The aim of the present study was to investigate the protective effects of yak-activated protein on hematopoiesis and cytokine function in radiation-induced injury in mice. A total of 180 Kunming mice were randomly divided into three groups (A, B and C). Of these, 60 were randomly divided into a normal control group, a radiation model group, a positive control group and 3 yak-activated protein groups (high, medium and low dose groups; 10, 5 and 2.5 mg/kg, respectively). The other 120 mice were used for the subsequent experiments on days 7 and 14 following radiation. Yak-activated protein was administered orally to mice in the treatment groups and an equal volume of saline was administered orally to mice in the normal control and radiation model groups for 14 days. The positive control group received amifostine (150 mg/kg) via intraperitoneal injection. With the exception of the control group, the groups of mice received a 5 Gy quantity of X-radiation evenly over their whole body once. Changes in the peripheral hemogram, thymus and spleen indices, DNA content in the bone marrow, interleukin (IL)-2 and IL-6 levels, and the expression levels of B cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) following irradiation were assessed. The low dose of yak-activated protein significantly increased Spleen indices in mice 14 days after irradiation and the high and middle dose of yak-activated protein significantly increased Thymus indices in mice 14 days after irradiation (P<0.05) compared with the control group. In addition, hemogram results increased gradually in the low-yak-activated protein dose group and were significantly higher 7 days after irradiation compared with the radiation model group (P<0.05). The DNA content in the bone marrow was markedly increased in the yak-activated protein groups, and increased significantly in the low dose group at 7 days post-irradiation compared with the radiation model group (P<0.05). The IL-2 content was significantly increased in the yak-activated protein groups (P<0.05). Furthermore, Bcl-2 expression was increased and Bax expression was decreased (P<0.05). These results suggest that yak-activated protein exerts protective effects against radiation-induced injury in mice. The optimal effects of yak-activated protein were observed in the medium dose group 14 days after irradiation.
Keywords: cytokines; hematopoiesis; radiation injury; yak-activated protein.