Inhibitory effect of tumor necrosis factor-alpha secretion from rat astrocytes by Chilbokeum

Substance P (SP) can stimulate secretion of tumor necrosis factor-alpha (TNF-alpha) from astrocytes stimulated with lipopolysaccharide (LPS). In this study, we have examined whether an aqueous extract of Chilbokeum inhibits secretion of TNF-alpha from primary cultures of rat astrocytes. Chilbokeum (10 microg/ml) significantly inhibited the TNF-alpha secretion by astrocytes stimulated with LPS and SP. Interleukin-1 (IL-1) has been shown to elevate TNF-alpha secretion from LPS-stimulated astrocytes while having no effect on astrocytes in the absence of LPS. We therefore examined whether IL-1 mediated inhibition of TNF-alpha secretion from primary astrocytes by Chilbokeum. Treatment of Chilbokeum (10 and 100 microg/ml) to astrocytes stimulated with both LPS and SP decreased IL-1 secretion significantly. Moreover, the secretion of TNF-alpha by LPS and SP in astrocytes was progressively inhibited with increasing amount of IL-1 neutralizing antibody. Our results suggest that Chilbokeum may inhibit TNF-alpha secretion by inhibiting IL-1 secretion and that Chilbokeum has an antiinflammatory activity in the central nervous system.