Bone Microstructure In Rats Research Articles

Network Pharmacological Analysis and Animal Experimental Study on Osteoporosis Treatment with GuBen-ZengGu Granules.

We explored the molecular pathway and material basis of GuBen-ZengGu granules (GBZGG) in treating osteoporosis using network pharmacology and animal experiments. The effective active components and potential targets of GBZGG were obtained from the TCMSP database and BATMAN-TCM database. Disease-related genes were obtained from GeneCard, NCBI, and DisGeNET. Next, a protein interaction network was established using the STRING database, and core genes were screened using the MCODE module. Cytoscape 3.8.0 was used to construct the network of component-disease-pathway-target, and KEGG pathway enrichment analyses were performed using the clusterProfiler R package to predict the mechanism of GBZGG in treating osteoporosis. An osteoporosis rat model was established by ovarian excision (OVX), and the partial results of network pharmacology were experimentally verified. Pharmacodynamic results showed that GBZGG increased bone mineral density (BMD) and significantly improved the indexes of femur microstructure in model rats. The network pharmacology results showed that quercetin, luteolin, stigmasterol, angelicin, kaempferol, bakuchiol, bakuchiol, 7-O-methylisomucronulatum, isorhamnetin, formononetin, and beta-sitosterol are the major components of GBZGG, with MAPK1, AKT1, JUN, HSP90AA1, RELA, MAPK14, ESR1, RXRA, FOS, MAPK8, NCOA1, MYC, and IL-6 as its core targets for treating osteoporosis. Biological effects could be exerted by regulating the signaling pathways of fluid shear stress and the signaling pathways of atherosclerosis, advanced glycation end products (AGE-RAGE) of diabetic complications, prostate cancer, interleukin (IL-17), tumor necrosis factor (TNF), hepatitis B, mitogen-activated protein kinase (MAPK), etc. The results of animal experiments showed that GBZGG could reduce the serum levels of IL-6 and TNF-α, increase the expression of bone morphogenetic protein-2 (BMP-2) and runt-related transcription factor 2 (RUNX2) protein, and inhibit the activity of extracellular-regulated protein kinases (ERK1/2) and phosphorylation ERK1/2 (p-ERK1/2) protein. GBZGG reduces the expression of ERK1/2 and p-ERK1/2 proteins and mRNAs through the inhibitory effects on IL-6 and TNF-α and negatively regulates the MAPK/ERK signaling pathway. The osteoporosis model showed that it effectively improved the loss of bone mass and destruction of bone microstructure in rats and maintained a positive balance for bone metabolism.

Effects of testosterone and exercise training on bone microstructure of rats.

Background and Aim:Male hypogonadism results from failure to produce physiological levels of testosterone. Testosterone in men is essential in masculine development, sperm production, and adult man’s health. Osteoporosis is one of the consequences of hypogonadism. Regular physical exercise and exogenous testosterone administration are frequently used to prevent or treat this condition. This study aimed to understand the effects of lifelong exercise training and testosterone levels (isolated and together) in the main bone structure parameters.Materials and Methods:A total of 24 rats were used and randomly divided into four groups: Control group (CG; n=6), exercised group (EG, n=6), testosterone group (TG, n=6), and testosterone EG (TEG, n=6). A micro-computed tomography equipment was used to evaluate 15 bone parameters.Results:Both factors (exercise training and testosterone) seem to improve the bone resistance and microstructure, although in different bone characteristics. Testosterone influenced trabecular structure parameters, namely, connectivity density, trabecular number, and trabecular space. The exercise promoted alterations in bone structure as well, although, in most cases, in different bone structure parameters as bone mineral density and medullar mineral density.Conclusion:Overall, exercise and testosterone therapy seems to have a synergistic contribution to the general bone structure and resistance. Further studies are warranted, comparing different individual factors, as gender, lifestyle, or testosterone protocols, to constantly improve the medical management of hypogonadism (and osteoporosis).

Effects of ursolic acid on muscle mass and bone microstructure in rats with casting-induced muscle atrophy.

