Prednisolone-induced Osteoporosis Research Articles

The effects of all-trans retinoic acid on prednisolone-induced osteoporosis in zebrafish larvae

Glucocorticoids (GCs) are extensively used as anti-inflammatory and immunosuppressive medications in the long-term treatment of rheumatic disorders, respiratory diseases, renal diseases, and organ transplantation. Prolonged use of GCs can reduce bone mineral density, leading to osteoporosis (Glucocorticoid Induced Osteoporosis, GIOP) and fracture. All-trans retinoic acid (ATRA) is an active vitamin A metabolite that regulates embryonic development and adult organ function. ATRA has been found in studies to enhance osteogenesis. To examine the interventional effects of ATRA on GIOP and the mechanisms of ATRA activities, we first performed bioinformatic analysis to identify potential gene targets of ATRA. Zebrafish larvae were recruited as experimental animals, and the frequently used GC, prednisolone, was administered to larvae to construct a GIOP model. We evaluated the influence of exogenous ATRA on the activities of bone metabolic enzymes, the expression of genes linked to osteoblasts and osteoclasts, and the restoration of bone mineral density and bone mass in GIOP zebrafish larvae. Furthermore, we studied the influence of RBM14, a transcriptional coactivator and negative reciprocal factor of ATRA, on the regulation of osteoblastic gene expression during the anti-GIOP process of ATRA using the morpholino knockdown approach. The findings of bone metabolic enzyme activity (alkaline phosphatase, ALP and tartrate-resistant acid phosphatase, TRAP) and expression assays of osteoblastic marker genes (Runx2a, Runx2b, SP7, Csf1a, RANKL, and CTSK) indicated that ATRA had bidirectional effects on osteogenesis. However, in the GIOP model, ATRA reversed the GIOP-induced osteoporosis phenotype by inhibiting the GIOP-induced suppression of osteoblastic metabolic enzyme (ALP) activities and osteoblastic marker gene expression (Runx2a, Runx2b, and SP7), and this antagonism was concentration-dependent. We also observed that ATRA inhibited RBM14 expression in zebrafish larvae, while ATRA alone and RBM14 knockdown showed a consistent induction of osteoblast marker gene expression, implying that ATRA's inhibitory effect on RBM14 expression may underlie ATRA's osteogenic effects. Based on these data, we postulated that ATRA may ameliorate GIOP by decreasing RBM14 expression, thereby enhancing osteoblastic marker gene expression.

N-Acetylcysteine Attenuates the Prednisolone-Induced Osteoporosis via Rescuing the Nuclear Factor Erythroid 2-Related Factor 2-Antioxidant Responsive Element Axis Activity in Mice

We aimed to investigate the effect and potentialmechanism of N-acetylcysteine (NAC), as an antioxidant, on prednisolone-induced osteoporosis. C57bl/6 mice were subcutaneously delivered with prednisolone to induce osteoporosis. The bone marrow mesenchymal stem cells (MSCs) from mice were induced to osteoblast differentiation and treated with prednisolone in vitro. Meanwhile, the NAC or Nrf2 activator Oltipraz (OPZ) was supplied in the prednisolone treatment. The osteoporosis was determined by bone mineral density, trabecular bone volume, and the parameters of bone absorption and formation. Additionally, the Nrf2, ARE-driven genes HMOX-1, GCLC, ME1, and NQO1 expression were measured by western blot or qRT-PCR. The reactive oxygen species (ROS) was measured by a commercial kit. Prednisolone significantly deceased the bone volume, osteoblastic bone formation, osteogenesis of MSCs, and the expression of Nrf2 and ARE-driven genes. On the contrary, prednisolone promoted ROS production and osteoclastic bone absorption. However, the supplement of NAC or OPZ with prednisolone treatment could markedly rescue the Nrf2 and ARE-droven genes expression, reduce the ROS, alleviate the bone loss, and protect the osteogenesis of MSCs. Our results demonstrated that NAC presented a protective property of Nrf2-ARE axis and resulting prevention of prednisolone-induced osteoporosis.

Analysis of Prednisolone-Induced Osteoporosis Using the Japanese Adverse Drug Event Report Database.

