Nicotinic acetylcholine receptors modulate osteoclastogenesis (original) (raw)
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Journal of immunology (Baltimore, Md. : 1950), 2016
The aryl hydrocarbon receptor (AhR) pathway plays a key role in receptor activator of NF-κB ligand (RANKL)-mediated osteoclastogenesis. However, the mechanism underlying the regulation of AhR expression in osteoclasts and the signaling pathway through which AhR controls osteoclastogenesis remain unclear. We found that the expression of AhR in bone marrow-derived osteoclasts was upregulated by RANKL at an earlier stage than was the expression of signature osteoclast genes such as those encoding cathepsin K and NFAT, cytoplasmic, calcineurin-dependent 1. In response to RANKL, bone marrow macrophages isolated from AhR(-/-) mice exhibited impaired phosphorylation of Akt and MAPK as well as NF-κB, whereas their response to M-CSF remained unchanged. Osteoclast differentiation mediated by the AhR signaling pathway was also regulated in an RANKL/c-Fos-dependent manner. Furthermore, ligand activation of AhR by the smoke toxin benzo[a]pyrene accelerated osteoclast differentiation in a recepto...
Nicotinic modulation of gene expression in osteoblast cells, MG-63
Bone, 2011
Exposure to nicotine causes a broad range of biological and molecular effects on osteoblasts which are known to play a crucial role in bone metabolism and fracture healing. Most effects of nicotine on the osteoblasts are long-term adaptations at the genomic level. To identify the nicotine-regulated genes, the Agilent technologies whole human genome gene expression microarray was performed on RNA samples from osteoblast-like cells, MG-63, exposed to 100 μM nicotine. Repeat and cross-controlled microarray analyses revealed 842 genes whose expression was consistently altered at P b 0.05 level following nicotine treatment. Gene ontology analysis suggested effects of nicotine on various biological and cellular processes which were associated with survival, proliferation, differentiation and apoptosis processes within the cell. Quantitative real-time reverse transcriptase PCR analysis confirmed altered expression in 7 out of 9 genes tested. The identified genes tested in the current study support our previous report that nicotine regulates the expression of genes that promote osteoblast proliferation and/or anti-apoptosis processes. Furthermore, using nicotinic acetylcholine receptor antagonists blocked the majority of the nicotine effects, indicating that these changes are dependent on nAChR activation. These results established a novel and consistent nicotinic activation of nAChR in osteoblast cells which has a broad role affecting cellular physiology through modulation of gene expression.
Small changes in bone structure of female α7 nicotinic acetylcholine receptor knockout mice
BMC Musculoskeletal Disorders, 2015
Background: Recently, analysis of bone from knockout mice identified muscarinic acetylcholine receptor subtype M3 (mAChR M3) and nicotinic acetylcholine receptor (nAChR) subunit α2 as positive regulator of bone mass accrual whereas of male mice deficient for α7-nAChR (α7KO) did not reveal impact in regulation of bone remodeling. Since female sex hormones are involved in fair coordination of osteoblast bone formation and osteoclast bone degradation we assigned the current study to analyze bone strength, composition and microarchitecture of female α7KO compared to their corresponding wild-type mice (α7WT). Methods: Vertebrae and long bones of female 16-week-old α7KO (n = 10) and α7WT (n = 8) were extracted and analyzed by means of histological, radiological, biomechanical, cell-and molecular methods as well as time of flight secondary ion mass spectrometry (ToF-SIMS) and transmission electron microscopy (TEM). Results: Bone of female α7KO revealed a significant increase in bending stiffness (p < 0.05) and cortical thickness (p < 0.05) compared to α7WT, whereas gene expression of osteoclast marker cathepsin K was declined. ToF-SIMS analysis detected a decrease in trabecular calcium content and an increase in C 4 H 6 N + (p < 0.05) and C 4 H 8 N + (p < 0.001) collagen fragments whereas a loss of osteoid was found by means of TEM.
FEBS Letters, 2010
Recent studies have indicated that acetylcholine (ACh) plays a vital role in various tissues, while the role of ACh in bone metabolism remains unclear. Here we demonstrated that ACh induced cell proliferation and reduced alkaline phosphatase (ALP) activity via nicotinic (nAChRs) and muscarinic acetylcholine receptors (mAChRs) in osteoblasts. We detected mRNA expression of several nAChRs and mAChRs. Furthermore, we showed that cholinergic components were up-regulated and subunits/subtypes of acetylcholine receptors altered during osteoblast differentiation. To our knowledge, this is the first report demonstrating that osteoblasts express specific acetylcholine receptors and cholinergic components and that ACh plays a possible role in regulating the proliferation and differentiation of osteoblasts.
Global spine journal, 2012
Previous studies by our group showed that nicotine delivered via a transdermal nicotine patch significantly enhanced posterior spinal fusion rates in rabbits. Nicotine transdermal patches provide a steady serum level; there may be a dose-dependent effect of nicotine on posterior spinal fusion. In an in vitro cell culture model of rabbit bone marrow-derived osteoblast-like cells, cells were exposed to different concentrations of nicotine (0, 20, 40, 80 ng/mL and 10, 100, 250 μg/mL). Wells were stained with an alkaline phosphatase (ALP) staining kit to determine ALP enzyme activity. Cells were stained with Von Kossa for mineralization. A two-way analysis of variance (ANOVA) using dose and time as variables showed significant differences among groups; post hoc analysis showed that the 100-μg/mL dose of nicotine significantly enhanced ALP activity over controls. A one-way ANOVA using dose as the variable showed that the 100- and 250-μg/mL doses had significantly greater mineralization t...
