Journal of Neuroscience, Vol 12, 1763-1771, Copyright © 1992 by Society for Neuroscience
Aluminum-induced neurofilamentous changes in cultured rat dorsal root ganglia explants
MR Gilbert, BL Harding, PN Hoffman, JW Griffin, DL Price and JC Troncoso
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Intrathecal administration of aluminum (AI) salts to susceptible species
causes prominent accumulations of neurofilaments (NFs) in neurons of the
CNS. Involved nerve cells display abnormal phosphorylation of perikaryal
NFs, impaired axonal transport of NFs, and reduced levels of mRNA for NF
proteins. Further understanding of the pathogenesis of AI toxicity has been
limited by difficulties inherent in the available in vivo systems. For this
reason, we have developed a model to study the effects of AI on cultured
sensory neurons. Explant cultures of rat dorsal root ganglia (DRG) were
exposed to 1 mM aluminum lactate for 1 d, 3 d, or 7 d and then examined
morphologically. Accumulations of NFs were noted as early as 1 d after
exposure, and prominent masses of NFs were seen at 3 and 7 d. Northern
analysis of mRNA extracted from the cultured ganglia showed that high,
medium, and low molecular weight NF protein mRNA levels were markedly
reduced compared to control values by 1 d of exposure. Class II beta-
tubulin mRNA was also moderately decreased. Reversibility of toxicity was
assessed by removing the aluminum lactate from the medium after a 3 d
exposure and examining the cultures 1 week later. The perikaryal masses of
NFs dispersed and the levels of mRNA coding for the NF proteins and class
II beta-tubulin increased. The neurotoxic effects of AI on cultured DRG
recapitulates the effects of intrathecal administration of AI on animals;
this model produces similar changes in neuronal morphology with
neurofilamentous masses and similar modifications of NF gene
expression.(ABSTRACT TRUNCATED AT 250 WORDS)