Extensive labelling of injured insect neurons with seven different heme peptides

Seven different heme peptides were used in neuronal uptake and labelling experiments in flies. The peptides were: catalase, lactoperoxidase, hemoglobin, horseradish peroxidase (HRP), myoglobin, cytochrome c and microperoxidase. All of these peroxidase active peptides were taken up by lesioned neurons and the markers spread throughout the entire cells resulting in a detailed labelling of their processes and cell bodies. Only HRP was taken up by intact neurons. Attempts were made to block axonal transport of HRP with colchicine, vinblastine and 2,4-dinitrophenol. These attempts were unsuccessful and it is proposed that HRP and the other six heme peptides testes are non-selectively diffusing through lesioned or damaged nerve cells in flies.