Serotonin regulates osteoclast differentiation through its transporter

Osteoporosis and multiple sclerosis: Exploring the complex intersection between bone and brain, a clarion call for change

Osteoporosis is a common but often underrecognized condition in people with multiple sclerosis (PwMS), occurring more frequently and at an earlier age compared to the general population. It leads to an increased risk of fractures due to reduced bone mineral density (BMD). This review identifies key risk factors contributing to osteoporosis in PwMS, including age, vitamin D deficiency, reduced mobility, and long-term corticosteroid use. In addition to these factors, shared inflammatory mechanisms between MS and osteoporosis, such as elevated pro-inflammatory cytokines, further exacerbate bone loss. Strategies for early identification and proactive management are also discussed, highlighting their importance in reducing fracture risk and improving outcomes. The ultimate aim is to promote tailored pharmacological treatments, effective interventions, and comprehensive management of osteoporosis in PwMS.

Fluoxetine inhibited RANKL-induced osteoclastic differentiation in vitro

Selective serotonin reuptake inhibitor correlates with decreased bone mineral density and impedes orthodontic tooth movement. The present study aimed to examine the effects of fluoxetine on osteoclast differentiation and function. Human peripheral blood mononuclear cells (hPBMCs) and murine RAW264.7 cells were cultured with RANKL to stimulate osteoclast differentiation. The resulting multinucleated cells displayed characteristics of mature osteoclasts. Fluoxetine at 0.01-1 μM did not impact cellular viability or oxidative stress. However, 10 μM fluoxetine significantly reduced clonal growth, cell viability, and increased cytotoxicity and lipid peroxidation in RAW 264.7 cells. Further, application of 0.1 μM fluoxetine potently suppressed osteoclast differentiation of both RAW264.7 and hPBMCs, with reduced osteoclast numbers and downregulation of osteoclastic genes matrix metalloproteinase-9, cathepsin K, and integrin β3 at mRNA and protein levels. Fluoxetine also disrupted F-actin ring formation essential for osteoclast resorptive function. Mechanistically, fluoxetine inhibited NF-kB signaling by reducing phosphorylation of pathway members IκBα and p65, preventing IκBα degradation and blocking p65 nuclear translocation. In conclusion, this study demonstrates fluoxetine suppressing osteoclast differentiation in association with disrupting NF-kB activation, providing insight into orthodontic treatment planning for patients taking fluoxetine.

Effects of fish oil supplementation on bone turnover markers in depression: a pilot study

Background and objective

There is a close correlation between bone loss, depression, and antidepressants. N-3 PUFA supplementation has been considered an effective add-on therapeutic approach in ameliorating bone loss and relieving depression. However, the adjunctive effect of n-3 PUFA on bone metabolism in participants with depression is still unknown. This is a pilot study to investigate the dynamics of bone metabolism in depression and evaluate the efficacy of fish oil on bone loss in depression.

Methods

In this study, we focused on the change of bone turnover markers in depression, the effect of n-3 PUFA supplementation on bone turnover markers, and its association with clinical characteristics. A case-control study and a secondary analysis of a previously published randomized clinical trial (NCT03295708) that evaluates the efficacy of n-3 PUFA supplementation in venlafaxine-treated depressed participants have been included.

Results

The levels of PINP (z = -2.233, p = 0.026) in depressed participants were significantly increased compared with healthy controls at baseline. The secondary analysis has shown significant differences exited on CTX (χ 2 = 4.848, p = 0.028) and OSTEOC (χ 2 = 6.178, p = 0.013) between n-3 PUFA and placebo group. The levels of CTX and OSTEOC (p < 0.05) significantly decreased in the placebo group, which indicates that venlafaxine treatment reduces both bone formation and resorption markers. While the levels of OSTEOC and PINP were increased in the n-3 PUFA group (p < 0.05). Moreover, the change in bone turnover markers showed consistency with clinical symptomatic outcomes.

Conclusion

Participants with first-diagnosed, drug-naïve depression show active bone formation. Venlafaxine decreases bone remodeling, while n-3 PUFA increases bone formation, bringing light to preventing and treating bone loss in depression.

Clinical trial registration

ClinicalTrials.gov, NCT03295708.

