Peripheral serotonin-mediated system suppresses bone development and regeneration via serotonin 6 G-protein-coupled receptor

Induced pluripotent stem cell-derived neural stem cells promote bone formation in mice with calvarial defects

Nerve-derived factors have attracted attention in bone regeneration therapy due to their ability to promote bone regeneration and nerve innervation. Mesenchymal stem cells transported to target sites promote osteogenesis. However, there are few reports on the effects of neural stem cells on bone regeneration. Therefore, the aim of this study was to investigate the role of neural stem cells in osteogenesis. Here, embryoid bodies (EB) or primary neurospheres (1NS) were generated using mouse induced pluripotent stem cells (iPS cells), which were then seeded onto gelatin (Gel) sponges. The seeded Gel sponges were then transplanted into mouse calvarial bone defects. We noted that 1NS-seeded Gel promoted bone regeneration and the presence of tartrate-resistant acid phosphatase (TRAP)-positive cells, whereas the EB-seeded Gel did not. RNA-sequencing of the 1NS-seeded and EB seeded Gels showed an upregulation of the transforming growth factor (TGF)-β signaling pathway in the 1NS-seeded Gel group. Immunostaining confirmed the presence of Id3 positive cells in mice with bone defects treated with the 1NS-seeded Gel. These findings suggest that the transplantation of neural stem cells may contribute to the promotion of bone regeneration. STATEMENT OF SIGNIFICANCE: This study aimed to investigate whether neural stem cells, when seeded in Gel sponges, promoted bone regeneration. It has been well documented that bone is tightly linked with the nervous systems. Bioscaffolds comprising factors that promote innervation and bone regeneration have been investigated for use in bone therapy. However, there is limited research on the use of neural stem cells for promoting bone formation. To assess this relationship, we conducted both in vivo and in vitro assays to determine whether neural stem cells promoted bone formation. We noted that 1NS-seeded Gel sponges promoted bone formation significantly in mice with calvarial defects after 4 weeks. This study provides a novel approach of neural stem cells for bone therapy.

Neuro-bone tissue engineering: emerging mechanisms, potential strategies, and current challenges

The skeleton is a highly innervated organ in which nerve fibers interact with various skeletal cells. Peripheral nerve endings release neurogenic factors and sense skeletal signals, which mediate bone metabolism and skeletal pain. In recent years, bone tissue engineering has increasingly focused on the effects of the nervous system on bone regeneration. Simultaneous regeneration of bone and nerves through the use of materials or by the enhancement of endogenous neurogenic repair signals has been proven to promote functional bone regeneration. Additionally, emerging information on the mechanisms of skeletal interoception and the central nervous system regulation of bone homeostasis provide an opportunity for advancing biomaterials. However, comprehensive reviews of this topic are lacking. Therefore, this review provides an overview of the relationship between nerves and bone regeneration, focusing on tissue engineering applications. We discuss novel regulatory mechanisms and explore innovative approaches based on nerve-bone interactions for bone regeneration. Finally, the challenges and future prospects of this field are briefly discussed.

Antipsychotic-induced bone loss: the role of dopamine, serotonin and adrenergic receptor signalling

Antipsychotics are commonly used in treating psychiatric disorders. These medications primarily target dopamine the serotonin receptors, they have some affinity to adrenergic, histamine, glutamate and muscarinic receptors. There is clinical evidence that antipsychotic use decreases BMD and increases fracture risk, with dopamine, serotonin and adrenergic receptor-signalling becoming an increasing area of focus where the presence of these receptors in osteoclasts and osteoblasts have been demonstrated. Osteoclasts and osteoblasts are the most important cells in the bone remodelling and the bone regeneration process where the activity of these cells determine the bone resorption and formation process in order to maintain healthy bone. However, an imbalance in osteoclast and osteoblast activity can lead to decreased BMD and increased fracture risk, which is also believed to be exacerbated by antipsychotics use. Therefore, the aim of this review is to provide an overview of the mechanisms of action of first, second and third generation antipsychotics and the expression profiles of dopamine, serotonin and adrenergic receptors during osteoclastogenesis and osteoblastogenesis.

