Synaptosomal degradation of substance P and some other neuropeptides.
Synaptosomes purified from spinal cord and from different rat brain areas exhibit peptide hydrolase activity, cleaving substance P (SP), bradykinin, THRH, LHRH, and neurotensin. The lowest activity for all the peptides tested was found in spinal cord, while the region with the highest degrading activity depended on the substrate: for substance P, it was striatum and cortex; for bradykinin, hypothalamus, and medulla oblongata; for THRH, striatum; for LHRH, midbrain; and for neurotensin, hippocampus. Degradation of substance P takes place at the plasma membrane of synaptosomes. Synaptosome ghosts cleave substance P (pH optimum 7-9, Km-2.5 X 10(-5) M, Vmax-130 nmol . hr-1 . mg protein-1) and also a number of its C-terminal fragments. Effects of the inhibitors show that several different classes of peptidases and proteases are involved in the degradation process. Peptide cleavage represents the probable pathway of synaptosomal inactivation of substance P.
A M
AM
Arzumanyan
A A
AA
Arutunyan
T N
TN
Akopyan
D000818:Animals; D001920:Bradykinin / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009496:Neurotensin / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism; D013373:Substance P / Q000378:metabolism*; D013574:Synaptosomes / Q000201:enzymology / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism
D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011480:Protease Inhibitors; D013373:Substance P; D009496:Neurotensin; D013973:Thyrotropin-Releasing Hormone; D007986:Luteinizing Hormone; D010447:Peptide Hydrolases; D001920:Bradykinin