Prolonged effect of endorphin treatment during pregnancy in the rat on the histamine content of immune cells of F1 and F2 offspring generations

Female rats were treated with beta-endorphin on the 19th day of pregnancy and the histamine content of immune cells (blood lymphocytes; peritoneal lymphocytes, monocyte-macrophage-granulocyte group, mast cells; thymic lymphocytes) of the 7-week-old progenies (171 generation) was studied using a flow-cytometric immunocytochemical technique. In an other group, female F, progenies of endorphin-treated mothers were mated with control males and the F-2 generation was monitored for histamine content similar to the F-1. In the F, generation each cell type, except peritoneal and blood lymphocytes, contained significantly more histamine than the control cells. In the F2 generation only mast cells contained significantly more histamine relative to the appropriate control. This means that the effect of endorphin (hormonal) imprinting is transmitted transgenerationally, but with decreasing intensity however. Mast cells retained the effect of imprinting for longer than the other cells. The results are compared with the levels of serotonin in similarly treated animals, studied in earlier experiments. As the endorphin level can be elevated during pregnancy (by pain, traumatization, or other stress conditions) this can the set biogenic an-tine content of adult immune cells. Copyright (c) 2006 John Wiley & Sons, Ltd.