有氧运动对二甲基苯蒽诱导大鼠乳腺癌发生及其机制探讨

Effect of aerobic exercise on 7,12-dimethylbenz{a}anthracene induced mammary cancer in rats

目的:研究中等强度有氧运动对二甲基苯蒽(7,12-dimethyl-benz{a}anthracene,DMBA)诱导大鼠乳腺癌发生的影响。方法:120只7周龄无特定病原体级(SPF)雌性Sprague-Dawley(SD)大鼠按2×2析因设计随机数字表法分为空白对照组(CON)、运动对照组(ECON)、药物诱导组(DI)和运动+药物诱导组(EDI),每组30只。ECON组和EDI组进行有氧运动训练,每周5d,25mL/min,30min/d。药物诱导组和运动+药物诱导组给予1mL的10mg/mL DMBA麻油溶液灌胃2次。每2周观察1次大鼠的体质量、乳腺肿瘤体积和荷瘤数。18周后处死所有大鼠,对所有乳房肿瘤进行病理诊断,并测定脂肪湿重、脂肪指数、Lee’s指数、血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)和血清雌二醇(E2)水平。结果:实验终末CON组、ECON组、DI组和EDI组的体质量分别为(352.67±32.93)、(322.30±29.18)、(296.50±28.60)和(289.30±27.05)g。析因分析显示,有氧运动(F=12.149,P=0.001)和DMBA(F=68.442,P<0.001)都显著影响大鼠的体质量增长,两者有交互作用,F=4.620,P=0.034。DI组和EDI组的潜伏期分别为(13.86±2.88)和(15.65±2.23)d,差异有统计学意义,t=-2.456,P=0.018;荷瘤数分别为(3.24±1.12)和(2.30±1.02)个,差异有统计学意义,t=3.111,P=0.003;肿瘤体积为(2 107.07±526.76)和(1 793.78±541.08)mm3,差异有统计学意义,t=2.105,P=0.040。有氧运动和DMBA可以显著影响大鼠的脂肪湿重、脂肪指数和Lee’s指数,P<0.01,且两者之间无明显交互作用,P>0.05。有氧运动可以显著影响大鼠血清TG、TC、HDL-C和LDL-C和雌激素水平,P<0.01,且与DMBA无明显交互作用,P>0.05。结论:有氧运动可以抑制二甲基苯蒽诱导的大鼠乳腺癌的发生,其机制可能与有氧运动通过影响大鼠体脂水平而降低体内E2水平有关。

OBJECTIVE： To observe the effect of moderate-intensity aerobic exercise on DMBA induced breast canc er in rats. METHODS： One hundred and twenty female Sprague-Dawley （SD） rats were randomly divided into control group（CON）, exercise control group（ECON）, drug induced group （DI） and exercise＋ drug induced group （EDI）, with 30 rats in each group. Rats in ECON group and EDI group were exercised on a motor-driven treadmill at a belt speed of 25 mL/min for 30 rain/day,5 day/week for 18 weeks. Rats in DI group and EDI group received 10 mg DMBA in 1.0 mL sesame oil via gastric intubation,and again after a week. The body weight,incidence of palpable breast cancer and tumor volume were observed every two weeks. All the rats were sacrificed after 18 weeks to observe fat wet weight,fat index, Lee＇s index, estradiol （E2）,TC,TG, HDL-C and LDL-C. RESULTS： At the end of the experiment, the body weight of CON group,ECON group,DI group and EDI group were （352.67±32.93）, （322.30±29.18）, （296.50±28.60） and （289.30±27.05） g. The result of factorial analysis showed that aerobic exercise （F= 12. 149,P=0. 001） and DMBA （F= 68. 442,P〈0. 001） could significantly affect the rats weight gain, and there were significant interactions between them （F=4. 620,P=0. 034）. The incubation period of DI and EDI group were （13.86±2.88） and （15.65±2.23） d,and the differences were statistically significant （t= 2. 456, P= 0. 018）. The number of breast cancers in DI and EDI group were 3.24± 2.30 and 1.12 ± 1.02, and the differences were statistically significant （t= 3.111, P= 0. 003）. The tumor size of DI and EDI group were （2 107.07±526.76） and （1 793. 78± 541.08） mm3, and the differences were statisticallysignificant （t= 2. 105, P= 0. 040）. Aerobic exercise and DMBA can significantly affect the wet weight of fat, fat index and Lee＇s index（P〈0.01）,and there were no interactions between the two factors （P：〉0.05）. Aerobic exercise can signifi cantly affect the TC,TG, HDL-C,LDL-C and E2 （P〈0. 01） ,and there were no interactions between the two factors（P〈 0.05）. CONCLUSION： Moderate intensity aerobic exercise can inhibit breast cancer induced by 7,12-dimethylbenz{ a}an- thracene and the mechanism may be that moderate intensity aerobic exercise could reduce the fat in the rats,and then in- hibit the function of Ez.