Osteoporosis is an adverse event of prednisolone. This study aimed to assess prednisolone-induced osteoporosis (PIO) profiles and patient backgrounds by analyzing data from the Japanese Adverse Drug Event Report (JADER) database. The current study focused only on orally administered prednisolone. PIO was defined using preferred terms from the Medical Dictionary for Regulatory Activities. Reporting odds ratio (ROR) at 95% confidence interval (CI) and the time-to-onset profile of PIO were used to evaluate adverse events. The RORs (95% CI) of the female and male subgroups were 4.73 (4.17-5.38) and 2.49 (2.06-3.00), respectively. The analysis of time-to-onset profiles demonstrated that the median values (interquartile range: 25.0-75.0%) of PIO were 136 (74.0-294.0). The prednisolone treatment duration was significantly longer in the PIO patient group than in the non-PIO patient group. The findings suggest that patients with rheumatoid arthritis, systemic lupus erythematosus, and nephrotic syndrome receiving prednisolone have different age-related PIO profiles. Our results suggest that longer prednisolone treatment duration and larger cumulative dose might be risk factors of PIO. The potential risk for PIO should not be overlooked, and careful observation is recommended.

Pharmacological characterization of AS2690168, a novel small molecule RANKL signal transduction inhibitor

Pathological osteolysis is associated with excessive bone resorption by activated osteoclasts. Given that receptor activator of NF-kB and its ligand (RANKL) are key players in the differentiation and activation of osteoclasts, the RANKL/RANK signaling pathway is considered a promising target for the development of effective osteoclastogenesis inhibitors. We previously found that the orally available compound, AS2690168, suppresses RANKL-induced osteoclastogenesis of RAW264 cells. In this report, we further characterized the pharmacological profiles of AS2690168 in vitro and in vivo. AS2690168 suppressed soluble RANKL (sRANKL)-induced NFATc1 mRNA expression in RAW264 cells at 0.3 and 3.0 μM. It also suppressed calcium release from parathyroid hormone-stimulated mouse calvaria with an IC50 value of 0.46 μM. Oral administration of AS2690168 completely suppressed the decrease in femoral bone mineral content in an sRANKL-induced osteopenic mice model at 3.0 mg/kg. It also significantly suppressed the decrease in femoral bone mineral density and increase in serum tartrate-resistant acid phosphatase-5b levels in ovariectomized rats at doses of 0.3, 1 and 3 mg/kg. Finally, AS260168 suppressed the increase in urine deoxypyridinoline in a rat prednisolone-induced osteoporosis model at 10 mg/kg. These results suggest that AS2690168 is a promising treatment for bone disorders with excessive bone resorption.

Молекулярно-клітинні механізми захисної дії вітаміну D3 при експериментальному преднізолон-індукованому остеопорозі