Integrated transcriptomics and untargeted metabolomics reveal bone development and metabolism of newly weaned mice in response to dietary calcium and boron levels

Epidemiological and animal studies have indicated that calcium and boron are essential for bone development and metabolism. However, limited information is available regarding the effects of boron supplementation on bone development and metabolism in newly weaned infants with either calcium deficiency or calcium sufficiency. This study assessed the effects of dietary boron supplementation (0 and 3 mg kg-1) on bone development and metabolism, in a newly weaned mouse model, under both calcium deficiency and sufficiency feeding conditions. The results show that mice fed a calcium sufficient diet exhibited lower fat percentage and final body weight than those fed a calcium deficient diet. Boron supplementation reduced the serum high-density lipoprotein cholesterol level and up-regulated the mRNA levels of FABP3, PPAR-γ, and CaMK in the intestinal mucosa. Importantly, boron supplementation increased the tibial weight in mice on a calcium-sufficient diet and enhanced the tibial volume in those on a calcium-deficient diet. Metabolomic analysis highlighted calcium and boron's impact on metabolites like carboxylic acids and derivatives, fatty acyls, steroids and steroid derivatives, benzene and substituted derivatives, organonitrogen compounds, organooxygen compounds, and phenols, and were related to lipid metabolism and the neural signaling pathway. Transcriptomic analysis corroborated the role of calcium and boron in modulating bone metabolism via the JAK-STAT, calcium signaling, lipid metabolism, and inflammatory pathways. Multi-omics analysis indicated a strong correlation between calcium signaling pathways, lipid metabolism signaling, and dietary calcium and boron contents. This research provides insights into these complex mechanisms, potentially paving the way for novel interventions against calcium and boron deficiencies and bone metabolism abnormalities in clinical settings.

Serotonin Availability Shapes the Effects of Phenelzine on Inflammatory Response and Gene Expression in Macrophages

Background Serotonin (5-HT) is a neurotransmitter with extensive physiological influence in the central nervous system (CNS) and various behavioral and biological functions, including immune regulation through 5-HT receptors (5-HTRs) expressed by immune cells. A variety of serotonin-modulating drugs have been developed to treat neurological disorders. Phenelzine, a drug indicated for the management of treatment-resistant depression, is a potent, non-selective inhibitor of monoamine oxidase (MAO), the enzyme that metabolizes serotonin to 5-hydroxyindole acetic acid (5-HIAA). Given the emerging evidence of a bidirectional link between depression and inflammation, as well as the potential therapeutic applications of serotonin-modulating drugs in autoimmune diseases and cancer, our study investigated the pro-inflammatory and anti-inflammatory factors influenced by serotonin and phenelzine. Methodology We conducted experiments on RAW264.7 macrophages, exposing them to various combinations and concentrations of serotonin, 5-HIAA, and phenelzine. We assessed the relative gene expression of monoamine oxidase-A (MAO-A), CYP1B1, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) using real-time PCR and measured the production of IL-6, TNF-α, and IL-10 cytokines using enzyme-linked immunosorbent assays (ELISA). Results Our findings revealed that phenelzine can downregulate genes associated with the production of reactive oxygen and nitrogen species, reduce aryl hydrocarbon receptor (AHR)-related gene expression induced by serotonin, and enhance the production of inflammatory cytokines. These effects were significantly influenced by the concentration of available serotonin. Conclusions Our study demonstrates that various mechanisms, including AHR activation, modulation of reactive oxygen and nitrogen species production, and others, in addition to the increased availability of serotonin due to phenelzine treatment, can significantly influence the inflammatory state.

Dental implant considerations in patients with systemic diseases: An updated comprehensive review

BACKGROUND

Various medical conditions and the drugs used to treat them have been shown to impede or complicate dental implant surgery. It is crucial to carefully monitor the medical status and potential post-operative complications of patients with systemic diseases, particularly elderly patients, to minimize the risk of health complications that may arise.

AIM

The purpose of this study was to review the existing evidence on the viability of dental implants in patients with systemic diseases and to provide practical recommendations to achieve the best possible results in the corresponding patient population.

