运动联合阿仑膦酸钠片对去卵巢大鼠RANKL/OPG平衡及MAPK信号通路的影响

目的观察运动联合阿仑膦酸钠片(Aln)对去卵巢(OVX)大鼠核因子κB受体活化因子配体(RANKL)/骨保护素(OPG)表达及丝裂原活化蛋白激酶(MAPK)信号通路的影响。方法 90只6月龄雌性SD大鼠随机分为假手术组(sham组)、OVX组、Aln治疗组(OVX+Aln组)、运动治疗组(OVX+EX组)、Aln与运动联合治疗组(OVX+Aln+EX组),每组18只,后4组大鼠切除双侧卵巢。大鼠切除卵巢8周后,各治疗组大鼠分别进行1mg/(kg·d)Aln灌胃和(或)跑台运动干预。干预12周后采用双能X线骨密度仪检测大鼠左、右股骨骨密度(BMD),ELISA法检测大鼠血清RANKL、OPG含量,real-timePCR检测大鼠骨组织RANKL、OPGmRNA表达,蛋白质印迹分析法检测骨组织c-Jun氨基末端激酶(JNK)、p38MAPK(p38)、细胞外调节激酶(ERK)的磷酸化水平及c-Fos表达。结果干预治疗12周后:(1)与sham组相比,OVX组大鼠左、右股骨BMD降低(P<0.05),血清RANKL含量增加、OPG含量降低、RANKL/OPG比值增大(P均<0.05),骨组织RANKLmRNA表达增加、OPGmRNA表达减少(P均<0.05)。(2)与OVX组相比,OVX+Aln组、OVX+EX组及OVX+Aln+EX组大鼠左、右股骨BMD均增加(P均<0.05),血清RANKL含量降低、OPG含量增加、RANKL/OPG比值减小(P均<0.05),骨组织RANKLmRNA表达减少、OPGmRNA表达增加(P均<0.05)。(3)与OVX+Aln组和OVX+EX组相比,OVX+Aln+EX组大鼠左、右股骨BMD,血清RANKL、OPG含量,骨组织RANKL、OPGmRNA表达差异有统计学意义(P均<0.05)。(4)与sham组相比,OVX组大鼠骨组织p-JNK、c-Fos表达增加(P均<0.05);OVX+Aln组、OVX+EX组及OVX+Aln+EX组与OVX组相比,大鼠骨组织p-JNK、c-Fos表达降低(P均<0.05),但3组间表达差异无统计学意义;p-p38、p-ERK在各组间的表达差异无统计学意义。结论运动联合Aln治疗能够提高OVX大鼠左、右股骨骨密度,其作用可能与调节RANKL/OPG平衡、抑制JNK磷酸化及c-Fos表达有关。

Effects of exercise combined with alendronate sodium tablets on RANKL/OPG balance and MAPK signaling pathways in ovariectomized rats

Objective To observe the effect of exercise combined with alendronate sodium tablets (Aln) on receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) expression and mitogen-activated protein kinase (MAPK) signaling pathways in ovariectomized (OVX) rats. Methods A total of 90 6-month-old female SD rats were evenly randomized into sham group, OVX group, Aln treatment (OVX+Aln) group, exercise therapy (OVX+EX) group, and Aln combined with exercise treatment (OVX+Aln+EX) group. Eight weeks after ovariectomy, rats in the latter three groups were treated with intragastric 1 mg/(kg·d) Aln and/or exercise. After 12 weeks of treatment, dual-energy X-ray absorptiometry was used to examine the bone mineral density (BMD) of the left and right femurs. Enzyme-linked immunosorbent assay (ELISA) was used to determine the serum levels of RANKL and OPG. Real-time PCR was used to examine RANKL and OPG mRNA expression in bone tissues. Western blotting analysis was used to examine the phosphorylation of c-Jun N-terminal kinase (JNK), p38 MAPK (p38), extracellular-regulated kinase (ERK), and c-Fos protein expression in bone tissues. Results The following results were observed after 12-week treatment. (1) Compared with sham group, the BMD values of the left and right femurs were significantly decreased in OVX group (P<0.05). The serum RANKL level was significantly increased, serum OPG level was significantly decreased, and the RANKL/OPG ratio was significantly increased (all P<0.05). The RANKL mRNA expression was significantly increased and OPG mRNA expression was significantly decreased in bone tissues (all P<0.05). (2) Compared with OVX group, the BMD values of left and right femurs of OVX+Aln, OVX+EX and OVX+Aln+EX groups were significantly increased (all P<0.05). The serum RANKL level was significantly decreased, serum OPG level was significantly increased, and the RANKL/OPG ratio decreased (all P<0.05). The RANKL mRNA expression was significantly decreased, and OPG mRNA expression was significantly increased in bone tissues (all P<0.05). (3) The femoral BMD values, serum RANKL and OPG levels, and RANKL and OPG mRNA expression in bone tissues in OVX+Aln+EX group were significantly different from those in OVX+Aln group and OVX+EX group (all P<0.05). (4) Compared with sham group, bone tissue p-JNK and c-Fos expression in OVX group was significantly increased (all P<0.05). However, compared with OVX group, bone tissue p-JNK and c-Fos expression in OVX+Aln, OVX+EX and OVX+Aln+EX groups was significantly decreased (all P<0.05), and there were no significant differences among the latter three groups. p-p38 and p-ERK expression was similar in all groups. Conclusion Exercise combined with Aln can improve the BMD values of left and right femurs in OVX rats, which may be related to the regulation of RANKL/OPG balance and inhibition of JNK phosphorylation and c-Fos expression.