Suffruticosol B Is an Osteogenic Inducer through Osteoblast Differentiation, Autophagy, Adhesion, and Migration

Suffruticosol B (Suf-B) is a stilbene found in Paeonia suffruticosa ANDR., which has been traditionally used in medicine. Stilbenes and their derivatives possess various pharmacological effects, such as anticancer, anti-inflammatory, and anti-osteoporotic activities. This study aimed to explore the bone-forming activities and mechanisms of Suf-B in pre-osteoblasts. Herein, >99.9% pure Suf-B was isolated from P. suffruticosa methanolic extracts. High concentrations of Suf-B were cytotoxic, whereas low concentrations did not affect cytotoxicity in pre-osteoblasts. Under zero levels of cytotoxicity, Suf-B exhibited bone-forming abilities by enhancing alkaline phosphatase enzyme activities, bone matrix calcification, and expression levels with non-collagenous proteins. Suf-B induces intracellular signal transduction, leading to nuclear RUNX2 expression. Suf-B-stimulated differentiation showed increases in autophagy proteins and autophagosomes, as well as enhancement of osteoblast adhesion and transmigration on the ECM. These results indicate that Suf-B has osteogenic qualities related to differentiation, autophagy, adhesion, and migration. This also suggests that Suf-B could have a therapeutic effect as a phytomedicine in skeletal disorders.

Gut bacterial aromatic amine production: aromatic amino acid decarboxylase and its effects on peripheral serotonin production

Colonic luminal aromatic amines have been historically considered to be derived from dietary source, especially fermented foods; however, recent studies indicate that the gut microbiota serves as an alternative source of these amines. Herein, we show that five prominent genera of Firmicutes (Blautia, Clostridium, Enterococcus, Ruminococcus, and Tyzzerella) have the ability to abundantly produce aromatic amines through the action of aromatic amino acid decarboxylase (AADC). In vitro cultivation of human fecal samples revealed that a significant positive correlation between aadc copy number of Ruminococcus gnavus and phenylethylamine (PEA) production. Furthermore, using genetically engineered Enterococcus faecalis-colonized BALB/cCrSlc mouse model, we showed that the gut bacterial aadc stimulates the production of colonic serotonin, which is reportedly involved in osteoporosis and irritable bowel syndrome. Finally, we showed that human AADC inhibitors carbidopa and benserazide inhibit PEA production in En. faecalis.

Chi3L1 is a therapeutic target in bone metabolism and a potential clinical marker in patients with osteoporosis

BMP2 is clinically used as an ectopic bone inducer and plays a significant role in bone development, formation, and diseases. Chitinase 3-like 1 protein (Chi3L1) is found in the skeletal system. However, Chi3L1-mediated bone metabolism and aging-related bone erosion via BMP2 signaling have not yet been demonstrated. Herein, Chi3L1 increased BMP2-induced osteoblast differentiation in mesenchymal precursor cells and human primary osteoblasts. Chi3L1^KO(-/-) showed abnormal bone development, and primary osteoblasts isolated from Chi3L1^KO(-/-) exhibited impaired osteoblast differentiation and maturation. Chi3L1 also potentiated BMP2 signaling and RUNX2 expression in primary osteoblasts. Chi3L1 interacted with BMPRIa, which increased the surface expression of BMPRIa and promoted BMP2 signaling to induce osteoblast differentiation. Chi3L1^KO(-/-) mice showed bone formation reduced with a decrease in RUNX2 expression in calvarial defects. Chi3L1^KO(-/-) mice exhibited aging-related osteoporotic bone loss with decreases in the levels of RUNX2 and OPG, while serum PYD level and osteoclast number increased. Chi3L1 increased OPG via non-canonical BMP2 signaling in osteoblasts, which suppressed osteoclastogenesis in BMMs. Furthermore, ROC analysis showed that serum Chi3L1 level clinically decreased in osteoporosis patients. Our findings demonstrate that Chi3L1 promotes bone formation, suppresses osteoclastogenesis, and prevents aging-related osteoporosis.

