Prostaglandin production in response to a bacterial infection in true armyworm larvae.

摘要

Prostaglandin concentrations were determined by fluorometric HPLC analysis of haemolymph collected from larvae of the true armyworm, Pseudaletia unipuncta [Mythimna unipuncta], that had been injected with bacteria. Prostaglandins were extracted andderivatized with the fluorogenic compound 9-anthryldiazomethane and detected by fluorescence HPLC. One of the prostaglandins produced was identified as prostaglandin F2alpha based on HPLC retention time. The chemical identity of prostaglandin F2alpha wasconfirmed by isolation and derivatization followed by gas chromatography-mass spectrometry analysis. Larvae injected with heat-killed bacteria, Serratia marcescens, produced about 4 times as much prostaglandin F2alpha as larvae injected with saline. Ina separate experiment, larvae injected with bacteria and the prostaglandin precursor arachidonic acid produced still higher concentrations of prostaglandin F2alpha. The production of prostaglandin was inhibited with phenidone, a dual cyclooxygenase and lipoxygenase inhibitor. These data indicate that bacterial injections stimulate increased eicosanoid biosynthesis in true armyworms, particularly biosynthesis of prostaglandin F2alpha, adding considerable support to the hypothesis that eicosanoids mediateinsect cellular immune reactions to bacterial infections.