Effects of exposure to aluminum on long-term potentiation and AMPA receptor subunits in rats in vivo.

OBJECTIVE To explore the effects of exposure to aluminum (Al) on long-term potentiation (LTP) and AMPA receptor subunits in rats in vivo. METHODS Different dosages of aluminum-maltolate complex [Al(mal)3] were given to rats via acute intracerebroventricular (i.c.v.) injection and subchronic intraperitoneal (i.p.) injection. Following Al exposure, the hippocampal LTP were recorded by field potentiation technique in vivo and the expression of AMPAR subunit proteins (GluR1 and GluR2) in both total and membrane-enriched extracts from the CA1 area of rat hippocampus were detected by Western blot assay. RESULTS Acute Al treatment produced dose-dependent suppression of LTP in the rat hippocampus and dose-dependent decreases of GluR1 and GluR2 in membrane extracts; however, no similar changes were found in the total cell extracts, which suggests decreased trafficking of AMPA receptor subunits from intracellular pools to synaptic sites in the hippocampus. The dose-dependent suppressive effects on LTP and the expression of AMPA receptor subunits both in the membrane and in total extracts were found after subchronic Al treatment, indicating a decrease in AMPA receptor subunit trafficking from intracellular pools to synaptic sites and an additional reduction in the expression of the subunits. CONCLUSION Al(mal)3 obviously and dose-dependently suppressed LTP in the rat hippocampal CA1 region in vivo, and this suppression may be related to both trafficking and decreases in the expression of AMPA receptor subunit proteins. However, the mechanisms underlying these observations need further investigation.