Effects of Triterpene Soyasapogenol B from Arachis hypogaea (Peanut) on Differentiation, Mineralization, Autophagy, and Necroptosis in Pre-Osteoblasts

Triterpenes are a diverse group of natural compounds found in plants. Soyasapogenol B (SoyB) from Arachis hypogaea (peanut) has various pharmacological properties. This study aimed to elucidate the pharmacological properties and mechanisms of SoyB in bone-forming cells. In the present study, 1–20 μM of SoyB showed no cell proliferation effects, whereas 30–100 μM of SoyB increased cell proliferation in MC3T3-E1 cells. Next, osteoblast differentiation was analyzed, and it was found that SoyB enhanced ALP staining and activity and bone mineralization. SoyB also induced RUNX2 expression in the nucleus with the increased phosphorylation of Smad1/5/8 and JNK2 during osteoblast differentiation. In addition, SoyB-mediated osteoblast differentiation was not associated with autophagy and necroptosis. Furthermore, SoyB increased the rate of cell migration and adhesion with the upregulation of MMP13 levels during osteoblast differentiation. The findings of this study provide new evidence that SoyB possesses biological effects in bone-forming cells and suggest a potentially beneficial role for peanut-based foods.

Dynamic transcriptome analysis of the muscles in high-fat diet-induced obese zebrafish (Danio rerio) under 5-HT treatment

Peripheral 5-hydroxytryptamine (5-HT, also called serotonin) is reportedly a potential therapeutic target in obesity-related metabolic diseases due to its regulatory role in energy homeostasis in mammals. However, information on the detailed effect of peripheral 5-HT on the energy metabolism in fishes, especially the lipid metabolism, and the underlying mechanism remains elusive. In this study, a diet-induced obesity model was developed in the zebrafish (Danio rerio), a prototypical animal model for metabolic disorders. The zebrafish were fed a high-fat diet for 8 weeks and were simultaneously injected with PBS, 0.1 mM and 10 mM 5-HT, intraperitoneally. The body weight was significantly lower in the zebrafish injected with 0.1 mM 5-HT (P < 0.05), however, there was no change in body length (P > 0.05) at the end of the 8-week treatment. The muscle tissues from the zebrafish treated with PBS and 5-HT were collected for transcriptomic analysis and the RNA-seq revealed 1134, 3713, and 2535 genes were screened out compared to the muscular DEGs among three groups. The enrichment analysis revealed DEGs to be significantly associated with multiple metabolic pathways, including ribosome, oxidative phosphorylation, proteasome, PPAR signaling pathway, and ferroptosis. Additionally, the qRT-PCR validated 12 DEGs out of which 10 genes exhibited consistent trends. Taken together, this data provided useful information on the transcriptional characteristics of the muscle tissue in the obese zebrafish exposed to 5-HT, offering important insights into the regulatory effect of peripheral 5-HT in teleosts, as well as novel approaches for preventing and treating obesity-related metabolic dysfunction.

Nutritional and health factors affecting the bioavailability of calcium: a narrative review

Calcium is responsible for the effectiveness of various processes, and its supply in the diet is necessary for the normal function of the human body. Apart from being an important component of the skeleton, calcium also helps maintain the structure of cell organelles and regulates intracellular and extracellular fluid homeostasis. This review presents the nutritional and health factors that affect the bioavailability of calcium. Physiological conditions and factors such as pregnancy, infancy, menopause, old age, hormones, growth factors associated with calcium metabolism, diseases limiting its absorption, and intestinal microbiota are distinguished among endogenous factors. Although the calcium supply in the body is genetically conditioned and specific to each person, its qualitative and quantitative composition can be modified by external factors. The exogenous factors include dietary modifications with particular nutrients and pharmacological treatment. Adequate calcium levels increase bone protection and prevent osteoporosis, a disease involving low mineral bone mass.

