DETERMINATION OF CRITICAL CELLULAR NEUROTOXIC CONCENTRATIONS IN HUMANNEUROBLASTOMA (SH-SY5Y) CELL-CULTURES

The effects of the neurotoxic compounds acrylamide, triethyltin chlori de (TET), methyl mercury (II) chloride (MeHg) and lindace on selected neurospecific and general cell functions in differentiated human neuro blastoma SH-SY5Y cells were investigated in an attempt to determine cr itical cellular neurotoxic concentrations. The cultures were exposed t o the neurotoxicants for three days, and then the effects on cell grow th, neuronal signal transaction and the induction of axonopathy were m easured. For comparison, general cytotoxicity was also determined in h uman epithelial (HeLa) cells. The cytotoxic activities (IC20 values) i n the SH-SY5Y cells were 0.18 +/- 0.03 mu M for TET, 0.20 +/- 0.03 mu M For MeHg, 32 +/- 10 mu M for lindane and 810 +/- 170 mu M for acryla mide. Inhibition of cell growth was similar in HeLa cells. Significant ly lower concentrations of MeHg, acrylamide and TET than the IC20 valu es were sufficient to induce axonopathy. In addition, MeHg and acrylam ide increased the basal intracellular free calcium concentration, [Ca2 +](i), as well as the carbachol-induced Ca2+ fluxes and the depolarisa tion-stimulated increase of [Ca2+](i) compared to control cells. The e levated [Ca-2+](i) may be a primary cause of the acrylamide-induced an d MeHg-induced neuropathy Treatment with lindane (1 mu M) slightly dec reased the depolarisation-evoked Ca2+ influx in the neuroblastoma cell s. A parallel to the documented neurotoxic mechanism of lindane (i.e. inhibition of the gamma-aminobutyric acid-activated Cl- channels) is p ossible.