Memory deficit in mice administered aluminum-maltolate complex.
Recently, aluminum (Al) has been identified as one of the environmental factors responsible for cause certain nerve degeneration diseases, particularly, Alzheimer's disease (AD). However, the relationship between Al and AD is controversial. We previously examined whether Al induced neurotoxin in the brain of mice when aluminum-maltolate complex (ALM) was administered daily for 120 days. Our results revealed that Al accumulated in the brain induced oxidative stress, and the nerve degeneration was detected in the brain of the ALM-treated group. On the basis of these results, we have tried to examine whether the incorporated Al affects memory in mice with regard to an indicator of spatial memory deficits depending on the chemical forms of Al, namely, as an ion (AlCl3) and in the form of a complex (ALM). We administered saline, AlCl3, and ALM at a concentration of 40 micromol Al/kg body weight to mice by daily ip injections for 60 days. We assessed spatial memory by a water maze task and determined the Al levels in the brain of the mice by the neutron activation analysis method. Spatial memory deficit as an indicator of the swimming time was related to Al accumulation in the brain of mice; the chemical form of the Al compound was important in order to exhibit the memory deficit in mice; the uptake of Al is higher in mice when it is administered in a complex form than in an ionic form.