Regional Distribution and Accumulation of Lead in Caprine Brain Tissues Following a Long-Term Oral Dosing Regimen

Abstract

It is well known that the brain is a key target organ for lead (Pb)-induced toxicity, with exposure potentially resulting in numerous adverse neurological effects. However, information on the distribution and accumulation of Pb within different brain regions is scarce. In this study, Pb uptake and accumulation were characterized in brain and related tissues obtained from a convenience sample of goats dosed with Pb. Tissues were harvested postmortem from 10 animals (9 dosed and 1 undosed) that are used to produce blood Pb pools for the New York State Department of Health’s Proficiency Testing program. Whole brains were subdivided into 14 distinct anatomical regions to explore interregional differences. Related tissues included the olfactory epithelium and spinal cord. Where sufficient tissue mass permitted, further subdivision into smaller sections was carried out to examine intraregional Pb variability. Determination of Pb content in these tissues was accomplished using inductively coupled plasma mass spectrometry (ICP-MS), with accuracy assessed using reference materials certified for Pb. Lead content (dry weight) varied from <10 ng/g, that is, below the method detection limit, to as much as 4.45 × 10⁴ ng/g Pb. Olfactory epithelium Pb content was several orders of magnitude greater than found in other regions analyzed. Enrichment of Pb was also observed in the olfactory bulb and choroid plexus. Data for each region analyzed were pooled from all goats to identify regions with the greatest propensity for Pb accumulation. Data related to Pb content were also assessed individually within each goat and significant differences in Pb content between regions were determined.