Antagonism of imidazole-induced shaking in the rat: a behavioural tool predictive of antidyskinetic activity?

In rats the intraperitoneal injection of imidazole (IMID) induced shaking behaviour, the effect appearing to be age- and sex-linked; younger animals responded less vigorously than older animals, while females always exhibited a significantly weaker response than males of the same age. After ovariectomy, however, the number of shakes of the two sexes was very similar. A number of drugs were examined for their antagonism of this highly reproducible syndrome. IMID-shakes were antagonized by reserpine, clonidine, high doses of B-HT 920, propranolol, haloperidol, morphine and diazepam, were not affected by apomorphine, (+)3-PPP, physostigmine, naloxone or methysergide, and were potentiated by sulpiride and scopolamine. The results are considered in the light of the possible neurochemical mechanisms underlying the IMID-syndrome; the suggested usefulness of this test for the study of human dyskinetic movements is disputed.