[Effect of bone marrow mediator myelopeptides on the summation-threshold index and behavioral reactions of rats].

Transmitter peptides having immunostimulant and endorphine-like properties were isolated from supernatant of medullary cell culture. Bioregulatory peptides were called myelopeptides. Myelopeptides provoked changes of the summation-threshold index in rats, which augmented in time. These changes pointed to the realization of the analgetic effect of myelopeptides via the spinal-stem structures of the central nervous system. Having a remarkable analgesic effect myelopeptides administered in the doses tested did not produce any action on the behavioral responses. The latter circumstance makes them differ from narcotic analgesics and known endorphines.