SunghyangJungki‐San Ga Pogongyoung inhibits IL‐1 mediated tumour necrosis factor‐α secretion in astrocytes

Abstract

Astrocytes play an important role in initiating and modulating inflammatory responses within the central nervous system (CNS). Extensive studies in rodents have shown that substance P induces inflammatory cytokine production in astrocytes. In this study we have examined whether an aqueous extract of SunghyangJungki-San Ga Pogongyoung (SSGP) inhibits the secretion of TNF-alpha from primary cultures of rat astrocytes. SSGP (10-1,000 microg/mL) significantly inhibited the TNF-alpha secretion by astrocytes stimulated with lipopolysaccharide (LPS) and substance P (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 SSGP. Treatment with SSGP (10-1,000 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 an increasing amount of IL-1 neutralizing antibody. Our results suggest that SSGP may inhibit TNF-alpha secretion by inhibiting IL-1 secretion and that SSGP has an antiinflammatory activity in the CNS.