T2-mapping和血氧水平依赖成像评估游泳康复运动对盘源性腰痛大鼠模型椎旁肌功能的影响

T2-mapping and BOLD to evaluate the effect of swimming rehabilitation exercise on paraspinal muscles in rats model with discogenic low back pain

目的探讨MRI T_(2)-mapping和血氧水平依赖成像(BOLD)评估盘源性腰痛(DLBP)大鼠游泳运动后椎旁肌功能改变。方法选取54只雌性1月龄SD大鼠,采用随机数字表法分为3组,假手术(Sham)组、DLBP非游泳组和DLBP游泳组,每组18只。在X线透视引导下,后入路穿刺DLBP非游泳组和DLBP游泳组大鼠的L4/5及L5/6椎间盘,破坏髓核后建立DLBP大鼠模型,Sham组只穿刺同层面椎旁肌。建模后DLBP游泳组进行连续5 d(30 min/d)的游泳运动干预,DLBP非游泳组和Sham组不做任何康复运动干预。每组平均分为3个时间点亚组,分别于建模后30、90和180 d扫描T_(2)-mapping和BOLD序列,获取椎旁肌T_(2)值、R_(2)^(*)值,而后取建模层面椎旁肌行免疫荧光染色,分析肌球蛋白重链(MYH)1(Ⅱ型肌纤维)和MYH7(Ⅰ型肌纤维)的荧光强度。3组间比较采用单因素方差分析,组间两两比较采用Bonferroni法,采用Pearson相关系数评价建模后180 d大鼠椎旁肌定量MRI参数T_(2)值、R_(2)^(*)值与MYH1、MYH7免疫荧光强度间相关性。结果建模后30 d,3组间T_(2)值和R_(2)^(*)值差异均无统计学意义(P均>0.05)。建模后90 d,DLBP游泳组T_(2)值高于DLBP非游泳组,DLBP非游泳组低于Sham组(P均<0.05);3组间R_(2)^(*)值差异无统计学意义(P>0.05)。建模后180 d,DLBP游泳组T_(2)值高于DLBP非游泳组,R_(2)^(*)值低于DLBP非游泳组;DLBP非游泳组T_(2)值低于Sham组,R_(2)^(*)值高于Sham组(P均<0.05)。建模后30、90 d,3组间MYH1和MYH7表达差异均无统计学意义(P均>0.05)。建模后180 d,DLBP游泳组较DLBP非游泳组MYH1表达减少,MYH7表达增加;DLBP非游泳组较Sham组MYH1表达增加,MYH7表达减少(P均<0.05)。建模后180 d,T_(2)值与MYH1荧光强度呈中度负相关(r=-0.511,P=0.043),与MYH7荧光强度呈中度正相关(r=0.564,P=0.023);R_(2)^(*)值与MYH1荧光强度呈中度正相关(r=0.625,P=0.010),与MYH7荧光强度呈中度负相关(r=-0.653,P=0.006)。结论游泳运动可以改善DLBP大鼠椎旁肌含水量和灌注的降低,减少肌纤维Ⅰ型向Ⅱ型转化,T_(2)值与R_(2)^(*)值的变化可在一定程度上反映椎旁肌纤维类型转化情况。

ObjectiveTo explore MRI T2-mapping and blood oxygenation level dependent(BOLD)to evaluate the functional changes of paraspinal muscle in rats with discogenic low back pain(DLBP)after swimming.MethodsTotally 54 female 1-month-old SD rats were selected,which were divided into 3 groups by random number table method,sham operation(Sham)group,DLBP non-swimming group and DLBP swimming group,with 18 rats in each group.Under the guidance of X-ray fluoroscopy,the L4/5 and L5/6 intervertebral discs of the rats in the DLBP non-swimming group and DLBP swimming group were punctured by the posterior approach,and establishment of DLBP rat model by destroying nucleus pulposus,and only paraspinal muscles at the same level were punctured in the Sham group.After modeling,the DLBP swimming group received swimming exercise intervention for 5 consecutive days(30 min/d),while the DLBP non-swimming group and Sham group did not receive any rehabilitation exercise intervention.Each group was divided into 3 time point subgroups on average,the T2-mapping and BOLD sequences were scanned at 30,90 and 180 days after modeling to obtain the T2 value,R_(2)^(*)value of the paraspinal muscles,and the paraspinal muscles at the modeling level were taken for immunofluorescence staining,and the fluorescence intensity of myosin heavy chain(MYH)1(typeⅡmuscle fiber)and MYH7(type I muscle fiber)was analyzed.One-way analysis of variance was used for comparison among the 3 groups,and the Bonferroni method was used for multiple comparisons,and Pearson correlation coefficient was used to evaluate the correlation between quantitative MRI parameters T2 value,R_(2)^(*)value and MYH1,MYH7 immunofluorescence intensity of rat paraspinal muscles at 180 days after modeling.ResultsAt 30 days after modeling,there was no significant difference in T2 value and R_(2)^(*)value among the 3 groups(all P>0.05).At 90 days after modeling,the T2 value of the DLBP swimming group was higher than that of the DLBP non-swimming group,and the T2 value of the DLBP non-swimming group was lower than that of the Sham group(all P<0.05),and there was no significant difference in the R_(2)^(*)value among the 3 groups(P>0.05).At 180 days after modeling,the T2 value of the DLBP swimming group was higher than that of the DLBP non-swimming group,and the R_(2)^(*)value was lower than that of the DLBP non-swimming group;the T2 value of the DLBP non-swimming group was lower than that of the Sham group,and the R_(2)^(*)value was higher than that of the Sham group(all P<0.05).At 30 and 90 days after modeling,there was no significant difference in the expressions of MYH1 and MYH7 among the 3 groups(all P>0.05).At 180 days after modeling,the expression of MYH1 decreased and the expression of MYH7 increased in the DLBP swimming group compared with the DLBP non-swimming group;the expression of MYH1 increased and the expression of MYH7 decreased in the DLBP non-swimming group compared with the Sham group(all P<0.05).At 180 days after modeling,the T2 value had a moderate negative correlation with the fluorescence intensity of MYH1(r=-0.511,P=0.043),and a moderate positive correlation with the fluorescence intensity of MYH7(r=0.564,P=0.023);R_(2)^(*)value was moderate positive correlated with the fluorescence intensity of MYH1(r=0.625,P=0.010),and moderate negative correlated with the fluorescence intensity of MYH7(r=-0.653,P=0.006).ConclusionsSwimming exercise can improve the reduction of water content and perfusion in the paraspinal muscles of DLBP rats,and reduce the transformation of muscle fibers from typeⅠto typeⅡ,the changes of T2 and R_(2)^(*)value can reflect the transformation of paraspinal muscle fiber types to a certain extent.