Zuogui Wan improves trabecular bone microarchitecture in ovariectomy-induced osteoporosis rats by regulating orexin-A and orexin receptor.

OBJECTIVE: To investigate the protective effects of Zuogui Wan (ZGW) on bone loss induced by ovariectomy (OVX) and its mechanism via orexin-A and orexin receptors in the osteoporosis rat model. METHODS: Fifty Sprague-Dawley female rats were randomly divided into sham-operated (sham) group and four OVX subgroups. Rats subjected to sham and OVX were treated with the vehicle (OVX, 1 mL/100 g weight, n = 10), 17ß-estradiol (E2, 50 µg*kg-1*d-1), and ZGW at the doses of 2.3 (ZGW-L) and 4.6 (ZGW-H) g/kg/day lyophilized powder daily for 3 months, respectively. The serum biochemical parameters of 17ß-estrogen (17ß-E2), tartrate-resistant acid phosphatase (TRACP-5b) and bone alkaline phosphatase (BALP) were measured by enzyme-linked immunosorbent assay. Hematoxylin-eosin staining was used to detect the changes in the morphological structure in bones. Microcomputed tomography was used to evaluate the bone mineral density and microarchitecture of the distal femur. The gene or protein expression of orexin-A, orexin receptor 1 (OX1R), orexin receptor 2 (OX2R), osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) were assayed by either quantitative polymerase chain reaction or Western blot analysis. RESULTS: Compared with the OVX group, ZGW could reduce the serum level of TRACP-5b and increased the serum levels of BALP and17ß-E2 (P < 0.01). Meanwhile, ZGW could prevent bone loss and improved bone trabecular microarchitecture by increasing the trabeculae structure thickness and trabecular number, and arranging the trabeculae structure properly. Compared with the OVX group, it was upregulated for the orexin-A and OX2R mRNA or protein expression from the hypothalamus and tibiae, and OPG in the tibiae of ZGW groups (P < 0.01, < 0.05), while downregulated for the OX1R mRNA and protein expression in the tibiae and hypothalamus and RANKL from the tibiae (P < 0.01). CONCLUSION: ZGW exhibited a protective effect for PMOP that may be mediated via orexin-A and orexin receptors regulation.

Clinical Utility of Trabecular Bone Score (TBS) in Fracture Risk Assessment of Patients with Rheumatic Diseases Treated with Glucocorticoids.

Chronic glucocorticoid therapy is associated with osteoporosis and can cause fractures in up to 50% of patients. Increased risk of fractures in patients with glucocorticoid-induced osteoporosis does not result only from the decreased bone mineral density (BMD) but also bone microarchitecture deterioration. Trabecular bone score (TBS) is a method complementary to DXA, providing additional information about trabecular bone structure. The aim of this study was to assess the clinical utility of TBS in fracture risk assessment of patients treated with glucocorticoids. Patients with rheumatic diseases treated with glucocorticoids for at least 3 months were enrolled. All recruited patients underwent DXA with additional TBS assessment. We analyzed the frequency of osteoporosis and osteoporotic fractures and assessed factors that might be associated with the risk of osteoporotic fractures. A total of 64 patients were enrolled. TBS and TBS T-score values were significantly lower in patients with osteoporosis compared to patients without osteoporosis. Low energy fractures occurred in 19 patients. The disturbed bone microarchitecture was found in 30% of patients with fractures without osteoporosis diagnosis based on BMD. In the multivariate analysis, only TBS and age were significantly associated with the occurrence of osteoporotic fractures. TBS reflects the influence of glucocorticoid therapy on bone quality better than DXA measured BMD and provides an added value to DXA in identifying the group of patients particularly prone to fractures.

Protective effect of rhaponticin on ovariectomy-induced osteoporosis in rats.