Актуальність. Довготривале введення глюкокортикоїдів (ГК) супроводжується порушенням мінерального обміну і, як наслідок, призводить до розвитку вторинного остеопорозу. Важливу роль у регулюванні процесу ремоделювання кісткової тканини відіграє вітамін D, який може реалізовувати свої біо­логічні ефекти через рецептор вітаміну D — VDR-опосередкований вплив на цитокінові системи, зокрема RANKL-RANK-OPG (ліганд рецептора активатора ядерного фактора транскрипції NF-κB — рецептор RANKL — остеопротегерин). Мета. Дослідження ГК-індукованих змін експресії детермінантних для процесів формування та резорбції кісткової тканини регуляторних протеїнів (RANK, RANKL, OPG, остеокальцин, VDR) залежно від біодоступності вітаміну D. Матеріали та методи. Щури-самиці лінії Wistar отримували преднізолон (5 мг/кг маси тіла) разом з вітаміном D3 (100 МО) або без нього протягом 30 днів. Рівні VDR, остеокальцину, RANK, RANKL і OPG у кістковій тканині визначали за методом вестерн-блот-аналізу. Рівень гідроксивітаміну D (25OHD) у сироватці крові аналізували, використовуючи метод ELISA. Вміст мінеральних компонентів (Ca2+ та Pi), активність лужної фосфатази (ЛФ) та її ізоформ визначали спектрофотометрично. Результати. Преднізолон значно знижував рівень 25OHD у сироватці крові та вміст протеїну VDR у кістковій тканині. Це супроводжувалось підвищенням загальної активності сироваткової ЛФ і її кісткової ізоформи, гіпокальціємією, гіпофосфатемією, а також зниженням вмісту мінеральних компонентів у кістковій тканині. Спостерігалось значне зниження експресії остеокальцину, ключового маркера остеосинтезу. Зміни у D-вітамінному статусі тварин, викликані ГК, призводили до зниження рівня RANK та OPG у кістковій тканині, тоді як рівень RANKL залишався без змін. Уведення вітаміну D3, підвищуючи рівні 25OHD і VDR, сприяло частковій або повній нормалізації викликаних преднізолоном змін мінерального обміну й кісткового гомеостазу через підвищення рівнів RANK, OPG та остеокальцину. Висновки. Преднізолон-індуковане дерегулювання цитокінової системи RANKL — RANK — OPG та остеокальцин-опосередковане формування кісткової тканини можуть бути тісно пов’язані зі зниженням біодоступності вітаміну D і порушенням клітинного сигналювання через VDR. Відновлення біодоступності вітаміну D є необхідною умовою, що протидіє негативним ефектам глюкокортикоїдної терапії у кістковій тканині.

10-Gingerol Suppresses Osteoclastogenesis in RAW264.7 Cells and Zebrafish Osteoporotic Scales.

Osteoporosis is the most common aging-associated bone disease and is caused by hyperactivation of osteoclastic activity. We previously reported that the hexane extract of ginger rhizome [ginger hexane extract (GHE)] could suppress receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis in RAW264.7 cells. However, the anti-osteoclastic components in GHE have not yet been identified. In this study, we separated GHE into several fractions using silica gel column chromatography and evaluated their effects on osteoclastogenesis using a RAW264.7 cell osteoclast differentiation assay (in vitro) and the zebrafish scale model of osteoporosis (in vivo). We identified that the fractions containing 10-gingerol suppressed osteoclastogenesis in RAW264.7 cells detected by tartrate-resistant acid phosphatase (TRAP) staining. In zebrafish, GHE and 10-gingerol suppressed osteoclastogenesis in prednisolone-induced osteoporosis regenerated scales to promote normal regeneration. Gene expression analysis revealed that 10-gingerol suppressed osteoclast markers in RAW264.7 cells [osteoclast-associated immunoglobulin-like receptor, dendrocyte-expressed seven transmembrane protein, and matrix metallopeptidase-9 (Mmp9)] and zebrafish scales [osteoclast-specific cathepsin K (CTSK), mmp2, and mmp9]. Interestingly, nuclear factor of activated T-cells cytoplasmic 1, a master transcription regulator of osteoclast differentiation upstream of the osteoclastic activators, was downregulated in zebrafish scales but showed no alteration in RAW264.7 cells. In addition, 10-gingerol inhibited CTSK activity under cell-free conditions. This is the first study, to our knowledge, that has found that 10-gingerol in GHE could suppress osteoclastic activity in both in vitro and in vivo conditions.

Grapefruit juice exerts anti-osteoporotic activities in a prednisolone-induced osteoporosis rat femoral fracture model, possibly via the RANKL/OPG axis.

This study aimed to shed light on the protective and therapeutic anti-osteoporotic effects and mechanisms of action of grapefruit juice (GFJ) on prednisolone-induced osteoporosis a rat femoral fracture model. We found that treating rats with GFJ before and/or after prednisolone-induced osteoporosis resulted in increased bone density, total mineral content, and calcium content to counteract the osteoporotic effects of prednisolone. In parallel, the histological and ultrastructural results of the GFJ-treated groups correlated well with enhanced breaking strength of femurs subjected to a constant load. Furthermore, GFJ treatment before and after prednisolone-induced osteoporosis decreased plasma alkaline phosphatase and tartrate-resistant acid phosphatase activities and increased the level of insulin-like growth factor 1. Mechanistically, our immunohistochemistry study showed that GFJ ameliorated prednisolone-induced osteocalcin depletion, decreased receptor activator of nuclear factor kappa-B ligand (RANKL) expression, and increased osteoprotegerin (OPG) expression. GFJ showed a beneficial anti-osteoporotic effect against prednisolone-induced osteoporosis in rats, possibly via the RANKL/OPG axis, suggesting that GFJ might be a good candidate for developing anti-osteoporotic drugs.

