Striatal microinjection of Sydenham chorea antibodies: using a rat model to examine the dopamine hypothesis.

We hypothesized that injection of anti-basal antibodies from patients with Sydenham's chorea into rats' striatum will induce behavioral and histological changes. Antibodies from eight Sydenham's chorea patients and eight age-matched controls were injected into the left caudate of 16 rats. Apomorphine- and amphetamine-induced rotations were performed on days 10 and 17, respectively, followed by immunohistochemical studies. Antibodies from patients with Sydenham's chorea, but not controls, bound to a ∼50-kDa molecule in the striatum extract; immunohistology staining demonstrated specific binding to cellular component(s) in rats' striatum. Contrary to our hypothesis, we could not detect in the rats injected with Sydenham's chorea antibodies changes in rotational behavior or immunohistochemistry staining for dopaminergic or GABAergic markers. Injection of small quantities of anti-neuronal antibodies present in patients with Sydenham's chorea into rat striatum is insufficient to alter motor behavior or cause detectable cellular changes.