Histamine protects bone marrow aginst damge induced by ionizing radiation

V MEDINA, M CROCI, E CRESCENTI, L SAMBUCO, N MASSARI, G CRICCO, G MARTÍN , R BERGOC, E RIVERA.

Buenos Aires , Argentina

Congreso; XII International Congress of the International Radiation Protection Association (IRPA); 2008

International Radiation Protection Association

After surgery, radiotherapy is arguably one of the most important treatments for cancer, especially forlocalized disease that has not spread. However, ionizing radiation is toxic not only to tumor cells but also to healthy tissues causing serious adverse effects to patients. We have recently reported that histamine prevents ionizing radiation-induced toxicity on mouse small intestine. The aim of the present work was to determine whether histamine is able to protect bone marrow cells against ionizing radiation damage. For that purpose 56 mice were divided into 4 groups. Histamine and Histamine-10Gy groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 20 hours before irradiation and continued till the end of experimental period; untreated group received saline. Histamine-10Gy and untreated-10Gy groups were irradiated with a single dose on whole-body using Cesium-137 source (7 Gy/min) and were sacrificed 3 days after irradiation. Bone marrow was removed, fixed and stained with hematoxylin and eosin. The number of megacariocytes per 40x field, bone marrow trophism, edema, vascular damage, and other histological characteristics of bone marrow cells were evaluated. We further determined by immunohistochemistry the expression of proliferating cell nuclear antigen (PCNA) and cells in the S phase of the cell cycle were identified by immunohistochemical detection of 5-bromo-2’-deoxyuridine (BrdU) incorporation. Results indicate that histamine treatment substantially reduced the grade of aplasia, the edema and the vascular damage induced by ionizing radiation on bone marrow. Additionally, histamine preserved medullar components increasing significantly the number of megacariocytes per field (5.4 ± 0.4 vs. 2.8 ± 0.4 in Control-10 Gy, P<0.01). This effect was associated with an increased proliferation rate determined by the augmented PCNA expression and BrdU incorporation of bone marrow cells. On the basis of these results, we conclude that histamine radioprotects bone marrow cells. Taking into account that we have previously determined that histamine enhances radiosensitivity of breast cancer cell lines; this might be of clinical value in patients undergoing radiotherapy.