Bombycis corpus Extract (BCE) Protects Hippocampal Neurons Against Excitatory Amino Acid-Induced Neurotoxicity

Bombycis corpus (BC) or Bombyx Batryticatus, a batryticated silkworm and white-stiff silkworm, is a drug consisting of the dried larva of silkworm, Mobyz mori L., dead and stiffened due to the infection of Beauveria (Bals.) Vuill. In a previous paper (Kim et al., Pharmacol. Res., 43, 12-16, 2001), BC was shown to protect amyloid-β-induced cytotoxicity. In the present study, we have found that BCE can prevent or reduce the neurotoxic actions in the hippocampus of the glutamate agonists N-methyl-D-aspartic acid (NMDA) in vitro or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainic acid in vitro. Pre-treatment with BCE (0, 1, 2, 5, and 10 μg/ml for 6-8 h) protected primary hippocampal cultures from embryonic day 18 (E18) embryos against NMDA-induced toxicity (0.1, 1, 10, and 50 mM/ml). BCE added either with NMDA (1 mM) or 1 h later had lesser, but still significant, protective actions. BCE also reduced NMDA-induced toxicity (1 mM). BCE (10 μg/ml) protected cultured neurons against the neurotoxic actions of either AMPA (25 μM) or kainic acid (1 mM) as well. Because the release of glutamate has been implicated in the neural damage after cerebral ischemia and other neural insults, these results suggest that BCE may contribute significantly to protect human brain to such damage.