The modulating influence of enkephalins on the bone marrow haemopoiesis in stress.

The influence of enkephalins on haemopoiesis was studied under conditions of stress. Administration of leu-enkephalin and dalargin to mice subjected to immobilization led to inhibition of proliferation and differentiation of haemopoietic precursor cells and to a reduction in the content of cellular elements of erythroid and granulocyte lineages of haemopoiesis. On the contrary, met-enkephalin produced a stimulating influence on the bone marrow haemopoiesis in stress. The regulatory influence of enkephalins is connected with reduction of glucocorticoid production and inhibition of migration to bone marrow of T-lymphocyte regulators of haemopoiesis of the phenotype Lyt-1+, Lyt-2+ and with the direct action on the bone marrow cells. Participation of endogenous leu-enkephalin in the haemopoiesis regulation in stress takes place at an early stage (the first 24 h) of the general adaptation syndrome formation.