Rhaponticin is a constituent isolated from numerous medicinal herbs. It has been reported earlier that rhaponticin possesses numerous biological effects like antiallergic, antidiabetic, hepatoprotective, and antithrombosis. The goal of this exploration was to scrutinize the therapeutic potential of rhaponticin on ovariectomy (OVX)-triggered osteoporosis in rats. Female Sprague Dawley rats were arbitrarily allocated to a sham-operated control group I, group II, which underwent OVX, and groups III and IV that underwent OVX were administered with rhaponticin (10 and 20 mg/kg). Rhaponticin was supplemented orally after 4 weeks of OVX and continued for about 16 weeks. Our findings exhibit that rhaponticin prevented the BMD diminution of femurs, induced by OVX, and protected the worsening of trabecular microarchitecture that are assisted through a noteworthy decline in skeletal remodeling as noticed through the diminished status of bone markers in a dose-dependent manner (10 and 20 mg/kg). OVX rats treated with rhaponticin efficiently enhanced body weight, lipid profiles, uterine index, bone turnover markers, inflammatory markers, and augmented the incidence of calcium in the OVX rats. Rhaponticin was established to restrain the functions of acid phosphatase, estradiol, and bone gla protein in OVX rats. Also, rhaponticin displayed some beneficial effects on histomorphometric and histopathological examination. It was observed that tabular area and thickness were reinstated in sham control and rhaponticin-treated OVX rats. We recognized that rhaponticin did not induce a damaging outcome on the skeletal organization of OVX rats. Moreover, we denote that rhaponticin can be an exceptional agent for the treatment and deal with associated bone diseases.

Solanum nigrum Line inhibits osteoclast differentiation and suppresses bone mineral density reduction in the ovariectomy­induced osteoporosis model.

Bone homeostasis is maintained by osteoclasts that absorb bone and osteoblasts that form bone tissue. Menopausal osteoporosis is a disease associated with aging and hormonal changes due to menopause causing abnormal activation of osteoclasts, resulting in a decrease in bone density. Existing treatments for osteoporosis have been reported to have serious side effects, such as jawbone necrosis and breast and uterine cancer; therefore, their use by patients is decreasing, whilst studies focusing on alternative treatments are increasingly popular. Solanum nigrum Line (SL) has been used as a medicinal plant that possesses several pharmacological effects, such as anti­inflammatory and hepatotoxic protective effects. To the best of our knowledge, however, its effects on osteoporosis and osteoclasts have not been demonstrated previously. In the present study, the anti­osteoporotic effect of SL was investigated using a postmenopausal model of osteoporosis in which Sprague­Dawley rat ovaries were extracted. In addition, the inhibitory effects on osteoclast differentiation and function of SL was confirmed using an osteoclast model treated with receptor activator of NF­κB ligand (RANKL) on murine RAW 264.7 macrophages. In vivo experiments showed that SL reduced the decrease in bone mineral density and improved changes in the morphological index of bone microstructure, such as trabecular number and separation. In addition, the number of tartrate resistant acid phosphatase­positive cells in the femur and the expression levels of nuclear factor of activated T­cells cytoplasmic 1 (NFATc1) and cathepsin K protein were inhibited. In vitro, SL suppressed RANKL­induced osteoclast differentiation and bone resorption ability; this was mediated by NFATc1/c­Fos, a key transcription factor involved in osteoclast differentiation, ultimately inhibiting expression of various osteoclast­associated genes. These experimental results show that SL may be an alternative treatment for osteoporosis caused by abnormal activation of osteoclasts in the future.

Ethanol Extract of Amomum tsao-ko Ameliorates Ovariectomy-Induced Trabecular Loss and Fat Accumulation.

In Asia, Amomum tsao-ko has long been used as a spice or seasoning in food to stimulate digestion. In the present study, we evaluated the effects of ethanol extract of Amomum tsao-ko (EEAT) on menopausal osteoporosis and obesity. After the administration of EEAT in ovariectomy (OVX) mice models for five weeks, microcomputed tomography and a histological analysis were performed to assess, respectively, the trabecular structure and the fat accumulation in adipose, liver, and bone tissues. We also examined the effects of EEAT on a bone marrow macrophage model of osteoclastogenesis by in vitro stimulation from the receptor activator of nuclear factor-kappa Β ligand (RANKL) through real-time PCR and Western blot analysis. In addition, ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) with authentic standards was applied to characterize the phytochemical profiling of EEAT. We found that EEAT significantly decreased OVX-induced body weight gain and fat accumulation, significantly prevented OVX-induced deterioration of bone mineral density and microstructure of trabecular tissues, and significantly inhibited osteoclast differentiation by downregulating NF-κB/Fos/NFATc1 signaling in osteoclasts. Furthermore, UHPLC-MS/MS identified eight beneficial phytochemicals in EEAT. Collectively, these results suggest that EEAT might be an effective nutraceutical candidate to attenuate menopausal osteoporosis by inhibiting osteoclastogenesis and to prevent obesity by suppressing fat accumulation.