Recent studies suggest that ursolic acid (UA) is a potential candidate for a resistance exercise mimetic that can increase muscle mass and alleviate the deleterious effect of skeletal muscle atrophy on bone health. However, these studies evaluated the effects of UA on skeletal muscle and bone tissues, and they have not verified whether such effect could occur concurrently on muscle and bone, as is the case with resistance exercise. Thus, the aim of this study was to analyze the effect of UA injection on muscle mass and bone microstructure using an animal model of atrophy to demonstrate the potential of UA as a resistance exercise mimetic. The immobilization (IM) method was used on the left hindlimb of Sprague Dawley (SD) rats for 10 days to induce muscle atrophy, whereas the right hindlimb was used as an internal control (IC). The animal models were divided into two groups, SED (sedentary, n=6) and UA (n=6) to demonstrate the effect of UA on atrophic skeletal muscles. The UA group received a daily intraperitoneal injection of UA (5 mg/kg/day) for 8 weeks. After 10 days of IM, the data collected for the IC were compared with that of IM to determine whether muscle atrophy might occur. Muscle atrophy was induced and bone mineral density (BMD) decreased significantly. The 8-week UA treatment significantly increased the gastrocnemius muscle mass compared to the SED group. In regard to the effect of UA on bones, negative results such as a decrease in BMD, trabecular bone volume fraction, and trabecular number, and an increase in trabecular separation, were observed in the SED group, but no such difference was observed in the UA group. No significant difference was observed in atrophic hindlimbs between SED and UA groups. These results alone are insufficient to suggest that UA is a potential resistance exercise mimetic for atrophic skeletal muscle and weakened bone. However, this study will help determine the potential of UA as a resistance exercise mimetic.

Effects of swimming exercise on high-fat diet-induced low bone mineral density and trabecular bone microstructure in rats

[Purpose] This study aimed to investigate the effect of swimming exercise on high-fat diet-induced low bone mineral density (BMD) and trabecular bone microstructure in rats. [Methods] Eight-week-old male Sprague- Dawley (SD) rats were divided into a normal diet group (n = 9) and a high-fat diet group (n = 15). Three rats in each group were sacrificed after 8 weeks of high-fat diet to evaluate the association between high-fat diet and bone health. The other 18 rats were reassigned to 3 groups (normal diet control, NC; high-fat diet control, HC; high-fat diet + Exercise, HEx) for up to another 8 weeks. Rats in the exercise group were trained for a swimming exercise program (1 h/day, 5 times/ week for 8 weeks). All rats were sacrificed 24 h after the last bout of exercise to analyze the BMD and trabecular bone microstructure in the femur and tibia, using micro-computed tomography. [Results] First, the effect of high-fat diet on bone health was examined. It was observed that BMD, percent bone volume (BV/TV), and trabecular number (Tb.N) of the femur and tibia were lower in rats in the high-fat diet group than in those in the normal diet group (p < .05). In addition, BMD, BV/TV, and Tb.N of the femur and tibia were significantly increased in rats that underwent the 8-week swimming exercise program, compared to the corresponding values in rats in the HC group (p < .05). [Conclusion] These results indicate that high-fat diets negatively affect bone health; however, these negative effects can be improved by exercises such as swimming. Keywords: Swimming exercise, Bone mineral density, Microstructure, Trabecular bone, High-fat diet

Effects of swimming exercise on high-fat diet-induced low bone mineral density and trabecular bone microstructure in rats.

[Purpose]This study aimed to investigate the effect of swimming exercise on high-fat diet-induced low bone mineral density (BMD) and trabecular bone microstructure in rats. [Methods]Eight-week-old male Sprague– Dawley (SD) rats were divided into a normal diet group (n = 9) and a high-fat diet group (n = 15). Three rats in each group were sacrificed after 8 weeks of high-fat diet to evaluate the association between high-fat diet and bone health. The other 18 rats were reassigned to 3 groups (normal diet control, NC; high-fat diet control, HC; high-fat diet + Exercise, HEx) for up to another 8 weeks. Rats in the exercise group were trained for a swimming exercise program (1 h/day, 5 times/ week for 8 weeks). All rats were sacrificed 24 h after the last bout of exercise to analyze the BMD and trabecular bone microstructure in the femur and tibia, using micro-computed tomography. [Results]First, the effect of high-fat diet on bone health was examined. It was observed that BMD, percent bone volume (BV/TV), and trabecular number (Tb.N) of the femur and tibia were lower in rats in the high-fat diet group than in those in the normal diet group (p < .05). In addition, BMD, BV/TV, and Tb.N of the femur and tibia were significantly increased in rats that underwent the 8-week swimming exercise program, compared to the corresponding values in rats in the HC group (p < .05). [Conclusion]These results indicate that high-fat diets negatively affect bone health; however, these negative effects can be improved by exercises such as swimming.

Low Levels of Vitamin D have a Deleterious Effect on the Articular Cartilage in a Rat Model.

