Immunohistochemical localization of a bombyxin-like peptide in the brain-retrocerebral complex of the insect Labidura riparia

Abstract

Summary Changes of bombyxin-like material in the brain-retrocerebral complex throughout the reproductive cycle of experimental Labidura riparia adult females have been examined with a monoclonal antibody raised against a synthetic decapeptide corresponding to the N-terminus of the bombyxin A-chain. In adult females immunostaining was detected in numerous intrinsic secretory cells of the corpora cardiaca (CC) and in six median protocerebral neurosecretory cells. During the previtellogenic period, a weak immunoreactivity was observed in a few cells of the CC and six median cells of the protocerebrum. Immunoreactivity gradually increased during vitellogenesis and disappeared after egg laying and during the following vitellogenesis arrest period. In pars lateralis -cauterized females, known to display continuous vitellogenesis but lower ecdysteroid levels than in normal vitellogenic females, a slight immunoactivity was present in a few CC cells only. Based on its cyclic variations in the brain-retrocerebral complex in relation to the reproductive cycle and ecdysteroid levels, the possible physiological role of this bombyxin-like peptide is discussed.