Search

Abstract The autonomic nervous system plays a crucial role in regulating bone metabolism, with sympathetic activation stimulating bone resorption and inhibiting bone formation. We found that fractures lead to increased sympathetic tone, enhanced osteoclast resorption, decreased osteoblast formation, and thus hastened systemic bone loss in ovariectomized (OVX) mice. However, the combined administration of parathyroid hormone (PTH) and the β-receptor blocker propranolol dramatically promoted systemic bone formation and osteoporotic fracture healing in OVX mice. The effect of this treatment is superior to that of treatment with PTH or propranolol alone. In vitro, the sympathetic neurotransmitter norepinephrine (NE) suppressed PTH-induced osteoblast differentiation and mineralization, which was rescued by propranolol. Moreover, NE decreased the PTH-induced expression of Runx2 but enhanced the expression of Rankl and the effect of PTH-stimulated osteoblasts on osteoclastic differentiation, whereas these effects were reversed by propranolol. Furthermore, PTH increased the expression of the circadian clock gene Bmal1, which was inhibited by NE-βAR signaling. Bmal1 knockdown blocked the rescue effect of propranolol on the NE-induced decrease in PTH-stimulated osteoblast differentiation. Taken together, these results suggest that propranolol enhances the anabolic effect of PTH in preventing systemic bone loss following osteoporotic fracture by blocking the negative effects of sympathetic signaling on PTH anabolism.

Laser speckle contrast imaging (LSCI) is a large measurement ranging, real-time, high spatial resolution optical imaging method. Exisiting reserches show that the low gray level (8-bit) and low resolution (752×480 pixels) camera can effectively monitor the flow of scattering media such as blood, but the defects such as large noise of scattered particles and small effective imaging area are difficult to be compensated by software, which seriously affects the imaging quality. Monitoring blood flow with a camera with a high gray level (16-bit) and a high resolution (2 048×2 048 pixels) will slow down the imaging speed of a single frame, and parallel computing can reduce the image processing time by 1/3. With the aid of an animal blood flow experiment, the results of high-gray-level and high-resolution spatial laser speckle contrast imaging (sLSCI), spatial approximate laser speckle contrast imaging (sLSCIa), and temporal laser speckle contrast imaging (tLSCI) were compared and analyzed using imaging speed and imaging quality as evaluation criteria. The parallel computation of high-gray-level and high-resolution sLSCI takes into consideration both imaging quality and imaging speed, which can meet the requirements of clinical real-time monitoring of blood flow.