EFFECT OF ALUMINUM-CHLORIDE, ALUMINUM CITRATE, AND ALUMINUM MALTOL ONTHE CALCIUM-MEDIATED DEGRADATION OF NEUROFILAMENT PROTEINS

Aluminum (Al) has been observed to cause neurofilament protein accumul ation in both experimental animals and cultured cells. Impairment of a xonal transport is thought to be a mechanism of toxicity. Inhibition o f the degradation of neurofilament proteins, however, resulting in acc umulation of these proteins may be an alternative mechanism for Al tox icity. In the present study, the effect of calcium (Ca) on the proteol ysis of the neurofilament triplet proteins by calcium-activated neutra l proteases (CANP) was studied in the isolated sciatic nerve explants. The extent of the degradation was found to be dependent on the Ca con centration. The effect of Al chloride, -citrate, and -maltol on the ca lcium-induced degradation was studied. No effect of any of the Al comp ounds was observed, suggesting that the metal may exert its neurotoxic effect via a mechanism other than impairment of neurofilament proteol ysis. Maltol itself was found to enhance the effect of Ca on the degra dation of neurofilament proteins, probably by facilitating the movemen t of Ca across the neuronal membrane. (C) 1993 Intox Press, Inc.