Fangchinoline Promotes Autophagy and Inhibits Apoptosis in Osteoporotic Rats.

BackgroundOsteoporosis is a common disorder leading to bone loss. At present, the treatment options available for the management of osteoporosis are limited. The present investigation evaluated the protective effect of fangchinoline against osteoporosis and also postulates the possible mechanism of action.Material/MethodsOsteoporosis was induced by subcutaneously injecting prednisolone (2.5 mg/pellet) for 4 weeks. Fangchinoline 1, 3 and 10 mg/kg was given intraperitoneally for the period. Protective effects of fangchinoline were assessed by estimating microarchitectural parameters and bone mineral density (BMD) in the vertebrae tissues, and biochemical parameters were also determined in the serum of rats with prednisolone-induced osteoporosis. Moreover, gene expression of microtubule-associated protein 1A/1B-light chain 3 (LC3), B cell lymphoma 2 (Bcl-2), caspase-3, bone morphogenetic protein 2 (BMP2), Beclin-1, autophagy-related 5 (ATG-5), Runt-related transcription factor 2 (RUNX-2), and receptor activator of nuclear factor kappa-β ligand (RANKL) protein in the vertebrae tissue were assessed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot assay.ResultsThere was a significant (p<0.01) decrease in the BMD and microarchitectural parameters in the vertebrae tissue of the fangchinoline-treated group compared to the prednisolone group. We also found that treatment with fangchinoline attenuated the altered expressions of LC3, Bcl-2, caspase-3, BMP2, Beclin-1, ATG-5, RUNX-2, and RANKL protein in the prednisolone-induced osteoporosis rats. Moreover, levels of biochemical parameters were attenuated in the serum of fangchinoline-treated and prednisolone-induced osteoporosis rat. Histopathology revealed that the apoptosis of osteoblasts was decreased in the fangchinoline-treated group compared to the prednisolone group of rats.ConclusionsFangchinoline inhibits apoptosis of osteoblasts and protects against bone loss in prednisolone-induced osteoporosis rats by inducing autophagy.

Possible mechanisms of prednisolone-induced osteoporosis in zebrafish larva

Glucocorticoid-induced osteoporosis (GIOP) is a serious clinical bone disease that results from the long-term consumption of glucocorticoids or glucocorticoid-like drugs. Although many studies have attempted to determine the mechanisms of GIOP, they are still unclear. In this study, we established a zebrafish model of glucocorticoid-like drug-induced osteoporosis by treating larvae with prednisolone. We then quantified the expression of a selection of extracellular matrix (ECM)-, osteoblast-, and osteoclast-related genes. Our results showed that at 15 days post fertilization, zebrafish larvae treated with 25 μM prednisolone are a suitable model for GIOP, not only owing to the decrease in robust bone mass but also because of significant alterations in gene expression. The quantification of the expression of ECM-, osteoblast-, and osteoclast- related genes revealed that mmp9 and mmp13 were significantly upregulated and entpd5a, acp5a, and sost were significantly downregulated. These genes may be a target for future research into GIOP. Our study thus provides new insights into GIOP.

A HILIC-UHPLC-MS/MS untargeted urinary metabonomics combined with quantitative analysis of five polar biomarkers on osteoporosis rats after oral administration of Gushudan.

