Age-related impairment of long-term depression in area CA1 and dentate gyrus of rat hippocampus following developmental lead exposure in vitro

Chronic developmental lead exposure is known to be associated with cognitiv e dysfunction in children. Impairment of the induction of long-term depress ion (LTD) has been reported in area CAI and dentate: gyrus (DG) of rat hipp ocampus following chronic lead exposure. The present study was carried out to investigate age-related alterations of LTD in area CA1 and DG of rat hip pocampus following developmental lead exposure in vitro. Neonatal Wistar ra ts were exposed to lead from parturition to weaning via milk of dams drinki ng 0.2% lead acetate: solution. Field excitatory postsynaptic potentials (E PSPs) were recorded in hippocampal slices at various postnatal ages: postna tal day (PND) 17-23, 27-33, and 57-63. Following low-frequency stimulation (LFS, 900 pulses/1 Hz), the average magnitude of LTD is age related. In the controls, LTD magnitude in area CA1 decreased with age, whereas in DG it i ncreased with age. In the lead-exposed groups, the magnitude of LTD decline d during development in both area CA1 and DG. The differences of LTD magnit ude between the control and lead-exposed rats were 27.26 +/- 9.15% (PND 17- 23), 21.59 +/- 12.93% (PND 27-33), and 16.96 +/- 9.33% (PND 57-63) in area CA1, and were 6.95 +/- 9.26%, 17.60 +/- 3.91%, and 33.63 +/- 10.47% in DG, respectively. These results demonstrated that the lead-induced impairment o f LTD magnitude was an age-related decline in area CA1 and an age-related i ncrease in area DG of rat hippocampus. Published by Elsevier Science Inc.