[Thermoregulatory activity of dermorphin fragments]

We studied the effect of C-terminal truncation of the dermorphin (DM) molecule and analogs of its N-terminal tetrapeptide, [DOrn2]-DM(1-4), [DArg2]-DM(1-4), [DAla4]-DM(1-4), [DArg2, DAla4]-DM(1-4), Arg-DM(1-4), Arg-[DArg2]-DM(1-4), Arg-[DAla4]-DM(1-4), and Arg-[DArg2, DAla4]-DM(1-4), on the functional status of the thermoregulation system in rats at different ambient temperatures. For the first time, we demonstrate that the N-terminal tetrapeptide is the minimal fragment with the hypothermic effect. Only the N-terminal octapeptide exerted the vasomotor effect. Amino acid substitutions in the tetrapeptide affected its hypothermic effect. [DArg2]-DM(1-4) and [DArg2, DAla4]-DM(1-4) had the greatest effect. Addition of Arg to the N-terminus of DM(1-4) analogs changed their thermoregulatory activity. The greatest thermoregulatory effect was observed for Arg-[DArg2]-DM(1-4) and Arg-[DArg2, DAla4]-DM(1-4).