Preliminary Study On The Effect Of Melatonin Used In The Early Stage Of A Novel Rat Aplastic Anemia Model

Objective To develop an acute aplastic anemia model with hematopoietic stem cell falLure in rats and study the effect of melatonin used in the early stage of the model. Methods 12 rats were i.h with benzene three times a week and p.o by busulfan once a week, both benzene and busulfan were used for 5 weeks. A benzene alone group and a busalfan alone group were as control. In the second part of the study, 24 rats were i.h with benzene three times a week and p.o by basulfan once a week, both benzene and busulfan were used for 3 weeks. Then they were randomly divided into four groups. The rats of MTlmg group were p.O by melatonin Img/kg.d, MTSmg group was 5mg/kg.d. The rats of third group were i.v with high dose of methylprednisolone every day. Both MT and HDMP were used for 2 weeks. The fouth group were as control. Incidence and mortality of aplastic anemia rats, RBC, WBC, PLT, BMNC and histology of hematopioetic organs were observed or tested. Results In the group of benzene and busulfan used for 5 weeks, the incidence of acute aplastic anemia was 100%, the mortality was 100% too. The average survival time was (43.5?.9)days. RBC,WBC, PLT and BMNC decreased gradually, and the patho-morphological examination showed that the bone marrow was replaced by fat cells, and the lymphoid tissue of spleen and lymph-nodes were remarkably atrophied without extra-medullary hematopoiesis. After treated with melatonin for 2 weeks, WRC, PLT and BMNC of the rats of both MTlmg group and MTSmg group increased more remarkably compared with those of the HDMP group, and the myologram of MTlmg group and MT 5mg group improved better. Conclusion Benzene combined with busulfan could make a rat aplastic aremia model with acute hematopoietic stem cell falLure. Using melatonin early could increase BMNC,WBC and PLT of aplastic anemia rats.