An Assessment of Low Level Lead Exposure on Encephalization and Cortical Quotients and its Relationships with Cortical Thinning & Neurodegeneration.

Abstract

Lead (Pb) is a neurotoxin that causes lifelong cognitive dysfunction. Depending upon 1) gender, 2) the developmental time-period, and 3) the duration of Pb exposure, different patterns of brain damage may emerge during neurodevelopment or following the majority of brain growth. We examined an environmentally relevant Pb exposure (25 ppm) given to rats during different stages of neurodevelopment (i.e., perinatal [Peri] vs. postnatal [PND]) would negatively affect their encephalization and the cortical quotients (EQ & CQ) when assessed at PND 55 (i.e., the time point of cortical maturation in rats). EQ and CQ data are used to assess brain mass: body weight ratios in the former and to assess cortical mass: brain weight ratios in the latter to predict intelligence. Our data revealed that female rats have significantly higher EQ and CQ values when compared to males. EQ data revealed in Peri-PND O, Peri-PND 22, and Birth-PND 55 males a 6%, 16%, and 12% reduction in brain mass and in females, an 11%, 3%, and 3% reduction in brain mass when compared to controls. CQ data revealed in Peri-PND 0, Peri-PND 22, and BirthPND 55 males a 7%, 18%, and 0% reduction in cortical mass and in females, a 16%, 2%, and 12% reduction in cortical mass when compared to controls. Pb exposure causes different patterns of brain volume loss that decreases both EQ and CQ intelligence outcomes. This model offers translation potential in using fMRl clinical screenings for Pb exposed children and later life outcomes (SUNY-OW Faculty Development Grant).