Nicotine induced proliferation and cytokine release in osteoblastic cells
International Journal of Molecular Medicine, 2006
Smoking has deleterious effects on osteoporosis and periodontitis both characterized by bone loss. Smoking also interferes with the protective effect that hormone replacement therapy (HRT) has on bone loss. Our study investigated two mechanisms by which smoking may affect bone metabolism: nicotine-induced proliferation and nicotine-induced cytokine secretion in osteoblasts. Two osteoblastic cell models were used: mouse osteoblasts derived from mouse calvaria and human osteoblasts. Thymidine incorporation and immunoassays were used to evaluate proliferation, interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) secretion. Parametric and nonparametric statistical analyses were used for comparisons. The results showed that nicotine induced stimulation and inhibition of proliferation in both osteoblastic cell models. In human osteoblasts, the proliferative and inhibitory effects were also donor dependent. Il-6 secretion showed different patterns in mouse and human osteoblasts. In mouse osteoblasts, nicotine significantly increased IL-6 secretion and estradiol significantly inhibited the nicotine-induced IL-6 release. In human osteoblasts, cells derived from one subject did not respond to nicotine. However, in the second sample, nicotine increased secretion of Il-6 but estradiol did not oppose this effect. In human osteoblasts, nicotine also induced an increase in the TNF-alpha secretion and estradiol opposed this increase. These results suggest that nicotine affects bone metabolism by modulating proliferation, and Il-6 and TNF-alpha secretion. These studies provide a possible explanation for differences in bone loss among subjects who smoke and offer a possible mechanism for the oppositional effect of smoking on HRT in subjects with bone loss.
Journal of Biosciences and Medicines, 2019
Osteoporosis is a systemic bone disease that results in the loss of bone mass and impared bone structure. Animal models for osteoporosis are generated by ovariectomy. Adult female Sprague-Dawley rats were divided into control, bilateral ovariectomy and bilateral ovariectomy and subcutaneous nicotine administered (received nicotine sulphate, 2 mg/kg) groups, daily for 28 days. At the end of the period, rats were sacrified under anesthesia blood samples were taken and femoral tissues were dissected. Estrogen, calcium and alkaline phosphatase levels were measured. Tissue samples were prepared for histopathogical examination. Sections were stained with Hematoxylin and Eosin and examined under light microcope. Biochemical parameters were decreased depending on the overiectomy, also decrement was notable with nicotine intake. In the ovariectomy group; increased inflammatory cells with degenerative changes around the femoral compact bone and dilatation of osteon structures in bone trabeculae and apoptotic changes in osteocyte cells in bone lacuna were apparent. In the ovariectomy with nicotine administration group, excessive dilatation of the havers lamellae in the compact bone region, increased osteoclastic activity, picnosis and apoptotic nucleus of the osteoclastic cells located in the lacuna, and increased collagen fibers in the matrix were observed. We suggest that ovariectomy and nicotine administration together effect estrogen and calcium metabolism negatively, stimulate alterations in the structural properties of bone matrix, also affect osteocyte development and bone lamellar structure that may accelerate osteoporosis development.
European Journal of Dentistry
Objective The success of dental implants is determined by the osteointegration process. Many studies state that smoking cigarettes can inhibit osseointegration, but the inhibition mechanism is still unclear.The aim of this study was to identify and analyze the effect of nicotine on the inhibition of dental implant osseointegration through the expression of nicotinic acetylcholine receptor (nAChR), nuclear factor of activated T cells cytoplasmic 1 (NFATc1), osteoclast, and osteoblast numbers. Materials and Methods This study is an experimental study of 16 New Zealand rabbits, randomized across two groups. Group 1 (eight rabbits) was a control group, and group 2 (eight rabbits) was a treatment group. The treatment group was given 2.5 mg/kg body weight/day of nicotine by injection 1 week before placement of the implant until the end of research. Observations were made in the first and the eighth week by measuring the number of osteoblast and osteoclast by immunohistology test and the e...
Effects of nicotine on markers of bone turnover in ovariectomized rats
Pan African Medical Journal
Introduction: osteoporosis is characterized by low bone mass and density, as well as change in microarchitecture of bone tissue leading to decreased bone strength. In vitro research shows nicotine can increase osteoblast activity and proliferation, also suppress osteoclast activity. Therefore we explore nicotine anti-resorptive property by in vivo true experimental and randomized posttest only controlled group research that was conducted in 18-20 weeks old Rattus norvegicus. Methods: twenty-five female rats were divided into five groups, with 5 rats per group. The first group represented normal rats (Sham), while the second to fifth group underwent bilateral ovariectomy. The second group serves as positive control group (ovariectomy-only/OVX). The third to fifth group serve as dose 1 (P1-0.25mg/kg), dose 2 (P2-0.5 mg/kg), and Dose 3 (P3-0.75 mg/kg) treatment group receiving daily per-oral nicotine for 28 days, started 3 weeks post-ovariectomy. After 28 days treatment, the serum was checked. Results: nicotine has dose-dependent manner on serum osteocalcin and serum DPD level. Level of osteocalcin in P2 group was significantly lower (Mann-Whitney, p = 0.008) compared to OVX group (59.4% lower). Level of DPD in all group was not significantly different (ANOVA, p < 0.05) but shows lowest level in P2 group. For serum calcitonin level, there's no significant different between groups. Conclusion: nicotine at right low-dose might be able to inhibit osteoclast activity, thus open a possibility of anti-resorptive property of nicotine.