Low-intensity Pulsed Ultrasound In Rat Model With Osteoporosis And Hyperlipidemia Of Experimental Research

Objective:The present study was designed to investigate the effects of low-intensity pulsed ultrasound (LIPUS) on bone mineral density (BMD), spongy bone microstructure and biomechanical properties in ovariectomized rats as an osteoporosis animal model. Meanwhile, we studied on the effects of LIPUS on total cholesterol (TC), total triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and high-density lipoprotein cholesterol (HDL-c) in hyperlipidemia animal model.Methods:3-month-old female Wistar rats were used for the study, randomized into control group (n=6), osteoporosis model group (n=6), ultrasound group (n=18) and estrogen group (n=6). The ultrasound group was subdivided into three groups (n=6/group):low-dose US group (OVX-US-L), medium-dose US group (OVX-US-M) and high-dose US group (OVX-US-H). After 3 months past ovariectomy (OVX), the rats were treated with 3 different doses LIPUS or estrogen, or untreated for another 3 months. At endpoint, bone mineral density (BMD) of the spines (lumbar vertebrae) were measured by DEXA; trabecular bone of the femur was decalcified and examined by bone histomorphological images; the other side femur was examined by three-points compression test. The major organs of the rats in OVX-US-H group were strained by HE to evaluate the ultrasonic biological safety.9-month-old female Wistar rats were randomized into 4 groups:control group (n=6), hyperlipidemic model group (n=6), ultrasound group (n=6) and simvastatin group (n=6). Model rats were fed high-fat emulsion via gavage for 10 days. The serum total cholesterol (TC), total triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and high-density lipoprotein cholesterol (HDL-c) were detected dynamically.Results:Treatment with LIPUS resulted in improved biomechanical properties. Maximal load force (Fmax) and elastic modulus (Emod) of femurs after US treatment was significantly enhanced compared to OVX group. Fmax and Emod in US treated rats reached the level observed in estrogen group. US significantly improved all measured histomorphometric parameters in the trabecular area, including trabecular density and width. US treated rats showed significantly improved bone mineral density (BMD) in femurs compared to untreated rats. There was no obvious injury in every major organ of the US group rats.In comparison with non-US group, ultrasonic treatment significantly reduced the serum total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-c). Compared to simvastatin treatment, US also significantly reduced the levels of serum TG. However, the LIPUS therapy did not improve HDL-c level and failed to reduce LDL-c/HDL-c.Conclusion:LIPUS stimulation effectively and safely improves bone strength, inhibits bone mass loss after OVX in the osteoporotic model and reduces the serum TC, TG and LDL-C in the hyperlipidemia model. In conclusion, LIPUS may be a possible nonpharmacologic treatment option for postmenopausal osteoporosis and hyperlipidemia.