Vitamin D appears to play an important role in bone and cartilage metabolism since its receptors are widely found in human articular chondrocytes. Thus, effects of variation of vitamin D may directly impact cartilage and bone biology. The aims of this study are to compare (1) articular cartilage structure and composition and (2) trabecular and cortical bone microstructure in rats with normal versus insufficient vitamin D levels. Twenty-five mature, male Sprague-Dawley rats were allocated to two groups: (1) control arm (vitamin D replete-12 rats) and (2) an experimental arm (vitamin D deficient-13 rats). Vitamin D deficiency was induced using a vitamin D-deficient diet and UV light restriction. Rats were sacrificed after 4 weeks vitamin D deficiency was confirmed. The right knee was harvested for analysis of both the medial (MFC) and lateral femoral condyles (LFC). A region of interest was established on both condyles to correlate subchondral bone architecture and the overlying cartilage. Histological analysis was performed and graded using the modified Mankin score. Subchondral and cortical bony architecture was evaluated with micro-CT. After 4 weeks, the vitamin D-deficient group had statistically significant changes in cartilage structure in both the MFC and LFC [1.55 ± 0.6 vs. 4.23 ± 4.1 (p = 0.035) and 1.55 ± 0.6 vs. 3.53 ± 2.4 (p = 0.009), respectively]. Micro-CT analysis revealed no correlation between subchondral bone values and the overlying cartilage Mankin score (p = 0.460). No significant difference was evident between the subchondral bone of the control and study group. Low levels of vitamin D have a deleterious effect on the cartilage. Given the high prevalence of vitamin D deficiency in the general population, these findings raise important questions about the potential role of vitamin D in articular cartilage health.

Whole-body vibration can attenuate the deterioration of bone mass and trabecular bone microstructure in rats with spinal cord injury

Experimental, controlled study. To examine the effects of whole-body vibration (WBV) on bone mass and trabecular bone microstructure (TBMS) during the early stage in juvenile rats with spinal cord injury (SCI). Studied at the Kio University in Japan. Thirty-four 8-week-old male Wistar rats were divided into 3 groups: the SCI group, the sham-operation group (SHAM) and the SCI+WBV group. WBV started on the 8th day after SCI. After 1 or 2 weeks of WBV treatment, measurements of tissue mineral density, trabecular bone mineral content (BMC) and parameters of TBMS were obtained by scanning the proximal tibias with x-ray micro-computed tomography. Serum levels of osteocalcin (OC) and of tartrate-resistant acid phosphatase 5b (TRACP 5b) were measured with ELISA. BMC, volume bone mineral density, bone volume (BV), BV fraction (BV/tissue volume) and connectivity density (Conn.D) of TBMS parameters were significantly higher in SCI+WBV rats than in SCI rats after 2-week WBV. The BMC and BV/TV of bone mass index correlated well with Conn.D, suggesting the preservation of Conn.D. induced by WBV. SCI+WBV rats showed a decrease in serum OC after 1-week WBV, but a quick recovery from that after 2-week WBV. There was no difference in serum TRACP 5b among the 3 groups throughout the experimental period. WBV treatment could attenuate the bone deterioration that occurs during the early stage in juvenile rats with SCI. In a clinic, this early WBV intervention may be an effective rehabilitation modality for preventing bone fragility in SCI patients.

High dietary cholesterol masks type 2 diabetes-induced osteopenia and changes in bone microstructure in rats.

Type 2 diabetes mellitus (T2DM) often occurs concurrently with high blood cholesterol or dyslipidemia. Although T2DM has been hypothesized to impair bone microstructure, several investigations showed that, when compared to age-matched healthy individuals, T2DM patients had normal or relatively high bone mineral density (BMD). Since cholesterol and lipids profoundly affect the function of osteoblasts and osteoclasts, it might be cholesterol that obscured the changes in BMD and bone microstructure in T2DM. The present study, therefore, aimed to determine bone elongation, epiphyseal histology, and bone microstructure in non-obese T2DM Goto-Kakizaki rats treated with normal (GK-ND) and high cholesterol diet. We found that volumetric BMD was lower in GK-ND rats than the age-matched wild-type controls. In histomorphometric study of tibial metaphysis, T2DM evidently suppressed osteoblast function as indicated by decreases in osteoblast surface, mineral apposition rate, and bone formation rate in GK-ND rats. Meanwhile, the osteoclast surface and eroded surface were increased in GK-ND rats, thus suggesting an activation of bone resorption. T2DM also impaired bone elongation, presumably by retaining the chondrogenic precursor cells in the epiphyseal resting zone. Interestingly, several bone changes in GK rats (e.g., increased osteoclast surface) disappeared after high cholesterol treatment as compared to wild-type rats fed high cholesterol diet. In conclusion, high cholesterol diet was capable of masking the T2DM-induced osteopenia and changes in several histomorphometric parameters that indicated bone microstructural defect. Cholesterol thus explained, in part, why a decrease in BMD was not observed in T2DM, and hence delayed diagnosis of the T2DM-associated bone disease.

