Enhanced neurite growth in cultured neuroblastoma cells exposed to aluminum

Patients with aluminum-induced encephalopathy syndromes have been shown to have a high level of aluminum concentration in the brain. In the present study, the effects of aluminum were studied in mouse neuroblastoma cells (N-2A) grown in medium supplemented with aluminum (100 microM). It was found that aluminum enhanced neurite growth within 2 days of exposure. The mean total length of neurites in the control after 14 days in culture was 29.8 +/- 4.7 microns, whereas the neurite length of cells pre-exposed to aluminum for 2 days and then maintained in normal media for an additional 12 days was 56.4 +/- 8.9 microns. Further, the duration of exposure did not significantly promote a greater neurite response. The neurite length of cells exposed to aluminum for 14 days (60.7 +/- 9.6 microns) was not statistically different from that of cells exposed to aluminum for 2 days. Using morin stain, intracellular aluminum was detected within 24 h of exposure in the majority of aluminum-exposed cells. Intracellular aluminum did not disappear from those cells even after they were grown for 12 days in control medium. Our finding suggests that a brief exposure (2 days) to low level aluminum (100 microM) is sufficient to cause long-lasting effects on the morphology of neuroblastoma cells in culture. Such neurite behavior associated with aluminum exposure may suggest a morphological basis for the dementia seen in aluminum encephalopathy.