· Tools for neurochemistry: determination of ectopeptidase activity in tissue

Goals: Understand the biochemistry of stroke, including the effect of neuroprotective peptides and the ectopeptidases that regulate their activity.

Approaches: Electroosmotic perfusion of brain tissue with neuroprotective peptides – ex vivo (in organotypic hippocampal slice cultures, OHSCs, via electroosmotic push-pull perfusion, EOPPP) and (in the near future via long-term iontophoresis/microdialysis, LTI-MD) in vivo. Ectopeptidases hydrolyze the peptides into smaller peptides that may be active or inactive. Peptides are quantitated using capillary liquid chromatography (cLC). Peptidase activity is inferred from peptide quantitation and a computed peptide residence time in the tissue.

Results: We find differences in the hydrolysis of the neuroprotective peptides galanin and leucine enkephalin in the CA1 and CA3 regions of the rat hippocampus that correlate with the regions’ different susceptibilities to injury.