Effect of Polygala tenuifolia root extract on the tumor necrosis factor-alpha secretion from mouse astrocytes

We investigated whether an aqueous extract of Polygala tenuifolia root (PTAE) inhibits secretion of tumor necrosis factor-alpha (TNF-alpha) from primary cultures of mouse astrocytes. PTAE dose-dependently inhibited the TNF-alpha secretion by astrocytes stimulated with substance P (SP) and lipopolysaccharide (LPS). 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 also investigated whether IL-1 mediated inhibition of TNF-alpha secretion from primary astrocytes by PTAE. Treatment of PTAE to astrocytes stimulated with both LPS and SP decreased IL-1 secretion to the level observed with LPS alone. Moreover, incubation of astrocytes with IL-1 antibody abolished the synergistic co-operative effect of LPS and SP. These results suggest that PTAE may inhibit TNF-alpha secretion by inhibiting IL-1 secretion and that PTAE has an anti-inflammatory activity on the central nervous system curing some pathological disease states.