Evaluation of the effects of pulsed wave LLLT on tibial diaphysis in two rat models of experimental osteoporosis, as examined by stereological and real-time PCR gene expression analyses

Abstract

Osteoporosis (OP) and osteoporotic fracture are major public health issues for society; the burden for the affected individual is also high. Previous studies have shown that pulsed wave low-level laser therapy (PW LLLT) has osteogenic effects. This study intended to evaluate the impacts of PW LLLT on the cortical bone of osteoporotic rats' tibias in two experimental models, ovariectomized and dexamethasone-treated. We divided the rats into four ovariectomized induced OP (OVX-d) and four dexamethasone-treated (glucocorticoid-induced OP, GIOP) groups. A healthy (H) group of rats was considered for baseline evaluations. At 14 weeks following ovariectomy, we subdivided the OVX-d rats into the following groups: (i) control which had OP, (ii) OVX-d rats treated with alendronate (1 mg/kg), (iii) OVX-d rats treated with LLLT, and (iv) OVX-d rats treated with alendronate and PW LLLT. The remaining rats received dexamethasone over a 5-week period and were also subdivided into four groups: (i) control rats treated with intramuscular (i.m.) injections of distilled water (vehicle), (ii) rats treated with subcutaneous alendronate injections (1 mg/kg), (iii) laser-treated rats, and (iv) rats simultaneously treated with laser and alendronate. The rats received alendronate for 30 days and underwent PW LLLT (890 nm, 80 Hz, 0.972 J/cm(2)) three times per week during 8 weeks. Then, the right tibias were extracted and underwent a stereological analysis of histological parameters and real-time polymerase chain reaction (RT-PCR). A significant increase in cortical bone volume (mm(3)) existed in all study groups compared to the healthy rats. There were significant decreases in trabecular bone volume (mm(3)) in all study groups compared to the group of healthy rats. The control rats with OP and rats from the vehicle group showed significantly increased osteoclast numbers compared to most other groups. Alendronate significantly decreased osteoclast numbers in osteoporotic rats. Concurrent treatments (compounded by PW LLLT and alendronate) produce the same effect on osteoporotic bone.

Effect of low‐level laser therapy and oxytocin on osteoporotic bone marrow‐derived mesenchymal stem cells

“…However, some recent studies show that LLLT alone is not effective in reversing the detrimental effects of OP in vivo …”

Gut Microbiome-Mediated Changes in Bone Metabolism Upon Infrared Light Exposure in Rats

“…Healthy lighting needs to take into account spectral regions outside the visible range, which have physiological and psychological impacts on humans, such as infrared radiation (IR), that is present in daylight but not white light-emitting LEDs [25] . Previous studies have demonstrated the potential value of infrared radiation from laser light in the prevention of bone loss in animal models [26,27] or in elderly osteoporosis patients [28] . These studies suggest that IR supplementation to white LEDs may be bene cial in creating an arti cial lighting environment conducive to the maintenance of bone health.…”

The Effect of Prenatal Exposure to 2.4 GHz Radio Frequency on the Histology and Expression of the osteocalcin and RUNX2 Gene of the Forelimb in an NMRI Mouse

“…The ΣP is estimated using the point-counting method. 20,21 The a/p stands for the area associated with each point projected on the limb bud. A sample of H&E staining with a point-counting grid is presented in Figure 1.…”