Effects of lead exposure on long-term potentiation induced by 2-deoxy-D-glucose in area CA1 of rat hippocampus in vitro

Chronic developmental lead exposure is known to be associated with cognitiv e dysfunction in children. Previous studies have demonstrated that chronic lead exposure could impair the induction and maintenance of long-term poten tiation induced by high-frequency stimulation (HFS-LTP). In area CA1 of rat hippocampus, long-term potentiation could also be induced following tempor ary replacement of 10 mM 2-deoxy-D-glucose (2-DG) for 10 mM glucose in the normal perfusate (artificial cerebrospinal fluid). The present study was ca rried out to investigate whether chronic lead exposure affected long-term p otentiation induced by 2-DG (2-DG-LTP). Neonatal Wistar rats were exposed t o lead from parturition to weaning via milk of dams whose drinking water co ntained 0.2% lead acetate. Field excitatory postsynaptic potentials (EPSPs) in area CA1 of hippocampus were recorded on postnatal days 25-30. 2-DG app lication was followed by an increase in EPSP slopes in a time-course-depend ent manner in both control and lead-exposed rats, while the amplitude of 2- DG-LTP in the lead-exposed rats (225.9 +/- 19.0%, n = 12) was significantly greater than that in controls (155.2 +/- 9.8%, n = 12). In contrast to the effects of lead exposure on 2-DG-LTP, the amplitude of HFS-LTP in the lead -exposed rats (121.5 +/- 13.7%, n = 12) was significantly less than that in controls (183.9 +/- 18.6%, n = 12). These results indicate that chronic le ad exposure had opposite effects on the two types of LTP induced by HFS and 2-DG. This would suggest that the effects of lead on HFS-LTP and 2-DG-LTP are the result of different sites of lead toxicity. (C) 2001 Elsevier Scien ce Inc. All rights reserved.