Histamine protects bone marrow against cellular damage induced by ionising radiation.
Based on our previous data on the histamine radioprotective effect on small intestine, in the present work we aimed to determine whether histamine is able to protect bone marrow cells against ionising radiation damage. 56 mice and 40 rats were divided into four groups. Histamine and histamine-irradiated groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 24 h before irradiation. Irradiated groups received a single dose on whole-body using Cesium-137 source and were sacrificed three days after irradiation. We evaluated the number of medullar components, bone marrow trophism, oedema, vascular damage, and other histological characteristics and also proliferation markers by immunohistochemistry. Histamine treatment substantially reduced the grade of aplasia, the oedema and vascular damage induced by ionising radiation on bone marrow of mice and rats. Additionally, histamine preserved medullar components increasing the number of megakaryocytes (14.0 +/- 1.0 vs. 7.3 +/- 1.0 in mice; and 9.9 +/- 1.3 vs. 4.1 +/- 1.0 in rats, P < 0.01) and also myeloid (253.4 +/- 37.6 vs. 7.8 +/- 1.5 in mice; and 52.0 +/- 3.7 vs. 31.8 +/- 3.1 in rats, P < 0.01), lymphoid (97.4 +/- 6.5 vs. 19.8 +/- 1.6 in mice; and 23.4 +/- 0.9 vs. 11.7 +/- 2.5 in rats, P < 0.01) and erythroid cells (165.0 +/- 9.1 vs. 8.8 +/- 2.8 in mice; and 27.3 +/- 2.3 vs. 15.6 +/- 3.5 in rats, P < 0.01) per mm(2). This effect was associated with an increased proliferation rate of bone marrow cells. Histamine reduces ionising radiation toxicity on bone marrow cells being a suitable candidate for use as radioprotector, especially for patients undergoing radiotherapy who are at the risk of bone marrow or small intestine damage.