Effect of Soman on Neuropeptide Metabolism

摘要

Profiles of the neuropeptides bradykinin, neurotensin, somatostatin, alpha-MSH, beta-lipotropin, TRH, leu-enkephalin, met-enkephalin and substance P have been examined by reverse phase HPLC before and after incubation with homogenates prepared from rat and guinea pig brain as well as with acetylcholinesterase (AChE) from fetal calf serum (FCS). Enzymes in brain tissue hydrolyzed all of the above peptides except beta-lipotropin. Soman, an irreversible inhibitor of cholinesterase and serine proteases, prevented hydrolysis of TRH but had not effect on the hydrolysis of other neuropeptides examined here. These results suggest that among the enzymes in brain tissue hydrolyzing the above peptides, only TRH is hydrolyzed by a serine protease. AChE from FCS hydrolyzed substance P, bradykinin, neurotensin, leu and met-enkephalin but not TRH. Pretreatment of FCS AChE with soman did not prevent hydrolysis of the neuropeptides by AChe, leading us to conclude either that the peptidase activity associated with FCS AChE is due to co-purification of a non-serine peptidase or that the AChE contains peptidase activity not affected by soman. Keywords: Thyrotropin releasing hormone. (aw)