Low Lead Exposure During Foetal and Early Postnatal Life Impairs Passive Avoidance Learning in Adulthood in Rats

Abstract

This follow-up study investigated the effects of low-level lead exposure during prenatal and early postnatal period on learning and memory in rats immediately after exposure has ceased at weaning and later in their adulthood. Male Wistar-derived rats were exposed to lead (as 0.2 % lead acetate solution) through their mothers during pregnancy and lactation until they were weaned. Mothers of control rats were given tap water during pregnancy and lactation. All pups were weaned on tap water at 21 days of age and were followed up until 120 days old. Low-level lead exposure did not affect their body weight at any time during the experiment. Blood lead in the exposed rats was signifi cantly higher on postnatal day 22 and dropped to control values by day 120. Passive avoidance test showed impaired memory retention in the exposed rats on postnatal days 25 and 120. This suggests that exposure to low-lead levels during foetal and early postnatal development of brain tissue can cause memory impairment that lasts into adulthood.

Inhibition of Astrocytic Glutamine Synthetase by Lead is Associated with a Slowed Clearance of Hydrogen Peroxide by the Glutathione System

“…Verbal and nonverbal memory is impaired in individuals who have been chronically exposed to lead, with the greatest deficits being evident in children, particularly with respect to their global intelligence and capacity to learn (Mason et al, 2014 ). The effects of lead intoxication on memory have been amply demonstrated in animal models (Kuhlmann et al, 1997 ; Barkur et al, 2011 ). While neurones are sensitive to the toxicity of lead, they preferentially accumulate it in lysosomes, whereas astrocytes accumulate lead at a higher rate than neurones and concentrate it in the nucleus and throughout the cytoplasm (Holtzman et al, 1987 ).…”

Long‐term consequences of early postnatal lead exposure on hippocampal synaptic activity in adult mice

“…For example, BLLs as low as 2 µg/dl were associated with decreased cognitive functions and lower academic success in children (Huang et al, ; Lucchini et al, ; Sobin, Flores‐Montoya, Gutierrez, Parisi, & Schaub, ). Other studies show that some of these childhood deficits can persist long after Pb exposure has ceased (Barkur, Rao, & Bairy, ; Gilbert & Lasley, ; Schwartz et al, ). Data from adults in their fifties (equivalent to 9‐ to 12‐month‐old mice) suggest that Pb exposure can accelerate cognitive decline (Mason, Harp, & Han, ) and worsen the memory impairment of Parkinson's and Alzheimer's disease patients (Eid & Zawia, ; Lee & Freeman, ).…”

“…For example, BLLs as low as 2 µg/dl were associated with decreased cognitive functions and lower academic success in children (Huang et al, 2012;Lucchini et al, 2012;Sobin, Flores-Montoya, Gutierrez, Parisi, & Schaub, 2015). Other studies show that some of these childhood deficits can persist long after Pb exposure has ceased (Barkur, Rao, & Bairy, 2011;Gilbert & Lasley, 2002;Schwartz et al, 2000).…”