Opposite effects of lead exposure on taurine- and HFS-induced LTP in rat hippocampus

The effect of lead exposure on taurine-induced long-term potentiation (LTPTAU) was examined and compared with high-frequency stimulation-induced one (LTPHFS). Field excitatory postsynaptic potentials (fEPSP) and fiber volley (FV) in area CA1 of hippocampal slice were recorded in control and lead-exposed rats. In contrast to the inhibitory effects of lead exposure on LTPHFS, the amplitude of LTPTAU in the lead-exposed rats (199.3 ± 13.7%, n = 12) was significantly larger than that in controls (152.3 ± 17.0%, n = 12). It was also observed that taurine induced greater FV potentiation in lead-exposed rats (162.6 ± 9.0%, n = 10) than controls (132.1 ± 6.9%, n = 11). In addition, after a previous HFS, sequent perfusion of taurine could further increase the synaptic efficacy in lead-exposed rats. These results provide the first evidence that chronic lead exposure has opposite effects on the two types of LTP resulting from different lead toxicity sites.