Abstract: Objective To study the effect of aluminum-maltolate(Almal₃) complex on long-term potentiation(LTP) in rat hippocampus in vivo.Methods The rats were exposed to Al(mal)₃ by acute intracerebroventricular injection.Field excitatory postsynapic potenial(fEPSP) in CAI region of hippocampus was recorded by field potentiation technique in vivo.Results The basal fEPSP of high dose Al(mal)₃(60.75 μg) groups with preinjection and postinjection were 109±4% and 111±7%,respectively,without significant difference(P>0.05).In 60 min-post high frequency stimulation,the fEPSP of 2.43μg,12.15 μg,and 60.75 μg groups were 157±8%,140±13%,and 110±7%,with significant differences compared to that of the control group.But under the same dose of exposure,Al(mal)₃ did not affect paired pulse facilitation(PPF)ratio.Conclusion Al(mal)₃ obviously suppresses the LTP in rat hippocampal CA1 region in a dose-dependent manner in vivo,probably through postsynaptic mechanism but not presynaptic transmitter release.