Microstructure and mechanical properties of subchondral bone are negatively regulated by tramadol in osteoarthritis in mice

Objectives: In the treatment of osteoarthritis (OA), tramadol, a common weak opioid, has become popular due to its effectiveness in inhibition of pain. In the present study, we aimed to explore the effect of tramadol on subchondral bone, especially changes in the microstructure and mechanical properties.

Methods: A mouse model of OA was established in the present study by destabilization of the medial meniscus (DMM). A vehicle or drug was administered for 4 weeks. Specimens were harvested and analyzed radiologically and histologically using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), atomic force microscopy (AFM) and histological staining to evaluate the knee joints of mice undergoing different forms of intervention.

Results: In the early stages of OA induced by DMM, the subchondral bone volume fraction in the OA group was significantly higher than in the sham+vehicle (sham+veh) group, while the volume in the treatment groups was lower than in the DMM+vehicle (DMM+veh) and sham+veh groups. In addition, the elastic moduli in the treatment groups clearly decreased compared with the DMM+veh and sham+veh groups. Observations of the subchondral bone surface by SEM indicated serious destruction, principally manifesting as a decrease in lacunae and more numerous and scattered cracks. Histological staining demonstrated that there was no difference in the degeneration of either the articular cartilage or synovial cells whether tramadol was used or not.

Conclusion: Although tramadol is effective in inhibiting pain in early OA, it negatively regulates the microstructure and mechanical properties of subchondral bone in joints.

Effects of the amide alkaloid piperyline on apoptosis, autophagy, and differentiation of pre-osteoblasts

BACKGROUND

Amide alkaloidsare typical constituents in plants of the Piperaceae family. Most of the pharmacological properties of Piper nigrum L. are attributed to the major amide alkaloid, piperine. Piperyline (PIPE) is a further amide alkaloid that has been isolated from P. nigrum.

HYPOTHESIS/PURPOSE

This study was performed to examine the biological effects of PIPE on pre-osteoblasts and elucidate the underlying mechanisms.

STUDY DESIGN

We investigated the effects of PIPE in MC3T3E-1 cells, which are widely used for studying osteoblast behavior in in vitro cell systems.

METHODS

We evaluated cell viability based on the MTT assay, apoptosis by TUNEL staining, adhesion and migration by cell adhesion and migration assays, and osteoblast differentiation by alkaline phosphatase activity and staining. Western blot and immunocytochemical analyses were used to investigate cell signaling pathways.

RESULTS

We found that at concentrations ranging from 1 to 30 μM, PIPE inhibited cell growth and induced apoptosis in pre-osteoblasts, which was accompanied by the upregulation of apoptotic proteins but downregulation of anti-apoptotic proteins. In contrast, PIPE had no appreciable effect on the autophagy pathway. Nevertheless, PIPE reduced cell adhesion and migration via the inactivation of non-receptor tyrosine kinase (Src)/focal adhesion kinase (FAK) and mitogen-activated protein kinases, and also promoted the downregulation of matrix metalloproteinase 2 and 9 levels. Furthermore, at concentrations of 10 and 30 μM, PIPE suppressed osteoblast differentiation, as indicated by reductions in alkaline phosphatase staining and activity. In addition, PIPE reduced the protein levels of phospho-Smad1/5/8 and runt-related transcription factor 2, and the mRNA levels of osteopontin, alkaline phosphatase, and osteocalcin.

CONCLUSION

The findings of this study indicate that PIPE has biological effects associated with cell adhesion, migration, proliferation, and osteoblast differentiation, and suggest a potential role for this alkaloid in the treatment of bone diseases.

