Preventive Effects And Mechanisms Of Steamed Rehmannia Root On Chemotherapeutic Side Effects Induced By Methotrexate In Rats

Cancer, a worldwide health challenge, seriously threaten human’s life and health. Many cancer treatments have been emerged and accepted by doctors and patients. However, chemotherapy is still the preferred treatment for patients in clinic. After chemotherapy, a series of side effects occurred in patients, such as shortness of breath and tiredness, no appetite, dry throat, redness of the tongue and little saliva, nausea and vomiting, abnormal micturition and defecation, spontaneous sweating or night sweating. The aboving symptoms belong to Qi and Yin deficiency according to the theory of Traditional Chinese Medicine. In clinic, steamed rehmannia root (SRR) has been frequently included in the formulas used to alleviate the adverse effects of chemotherapy in recent years. However, the role of SRR in these formulas still remains unknown. In this study, a rat model of chemotherapy was established by intraperitoneal administration of methotrexate (MTX), the preventive effects and its possible mechanisms of SRR on the side effects of chemotherapy were evaluated with calcium folinate (CF), a clinical antidote of MTX, and CF plus SRR as positive controls. Moreover, a preliminary research on the main active fraction of SRR was also carried out. The main results are as follows:1. The preventive effects of SRR on chemotherapeutic side effects induced by MTXThirty male Wistar rats were randomly assigned into five groups (control, MTX, SRR, CF, and SRR plus CF). SRR was administered by gavage three days in advance (1.08 g/kg, twice daily at 8 am and 8 pm). On day 4, the rats in MTX, SRR, CF, and SRR plus CF groups was given a single dose of MTX (i.p.,25 mg/kg) 1 h after administration of SRR, and the control rats received the same volume of normal saline. The rats in CF and SRR plus CF groups received CF (1 mg/kg, twice a day at 8 am and 8 pm) 36 h after MTX injection. On day 8, rats were sacrificed under anesthetization and then blood and proximal jejunum were collected for futher determination of physiological and biochemical indexes. The main results are as follows:(1) Rats in MTX group had the symptoms of weight loss, inappetence, fatigue and diarrhea, and their weight gains were significantly lower than those of control rats; In SRR group, the above-mentioned symptoms obviously improved.(2) The numbers of leukocyte, lymphocyte and monocyte in MTX group all fell significantly compared to those in control group. On the contrary, erythrocyte, hemoglobin, hematocrit, platelet-large cell ratio and platelet distribution width increased significantly. These indexes in blood cell count were improved to different degrees by administration of SRR.(3) The average damage score of the rats in MTX group was 4.31 times that of control group, and the average villus length and percentage of PCNA positive cells were only 33.77% and 51.95% of control group, respectively. Administration of SRR significantly attenuated jejunum damage induced by MTX injection.(4) The MDA and TNF-a levels in jejunum mucosa in MTX group were found increased by 1.94 times and 2.57 times, respecttively, when compared with those of control group, and GSH level was only 10.27% that of control group. These biochemical indexes were signifcantly improved by administration of SRR.(5) CF or CF plus SRR could also alleviate the side effects of chemltherapy to some degree, but was inferior to SRR.2. The effect of SRR on the proliferation of human leukemia cell line K562By the mehod of MTT test, the effect of SRR on leukemia cell line K562 was investigated. The results showed that SRR could dose-dependently inhibt the proliferation of K562 cell in the range from 0.046875 to 1.5 mg/mL.3. The preliminary study on active fraction sreening of SRRSRR water extrat was fractionated on anion exchange resin colum with aqueous solution of different pH values, and 11 fractions of SRR were achieved. DPPH scavenging activity and inhibiting activity of AAPH induced hemolysis suggested that the neutral fraction should be mainly responsible to the antioxidative action of SRR.The results suggested that SRR could attenuate chemotherapy-induced side effects and the mechanism might lie in its anti-oxidation and anti-inflammation. Moreover, the neutral fraction may be its main active fraction.