A HILIC-UHPLC-MS/MS untargeted urinary metabonomic method combined with quantitative analysis of five potential polar biomarkers in rat urine was developed and validated, to further understand the anti-osteoporosis effect of Gushudan(GSD) and its mechanism on prednisolone-induced osteoporosis(OP) rats in this study. The metabolites were separated and identified on Waters BEH HILIC (2.1mm×100mm, 1.7μm) column using the Waters ACQUITY™ ultra performance liquid chromatography system (Waters Corporation, Milford, USA) coupled with a Micromass Quattro Micro™ API mass spectrometer (Waters Corp, Milford, MA, USA). Principal component analysis (PCA) was used to identify potential biomarkers. Primary potential polar biomarkers including creatinine, taurine, betaine, hypoxanthine and cytosine, which were related to energy metabolism, lipid metabolism and amino acid metabolism, were found in the untargeted metabonomic research. Moreover, these targeted biomarkers were further separated and quantified in multiple-reaction monitoring (MRM) with positive ionization mode, using tinidazole as internal standard (I.S.). Good linearities (r>0.99) were obtained for all the analytes with the low limit of quantification from 1.00 to 12.8μg/mL. The relative standard deviation (RSD) of the intra-day and inter-day precisions were within 15.0% and the accuracy ranged from -14.3% to 13.5%. The recovery was more than 85.0%. And the validated method was successfully applied to investigate the urine samples of the control group, prednisolone-induced osteoporosis model group and Gushudan-treatment group in rats. Compared to the control group, the level of creatinine, taurine, betaine, hypoxanthine and cytosine in the model group revealed a significant decrease trend (p<0.05), while the Gushudan-treatment group showed no statistically differences by an independent sample t-test. This paper provided a better understanding of the therapeutic effect and mechanism of GSD on prednisolone-induced osteoporosis rats.

The experimental evaluation of the protective effect of the extract of the cyclodextrin-containing phytotherapeutic composition on the development of osteoporosis

The relevance of the problem considered in the present communication arises to-day from the widespread prevalence of osteoporosis (OP), the rather low effectiveness of the methods currently available for the treatment of this condition, and iatrogenic effects of its medication therapy. The great diversity of phytotherapeutic modalities of traditional medicine are is only poorly supported by the results of the scientific studies results; moreover, most of them are coming from the foreign literature publications. The objective of the present study was to evaluate the influence of the phytotherapeutic preparation (Phytocost) having cyclodextrin in its composition on the restoration of the cartilaginous and bony tissues based on the experimental research with the use of the OP experimental model. The experimental studies were performed on 5 month-old Balb/c mice used as the prednisolone-induced osteoporosis model. The animals were divided into four study groups according to the daily doses administered to them: 0.005; 0.05; 0.5 and 5.0 mg/mouse during 30 days and 3 control groups: intact, 14 and 30 days after prednisolone administration, naïve mice. The study has demonstrated the dose-dependent protective effect of cyclodextrin-containing Phytocost. The most pronounced effect in the form of reduction of osteoblast number and the increase in the number of osteocytes was obtained at a Phytocost dose of 0.5 mg/mouse. No undesirable adverse reactions were documented during the study. The domestically produced Phytocost composition differs from its foreign analogues in that it contains a significantly greater number of constituent components because the ultimate goal of the study was to create a medication acting on all currently known mechanisms of OP pathogenesis, whereas our Chinese colleagues proceed from the ancient knowledge gained by traditional medicine that it is sometimes difficult to understand and explain in the light of the modern concepts. All the plants used as raw materials for Phytocost production grow at the territory of the Russian Federation which provides the possibilities for the efficient import substitution of the components necessary for the manufacture of the preparation in question.

An intergated serum and urinary metabonomic research based on UPLC-MS and therapeutic effects of Gushudan on prednisolone-induced osteoporosis rats

