Neurofilament phosphorylation is enhanced in cultured chick spinal cord neurons exposed to cerebrospinal fluid from amyotrophic lateral sclerosis patients.

Amyotrophic lateral sclerosis (ALS), a neurodegenerative disease, is characterized by degeneration of lower and upper motor neurons. Serum and cerebrospinal fluid (CSF) of ALS patients have been found to exert toxic effects on neurons in culture. We report here increased phosphorylation of neurofilaments (NF) in the soma of chick spinal cord neurons in culture when exposed to CSF of ALS patients. Spinal cord neurons were cultured from 10-day embryonic chick and exposed to culture medium supplemented with CSF or serum (10%) from ALS and non-ALS patients for 48 h. There was a significant increase in the number of neuronal soma staining with antibodies against phosphorylated NF, following exposure to CSF from ALS patients. Such an increase, however, was not observed in cultures exposed to serum from ALS patients and also serum and CSF from non-ALS patients. These results suggest that the CSF of ALS patients may contain factor(s) which induces aberrant phosphorylation of NF in the soma, a probable forerunner to the formation of neurofibrillary tangles and eventual degeneration of neurons.