Receptor fingerprinting the circling ci2 rat mutant: insights into brain asymmetry and motor control.

Circling behaviour of the ci2 rat mutant, a model for hyperkinetic movement disorders, is associated with an abnormal asymmetry in striatal dopaminergic activity. Since it is more likely that imbalances in several neurotransmitter systems result in the cascade of neurochemical disturbances underlying disorders involving motor dysfunctions, we measured the densities of 12 neurotransmitter receptors in the basal ganglia and vestibular nuclei of adult circling mutants (ci2/ci2), non-circling littermates (ci2/+) and controls from the background strain (LEW/Ztm). In controls, the left caudate putamen (CPu) contains lower kainate and the left globus pallidus higher AMPA densities than their right counterparts.

Auditory and vestibular defects and behavioral alterations after neonatal administration of streptomycin to Lewis rats: Similarities and differences to the circling (ci2/ci2) Lewis rat mutant.

The clinical usefulness of aminoglycoside antibiotics is limited by their ototoxicity. In rodents, damage to the inner ear is often associated with rotational behavior and locomotor hyperactivity reminiscent of such behaviors resulting from an imbalance of forebrain dopamine systems. Based on previous observations in the circling (ci2/ci2) Lewis (LEW) rat mutant, a spontaneous mutation leading to hair cell loss, deafness, impairment of vestibular functions, lateralized circling, hyperactivity and alterations in the nigrostriatal dopamine system, we have recently hypothesized that vestibular defects during postnatal development, independent of whether induced or inherited, lead to secondary changes in the dopaminergic system within the basal ganglia, which would be a likely explanation for the typical behavioral phenotype seen in such models.

Marked differences in response to dopamine receptor antagonism in two rat mutants, ci2 and ci3, with lateralized rotational behavior.

We have recently described two rat mutants, ci2 and ci3, in which abnormal lateralized rotational behavior and locomotor hyperactivity occur either spontaneously or in response to external stimuli, such as new environment. While cochlear and vestibular defects are found in ci2 rats, ci3 rats do not exhibit any inner ear abnormalities. Both mutants show abnormal lateralities in striatal dopamine and in the density of dopaminergic neurons in substantia nigra or ventral tegmental area, which may be involved in the behavioral phenotype of these rats.