Therapeutic potential of russelioside B as anti-arthritic agent in Freund's adjuvant-induced arthritis in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Caralluma species are traditional edible herbs used in folkloric medicine as antidiabetic, antioxidant, antipyretic, antirheumatic, anti-inflammatory and anthelmintic agents. C. quadrangula was selected in this study to document the traditional use of the genus as anti-rheumatic treatment and the possible mechanisms of action. AIM OF THE STUDY: The higher mortality rates and shorter survival among the patients suffering from rheumatoid arthritis (RA) led to the increased interest on searching for new treatments for RA. Russelioside B (RB), a major pregnane glycoside found in C. quadrangula, was evaluated as a new anti-rheumatic agent. MATERIALS AND METHODS: The n-butanol fraction of C. quadrangula was chromatographed on a silica gel column to isolate RB. The adjuvant-induced arthritis (AIA) model was established in rats by intradermal injection of complete Freund's adjuvant (CFA) to evaluate its anti-arthritic effect. Ibuprofen was used as a reference drug. Forty rats were randomly divided into 5 groups (n = 8): normal (NOR); CFA model (CFA); ibuprofen, 5 mg/kg; RB, 25 mg/kg and RB, 50 mg/kg. The treatments were initiated from day 16 when AIA model was established and continued up to day 40. Serum diagnostic rheumatoid markers, inflammatory cytokines, oxidative stress biomarkers, cartilage and bone degeneration enzymes were assessed. RESULTS: RB at 50 mg/kg b. wt., showed significant decreases in the activities of hyaluronidase and ß-glucouronidase enzymes as well significant decreases in the levels of proinflammatory cytokines as nuclear factor-kappa-B (NF-κB), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) compared to the CFA group; 11.04 ± 0.61 pg/mg protein, 4.35 ± 0.25 pg/mg protein, 3.32 ± 0.13 pg/mg protein & 2.75 ± 0.14 pg/mg protein for RB, 50 mg/kg b. wt. group vs. 25.33 ± 2.13 pg/mg protein, 25.65 ± 2.1 pg/mg protein, 22.20 ± 1.34 pg/mg protein & 13.27 ± 1.40 pg/mg protein for the arthritic group, respectively. The total antioxidant capacity (TAC) was significantly restored to normal values in RB, 50 mg/kg treated rats (4.01 ± 0.09 nmol/mL vs. 3.71 ± 0.27 nmol/mL) and the levels of myeloperoxidase (MPO) reduced by 10-folds of the CFA arthritic group. Bone histomorphometry revealed that RB treatment significantly attenuated the CFA-induced bone loss in a dose-dependent manner. CONCLUSIONS: These findings suggested that the anti-arthritic effect of RB was mediated through the reduction of the rheumatoid markers, anti-inflammatory and antioxidant action, inhibition of cartilage and bone degenerative enzymes as well as attenuation of bone loss and osteoclastogenesis.

Water Extract of Fritillariae thunbergii Bulbus Inhibits RANKL-Mediated Osteoclastogenesis and Ovariectomy-Induced Trabecular Bone Loss.

Fritillariae thunbergii bulbus has been widely used to treat symptoms of coughs and airway congestion in the chest due to pathological colds and damp phlegm in traditional Chinese medicine. Despite its long history of traditional use, its pharmacological activities on osteoclastogenesis and osteoporosis have not been evaluated. This study investigated the effects of the water extract of Fritillariae thunbergii bulbus (WEFT) on osteoclast differentiation in bone marrow-derived macrophage cells and on ovariectomy (OVX)-induced osteoporosis in mice. We found that WEFT significantly inhibited osteoclastogenesis by downregulating the receptor activator of the NF-κB ligand (RANKL) signaling-induced nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) expression. In an OVX-induced osteoporosis model, WEFT significantly prevented the OVX-induced trabecular loss of femurs, accompanied by a reduction in fat accumulation in the bone marrow and liver. In addition, WEFT significantly prevented weight gain and gonadal fat gain without recovering uterine atrophy. Using ultrahigh-performance liquid chromatography-tandem mass spectrometry, seven alkaloids (peimisine glucoside, yibeissine, peiminoside, sipeimine-glucoside, peimisine, peimine, and peiminine) were identified in WEFT. The results of this study suggest that WEFT can be a potential pharmacological candidate to reduce menopausal osteoporosis and menopause-related symptoms, such as fat accumulation.

