Chronic exposure to low-level lead impairs learning ability during aging and energy metabolism in aged rat brain

The neurotoxic effect of chronic exposure to low-level lead (Pb) with advan cing age is becoming an important social issue of public health. To examine the effects of low-level Pb treatment on behavior, cognition and brain ene rgy metabolism in aging, we administered 200 ppm Pb acetate to adult (10-mo nth-old) male Wistar rats for 12.5 months. After 12.5 months' exposure, the mean Pb levels in blood and brain had increased to 17.5 mu g/dl and 0.07 m u g/g, respectively, and the rats showed impaired learning and memory funct ions in a holeboard spatial memory test. No significant difference was foun d between experimental and control groups in locomotor activity and passive avoidance tests. By HPLC analysis of energy-rich phosphate concentrations, mild abnormalities were found in parietotemporal cortex and hippocampus, b ut only the 4.4% decrease of ATP in the parietotemporal cortex was statisti cally significant. These results suggest that chronic exposure to Pb during aging stage may selectively impair learning and memory functions and may c ause slight cerebral energy impairment. (C) 2000 Elsevier Science Ireland L td. All rights reserved.