No changes in lymphocyte muscarinic receptors and platelet monoamine oxidase-B examined as surrogate central nervous system biomarkers in a Faroese children cohort prenatally exposed to methylmercury and polychlorinated biphenyls

Abstract

Experimental evidence suggests that monoamine oxidase B (MAO-B) and muscarinic cholinergic receptors (mAChRs) are involved in the pathogenesis of neurotoxicity caused by methylmercury and polychlorinated biphenyls (PCBs). Blood samples from 7-year-old exposed children were analyzed for platelet MAO-B and lymphocyte mAChRs as potential markers of exposure to these neurotoxicants. The blood neurotoxicity biomarkers were compared with prenatal and current exposures and with neuropsychological test results. Both biomarkers showed homogeneous distributions within this cohort (mAChR, range 0.04–36.78 fmol/million cells; MAO-B, 0.95–14.95 nmol mg⁻¹ protein h⁻¹). No correlation was found between the two biomarkers and either blood neurotoxicant concentrations or clinical findings. MAO-B and mAChR sensitivity may not be sufficiently high to assess early, subclinical responses to low/moderate methylmercury and/or PCB exposure, whereas these markers are significantly altered in sustained exposure scenarios, as shown by clinical studies in drug addicts or patients treated with psychopharmacological agents.

Key words::

• Neurochemical markers
• MeHg
• polychlorinated biphenyls
• brain development
• MAO-B
• cholinergic receptors

Acknowledgements

The present study was part of projects supported by the European Commission (ANEMONE – QLK4-CT-2001-00186, Quality of Life and Management of Living Resources Programme) and the Italian Ministry of Health. Professor åke Bergman (Stockholm University) kindly provided the PCB congeners that were synthesized in his laboratory. The authors wish to thank Mr Davide Acerbi for his excellent technical assistance.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.