Both NPY-Expressing and CART-Expressing Neurons Increase Energy Expenditure and Trabecular Bone Mass in Response to AP1 Antagonism, But Have Opposite Effects on Bone Resorption.

Energy metabolism and bone homeostasis share several neuronal regulatory pathways. Within the ventral hypothalamus (VHT), the orexigenic neurons co-express Agouti-related peptide (AgRP) and neuropeptide Y (NPY) and the anorexigenic neurons co-express, α-melanocyte stimulating hormone derived from proopiomelanocortin (POMC), and cocaine and amphetamine-regulated transcript (CART). These neurons regulate both processes, yet their relative contribution is unknown. Previously, using genetically targeted activator protein (AP1) alterations as a tool, we showed in adult mice that AgRP or POMC neurons are capable of inducing whole-body energy catabolism and bone accrual, with different effects on bone resorption. Here, we investigated whether co-residing neurons exert similar regulatory effects. We show that AP1 antagonists targeted to NPY-producing or CART-producing neurons in adult mice stimulate energy expenditure, reduce body weight gain and adiposity and promote trabecular bone formation and mass, yet again via different effects on bone resorption, as measured by serum level of carboxy-terminal collagen type I crosslinks (CTX). In addition, AP1 antagonists promote neurite expansion, increasing neurite number, length, and surface area in primary hypothalamic neuronal cultures. Overall, our data demonstrate that the orexigenic NPY and anorexigenic CART neurons both have the capacity to stimulate energy burning state and increase bone mass. © 2020 American Society for Bone and Mineral Research.

Melatonin prevents bone destruction in mice with retinoic acid-induced osteoporosis.

BACKGROUND: The protective effect of melatonin against bone metabolism imbalance in osteoporosis (OP) induced by drugs such as retinoic acid (RA) is unclear. The aim of this study was to explore the role of melatonin in bone destruction based on a mouse model. METHODS: RA-induced OP model mice were established. To assess the effect of melatonin on these mice, micro-CT was used to characterize the trabecular structure of normal mice and those treated with RA (model), RA + low-dose melatonin (Mlt-L), RA + high-dose melatonin (Mlt-H), and RA + alendronate sodium (positive control). The shape of the trabecular bone, the length and diameter of the femoral head and the height and diameter of vertebra(L1) of each group were also measured and the number of osteoclasts was determined by Tartrate-resistant acid phosphatase (TRACP) staining. Meanwhile, the expression of alkaline phosphatase (ALP) was evaluated by immunohistochemistry assays. The differences between groups in terms of liver and kidney oxidation-related indexes and serum and urinary indicators related to bone metabolism were also analyzed. Furthermore, qRT-PCR and western blotting were used to evaluate the effect of melatonin on osteogenic and osteoclastic differentiation in MC3T3-E1 and RAW264.7 cells, respectively. RESULTS: RA induction led to a decrease in the amount and density of trabecular bone, a decrease in the length and diameter of the femur and height, diameter of the vertebra (L1), a decrease in bone mass and density and the expression of ALP, and an increase in the number of osteoclasts. Melatonin treatment alleviated these effects induced by RA, increasing the amount of trabecular bone in OP mice, improving the microstructure of the femur and vertebra(L1) and increasing bone mass bone density and the expression of ALP, as well as decreasing the number of osteoclasts. Additionally, blood and urinary bone metabolism-related indicators showed that melatonin promoted bone formation and inhibited bone resorption. Determination of oxidant and antioxidant biomarkers in the livers and kidneys of the mice revealed that melatonin promoted the antioxidant level and suppressed the level of oxidant molecules in these organs. In vitro, RA promoted osteoclasts and inhibit osteogenesis by increasing oxidative stress levels in the RAW264.7 and MC3T3-E1 cells, but melatonin reversed this effect. Melatonin may, therefore, play a role in the ERK/SMAD and NF-κB pathways. CONCLUSIONS: Melatonin can alleviate bone loss in RA-induced OP model mice, repair the trabecular microstructure, and promote bone formation. These effects may be related to reducing oxidation levels in vivo and vitro through the ERK/SMAD and NF-κB pathways.

Metabolic and skeletal homeostasis are maintained in full locus GPRC6A knockout mice.