A Phytochemical Constituent, (E)-Methyl-Cinnamate Isolated from Alpinia katsumadai Hayata Suppresses Cell Survival, Migration, and Differentiation in Pre-Osteoblasts

BACKGROUND

(E)-methyl-cinnamate (EMC), a phytochemical constituent isolated from Alpinia katsumadai Hayata, is a natural flavor compound with anti-inflammatory properties, which is widely used in the food and commodity industry. However, the pharmacological effects of methyl-cinnamate on pre-osteoblasts remain unknown. This study aimed to investigate the pharmacological effects and mechanisms of EMC in pre-osteoblast MC3T3-E1 cells (pre-osteoblasts).

METHODS

Cell viability and apoptosis were evaluated using the MTT assay and TUNEL staining. Cell migration and osteoblast differentiation were examined using migration assays, as well as alkaline phosphatase activity and staining assays. Western blot analysis was used to examine intracellular signaling pathways and apoptotic proteins.

RESULTS

EMC decreased cell viability with morphological changes and increased apoptosis in pre-osteoblasts. EMC also induced the cleavage of Poly (ADP-ribose) polymerase (PARP) and caspase-3 and reduced the expression of anti-apoptotic proteins. In addition, EMC increased TUNEL-positive cells in pre-osteoblasts, decreased the activation of mitogen-activated protein kinases, and suppressed cell migration rate in pre-osteoblasts. Subsequently, EMC inhibited the osteoblast differentiation of pre-osteoblasts, as assessed by alkaline phosphatase staining and activity assays.

CONCLUSION

These findings demonstrate that EMC has a pharmacological and biological role in cell survival, migration, and osteoblast differentiation. It suggests that EMC might be a potential phytomedicine for treating abnormalities of osteoblast function in bone diseases.

RANKL-induced osteoclastogenesis in bone marrow-derived macrophages is suppressed by cisapride

Cisapride is a selective 5-hydroxytryptamine (5-HT)₄ receptor (5-HT₄R) agonist. However, the effects of cisapride on osteoclasts and osteoblasts have not been fully explored. We therefore examined the effects of cisapride on osteoclastogenesis in cultured primary bone marrow-derived macrophages (BMMs), and on osteoblast differentiation in cultured primary calvarial pre-osteoblasts. Cisapride significantly inhibited tartrate-resistant acid phosphatase (TRAP)-positive multinuclear osteoclasts and F-actin ring formation during receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis. No cytotoxicity was observed. Cisapride also suppressed RANKL-induced expression of NF-ATc1, TRAP, and cathepsin K genes in BMMs. In addition, cisapride significantly stimulated apoptotic cell death of osteoclasts. However, cisapride had no effect on osteoblast differentiation, as assessed by alkaline phosphatase (ALP) activity and mineralized nodule formation in the cultured primary pre-osteoblasts. Overall, our findings suggest that cisapride may improve the clinical management of metabolic bone diseases such as osteoporosis.

The impact of the intestinal microbiome on bone health

Intestinal microbial flora, known as the second gene pool of the human body, play an important role in immune function, nutrient uptake, and various activities of host cells, as well as in human disease. Intestinal microorganisms are involved in a variety of mechanisms that affect bone health. Gut microbes are closely related to genetic variation, and gene regulation plays an important part in the development of bone-related diseases such as osteoporosis. Intestinal microorganisms can disrupt the balance between bone formation and resorption by indirectly stimulating or inhibiting osteoblasts and osteoclasts. In addition, intestinal microorganisms affect bone metabolism by regulating growth factors or altering bone immune status and can also alter the metabolism of serotonin, cortisol, and sex hormones, thereby affecting bone mass in mice. Moreover, probiotics, antibiotics, and diet can change the composition of the intestinal microbial flora, thus affecting bone health and also potentially helping to treat bone disease. Studying the relationship between intestinal flora and osteoblasts, osteoclasts, and bone marrow mesenchymal stem cells may provide a basis for preventing and treating bone diseases. This paper reviews recent advances in the study of the relationship between intestinal microflora and bone disease.

