A brain derived peptide preparation reduces the translation dependent loss of a cytoskeletal protein in primary cultured chicken neurons

Abstract

Neuronal cytoskeletal proteins like the microtubule associated protein 2 (MAP2) are objected to pathological proteolysis in case of Alzheimer's disease and brain ischemia. The neurotrophic peptidergic drug Cerebrolysin® (EBEWE Arzneimittel, Austria, Europe) is produced by a standardized enzymatic break-down of lipid free porcine brain proteins. Cerebolysin® protected MAP2 in primary neuronal cultures after a brief histotoxic hypoxia and in a rat model of acute brain ischemia. Furthermore the drug was shown to inhibit the proteases μ- and m-calpain dose dependently in several cell free protease activity assays. The question if the higher MAP2 levels are due to an alleviation of proteolysis, to a higher synthesis rate or both is addressed in the current investigation: Monitoring the MAP2 content of primary neuronal cell cultures over a period of eight days revealed MAP2 to reach a peak level on day six in vitro followed by a degradation phase. In other experiments the protein synthesis of Cerebrolysin® treated and untreated cells was blocked with cycloheximide at that moment when all cells exhibited the same MAP2 content. After the following MAP2 degradation phase - i.e. after eight days in vitro - the MAP2 contents were determined by western blotting. Cerebrolysin® treated cells contained more MAP2 than untreated controls proving that the drug protects MAP2 independently from de novo synthesis, although further work is in progress to investigate if the drug supplementary boosts this effect by increasing MAP2 synthesis.