Gushudan, a Chinese compound formulation based on the theory of traditional Chinese medicine and desgined to treat osteoporosis. However, its intergated intervention effective mechanism in vivo is not well understood. In this study, an intergated serum and urinary metabonomic strategy based on UPLC-MS technique have been developed to increase the understanding of the metabolism characters of osteoporosis and to investigate the holistic therapeutic efficacy of Gushudan on prednisolone-induced osteoporosis rat model. Principle component analysis (PCA) was utilized to identify differences in metabolic profiles of rats in the control group, prednisolone-induced osteoporosis model group and Gushudan-treatment group and clear separation was achieved among three groups. Furthermore, 17 potential biomarkers from urine and 10 potential biomarkers from serum were identified, primiarily related to amino acid metabolism, energy metabolism, lipid metabolism, intestinal flora metabolism and kidney damage. Gushudan has therapeutic effects on rat with osteoporosis via the regulation of multiple metabolic pathways. It's worth mentioning that some new biomarkers associated with osteoporosis such as 3-methoxydopa, 2,8-digydroxyadenine have been discovered in this study for the first time. This study provides a useful approach to get insight into the intergated metabonomic mechanism of prednisolone-induced osteoporosis and to assess the efficacy of Gushudan on osteoporotic rats. The work also shows that the metabonomics method is a promising tool in the efficacy and mechanism research of traditional Chinese compound medicines.

Effects of bioactive fatty acid amide derivatives in zebrafish scale model of bone metabolism and disease

The endocannabinoid system (which includes fatty acid derivatives, receptors, and metabolizing enzymes) is involved in a variety of physiological processes, including bone metabolism in which it regulates the function of osteoblasts and osteoclasts, as well as differentiation of their precursors. The zebrafish (Danio rerio) provides a useful animal model for bone research since zebrafish bones develop rapidly and are anatomically similar to mammalian bones. Putative orthologues and paralogs of endocannabinoid genes have recently been identified in zebrafish, demonstrating the presence of cannabinoid type 1 (CB1) and type 2 (CB2) receptors with affinity to endocannabinoid ligands.To identify therapeutic molecules potentially useful in bone-related diseases, we evaluated the in vivo effects of exposure to long-chain fatty acid amides in adult zebrafish. Using a well-established zebrafish scale model, we found that anandamide and N-linoleoylethanolamine are able to stimulate bone formation by increasing alkaline phosphatase activity in physiological conditions. In addition, they prevent the alteration of bone markers in a prednisolone-induced osteoporosis model in adult zebrafish scales, whereas their esterified forms do not. These data suggest that long-chain fatty acid amides are involved in regulating bone metabolism in zebrafish scales and that the CB2 receptor is a key mediator in this process.

RANKL is downregulated in bone cells by physical activity (treadmill and vibration stimulation training) in rat with glucocorticoid-induced osteoporosis.

The aim of this study was to investigate bone tissue and plasma levels of RANKL and OPG in rats with prednisolone-induced osteoporosis and to evaluate the outcomes of physical activity on the skeletal system by treadmill and vibration platform training. Osteoporosis is a disease characterised by low bone mass and structural deterioration of bone tissue leading to bone fragility. Vibration exercise is a new and effective measure to prevent muscular atrophy and osteoporosis. The animals were divided into 5 groups. 1: control rats; 2: rats with osteoporosis receiving prednisolone; 3: rats receiving prednisolone and treadmill training; 4: rats receiving prednisolone and vibration stimulation training; 5: rats receiving prednisolone, treadmill and vibration stimulation training. For bone evaluations we used whole-body scans, histology and histomorphometric analysis. RANKL and OPG expression was evaluated by immunohistochemistry and biochemical analysis. After treatment, our data demonstrated that RANKL expression was significantly increased in groups 2 and 3 and decreased in groups 4 and 5. Conversely, OPG expression was significantly decreased in groups 2 and 3 and increased in groups 4 and 5. In conclusion, our findings suggest that mechanical stimulation inhibits the activity of RANKL. This finding provides new insights into the occurrence and progression of osteoporosis.

The effects of physical activity (treadmill and vibration stimulation training) on RANKL and OPG expression in bone cells, in rats with glucorticoid-induced osteoporosis

