Effects of exercise combined with alendronate sodium tablets on RANKL/OPG balance and MAPK signaling pathways in ovariectomized rats
10.3724/sp.j.1008.2013.00857
- Author:
Zhi-Qiang KUANG
1
Author Information
1. Department of Rehabilitation, The First Affiliated Hospital of Jinan University
- Publication Type:Journal Article
- Keywords:
Alendronate sodium;
Exercise;
Osteoporosis;
Osteoprotegerin
- From:
Academic Journal of Second Military Medical University
2013;34(8):857-863
- CountryChina
- Language:Chinese
-
Abstract:
Objective Toobserve the effect of exercise combined with alendronate sodium tablets (Ain) 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 SDrats were evenly randomized into sham group, OVX group, Ain treatment (OVX+Aln) group, exercise therapy (OVX+EX) group, and Ain 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) Ain 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 resultswere observed after 12-week treatment. (1) Compared with sham group, the BMD values of the lett 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) ComparedwithOVX 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). 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-JNKand c-Fos expression in OVX group was significantly increased (all P<0. 05). However, compared withOVX 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 Ain 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.
