Exploring Exercise- and Context-Induced Peptide Changesin Mice by Quantitative Mass Spectrometry

摘要

Recent research suggests that exercise may help facilitate abstinence from cocaine addiction, though the mechanisms are not well understood. In mice, wheel running accelerates the extinction of conditioned place preference (CPP) for cocaine, providing an animal model for evaluating potential neurological mechanisms. The objective of this study was to quantify dynamic changes in endogenous peptides in the amygdala and dentate gyrus of the hippocampus in mice exposed to a context paired with the effects of cocaine, and in response to exercise. Male C57BL/6J mice conditioned to cocaine were housed with or without running wheels for 30 days. Following a CPP test and final exposure to either a cocaine- or saline-associated context, peptides were measured in brain tissue extracts using label-free matrix-assisted laser desorption/ionization mass spectrometry (MS) and stable isotopic labeling with liquid chromatography and electrospray ionization MS. CPP in mice was significantly reduced with running, which correlated to decreased myelin basic protein derivatives in the dentate gyrus extracts, possibly reflecting increased unmyelinatedgranule neuron density. Exposure to a cocaine-paired context increasedhemoglobin-derived peptides in runners and decreased an actin-derivedpeptide in sedentary animals. These results allowed us to characterizea novel set of biomarkers that are responsive to exercise in the hippocampusand in a cocaine-paired context in the amygdala.