The aim of this study was to investigate bone tissue and plasma levels of RANKL and OPG in rats with prednisolone-induced osteoporosis and to evaluate the outcomes of physical activity on the skeletal system by treadmill and vibration platform training. Osteoporosis is a disease characterised by low bone mass and structural deterioration of bone tissue leading to bone fragility. Vibration exercise is a new and effective measure to prevent muscular atrophy and osteoporosis. The animals were divided into 5 groups. 1: control rats; 2: rats with osteoporosis receiving prednisolone; 3: rats receiving prednisolone and treadmill training; 4: rats receiving prednisolone and vibration stimulation training; 5: rats receiving prednisolone, treadmill training and vibration stimulation training. Bone evaluations used whole-body scans, histology and histomorphometric analysis. RANKL and OPG expression was evaluated by immunohistochemistry and biochemical analysis. After treatment, our data demonstrated that RANKL expression was significantly increased in groups 2 and 3 and decreased in groups 4 and 5. Conversely, OPG expression was significantly decreased in groups 2 and 3 and increased in groups 4 and 5. In conclusion, our findings suggest that mechanical stimulation inhibits the activity of RANKL. This finding provides new insights into the occurrence and progression of osteoporosis.

The effects of physical activity on apoptosis and lubricin expression in articular cartilage in rats with glucocorticoid-induced osteoporosis

Glucocorticoids are considered the most powerful anti-inflammatory and immunomodulating drugs. However, a number of side-effects are well documented in different diseases, including articular cartilage, where increases or decreases in the synthesis of hormone-dependent extracellular matrix components are seen. The objective of this study has been to test the effects of procedures or drugs affecting bone metabolism on articular cartilage in rats with prednisolone-induced osteoporosis and to evaluate the outcomes of physical activity with treadmill and vibration platform training on articular cartilage. The animals were divided into 5 groups, and bone and cartilage evaluations were performed using whole-body scans and histomorphometric analysis. Lubricin and caspase-3 expression were evaluated by immunohistochemistry, Western blot analysis and biochemical analysis. These results confirm the beneficial effect of physical activity on the articular cartilage. The effects of drug therapy with glucocorticoids decrease the expression of lubricin and increase the expression of caspase-3 in the rats, while after physical activity the values return to normal compared to the control group. Our findings suggest that it might be possible that mechanical stimulation in the articular cartilage could induce the expression of lubricin, which is capable of inhibiting caspase-3 activity, preventing chondrocyte death. We can assume that the physiologic balance between lubricin and caspase-3 could maintain the integrity of cartilage. Therefore, in certain diseases such as osteoporosis, mechanical stimulation could be a possible therapeutic treatment. With our results we can propose the hypothesis that physical activity could also be used as a therapeutic treatment for cartilage disease such as osteoarthritis.

Influence of prednisolone-induced osteoporosis on bone mass and bone quality of the mandible in rats

The aim of this study was to clarify the effects of steroid treatment on the mandible. We divided 24 male Fisher rats, aged 10 weeks, into 2 groups: a control group (n = 11) and a prednisolone (Pred) treatment group (n = 13). The dose for the Pred group was 40 mg kg(-1) and was administered orally three times per week for 8 weeks. At the end of the experiment, we measured bone mass, bone strength and trabecular structure of the mandible and femur. Pred treatment decreased cortical bone mineral content (BMC), cortical thickness, stress/strain index and tissue volume of the mandible. However, there were no marked changes in trabecular structure parameters. A strong correlation was seen between mandibular and femoral cortical BMC (r = 0.71). These findings suggest that steroid treatment decreases the cortical BMC, bone area and bone strength of the mandible.

Effect of D-003, a mixture of very high molecular weight aliphatic acids, on prednisolone-induced osteoporosis in Sprague-Dawley rats.

