Influence of age on aluminum-induced neurobehavioral effects and morphological changes in rat brain

Aluminum (Al) is potentially toxic for mammals. In contrast to well documented Al neurotoxicity, neurobehavioral studies of Al in rodents have generally not produced robust or consistent results. In the present study, 16 young male (21 days old) and 16 old male (18 months) rats were exposed to 0 (control group) and 100 mg/kg/day of Al administered as Al nitrate nonahydrate in drinking water concurrently with citric acid (356 mg/kg/day) for a period of 100 days. At the end of the exposure period, rats were evaluated for motor activity in an open-field apparatus and learning in a passive avoidance test. After behavioral testing, rats were sacrificed and brain samples were collected to determine Al concentrations and to study synapses in the left CA1 fields of hippocampal formation. While no significant effects of Al exposure between groups could be detected on behavior, the total number of synapses decreased with age and Al exposure. In turn, the percentage of perforated synapses significantly increased in old Al-loaded rats. (C) 2002 Elsevier Science Inc. All rights reserved.