Analysis of Bone Architecture in Rodents Using Micro-Computed Tomography.

This chapter describes the use of micro-computed tomography scanning for analyzing bone structure, focussing on rodent bone. It discusses sample preparation, the correct setup of the scanner, the impact of some of the important scanner settings and new applications.

The Calvarial Injection Assay.

This chapter describes the calvarial injection method, whereby the effect of a substance on bone is tested by subcutaneous injection over the calvarium of a mouse. This assay allows testing of the effect of substances on both bone resorption and bone formation in a relatively simple in vivo model. The analysis is carried out by histological means, usually in glycolmethacrylate-embedded tissue, allowing for histochemical analysis and for a variety of different histological staining methods which are also described in detail.

Zoledronic acid prevents pagetic-like lesions and accelerated bone loss in the p62 mouse model of Paget's disease.

Paget's disease of bone (PDB) is an age-related metabolic bone disorder, characterised by focally increased and disorganised bone remodelling initiated by abnormal and hyperactive osteoclasts. The germline P392L mutation of (encoding p62) is a strong genetic risk factor for PDB in humans, and the equivalent mutation in mice (P394L) causes a PDB-like disorder. However, it is unclear why pagetic lesions become more common with age.

Development of triarylsulfonamides as novel anti-inflammatory agents.

Triaylsulfonamides were identified as novel anti-inflammatory agents, acting by inhibition of RANKL and TNFα signaling. Structure-activity studies led to the identification of compounds with in vitro potencies of <100 nM against J774 macrophages and osteoclasts, but with little activity against osteoblasts or hepatocytes (IC(50) >50 μM). A representative compound (4k, ABD455) was able to completely prevent inflammation in vivo in a prevention model and was highly effective at controlling inflammation in a treatment model.

The calvarial injection assay.

This chapter describes the calvarial injection method, whereby the effect of a substance on bone is tested by subcutaneous injection over the calvarium of a mouse. This assay allows testing of the effect of substances on both bone resorption and bone formation in a relatively simple in vivo model. The analysis is carried out by histological means, usually in glycolmethacrylate-embedded tissue, allowing for histochemical analysis and for a variety of different histological staining methods which are also described in detail.

Analysis of bone architecture in rodents using microcomputed tomography.

This chapter describes the use of microcomputed tomography scanning for analysing bone structure, focussing on rodent bone. It also discusses sample preparation, the correct set-up of the scanner, and the impact of some of the important scanner settings.

Osteoclast formation in mouse co-cultures.

The murine co-culture assay is used to generate mature osteoclasts from bone marrow precursors by culturing them with osteoblasts that are stimulated with 1,25-dihydroxy vitamin D(3) and prostaglandin E(2). This assay is used particularly to analyse osteoblast-osteoclast interactions and to determine the cell type affected in knock-out or transgenic mice. This chapter describes also the isolation of bone marrow cells from mice and the methods to purify and replate mature osteoclasts.

A point mutation in the ubiquitin-associated domain of SQSMT1 is sufficient to cause a Paget's disease-like disorder in mice.

Mutations of SQSTM1 occur in about10% of patients with Paget's disease of bone (PDB), but it is unclear whether they play a causal role or regulate susceptibility to an environmental trigger. Here we show that mice with a proline to leucine mutation at codon 394 of mouse sqstm1 (P394L), equivalent to the P392L SQSTM1 mutation in humans, develop a bone disorder with remarkable similarity to PDB. The P394L mutant mice developed focal bone lesions with increasing age and by 12 months, 14/18 (77%) heterozygotes and 20/21 (95%) homozygotes had lesions, compared with 0/18 (0%) wild-type littermates (P< 0.

The type 2 cannabinoid receptor regulates bone mass and ovariectomy-induced bone loss by affecting osteoblast differentiation and bone formation.

The type 2 cannabinoid receptor (CB2) has been reported to regulate bone mass and bone turnover but the mechanisms responsible are incompletely understood. In this study we investigated the role that the CB2 pathway plays in bone metabolism using a combination of genetic and pharmacological approaches. Bone mass and turnover were normal in young mice with targeted inactivation of CB2 receptor (CB2(-/-)), but by 12 months of age, they had developed high-turnover osteoporosis with relative uncoupling of bone resorption from bone formation.

Cannabinoid receptor type 1 protects against age-related osteoporosis by regulating osteoblast and adipocyte differentiation in marrow stromal cells.

Age-related osteoporosis is characterized by reduced bone formation and accumulation of fat in the bone marrow compartment. Here, we report that the type 1 cannabinoid receptor (CB1) regulates this process. Mice with CB1 deficiency (CB1(-/-)) had increased peak bone mass due to reduced bone resorption, but developed age-related osteoporosis with reduced bone formation and accumulation of adipocytes in the bone marrow space.

Regulation of bone mass, osteoclast function, and ovariectomy-induced bone loss by the type 2 cannabinoid receptor.

The endocannabinoid system has recently been shown to play a role in the regulation of bone metabolism. The type 2 cannabinoid receptor (CB2) has been reported to regulate bone mass, but conflicting results have been reported with regard to its effects on bone resorption and osteoclast function. Here we investigated the role that CB2 plays in regulating bone mass and osteoclast function using a combination of pharmacological and genetic approaches.

Regulation of bone mass, bone loss and osteoclast activity by cannabinoid receptors.

Accelerated osteoclastic bone resorption has a central role in the pathogenesis of osteoporosis and other bone diseases. Identifying the molecular pathways that regulate osteoclast activity provides a key to understanding the causes of these diseases and to the development of new treatments. Here we show that mice with inactivation of cannabinoid type 1 (CB1) receptors have increased bone mass and are protected from ovariectomy-induced bone loss.

Regulation of bone mass and bone turnover by neuronal nitric oxide synthase.

Nitric oxide (NO) is produced by NO synthase (NOS) and plays an important role in the regulation of bone cell function. The endothelial NOS isoform is essential for normal osteoblast function, whereas the inducible NOS isoform acts as a mediator of cytokine effects in bone. The role of the neuronal isoform of NOS (nNOS) in bone has been studied little thus far.