The G protein-coupled receptor class C, group 6, subtype A (GPRC6A) is suggested to have a physiological function in glucose and bone metabolism, although the precise role lacks consensus due to varying findings in different knockout (KO) mouse models and inconsistent findings on the role of osteocalcin, a proposed GPRC6A agonist. We have further characterized a full locus GPRC6A KO model with respect to energy metabolism, including a long-term high-dose glucocorticoid metabolic challenge. Additionally, we analyzed the microarchitecture of tibiae from young, middle-aged and aged GPRC6A KO mice and wildtype (WT) littermates. Compared to WT, vehicle-treated KO mice presented with normal body composition, unaltered insulin sensitivity and basal serum insulin and glucose levels. Corticosterone (CS) treatment resulted in insulin resistance, abnormal fat accrual, loss of lean mass and suppression of serum osteocalcin levels in both genotypes. Interestingly, serum osteocalcin and skeletal osteocalcin mRNA levels were significantly lower in vehicle-treated GPRC6A KO mice compared to WT animals. However, WT and KO age groups did not differ in long bone mass and structure assessed by micro-computed tomography. We conclude that GPRC6A is not involved in glucose metabolism under normal physiological conditions, nor does it mediate glucocorticoid-induced dysmetabolism in mice. Moreover, GPRC6A does not appear to possess a direct, non-compensable role in long bone microarchitecture under standard conditions.

Protective Effects of Ligustroflavone, an Active Compound from Ligustrum lucidum, on Diabetes-Induced Osteoporosis in Mice: A Potential Candidate as Calcium-Sensing Receptor Antagonist.

Ligustroflavone is one major compound contained in active fraction from Fructus Ligustri Lucidi (the fruit of Ligustrum lucidum), which could regulate parathyroid hormone (PTH) levels and improve calcium balance by acting on calcium-sensing receptors (CaSR). This study aimed to explore the potency of ligustroflavone as a CaSR antagonist and its protective effects against diabetic osteoporosis in mice. LF interacted well with the allosteric site of CaSR shown by molecular docking analysis, increased PTH release of primary parathyroid gland cells and suppressed extracellular calcium influx in HEK-293 cells. The serum level of PTH attained peak value at 2 h and maintained high during the period of 1 h and 3 h than that before treatment in mice after a single dose of LF. Treatment of diabetic mice with LF inhibited the decrease in calcium level of serum and bone and the enhancement in urinary calcium excretion as well as elevated circulating PTH levels. Trabecular bone mineral density and micro-architecture were markedly improved in diabetic mice upon to LF treatment for 8 weeks. LF reduced CaSR mRNA and protein expression in the kidneys of diabetic mice. Taken together, ligustroflavone could transiently increase PTH level and regulate calcium metabolism as well as prevent osteoporosis in diabetic mice, suggesting that ligustroflavone might be an effective antagonist on CaSR.

Interaction among Calcium Diet Content, PTH (1-34) Treatment and Balance of Bone Homeostasis in Rat Model: The Trabecular Bone as Keystone.

The present study is the second step (concerning normal diet restoration) of the our previous study (concerning the calcium-free diet) to determine whether normal diet restoration, with/without concomitant PTH (1-34) administration, can influence amounts and deposition sites of the total bone mass. Histomorphometric evaluations and immunohistochemical analysis for Sclerostin expression were conducted on the vertebral bodies and femurs in the rat model. The final goals are (i) to define timing and manners of bone mass changes when calcium is restored to the diet, (ii) to analyze the different involvement of the two bony architectures having different metabolism (i.e., trabecular versus cortical bone), and (iii) to verify the eventual role of PTH (1-34) administration. Results evidenced the greater involvement of the trabecular bone with respect to the cortical bone, in response to different levels of calcium content in the diet, and the effect of PTH, mostly in the recovery of trabecular bony architecture. The main findings emerged from the present study are (i) the importance of the interplay between mineral homeostasis and skeletal homeostasis in modulating and guiding bone's response to dietary/metabolic alterations and (ii) the evidence that the more involved bony architecture is the trabecular bone, the most susceptible to the dynamical balance of the two homeostases.

Intermittent PTH treatment improves bone and muscle in glucocorticoid treated Mdx mice: A model of Duchenne Muscular Dystrophy.

