Effects of pulsed electromagnetic fields on bone mass and Wnt/β-catenin signaling pathway in ovariectomized rats.
OBJECTIVE
The therapeutic effects of pulsed electromagnetic fields (PEMFs) on osteoporosis have been documented. However, the precise mechanisms by which PEMFs elicit these favorable biological responses are still not fully understood. This study aimed to systematically investigate the effects of PEMFs on bone mass and Wnt/β-catenin signaling pathway in ovariectomized rats.


METHODS
Thirty 3-month-old female Sprague Dawley rats were randomly assigned to one of three groups: sham-operated control (sham), ovariectomy (OVX), and ovariectomy with PEMFs treatment (PEMFs). One week following ovariectomy surgery, rats in the PEMFs group were exposed to PEMFs for 40 min/day, 5 days/week, for 12 weeks.


RESULTS
After 12-week interventions, serum 17β-estradiol and bone-specific alkaline phosphatase levels increased in the PEMFs group. Bone mineral density of the femur and the fifth lumbar vertebral body also increased in the PEMFs group. Histomorphometrical studies showed that PEMFs improved trabecular area, trabecular width, and trabecular number by 77.50%, 17.38% and 51.06%, respectively, and reduced trabecular separation by 44.28% compared with the OVX group. Biomechanical studies showed that PEMFs increased maximum load and energy to failure in the fifth lumbar vertebral body. Quantitative real-time RT-PCR analysis showed that PEMFs increased the mRNA expressions of Wnt3a, low-density lipoprotein receptor-related protein 5(LRP5), β-catenin, c-myc and runt-related gene 2 (Runx2), and reduced dickkopf1 (DKK1) in ovariectomized rats. However, mRNA expression of Axin2 was not affected by PEMFs.


CONCLUSIONS
PEMFs can prevent ovariectomy-induced bone loss and deterioration of bone microarchitecture and strength, at least partly, through activation of Wnt/β-catenin signaling pathway.
Rehabilitation Key Laboratory of Sichuan Province, Department of Rehabilitation, West China Hospital, Sichuan University, Chengdu, People's Republic of China.
Jun
J
Zhou
Hongchen
H
He
Lin
L
Yang
Shiju
S
Chen
Hua
H
Guo
Lu
L
Xia
Huifang
H
Liu
Yuxi
Y
Qin
Chuan
C
Liu
Xiaofei
X
Wei
Yujing
Y
Zhou
Chengqi
C
He
D015502:Absorptiometry, Photon; D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D015519:Bone Density / Q000528:radiation effects*; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis / Q000235:genetics; D004195:Disease Models, Animal; D004599:Electric Stimulation Therapy; D004958:Estradiol / Q000097:blood; D005260:Female; D005269:Femur / Q000528:radiation effects / Q000648:ultrastructure; D005786:Gene Expression Regulation / Q000528:radiation effects; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics; D060492:Low Density Lipoprotein Receptor-Related Protein-5 / Q000096:biosynthesis / Q000235:genetics; D008159:Lumbar Vertebrae / Q000528:radiation effects / Q000648:ultrastructure; D055909:Magnetic Field Therapy; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000528:radiation effects*; D060449:Wnt Signaling Pathway / Q000528:radiation effects*; D060509:Wnt3A Protein / Q000096:biosynthesis / Q000235:genetics
D050659:Core Binding Factor Alpha 1 Subunit; C531384:Dkk1 protein, rat; D036341:Intercellular Signaling Peptides and Proteins; D060492:Low Density Lipoprotein Receptor-Related Protein-5; C555484:Lrp5 protein, rat; C493717:Runx2 protein, rat; D060509:Wnt3A Protein; D004958:Estradiol; D000469:Alkaline Phosphatase