Evaluation of chick embryo spinal motoneuron cultures for the study of neurotoxicity.

The objective of this study was to assess the performance of chick embryo motoneuron cultures for the study of neurotoxicants. The response of motoneurons to the cytotoxic effects of picrotoxin, strychnine, bulbocapnine, and the naturally occurring excitatory amino acids, N-methyl D-aspartate (NMDA) and L-glutamate was studied by using a colorimetric viability assay using a vital dye. Selective cellular responses other than cell death were evaluated using a spectrofluorometric assay based on the response of an electrochromic styryl dye (Di-4-Anneps) to determine the expression of receptors for glycine, gamma-aminobutyric acid (GABA), NMDA, and L-glutamate by motoneurons in culture. The performance of chick embryo motoneurons (E7) in culture was useful and informative in neurotoxicologic studies. Motoneurons (E7) were found to express receptors for glycine, GABA, NMDA, and dopamine. The presence of the receptors and the inherent characteristics of motoneurons to generate action potential at an early embryonic stage (E4) makes this culture system a reliable model to conduct mechanistic studies as well as for predictive screening tests for agents of pharmacologic and toxicologic potential.

Laboratory diagnosis of zinc phosphide poisoning.

Zinc phosphide, a readily-available rodenticide, poses a significant risk for intoxication in animals. Animals have been poisoned by ingesting treated bait or the carcasses of poisoned rodents. Toxicity is due to the liberation of phosphine gas in the stomach. Clinical signs include central nervous system excitation, depression and vomition. Similarities of clinical signs with other central nervous system toxicants make the diagnosis difficult without a specific diagnostic test. The procedure outlined in this paper detects phosphine liberated from zinc phosphide by the addition of hydrochloric acid as well as the phosphine previously generated by contact with stomach acid.