Duchenne Muscular Dystrophy (DMD) is a progressive muscle disorder caused by genetic mutations of the dystrophin encoding gene. In the absence of functional dystrophin, DMD patients suffer from muscle inflammation and wasting, as well as compromised bone health with increased risk of fracture. The use of high dose glucocorticoids (GC) as the standard therapy also contributes to bone fragility. This study examined the effects of intermittent, daily administered parathyroid hormone (iPTH), an approved bone anabolic therapy, on growing bone and dystrophic muscle in the presence and absence of prednisone treatment using the Mdx mouse model of DMD. Five-weeks of prednisone treatment in Mdx mice decreased cortical bone thickness and area (p < 0.001), with a large increase in endocortical osteoclasts that were significantly improved by PTH treatment (p < 0.001). GC-induced decreases in cortical bone toughness and modulus were improved with iPTH therapy (p < 0.05). Mdx mice showed significantly less bone mass in trabecular compartments of lumbar vertebrae and iPTH treatment, with or without glucocorticoids, significantly improved structural and material properties of this bone. Prednisone improved grip strength and endurance of treadmill running, which were maintained and further improved, respectively, in co-treated Mdx mice. Altogether, our study demonstrates that iPTH therapy significantly ameliorated GC-induced bone loss and maintained or further enhanced the positive effects of GCs on dystrophic muscle function. These findings give insight into the potential for use of teriparatide to treat growing bone in children with DMD.

Metabolomics profiling provides valuable insights into the underlying mechanisms of Morinda officinalis on protecting glucocorticoid-induced osteoporosis.

Morinda officinalis (MO) has long been used as a traditional herbal medicine for the treatment of bone fractures and joint diseases in China. Monotropein (Mon) and rubiadin-1-methyl ether (Rub) are major bioactive components in MO. Ample evidence shows that MO and its chemical constituents can prevent osteoporosis induced by estrogen-deficiency and ageing. However, there is no study reporting glucocorticoid-induced osteoporosis (GIOP). The aim of the present study was to explore the protective effect of MO on GIOP modeled rats and osteoblasts, and elucidate the underlying mechanisms via UHPLC-Q-TOF/MS based metabolomics profiling. Eight weeks after dexamethasone (DEX) injection and MO treatment in female SD rats aged 12 weeks, bone mineral density (BMD), the micro-architecture of the trabecular bone, serum level of bone metabolism markers, and urine metabolomics were assayed in vivo. Cultured osteoblasts were injured with DEX, and the effects of MO, Mon and Rub on osteoblastic proliferation, differentiation and mineralization were examined in vitro. The results showed that MO was able to increase BMD, improve the micro-architecture and intervene bone metabolism via regulating alkaline phosphatase (ALP), tartrate resistant acid phosphatase (TRAP) and c-terminal telopeptides of type I collagen (CTX-I) levels in DEX-treated rats. The in vitro experiment showed that MO, Mon and Rub all increased the cell proliferation and ALP activity, and enhanced extracellular matrix mineralization in DEX-injured osteoblasts. Metabolomics profiling identified a total of 37 differential metabolites in DEX group vs. the control group, of which 20 were reversed significantly after MO treatment. Further metabolic pathway enrichment and Western blotting analysis showed that MO prevented bone loss mainly by interfering with arachidonic acid metabolism. These results suggested MO had a notable anti-GIOP effect, and the underlying mechanisms might be related to arachidonic acid metabolism.

Central adiponectin induces trabecular bone mass partly through epigenetic downregulation of cannabinoid receptor CB1.

Central adiponectin (APN) in either the globular (gAPN) or full-length forms decreases sympathetic tone and increases trabecular bone mass in mice through the hypothalamus. It is known that cannabinoid type-1 (CB1) receptors are expressed in the hypothalamic ventromedial nucleus and participate in energy metabolism by controlling sympathetic activity. However, whether central APN could influence endocannabinoid signaling through CB1 receptor to regulate bone metabolism has not been characterized. Here we demonstrate that gAPN downregulated CB1 expression in embryonic mouse hypothalamus N1 cells in vitro. gAPN intracerebroventricular (icv) infusions also decreased hypothalamic CB1 expression and bone formation parameters in APN-knockout (APN-KO) and wild-type mice. Most importantly, mice pretreated with icv infusions with the CB1 receptor agonist arachidonyl-2'-chloroethylamine or antagonist rimonabant attenuated or enhanced respectively central APN induction of bone formation. We then investigated whether epigenetic signaling mechanisms were involved in the downregulation of hypothalamic CB1 expression by gAPN. We found gAPN enhanced expression levels of various histone deacetylases (HDACs), especially HDAC5. Furthermore, chromatin immunoprecipitation assays revealed HDAC5 bound to the transcriptional start site transcription start site 2 region of the CB1 promoter. In summary, our study identified a possible novel central APN-HDAC5-CB1 signaling mechanism that promotes peripheral bone formation through epigenetic regulation of hypothalamic CB1 expression.

