Verapamil Aggravates Hyperkinesia Produced by Intrastriatal Administration of Picrotoxin in Rats

Abstract

The effects of slow Ca2+ channel blocker verapamil and Ca2(+)-binding agent EDTA were studied on the model of choreic hyperkinesia induced by chronic intrastriatal microinjections GABAA receptor antagonist picrotoxin. Normal and pathological movements were recorded. The test preparations facilitated the effect of picrotoxin on spontaneous and learned behavior. They exerted a permissive effect on picrotoxin-induced hyperkinesia: increase reproducibility and duration of hyperkinesia and decrease the latency of this reaction. Our results indicate that Ca2+ channels are involved into the development and progression of hyperkinesia.

Intrastrial injection of magnesium after picrotoxin does not reduce motor hyperactivity in rats

“…The characteristics of spontaneous motor activity on a certain day of microinjections were compared with the results of testing of the same group of animals before implantation and with the values in control rats on the same day. Parameters of hyperkinesia were compared between two experimental groups of animals and the results of previous experiments with microinjections of PT alone [1,4,5].…”

“…Our previous studies [1,4,5] showed that one of the mechanisms of hyperkinesia caused in rats by microinjection of picrotoxin (PT; GABA A receptor antagonist) into the neostriatum (NS) is distortion of neuronal calcium homeostasis. These data agree with the notions on the pathogenesis of Huntington's chorea [2,8] (picrotoxin hyperkinesia is an analog of this condition).…”