Dysregulation of 5-hydroxytryptamine 6 receptor accelerates maturation of bone-resorbing osteoclasts and induces bone loss

Rationale: Characterizing the regulation of bone-resorbing osteoclasts is central to the understanding of the pathogenesis and treatment of bone diseases, such as osteoporosis and periodontitis. 5-hydroxytryptamine (5-HT) has drawn considerable attention for its role in bone; however, it remains unknown whether the intracellular signaling of 5-HT receptors (5-HTRs) is linked to any of the regulatory mechanisms in osteoclasts. Herein, we report 5-HT₆R to be a key regulatory receptor for osteoclastogenesis.

Methods: In order to explore the critical role of 5-HT₆R in bone-resorbing osteoclasts, in vitro experiments were performed using mouse whole bone marrow cells isolated from femora and tibiae and In vivo animal experiments were performed using 5-HT₆R-deficient (5-HT₆R^KO-/-) mice, bone resorption mice model, and osteoporosis mice model.

Results: Compared to other 5HTRs, activation of 5-HT₆R relatively increased TRAP (tartrate-resistant acid phosphatase) activity during osteoclastogenesis. 5-HT₆R^KO(-/-) mice and 5-HT₆R^KO(-/-) osteoclast lineages presented with an abnormal phenotype and impaired osteoclastogenesis and impaired osteoclastogenesis. Activation of 5-HT₆R increased the number of TRAP-positive multinuclear osteoclasts, actin ring formation, and expression of early osteoclast markers with osteoclast lineage commitment. Intracellular 5-HT₆R signaling was found to be linked to RhoA GTPase activation and was involved in the maturation of osteoclasts. This signaling pathway also showed enhanced bone destruction after lipopolysaccharide (LPS) administration in mice. Furthermore, inhibition of 5-HT₆R-mediated RhoA GTPase signaling protected against ovariectomy(OVX)-induced bone loss in mice.

Conclusion: Taken together, our findings place the 5-HT₆R system in a new context of osteoclast lineages in both an in vitro and in vivo system, and also it may offer a novel molecular target for the treatment of bone diseases.

Regulation of Bone Metabolism by Serotonin

The processes of bone growth and turnover are tightly regulated by the actions of various signaling molecules, including hormones, growth factors, and cytokines. Imbalances in these processes can lead to skeletal disorders such as osteoporosis or high bone mass disease. It is becoming increasingly clear that serotonin can act through a number of mechanisms, and at different locations in the body, to influence the balance between bone formation and resorption. Its actions on bone metabolism can vary, based on its site of synthesis (central or peripheral) as well as the cells and subtypes of receptors that are activated. Within the central nervous system, serotonergic neurons act via the hypothalamus to suppress sympathetic input to the bone. Since sympathetic input inhibits bone formation, brain serotonin has a net positive effect on bone growth. Gut-derived serotonin is thought to inhibit bone growth by attenuating osteoblast proliferation via activation of receptors on pre-osteoblasts. There is also evidence that serotonin can be synthesized within the bone and act to modulate bone metabolism. Osteoblasts, osteoclasts, and osteocytes all have the machinery to synthesize serotonin, and they also express the serotonin-reuptake transporter (SERT). Understanding the roles of serotonin in the tightly balanced system of bone modeling and remodeling is a clinically relevant goal. This knowledge can clarify bone-related side effects of drugs that affect serotonin signaling, including serotonin-specific reuptake inhibitors (SSRIs) and receptor agonists and antagonists, and it can potentially lead to therapeutic approaches for alleviating bone pathologies.