METHODS

The information for our study was compiled using data from PubMed, Scopus, Web of Science and Google Scholar databases and searched separately for each systemic disease included in our work until October 2023. An additional manual search was also performed to increase the search sensitivity. Only English-language publications were included and assessed according to titles, abstracts and full texts.

RESULTS

In total, 6784 studies were found. After checking for duplicates and full-text availability, screening for the inclusion criteria and manually searching reference lists, 570 articles remained to be considered in this study.

CONCLUSION

In treating patients with systemic conditions, the cost-benefit analysis should consider the patient's quality of life and expected lifespan. The success of dental implants depends heavily on ensuring appropriate maintenance therapy, ideal oral hygiene standards, no smoking and avoiding other risk factors. Indications and contraindications for dental implants in cases of systemic diseases are yet to be more understood; broader and hardcore research needs to be done for a guideline foundation.

Emerging roles of nerve-bone axis in modulating skeletal system

Over the past decades, emerging evidence in the literature has demonstrated that the innervation of bone is a crucial modulator for skeletal physiology and pathophysiology. The nerve-bone axis sparked extensive preclinical and clinical investigations aimed at elucidating the contribution of nerve-bone crosstalks to skeleton metabolism, homeostasis, and injury repair through the perspective of skeletal neurobiology. To date, peripheral nerves have been widely reported to mediate bone growth and development and fracture healing via the secretion of neurotransmitters, neuropeptides, axon guidance factors, and neurotrophins. Relevant studies have further identified several critical neural pathways that stimulate profound alterations in bone cell biology, revealing a complex interplay between the skeleton and nerve systems. In addition, inspired by nerve-bone crosstalk, novel drug delivery systems and bioactive materials have been developed to emulate and facilitate the process of natural bone repair through neuromodulation, eventually boosting osteogenesis for ideal skeletal tissue regeneration. Overall, this work aims to review the novel research findings that contribute to deepening the current understanding of the nerve-bone axis, bringing forth some schemas that can be translated into the clinical scenario to highlight the critical roles of neuromodulation in the skeletal system.

Emerging factors affecting peri-implant bone metabolism

Implant dentistry has evolved to the point that standard implant osseointegration is predictable. This is attributed in part to the advancements in material sciences that have led toward improvements in implant surface technology and characteristics. Nonetheless, there remain several cases where implant therapy fails (specifically at early time points), most commonly attributed to factors affecting bone metabolism. Among these patients, smokers are known to have impaired bone metabolism and thus be subject to higher risks of early implant failure and/or late complications related to the stability of the peri-implant bone and mucosal tissues. Notably, however, emerging data have unveiled other critical factors affecting osseointegration, namely, those related to the metabolism of bone tissues. The aim of this review is to shed light on the effects of implant-related factors, like implant surface or titanium particle release; surgical-related factors, like osseodensification or implanted biomaterials; various drugs, like selective serotonin reuptake inhibitors, proton pump inhibitors, anti-hypertensives, nonsteroidal anti-inflammatory medication, and statins, and host-related factors, like smoking, diet, and metabolic syndrome on bone metabolism, and aseptic peri-implant bone loss. Despite the infectious nature of peri-implant biological complications, these factors must be surveyed for the effective prevention and management of peri-implantitis.

Antidepressant duloxetine hydrochloride protects against ovariectomy-induced bone loss in mice by inhibiting osteoclast differentiation

BACKGROUND

Several studies have reported the association between osteoporosis and major depressive disorder (MDD) as well as the use of antidepressants. However, it remains to be elucidated whether these associations are related to exposure to antidepressants, a consequence of a disease process, or a combination of both.

METHODS

This study investigates the independent effect of the antidepressant duloxetine hydrochloride (DH) on ovariectomy-induced bone loss in mice. One week after ovariectomy, the treated mice received DH. To explore the mechanism underlying the rescue of bone loss, bone marrow cells were isolated from mouse femurs and tibias, and macrophages extracted from them were induced to become osteoclasts in vitro while being treated with DH. Subsequently, the osteoclasts underwent Bulk RNA-Seq to reveal the involved signaling pathways. The results of the bioinformatic analysis were then validated through in vitro experiments.

