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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 38 (1980), S. 221-227 
    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
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  • 2
    ISSN: 1432-0738
    Keywords: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) ; Mice ; Mutant strains ; Porphyria ; Liver functiontests ; Oxygen consumption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Treatment of mice of the A2G-hr/+ congenic line with 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) resulted in the development of hepatic porphyria over a period of 4 weeks. Female mice responded to a lesser extent than did males. The degree of porphyria in haired heterozygotes (hr/+) was less than in the corresponding hairless homozygotes (hr/hr) and the haired mice had lower resting metabolic rates than hairless mice. Adaptation of mice of either genotype to a 32–33 °C environment resulted in a decrease in resting metabolic rate and a reduction in hepatic porphyrin levels. Histologically-demonstrated necrotic changes in livers were accompanied by increased activity of alanine aminotransferase and sorbitol dehydrogenase in the plasma; however, there was no clear temporal trend in plasma enzyme levels. Elevated environmental temperature reduced the plasma alanine aminotransferase activity. The study provided evidence for a pleiotropic effect of variation at the hr locus being expressed in TCDD hepatotoxicity. Suggestions for mechanisms whereby the effect can be mediated through alterations in resting metabolic rate are made.
    Type of Medium: Electronic Resource
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