Bombycis corpus extract prevents amyloid-beta-induced cytotoxicity and protects superoxide dismutase activity in cultured rat astrocytes

Bombycis corpus (BC) or Bombyx Batryticatus, a batryticated silkworm and wh ite-stiff silkworm, is a drug consisting of the dried larva of silkworm, Mo byz mori L., dead and stiffened due to the infection of Beauveria (Bals.) V uill. In the present study, we have examined the protective effect of the w ater extracts against Amyloid-beta (A beta) 25-35 peptide-induced cytotoxic ity by microscopic observation and LDH assay, and its action on antioxidati ve enzymes using cultured astrocyte cells. A beta 25-35-induced cell death was protected by the application of water extract of BC in a dose-dependent manner, and concentrations of 10(-6) to 10(-7) g ml(-1) showed a significa nt effect compared to exposure of A beta 25-35 alone. When antioxidative en zyme activities such as catalase, superoxide dismutase (SOD), glutathione p eroxidase (GSH-Px) and glutathione-S transferase (GST) were assayed after A beta 25-35 treatment, most enzyme activities were decreased in a similar f ashion. BC treatment of A beta 25-35-treated astrocytes did not affect the enzyme activities of catalase, GSH-Px and GST However, only SOD activity wa s enhanced by BC treatment and this may result from the potentiation of the antioxidative ability of BC. The protective effect of BC against cytotoxic ity induced by A beta 25-35 strongly indicates that BC could be a protectiv e agent for free radical generating compounds, and that A beta 25-35 is not only a potent lipid peroxide inducer, but can also cause changes in antiox idative enzymes. From the results, it was concluded that BC has a protectiv e effect against A beta -induced cytotoxicity in cultured astrocyte cells t hrough the inhibition of lipid peroxidation and protection of antioxidative enzymes. (C) 2001 Academic Press.