Effect of tetrandrine on calcium-dependent tumour necrosis factor-alpha production in glia-neurone mixed cultures.

Tumour necrosis factor-alpha is believed to have a deleterious role in the pathophysiology of brain injury. Tetrandrine has protective effect on neuronal cells, however, the mechanisms involved in its action have not been clearly established. The aim of this study was to investigate the role of tetrandrine on calcium-dependent tumour necrosis factor-alpha production in glia-neurone mixed cultures. Glia-neurone mixed cultures were treated by addition of Ca2+ regulating agents for a period of 6 hr. Tetrandrine or/and TMB-8 were added 30 min. before the stimulation. The supernatant tumour necrosis factor-alpha levels were quantified by enzyme-linked immunosorbent assay. Exposure of lipopolysaccharide 10 and 100 ng/ml caused significant increase in tumour necrosis factor-alpha production respectively, with no alteration in cultures treated with 1 ng/ml lipopolysaccharide. Glia-neurone mixed cultures exhibited a marked elevation in tumour necrosis factor-alpha production after exposure to CaCl2, KCl, thapsigargin, BHQ and norepinephrine in the presence of lipopolysaccharide at 1 ng/ml respectively. Tetrandrine 0.3, 1, and 3 microM concentration-dependently reduced tumour necrosis factor-alpha production evoked by CaCl2 or KCl. Tetrandrine preincubation had no significant effect on the response to Ca2+-ATPase inhibitor thapsigargin or BHQ. Norepinephrine-induced tumour necrosis factor-alpha production was significantly reduced by tetrandrine and almost abolished by combination of tetrandrine and intracellular Ca2+ release inhibitor TMB-8. These results suggested that tetrandrine at a concentration of 0.3, 1, or 3 microM inhibited tumour necrosis factor-alpha production induced by Ca2+ entry in glia-neurone mixed cultures.