Aluminum induced encephalopathy in the rat

Aluminum tartrate (AlT) but not sodium tartrate (NaT) produces a progressive encephalopathy when injected intracerebroventricularly in the rat. This syndrome, lethal within 30-35 days, is characterized by progressively deranged behavior. An early startle reaction (day 14), later joined by locomotor discoordination (day 19) is followed by locomotor and electrocorticographic (ECoG) seizures (day 21) in chronically instrumented AlT rats. There is early dissociation between ECoG and locomotor aspects. When tested in the shuttlebox for estimation of learning and memory function 7-8 days after AlT injection, marked impairment of both active and passive avoidance was observed. Glucose uptake capacity of synaptosomes from brain areas of AlT and NaT animals was indexed by the 2-deoxy-D-glucose method. Striatal and cortical synaptosomes showed reduced uptake activity 7 days following AlT injection. By day 14, hypothalamic areas also became affected, striatal uptake was further inhibited, and cortical uptake was reduced to 57% of control. The ECoG background rhythm remained unchanged until days 20-23, when the mean peak frequency was reduced. The model may be useful in the study of central aluminum toxicity and may have predictive validity in the testing of procedures to counter aluminum-associated encephalopathies in man.