Blackcurrant Supplementation Improves Trabecular Bone Mass in Young but Not Aged Mice.

Due to deleterious side effects of currently available medications, the search for novel, safe, and effective preventive agents for improving bone health in aging continues and is urgently needed. This study aimed to determine whether dietary blackcurrants (BC), an anthocyanin-rich berry, can improve bone mass in a mouse model of age-related bone loss. Thirty-five female C57BL/6J mice, 3 months old (n = 20) and 18 months old (n = 15), were randomized to consume either a standard chow diet or a standard chow diet with 1% (w/w) BC for four months. Dual-energy X-ray absorptiometry, Micro computed tomography (µCT), and histomorphometric analyses were conducted to assess bone parameters on femurs. Biochemical assays were conducted to determine bone resorption, antioxidant activity, and inflammation in humerus homogenates. Trabecular bone volume (BV/TV) was significantly lower in aged mice compared to young mice (young control, 3.7 ± 0.4% vs aged control, 1.5 ± 0.5%, mean ± SEM (standard error of mean), p < 0.01; young BC, 5.3 ± 0.6% vs aged BC, 1.1 ± 0.3%, p < 0.001). µCT analysis revealed that BC supplementation increased trabecular BV/TV in young mice by 43.2% (p < 0.05) compared to controls. Histomorphometric analysis revealed a 50% increase, though this effect was not statistically significant (p = 0.07). The osteoblast surface increased by 82.5% in aged mice with BC compared to controls (p < 0.01). In humerus homogenates of young mice, BC consumption reduced C-telopeptide of type I collagen by 12.4% (p < 0.05) and increased glutathione peroxidase by 96.4% (p < 0.05). In humerus homogenates of aged mice, BC consumption increased catalase by 12% (p = 0.09). Aged mice had significantly elevated concentrations of tumor necrosis factor α (TNF-α), a pro-inflammatory cytokine contributing to bone resorption, which was reduced by 43.3% with BC consumption (p = 0.06). These results suggest that early consumption of BC may protect from aging-associated bone loss.

Beneficial impact of zinc supplementation on the collagen in the bone tissue of cadmium-exposed rats.

Cadmium (Cd) is a toxic metal that damages bone tissue by affecting its mineral and organic components. The organic matrix is mainly (90%) composed of collagen, which determines the biomechanical strength of bone. The aim of this study was to evaluate the effect of zinc (Zn) supplementation (30 or 60 mg l-1 ) under moderate and relatively high exposure to Cd (5 and 50 mg l-1 ) on collagen in the rat tibia proximal epiphysis and diaphysis (regions abundant in trabecular and cortical bone, respectively). Significant decrease in collagen type I biosynthesis was found in both regions of the tibia in Cd-treated rats, whereas the supplementation with Zn provided significant protection against this effect. Western blot confirmed the presence of the major type I collagen in the tibia epiphysis and diaphysis, but collagen type II was revealed only in the epiphysis. Acetic acid- and pepsin-soluble collagen concentration in the tibia epiphysis and diaphysis was significantly increased due to the exposure to Cd, whereas the supplementation with Zn protected, partially or totally, from these effects, depending on the used concentration. The supplementation with Zn also provided protection from unfavorable Cd impact on the maturation of the bone collagen, as the ratio of cross-links to monomers was higher compared to the Cd-treated group. This report confirms our previous findings on the preventive action of Zn against harmful effects of Cd on bone, but additionally, and to the best of our knowledge for the first time, explains the possible mechanism of the beneficial influence of this bioelement.

Strontium ranelate stimulates trabecular bone formation in a rat tibial bone defect healing process.

