In vitro activation of neurosecretory brain cells in Mamestra brassicae by β-ecdysone

Abstract

The effect of ecdysone or of the prothoracic gland on the neurosecretory cells of brains taken from diapausing pupae of the cabbage armyworm, Mamestra brassicae L., was investigated histologically and functionally in vitro. When the diapausing brain was cultured in a medium containing β-ecdysone, the neurosecretory cells of the median group I in the pars intercerebralis increased staining intensity more than those of brains cultured in medium alone. Furthermore, when the prothoracotropic activity of a brain treated with β-ecdysone was compared with that of an untreated brain in vitro, the brain treated with hormone showed higher activity than the untreated one. These results suggest that β-ecdysone acts on the neurosecretory cells of pupal brain in M. brassicae as a positive feedback regulator.