PROTEOLYTIC PROCESSES IN RAT-BRAIN AND BLOOD-SERUM UNDER HYPOKINESIA AND THE ADAPTIVE INFLUENCE OF DELTA-SLEEP-INDUCING PEPTIDE

We demonstrate for the first time that a single injection of delta-sle ep inducing peptide (DSIP) results in long-term changes in proteolytic enzyme activities over a broad range of pH values. Using Ca2+-indepen dent neutral endopeptidases from the synaptosomal fraction of rat brai n and blood serum kallikrein as examples, we show that DSIP activates limited proteolysis. This effect may contribute to changes in the set and ''active'' concentrations of regulatory peptides and peptide hormo nes to the induction of the preadaptive state. DSIP also causes a redi stribution of activity between Ca2+-dependent and Ca2+-independent neu tral endopeptidases associated with synaptosomal membranes, especially under hypokinetic conditions. The significant decrease in the activit y of Ca2+-activated neutral proteinase I may be one of the mechanisms whereby tbe modulating effect of DSIP manifested as a regulation of th e number of glutamate receptors and a limitation of the effect of this excitatory neuromediator is realized under stress. Preliminary inject ion with DSIP prevents disturbances in the permeability of lysosomal m embranes under long-term (24 h) hypokinesia.