Strontium ranelate treatment is known to prevent fractures. Here, we showed that strontium ranelate treatment enhances bone healing and affects bone cellular activities differently in intact and healing bone compartments: Bone formation was increased only in healing compartment, while resorption was reduced in healing and normal bone compartments. INTRODUCTION: Systemic administration of strontium ranelate (SrRan) accelerates the healing of bone defects; however, controversy about its action on bone formation remains. We hypothesize that SrRan could affect bone formation differently in normal mature bone or in the bone healing process. METHODS: Proximal tibia bone defects were created in 6-month-old female rats, which orally received SrRan (625 mg/kg/day, 5/7 days) or vehicle (control groups) for 4, 8, or 12 weeks. Bone samples were analyzed by micro-computed tomography and histomorphometry in various regions, i.e., metaphyseal 2nd spongiosa, a region close to the defect, within the healing defect and in cortical defect bridging region. Additionally, we evaluated the quality of the new bone formed by quantitative backscattered electron imaging and by red picosirius histology. RESULTS: Healing of the bone defect was characterized by a rapid onset of bone formation without cartilage formation. Cortical defect bridging was detected earlier compared with healing of trabecular defect. In the healing zone, SrRan stimulated bone formation early and laterly decreased bone resorption improving the healing of the cortical and trabecular compartment without deleterious effects on bone quality. By contrast, in the metaphyseal compartment, SrRan only decreased bone resorption from week 8 without any change in bone formation, leading to little progressive increase of the metaphyseal trabecular bone volume. CONCLUSIONS: SrRan affects bone formation differently in normal mature bone or in the bone healing process. Despite this selective action, this led to similar increased bone volume in both compartments without deleterious effects on the newly bone-formed quality.

Estradiol-loaded PLGA nanoparticles for improving low bone mineral density of cancellous bone caused by osteoporosis: Application of enhanced charged nanoparticles with iontophoresis.

Postmenopausal osteoporosis among older women, which occurs by an ovarian hormone deficiency, is one of the major public health problems. 17 ß-estradiol (E2) is used to prevent and treat this disease as a drug of hormone replacement therapy. In oral administration, E2 is significantly affected by first-pass hepatic metabolism, and high dose administration must be needed to obtain drug efficacy. Therefore, alternative administration route is needed, and we have focused on the transdermal drug delivery system. In this study, we have prepared E2-loaded poly(DL-lactide-co-glycolide) (PLGA) nanoparticles for osteoporosis by using a combination of an antisolvent diffusion method with preferential solvation. The average particle diameter of the nanoparticles was 110.0±41.0nm and the surface charge number density was 82 times higher than that of conventional E2-loaded PLGA nanoparticles. Therapeutic evaluation of E2-loaded PLGA nanoparticles was carried out using ovariectomized female rats. Therapeutic efficacy was evaluated to measure bone mineral density of cancellous bone using an X-ray CT system. When the E2-loaded PLGA nanoparticles were administrated once a week, bone mineral density was significantly higher than that of the non-treated group at 60days after the start of treatment. Also, in the group administered this nanoparticle twice a week, the bone mineral density increased significantly at 45days after the start of treatment. From these results, it was revealed that E2-loaded PLGA nanoparticles with iontophoresis were useful to recover bone mineral density of cancellous bone, and it was also suggested that they extend the dosing interval of E2.

Increasing dietary nitrate has no effect on cancellous bone loss or fecal microbiome in ovariectomized rats.

SCOPE: Studies suggest diets rich in fruit and vegetables reduce bone loss, although the specific compounds responsible are unknown. Substrates for endogenous nitric oxide (NO) production, including organic nitrates and dietary nitrate, may support NO production in age-related conditions, including osteoporosis. We investigated the capability of dietary nitrate to improve NO bioavailability, reduce bone turnover and loss. METHODS AND RESULTS: Six-month-old Sprague Dawley rats [30 ovariectomized (OVX) and 10 sham-operated (sham)] were randomized into three groups: (i) vehicle (water) control, (ii) low-dose nitrate (LDN, 0.1 mmol nitrate/kg bw/day), or (iii) high-dose nitrate (HDN, 1.0 mmol nitrate/kg bw/day) for three weeks. The sham received vehicle. Serum bone turnover markers; bone mass, mineral density, and quality; histomorphometric parameters; and fecal microbiome were examined. Three weeks of LDN or HDN improved NO bioavailability in a dose-dependent manner. OVX resulted in cancellous bone loss, increased bone turnover, and fecal microbiome changes. OVX increased relative abundances of Firmicutes and decreased Bacteroideceae and Alcaligenaceae. Nitrate did not affect the skeleton or fecal microbiome. CONCLUSION: These data indicate that OVX affects the fecal microbiome and that the gut microbiome is associated with bone mass. Three weeks of nitrate supplementation does not slow bone loss or alter the fecal microbiome in OVX.