| Polychlorinated Biphenyls Alter Extraneuronal but Not Tissue Dopamine Concentrations in Adult Rat Striatum: An in Vivo Microdialysis Study Richard F. Seegal,1,2 Richard J. Okoniewski,1 Karl O. Brosch,1 and Jeffrey C. Bemis2 1Wadsworth Center, New York State Department of Health, Albany, New York, USA; 2School of Public Health, University at Albany, Albany, New York, USA Abstract
Polychlorinated biphenyls (PCBs) reduce tissue dopamine (DA) concentrations and increase media DA concentrations in both in vitro preparations of bovine adrenal chromaffin cells and adult rat striatal tissue. To determine whether these changes also occur in the intact animal, we used in vivo microdialysis to determine changes in concentrations of DA in striatal dialysates from freely moving adult male rats after exposure to 25 mg/kg/day Aroclor 1254 for varying periods of time. We also determined DA concentrations in striatal tissue obtained postmortem from similarly treated animals. The effects of PCBs on dialysate DA concentrations depended on the length of exposure ; DA concentrations were significantly elevated after 3 days of exposure and were significantly reduced after exposure for periods of 1 week or longer. On the other hand, striatal tissue concentrations of DA, determined postmortem in rats exposed to PCBs for the same periods of time, were not significantly altered. We suggest that these time-dependent alterations in dialysate DA concentrations a) reflect PCB-induced alterations of both plasma membrane and vesicular DA transporter function ; b) provide a more sensitive index of altered central DA function after exposure to PCBs than does measurement of postmortem tissue DA concentrations ; and c) play an important role in mediating some PCB-mediated changes in behavior. Key words: brain, dopamine, in vivo, microdialysis, polychlorinated biphenyls, striatum. Environ Health Perspect 110:1113-1117 (2002) . [Online 18 September 2002] http://ehpnet1.niehs.nih.gov/docs/2002/110p1113-1117seegal/ abstract.html Address correspondence to R.F. Seegal, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12201 USA. Telephone: (518) 473-4378. Fax: (518) 486-1505. E-mail: seegal@wadsworth.org Research support for this work was provided in part by National Institute of Environmental Health Sciences grant ES07921 and U.S. Environmental Protection Agency grant R825812 to R.F.S. Received 14 February 2002 ; accepted 9 April 2002.
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