RESULTS

The in vivo experiments demonstrated that DH treatment compromised ovariectomy-induced bone loss after 7 weeks. The in vitro experiments suggested that DH treatment attenuated osteoclast differentiation via the MAPKs/NFATc1 signaling pathway.

CONCLUSION

The findings from this study suggest that DH, instead of causing bone mass loss, may assist in alleviating postmenopausal osteoporosis. These results can serve as a reference for the clinical treatment of patients with perimenopausal or postmenopausal depression using antidepressants.

An Update on Drug-Nutrient Interactions and Dental Decay in Older Adults

In recent decades, the global demographic landscape has undergone a discernible shift that has been characterised by a progressive increase in the proportion of elderly individuals, indicative of an enduring global inclination toward extended lifespans. The aging process, accompanied by physiological changes and dietary patterns, contributes to detrimental deviations in micronutrient consumption. This vulnerable aging population faces heightened risks, including dental caries, due to structural and functional modifications resulting from insufficient nutritional sustenance. Factors such as physiological changes, inadequate nutrition, and the prevalence of multiple chronic pathologies leading to polypharmacy contribute to the challenge of maintaining an optimal nutritional status. This scenario increases the likelihood of drug interactions, both between medications and with nutrients and the microbiome, triggering complications such as dental decay and other pathologies. Since the drug industry is evolving and new types of food, supplements, and nutrients are being designed, there is a need for further research on the mechanisms by which drugs interfere with certain nutrients that affect homeostasis, exemplified by the prevalence of caries in the mouths of older adults. Infectious diseases, among them dental caries, exert serious impacts on the health and overall quality of life of the elderly demographic. This comprehensive review endeavours to elucidate the intricate interplay among drugs, nutrients, the microbiome, and the oral cavity environment, with the overarching objective of mitigating the potential hazards posed to both the general health and dental well-being of older adults. By scrutinising and optimising these multifaceted interactions, this examination aims to proactively minimise the susceptibility of the elderly population to a spectrum of health-related issues and the consequences associated with dental decay.

Fluoxetine treatment during the postpartal period may have short-term impacts on murine maternal skeletal physiology

Postpartum depression affects many individuals after parturition, and selective serotonin reuptake inhibitors (SSRIs) are often used as the first-line treatment; however, both SSRIs and lactation are independently associated with bone loss due to the role of serotonin in bone remodeling. Previously, we have established that administration of the SSRI fluoxetine during the peripartal period results in alterations in long-term skeletal characteristics. In the present study, we treated mice with either a low or high dose of fluoxetine during lactation to determine the consequences of the perturbation of serotonin signaling during this time period on the dam skeleton. We found that lactational fluoxetine exposure affected both cortical and trabecular parameters, altered gene expression and circulating markers of bone turnover, and affected mammary gland characteristics, and that these effects were more pronounced in the dams that were exposed to the low dose of fluoxetine in comparison to the high dose. Fluoxetine treatment during the postpartum period in rodents had short term effects on bone that were largely resolved 3 months post-weaning. Despite the overall lack of long-term insult to bone, the alterations in serotonin-driven lactational bone remodeling raises the question of whether fluoxetine is a safe option for the treatment of postpartum depression.

Effect of Selective Serotonin Reuptake Inhibitor (Paroxetine) on Newly Formed Bone Volume: Real-Time In Vivo Micro-computed Tomographic Analysis

INTRODUCTION

Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat depression and anxiety. The purpose of this study was to assess in real time the effect of paroxetine, an SSRI, on newly formed bone volume (NFBV) in standardized calvarial defects (SCDs) in rats.

METHODS

Fourteen Wistar albino female rats with a mean age of 7.5 months and a mean weight of 275 g were used. The animals were randomly divided into 2 groups. The experimental group was given paroxetine 8 weeks before the surgical procedure and throughout the experiment, and the control group was given a placebo 8 weeks before the surgical procedure and throughout the experiment. In each group, 14 SCDs measuring 4.6 mm in diameter were created on the parietal bone. In both groups, a Bio-Oss + collagen membrane was placed. All defects showed primary closure. The volume of the newly formed bone (NFBV) was measured using in vivo micro-computed tomographic imaging. Measurements were taken at days 0, 14, 28, 42, and 56 after surgery using real-time assessment with micro-computed tomographic imaging.

