ISSN:
1432-1106
Keywords:
Basal ganglia
;
Choreoathetosis
;
Insecticides
;
Electroencephalogram
;
Rats
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Decamethrin (NRDC 161) is a neurotoxic pyrethroid insecticide which produces a reversible sequence of motor symptoms in rats involving hind limb rigidity and choreoathetosis. This paper represents an evaluation of the usefulness of decamethrin as an experimental method of inducing extrapyramidal hyperexcitability. EEG records from conscious rats showed a specific slowing of movement related θ activity to parallel the development of hind limb rigidity, but no discernible change in other components until shortly before the onset of choreoathetosis. At this point localised sharp waves could be evoked by sensory stimuli. These developed rapidly into spontaneous generalised spike sequences which followed individual spasms. Cortical auditory evoked potentials were decreased in amplitude during this phase. Depth electrodes showed discharges initially in the globus pallidus and caudate nucleus which spread to the frontal cortex and thence to the rest of the cortex and to other areas. During continued spontaneous choreoathetosis spikes and slow wave activity developed, dominating all records until recovery or death. In anaesthetised rats extracellular unit records from cells in the caudate nucleus showed a rapid increase in firing rate after intravenous decamethrin as EEG spikes developed. Cortical somato-sensory evoked potentials were decreased in amplitude as in the conscious rats but with additional development of a sharp late component during generalised EEG spiking. It is concluded that the symptoms, distribution, and nature of cortical and subcortical spiking, supression of cortical evoked responses, and increase in caudate neuronal activity all are consistent with a primary action of decamethrin upon the extrapyramidal motor system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00236743
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