1977).