Changes in brain blood flow associated with deltamethrin-induced choreoathetosis in the rat.

Deltamethrin is a pyrethroid insecticide which produces reversible motor symptoms in mammals involving facial movements, progressive incoordination, and choreoathetosis. These symptoms were found to be preceded and accompanied by increases in blood flow in the caudate nucleus and cerebral cortex of conscious rats. Blood flow, measured by the hydrogen polarography method, showed a 2.8-3.8 fold increase in the caudate nucleus and a 1.9-2.6 increase in the cortex after intraperitoneal deltamethrin. The increase in caudate blood flow provided an early and sensitive indicator of the development of motor symptoms, and preceded development of EEG spike discharges. A different pattern of motor symptoms consisting largely of tremor with no choreoathetosis was produced for comparison using another pyrethroid, cismethrin. This, whilst producing a similar increase in cortical flow, did not produce the disproportionate increase in caudate flow characteristic of deltamethrin. Although the actions of deltamethrin were shown not to be restricted to the extrapyramidal system, the selectivity of the blood flow increases, and the nature of the symptoms produced show deltamethrin to be a useful tool for the production of experimental extrapyramidal motor hyperactivity.