Effects of Arsenic on Osteoblast Differentiation in Vitro and on Bone Mineral Density and Microstructure in Rats

Background: Arsenic is a ubiquitous toxic element and is known to contaminate drinking water in many countries. Several epidemiological studies have shown that arsenic exposure augments the risk of bone disorders. However, the detailed effect and mechanism of inorganic arsenic on osteoblast differentiation of bone marrow stromal cells and bone loss still remain unclear.Objectives: We investigated the effects and mechanism of arsenic on osteoblast differentiation in vitro and evaluated bone mineral density (BMD) and bone microstructure in rats at doses relevant to human exposure from drinking water.Methods: We used a cell model of rat primary bone marrow stromal cells (BMSCs) and a rat model of long-term exposure with arsenic-contaminated drinking water, and determined bone microstructure and BMD in rats by microcomputed tomography (μCT).Results: We observed significant attenuation of osteoblast differentiation after exposure of BMSCs to arsenic trioxide (0.5 or 1 μM). After arsenic treatment during differentiation, expression of runt-related transcription factor-2 (Runx2), bone morphogenetic protein-2 (BMP-2), and osteocalcin in BMSCs was inhibited and phosphorylation of enhanced extracellular signal-regulated kinase (ERK) was increased. These altered differentiation-related molecules could be reversed by the ERK inhibitor PD98059. Exposure of rats to arsenic trioxide (0.05 or 0.5 ppm) in drinking water for 12 weeks altered BMD and microstructure, decreased Runx2 expression, and increased ERK phosphorylation in bones. In BMSCs isolated from arsenic-treated rats, osteoblast differentiation was inhibited.Conclusions: Our results suggest that arsenic is capable of inhibiting osteoblast differentiation of BMSCs via an ERK-dependent signaling pathway and thus increasing bone loss.Citation: Wu CT, Lu TY, Chan DC, Tsai KS, Yang RS, Liu SH. 2014. Effects of arsenic on osteoblast differentiation in vitro and on bone mineral density and microstructure in rats. Environ Health Perspect 122:559–565; http://dx.doi.org/10.1289/ehp.1307832

Effects of treadmill running and swimming exercise on bone microstructure in rats with ovariectomy

Effects of treadmill running and swimming exercise on bone microstructure in rats with ovariectomy

Bone Degeneration and Recovery after Early and Late Bisphosphonate Treatment of Ovariectomized Wistar Rats Assessed by In Vivo Micro-Computed Tomography

Bisphosphonates are antiresorptive drugs commonly used to treat osteoporosis. It is not clear, however, what the influence of the time point of treatment is. Recently developed in vivo micro-computed tomographic (CT) scanners offer the possibility to study such effects on bone microstructure in rats. The aim of this study was to determine the influence of early and late zoledronic acid treatment on bone in ovariectomized rats, using in vivo micro-CT. Twenty-nine female Wistar rats were divided into the following groups: ovariectomy (OVX, n = 5), OVX and zoledronic acid (ZOL) at week 0 (n = 8), OVX and ZOL at week 8 (n = 7), and sham (n = 9). CT scans were made of the proximal tibia at weeks 0, 2, 4, 8, 12, and 16; and bone structural parameters were determined in the metaphysis. Two fluorescent labels were administered to calculate dynamic histomorphometric parameters. At week 16, all groups were significantly different from each other in bone volume fraction (BV/TV), connectivity density, and trabecular number (Tb.N), except for the early ZOL and control groups which were not significantly different for any structural parameter. After ZOL treatment at week 8, BV/TV, structure model index, Tb.N, and trabecular thickness significantly improved in the late ZOL group. The OVX and ZOL groups showed, respectively, higher and lower bone formation rates than the control group. Early ZOL treatment inhibited all bone microstructural changes seen after OVX. Late ZOL treatment significantly improved bone microstructure, although the structure did not recover to original levels. Early ZOL treatment resulted in a significantly better microstructure than late treatment. However, late treatment was still significantly better than no treatment.

Microfocus Computed Tomography Analysis of Early Changes in Bone Microstructure in Rats with Chronic Renal Failure

Background/Aims: Little is known about the microstructural changes in bone tissue in the early phase of chronic renal failure (CRF). In this study, we analyzed the bone tissue in a rat model of early CRF using a high-resolution X-ray tomographic system, i.e. microfocus computed tomography (MXCT), which is capable of detecting microscopic structural changes in bone tissue. Methods: CRF rats were created by 7/8 nephrectomy by ligation of the renal artery branches, and were sacrificed 24 weeks after surgery. MXCT and bone mineral densitometry by single-energy X-ray absorptiometry (SXA) were performed using extracted bone samples. Images obtained by MXCT were further analyzed by node-strut morphometry. Results: Biochemical analysis confirmed that CRF was induced in 7/8-renal artery-ligated rats. MXCT demonstrated a significant decrease in trabecular bone in uremic rats, whereas SXA was unable to detect the difference. The node-strut method revealed decreased trabecular connectivity, with little change in the thickness of the trabecular bone in uremic rats. Conclusion: MXCT was able to detect significant changes in trabecular bone at an early stage of renal failure. The observed structural changes differed from those found in long-term dialysis patients. MXCT is a practical and promising device used for the non-invasive evaluation of early bone changes in uremic patients.