Drugs inhibiting cholesterol biosynthesis may affect bone metabolism through inhibition of the mevalonate pathway resulting in the inhibition of protein prenylation required for osteoclast activity. D-003 is a mixture of high molecular weight aliphatic primary acids purified from sugar-cane (Saccharum officinarum) wax, with cholesterol-lowering effects demonstrated in experimental and clinical studies. D-003 inhibits cholesterol biosynthesis through indirect regulation of HMG-CoA reductase activity. A previous study demonstrated that D-003 prevented bone loss and bone resorption on ovariectomy-induced osteoporosis in rats. Corticosteroid-induced osteoporosis is the result of changes affecting calcium homeostasis, but the hallmark of corticosteroid-induced bone loss is the direct effects on bone cells, such as inhibition of osteoblastogenesis, promotion of apoptosis of osteoblasts and osteocytes, and decrease in bone formation. To determine whether D-003 could prevent the bone loss induced with prednisolone in Sprague-Dawley rats. Rats were randomly distributed in five groups (ten rats per group): a sham-operated control and four groups orally treated with prednisolone 6 mg/kg for 80 days; a positive control orally treated with vehicle; and three groups orally treated with D-003 at 5, 25 and 200 mg/kg, respectively. Rats were killed, bones removed and histological variables of bone resorption and formation studied for histomorphometry. Compared with the sham group, prednisolone significantly (p < 0.01) reduced trabecular bone volume (TBV), while D-003 significantly (p < 0.001) and dose-dependently prevented the prednisolone-induced reduction of TBV. Treatment with prednisolone lowered (p < 0.001) trabecular thickness (TbTh) and number (TbN), while increasing (p < 0.001) the gap between trabeculae. D-003 (5, 25 and 200 mg/kg/day) significantly (p < 0.001) and dose-dependently prevented the reduction of TbTh and TbN and the increase of trabecular gap induced with prednisolone. Treatment with prednisolone increased both the surface and number of osteoclasts compared with sham (p < 0.001). D-003 (5-200 mg/day), however, prevented this effect (p < 0.001 for all comparisons). D-003 also prevented (p < 0.001) the reduction of osteoblast surface (ObS/BS) induced by prednisolone. Osteonecrotic areas were observed in all positive controls, but in none of the sham animals. Positive controls showed hypertrophy of bone marrow adipocytes and lipid-laden pluripotential stromal cells in bones. A significant and dose-dependent reduction of the frequency of animals showing prednisolone-induced osteo-necrosis was observed across the doses of D-003 (5, 25 and 200 mg/kg) investigated here. D-003 (5, 25 and 200 mg/kg) prevented trabecular bone loss and femoral neck osteonecrosis induced with prednisolone in Sprague Dawley rats, also increasing osteoblast surface and reducing bone resorption parameters. These results suggest that D-003 could be useful for managing corticosteroid-induced osteoporosis.

Effect of swimming on prednisolone-induced osteoporosis in elderly rats.

We investigated the possible ameliorating and preventive effect of swimming on prednisolone-induced osteoporosis in elderly rats. A total of 48 female Sabra strain rats were randomly assigned to the following groups and treatments: (1) control (C), (2) swimming (S), (3) prednisolone-treated (CP), and (4) swimming + prednisolone (SP). An additional 8 rats were sacrificed and examined at the onset of the study. Groups C and S were sham injected; groups CP and SP were injected with prednisolone (Ultracorten), 80 mg/kg three times per week for 10 weeks. Groups S and SP swam 1 h daily, 5 days per week for 10 weeks. SP rats swam simultaneously with prednisolone administration. At the end of the swimming period, in vivo bone mineral content (BMC) measurements were performed on rat vertebrae L4-5 by single-photon absorptiometry. Later, the humerus and femur were removed for the following measurements: morphometric, bone density (BD) by Compton scattering technique, bone ion content by atomic absorption, and hydration fraction by proton magnetic resonance (PMR). We found that the humeral BD of S rats was greater by 14% for group S over C and 3% greater for group SP over CP (P less than 0.05). Vertebral BMC was higher by 15% in group S over C and 11% higher for group SP over CP (P less than 0.05). Femoral calcium (mg/g dry bone) ion content was higher by 5% in group S over C and 8% in group SP over CP group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ipriflavone on glucocorticoid-induced osteoporosis in rats

Ipriflavone, 7-isopropoxy-3-phenyl-4H-1-benzopyran-4-one, was administered orally for 12 weeks to male rats with prednisolone-induced osteoporosis. Microdensitometric analysis of a roentgenograph of the femurs revealed that ipriflavone increased the density of the distal metaphysis dose-dependently and tended to increase the density of the diaphysis. It also inhibited dose-dependently the decreases in the mechanical strength of the tibia, breaking strain and breaking energy, and the fractional content of ash in femurs. These results indicate that ipriflavone markedly suppresses bone resorption at the metaphysis where the content of trabecular bone with a rapid turnover rate is high, and possibly inhibits bone reduction at the diaphysis.