The toxic effects of
physostigmine, an
anticholinesterase drug, and its metabolite
eseroline were investigated in three neuronal cell culture systems, mouse
neuroblastoma N1E-115, rat
glioma C6, and
neuroblastoma-
glioma hybrid NG 108-15.
Physostigmine and
eseroline (0.5 nM) elicited a time-dependent leakage of
lactic acid dehydrogenase (LDH) from all three cell types. An increased release of [14C]
adenine nucleotides was also detected from cells when they were prelabeled with [14C]
adenine.
Eseroline was comparatively more toxic than the parent compound,
physostigmine.
Eseroline elicited a dose- and time-dependent leakage of LDH and release of
adenine nucleotides from the neuronal cells. A nonneuronal cell line, rat liver ARL-15, was comparatively the most resistant cell type to
eseroline toxicity. The concentrations of
eseroline needed for 50% release of
adenine nucleotides or 50% leakage of LDH from NG-108-15 and N1E-115 cells in 24 hr ranged from 40 to 75 microM. The concentrations of
eseroline needed to obtain similar responses in C6 and ARL-15 cells were much higher and ranged from 80 to 120 microM. Phase contrast microscopy showed extensive damage to three neuronal cell lines at concentrations of
eseroline as low as 75 microM. The loss of
ATP from N1E-115 cells exceeded 50% when they were treated with 0.3 mM
eseroline for 1 hr--at which time the leakage of LDH was not detectable. It seems that
eseroline causes neuronal cell death by a mechanism involving loss of cell
ATP. Thus, the formation of
eseroline may contribute to the toxic effect of
physostigmine.