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Verónica M. Rodríguez,¹ Leticia Dufour,¹ Leticia Carrizales,² Fernando Díaz-Barriga,² and María E. Jiménez-Capdeville¹

¹Departamento de Bioquímica, Facultad de Medicina and ²Laboratorio de Toxicología Ambiental, Departamento de Biología Celular, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México

Abstract

Several single components of mining waste (arsenic, manganese, lead, cadmium) to which humans are exposed at the mining area of Villa de la Paz, Mexico, are known to provoke alterations of striatal dopaminergic parameters. In this study we used an animal model to examine neurochemical changes resulting from exposure to a metal mixture. We used microdialysis to compare in vivo dopamine release from adult rats subchronically exposed to a mining waste by oral route with those from a control group and from a sodium arsenite group (25 mg/kg/day) . We found that arsenic and manganese do accumulate in rat brain after 2 weeks of oral exposure. The mining waste group showed significantly decreased basal levels of dihydroxyphenylacetic acid (DOPAC ; 66.7 ± 7.53 pg/µl) when compared to a control group (113.7 ± 14.3 pg/µl) . Although basal dopamine release rates were comparable among groups, when the system was challenged with a long-standing depolarization through high-potassium perfusion, animals exposed to mining waste were not able to sustain an increased dopamine release in response to depolarization (mining waste group 5.5 ± 0.5 pg/µl versus control group 21.7 ± 5.8 pg/µl) . Also, DOPAC and homovanillic acid levels were significantly lower in exposed animals than in controls during stimulation with high potassium. The arsenite group showed a similar tendency to that from the mining waste group. In vivo microdialysis provides relevant data about the effects of a chemical mixture. Our results indicate that this mining waste may represent a health risk for the exposed population. Key words: arsenic, chemical mixtures, dopamine, manganese, metals, mining waste, toxic waste. Environ Health Perspect 106:487-491 (1998) . [Online 9 July 1998]

http://ehpnet1.niehs.nih.gov/docs/1998/106p487-491rodriguez/ abstract.html

Address correspondence to M.E. Jiménez-Capdeville, Departamento de Bioquímica, Facultad de Medicina, Av. Venustiano Carranza 2405, 78210 San Luis Potosí S.L.P., Mexico.

We acknowledge the technical assistance of J.M. Delgado. This work was supported by grants 0191-N from the Consejo Nacional de Ciencia y Tecnología (CONACYT) and C96-FAI-07-2.53 from the University of San Luis Potosí. V.M Rodríguez was supported by a fellowship from CONACYT (92291) .

Received 10 October 1997 ; accepted 6 April 1998.