The iminodipropionitrile (IDPN) model of persistent spasmodic dyskinesias: regional serotonin metabolism in rat brain.

Chronic administration of iminodipropionitrile (IDPN) in rats causes a persistent behavioral syndrome which consists of lateral and vertical twitches, random circling, and hyperactivity. These abnormalities are very similar to those induced by the acute injection of serotonin (5-HT) agonists. The present study reveals significant increases in the levels of 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in the caudate-putamen and in the nucleus accumbens during treatment with IDPN. In the striatum, these changes lasted up to one month after the last injection of the drug. There were less prominent increases in 5-HT and decreases in 5-HIAA in the brainstem of these animals. These data are consistent with our previous study in which we found significant decreases in the number of 5-HT2 receptors in both the striatum and the accumbens of rats which were suffering from the IDPN-induced syndrome for a period of one month. These results are discussed in terms of their support for a possible role of the serotonin system in both the appearance and the persistence of this dyskinetic syndrome.