Regional changes in brain 5-HT1A serotonin receptors in the rat model of persistent spasmodic dyskinesias induced by iminodipropionitrile.

Chronic injection of iminodipropionitrile (IDPN) to rats causes persistent motor abnormalities such as hyperactivity, lateral and vertical dyskinesia of the neck, and random circling. These behavioral changes are very similar to those observed after the acute administration of serotonin (5-HT) agonists in rodents. Moreover, some aspects of this syndrome are reproduced by stimulation of 5-HT1A receptors. The present quantitative autoradiographic study revealed a number of changes in 8-hydroxy-2-[di-n-propylamino-3H]tetralin (8-OH[3H]DPAT)-labeled 5-HT1A receptors in the brains of IDPN-treated rats. There were significant increases of 8-OH[3H]DPAT binding in the frontal cortex and in the caudate-putamen. In contrast, there were significant decreases in the interpeduncular nucleus, the pyramidal layer of the CA3 field of hippocampus, the superior colliculus and the pars reticulata of the substantia nigra. These results provide further evidence for the involvement of the 5-HT system in the development of the IDPN-induced dyskinetic syndrome.