Modification of glutamate- effects on neuroblastoma cells in culture by heavy metals

Sodium L-glutamate inhibited the growth (due to inhibition of cell division and cell death) of mouse neuroblastoma (NB) cells in culture in a dose dependent fashion. The sensitivity of adrenergic (NBA₂₍₁₎) and cholinergic (NBE^?) clones to L-glutamate was similar. Sodium D-glutamate, L-aspartate, α-ketoglutarate, glutamine, γ-aminobutyric acid and carbachol did not inhibit the growth of NB cells. Methylmercuric chloride (CH₃HgCl), inorganic mercury (HgCl₂), manganese chloride (MnCl₂) and lead tri-butyl acetate, by themselves inhibited the growth of NB cells in culture to a varying degree ranging from 41% to 49%. However, the combination of glutamate with CH₃HgCl, HgCl₂ and MnCl₂, produced a synergestic effect on growth inhibition of NB cells in culture. The combination of glutamate with lead tri-butyl acetate produced only an additive effect. Sodium kainate neither inhibited the growth nor potentiated the growth inhibitory effect of L-glutamate on NB cells. Neuroblastoma cells contained high levels of receptors for glutamate but not for kainate. These results show that neuroblastoma culture may be a useful model to study the mechanisms of glutamate effects and their modification by various agents.