RESULTS

The mean NFBV was 17.12 ± 4.52 mm3 and 12.52 ± 4.78 mm3 for the control and experimental groups, respectively, at day 56. The differences between the 2 groups were statistically significant (P < .05) at all time intervals.

CONCLUSIONS

Paroxetine intake significantly reduced the amount of regenerated NFBV and the rate of new bone formation.

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.

The Serotonergic System and Bone Metabolism During Pregnancy and Lactation and the Implications of SSRI Use on the Maternal-Offspring Dyad

Lactation is a physiological adaptation of the class Mammalia and is a product of over 200 million years of evolution. During lactation, the mammary gland orchestrates bone metabolism via serotonin signaling in order to provide sufficient calcium for the offspring in milk. The role of serotonin in bone remodeling was first discovered over two decades ago, and the interplay between serotonin, lactation, and bone metabolism has been explored in the years following. It is estimated that postpartum depression affects 10-15% of the population, and selective serotonin reuptake inhibitors (SSRI) are often used as the first-line treatment. Studies conducted in humans, nonhuman primates, sheep, and rodents have provided evidence that there are consequences on both parent and offspring when serotonin signaling is disrupted during the peripartal period; however, the long-term consequences of disruption of serotonin signaling via SSRIs during the peripartal period on the maternal and offspring skeleton are not fully known. This review will focus on the relationship between the mammary gland, serotonin, and bone remodeling during the peripartal period and the skeletal consequences of the dysregulation of the serotonergic system in both human and animal studies.

Multi-omic analysis of host-microbial interactions central to the gut-brain axis

The gut microbiota impact numerous aspects of human physiology, including the central nervous system (CNS). Emerging work is now focusing on the microbial factors underlying the bi-directional communication network linking host and microbial systems within the gastrointestinal tract to the CNS, the "gut-brain axis". Neurotransmitters are key coordinators of this network, and their dysregulation has been linked to numerous neurological disease states. As the bioavailability of neurotransmitters is modified by gut microbes, it is critical to unravel the influence of the microbiota on neurotransmitters in the context of the gut-brain axis. Here we review foundational studies that defined molecular relationships between the microbiota, neurotransmitters, and the gut-brain axis. We examine links between the gut microbiome, behavior, and neurological diseases, as well as microbial influences on neurotransmitter bioavailability and physiology. Finally, we review multi-omics technologies uniquely applicable to this area, including high-throughput genetics, modern metabolomics, structure-guided metagenomics, targeted proteomics, and chemogenetics. Interdisciplinary studies will continue to drive the discovery of molecular mechanisms linking the gut microbiota to clinical manifestations of neurobiology.

Mental health and periodontal and peri-implant diseases

Mental health disorders, particularly depression and anxiety, affect a significant number of the global population. Several pathophysiological pathways for these disorders have been identified, including the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and the immune system. In addition, life events, environmental factors, and lifestyle affect the onset, progression, and recurrence of mental health disorders. These may all overlap with periodontal and/or peri-implant disease. Mental health disorders are associated with more severe periodontal disease and, in some cases, poorer healing outcomes to nonsurgical periodontal therapy. They can result in behavior modification, such as poor oral hygiene practices, tobacco smoking, and alcohol abuse, which are also risk factors for periodontal disease and, therefore, may have a contributory effect. Stress has immunomodulatory effects regulating immune cell numbers and function, as well as proinflammatory cytokine production. Stress markers such as cortisol and catecholamines may modulate periodontal bacterial growth and the expression of virulence factors. Stress and some mental health disorders are accompanied by a low-grade chronic inflammation that may be involved in their relationship with periodontal disease and vice versa. Although the gut microbiome interacting with the central nervous system (gut-brain axis) is thought to play a significant role in mental illness, less is understood about the role of the oral microbiome. The evidence for mental health disorders on implant outcomes is lacking, but may mainly be through behaviourial changes. Through lack of compliance withoral hygiene and maintenance visits, peri-implant health can be affected. Increased smoking and risk of periodontal disease may also affect implant outcomes. Selective serotonin reuptake inhibitors have been linked with higher implant failure. They have an anabolic effect on bone, reducing turnover, which could account for the increased loss.