Prebiotics, Bone and Mineral Metabolism

Increasing interest in functional foods has driven discovery in the area of bioactive compounds. Prebiotics are non-digestible carbohydrate compounds that, when consumed, elicit health benefits and aid in the prevention and treatment of chronic diseases. While prebiotics have been shown to improve a number of chronic, inflammatory conditions, growing evidence exists for prebiotic effects on calcium metabolism and bone health. These novel dietary fibers have been shown to increase calcium absorption in the lower intestines of both preclinical and human models. Rodent models have also been imperative for understanding prebiotic effects on bone mineral density and measures of skeletal strength. Although fewer data are available for humans, bone-related prebiotic effects exist across the lifecycle, suggesting benefits for attainment of peak bone mass during adolescence and minimized bone resorption among postmenopausal women. These effects are thought to occur through prebiotic-microbe interactions in the large intestine. Current prebiotic mechanisms for improved mineral absorption and skeletal health include alterations in gut microbiota composition, production of short-chain fatty acids, altered intestinal pH, biomarker modification, and immune system regulation. While the majority of available data support improved mineral bioavailability, emerging evidence suggests alternate microbial roles and the presence of an intricate gut-bone signaling axis. Overall, the current scientific literature supports prebiotic consumption as a cost-effective and sustainable approach for improved skeletal health and/or fracture prevention. The goal of this review is to discuss both foundational and recent research in the area of prebiotics, mineral metabolism, and bone health.

Sulfuretin promotes osteoblastic differentiation in primary cultured osteoblasts and in vivo bone healing

Although sulfuretin, the major flavonoid of Rhus verniciflua Stokes, has a variety of biological actions, its in vitro and in vivo effects on osteogenic potential remain poorly understood. The objective of the present study was to investigate the effects of sulfuretin on in vitro osteoblastic differentiation and the underlying signal pathway mechanisms in primary cultured osteoblasts and on in vivo bone formation using critical-sized calvarial defects in mice. Sulfuretin promoted osteogenic differentiation of primary osteoblasts, with increased ALP activity and mineralization, and upregulated differentiation markers, including ALP, osteocalcin, and osteopontin, in a concentration-dependent manner. The expression levels of Runx2, BMP-2, and phospho-Smad1/5/8 were upregulated by sulfuretin. Moreover, sulfuretin increased phosphorylation of Akt, mTOR, ERK, and JNK. Furthermore, sulfuretin treatment increased mRNA expression of Wnt ligands, phosphorylation of GSK3, and nuclear β-catenin protein expression. In vivo studies with calvarial bone defects revealed that sulfuretin significantly enhanced new bone formation by micro-computed tomography and histologic analysis. Collectively, these data suggest that sulfuretin acts through the activation of BMP, mTOR, Wnt/β-catenin, and Runx2 signaling to promote in vitro osteoblast differentiation and facilitate in vivo bone regeneration, and might be have therapeutic benefits in bone disease and regeneration.

Elucidating the Mechanism(s) Underlying Antipsychotic and Antidepressant-Mediated Fractures

Mood spectrum disorders and medications used to treat these disorders, such as atypical antipsychotic drugs (AA), are associated with metabolic and endocrine side effects including obesity, dyslipidemia, hyperglycemia and increased risk of fractures. Antidepressant medications, including selective serotonin reuptake inhibitors (SSRI), have also been reported to increase fracture risk in some patients. The pharmacology underlying the increased risk of fractures is currently unknown. Possible mechanisms include alternations in dopaminergic and/or serotonergic signaling pathways. As these medications distribute to the bone marrow as well as to the brain, it is possible that drug-induced fractures are due to both centrally mediated effects as well as direct effects on bone turnover. Given the growing patient population that is prescribed these medications for both on- and off-label indications, understanding the level of risk and the mechanisms underlying drug-induced fractures is important for informing both prescribing and patient monitoring practices.

A novel organosulfur compound, thiacremonone, regulates RANKL-induced osteoclast differentiation

The medicinal properties of functionally active organosulfur compounds have received great attention for applications in treating various diseases.