title: Role of synaptic structural plasticity in impairments of spatial learning and memory induced by developmental lead exposure in Wistar rats.
abstract: Lead (Pb) is found to impair cognitive function. Synaptic structural plasticity is considered to be the physiological basis of synaptic functional plasticity and has been recently found to play important roles in learning and memory. To study the effect of Pb on spatial learning and memory at different developmental stages, and its relationship with alterations of synaptic structural plasticity, postnatal rats were randomly divided into three groups: Control; Pre-weaning Pb (Parents were exposed to 2 mM PbCl2 3 weeks before mating until weaning of pups); Post-weaning Pb (Weaned pups were exposed to 2 mM PbCl2 for 9 weeks). The spatial learning and memory of rats was measured by Morris water maze (MWM) on PND 85-90. Rat pups in Pre-weaning Pb and Post-weaning Pb groups performed significantly worse than those in Control group (p<0.05). However, there was no significant difference in the performance of MWM between the two Pb-exposure groups. Before MWM (PND 84), the number of neurons and synapses significantly decreased in Pre-weaning Pb group, but not in Post-weaning Pb group. After MWM (PND 91), the number of synapses in Pre-weaning Pb group increased significantly, but it was still less than that of Control group (p<0.05); the number of synapses in Post-weaning Pb group was also less than that of Control group (p<0.05), although the number of synapses has no differences between Post-weaning Pb and Control groups before MWM. In both Pre-weaning Pb and Post-weaning Pb groups, synaptic structural parameters such as thickness of postsynaptic density (PSD), length of synaptic active zone and synaptic curvature increased significantly while width of synaptic cleft decreased significantly compared to Control group (p<0.05). Our data demonstrated that both early and late developmental Pb exposure impaired spatial learning and memory as well as synaptic structural plasticity in Wistar rats.
authors.affiliation: Department of Preventive Medicine, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, United States of America.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Fu
authors.affiliation: Department of Preventive Medicine, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Han
authors.affiliation: Department of Preventive Medicine, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Hu
authors.affiliation: School of Medicine, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Huaiyu
authors.initials: H
authors.lastname: Gu
authors.affiliation: Department of Preventive Medicine, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Yilin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Preventive Medicine, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Wei
authors.affiliation: Department of Preventive Medicine, School of Public Health, Sun Yat-Sen University, Guangzhou 510080, China.
authors.forename: Qiansheng
authors.initials: Q
authors.lastname: Hu
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D056547:CA1 Region, Hippocampal / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology / Q000648:ultrastructure; D002452:Cell Count; D005260:Female; D048788:Growth and Development / Q000187:drug effects*; D007854:Lead / Q000097:blood / Q000633:toxicity*; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects*; D009473:Neuronal Plasticity / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects / Q000473:pathology; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D065853:Spatial Learning / Q000187:drug effects*; D013569:Synapses / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D014886:Weaning
chemical_list: D007854:Lead