Is mandibular osteomyelitis a sequela of SSRI-induced dental implant failure? A systematic review & case report

BACKGROUND

To determine if the utilization of selective serotonin reuptake inhibitors (SSRIs) increases the risk of osteomyelitis as a sequela of dental implant failure. We also report the case of a patient on long-term SSRIs who presented with dental implant failure and subsequently developed mandibular osteomyelitis.

METHODS

We performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) in PubMed, Google Scholar and Embase, for all records pertaining to SSRIs, dental implants, and mandibular osteomyelitis.

RESULTS

SSRIs are associated with increased risk of dental implant failure, and our results suggest that they may be independently associated with mandibular osteomyelitis in the setting of implant failure. Though there was no evidence of mandibular osteomyelitis specifically following SSRI-related dental implant failure, there were a few case reports on osteomyelitis resulting from failed dental implant osseointegration.

CONCLUSIONS

In the context of long-term SSRI utilization, our findings suggest that osteomyelitis should be considered in the differential diagnosis of patients with recent dental implant placement or failure.

Gut-Bone Axis: A Non-Negligible Contributor to Periodontitis

Periodontitis is a polymicrobial infectious disease characterized by alveolar bone loss. Systemic diseases or local infections, such as diabetes, postmenopausal osteoporosis, obesity, and inflammatory bowel disease, promote the development and progression of periodontitis. Accumulating evidences have revealed the pivotal effects of gut microbiota on bone health via gut-alveolar-bone axis. Gut pathogens or metabolites may translocate to distant alveolar bone via circulation and regulate bone homeostasis. In addition, gut pathogens can induce aberrant gut immune responses and subsequent homing of immunocytes to distant organs, contributing to pathological bone loss. Gut microbial translocation also enhances systemic inflammation and induces trained myelopoiesis in the bone marrow, which potentially aggravates periodontitis. Furthermore, gut microbiota possibly affects bone health via regulating the production of hormone or hormone-like substances. In this review, we discussed the links between gut microbiota and periodontitis, with a particular focus on the underlying mechanisms of gut-bone axis by which systemic diseases or local infections contribute to the pathogenesis of periodontitis.

Gut microbiota and bone metabolism

Osteoporosis is the most common metabolic skeletal disease. It is characterized by the deterioration of the skeletal microarchitecture and bone loss, leading to ostealgia, and even bone fractures. Accumulating evidence has indicated that there is an inextricable relationship between the gut microbiota (GM) and bone homeostasis involving host-microbiota crosstalk. Any perturbation of the GM can play an initiating and reinforcing role in disrupting the bone remodeling balance during the development of osteoporosis. Although the GM is known to influence bone metabolism, the mechanisms associated with these effects remain unclear. Herein, we review the current knowledge of how the GM affects bone metabolism in health and disease, summarize the correlation between pathogen-associated molecular patterns of GM structural components and bone metabolism, and discuss the potential mechanisms underlying how GM metabolites regulate bone turnover. Deciphering the complicated relationship between the GM and bone health will provide new insights into the prevention and treatment of osteoporosis.

Use of serotonin reuptake inhibitors and risk of subsequent bone loss in a nationwide population-based cohort study

This study examined whether the use of SRIs is associated with an increased risk of bone loss using a nested case-control design with a nationwide population-based cohort in Korea. Using the Korean National Health Screening Cohort, subjects newly diagnosed with osteoporosis or osteopenia (n = 55,799) were matched with controls (n = 278,995) at a ratio of 1:5. We stratified the participants by their time-dependent use of SRIs and sex and controlled for various confounders, including lifestyle habits, laboratory data, and comorbidities. Conditional logistic regression showed that both recent and former users of SRIs had an increased risk of subsequent bone loss compared with non-users: men [recent users: odds ratio (OR) 1.35, 95% confidential interval (CI) 1.20, 1.53; former-users: OR 1.10, 95% CI 1.01, 1.20]; women (recent users: OR 1.38, 95% CI 1.28-1.48; former-users: OR 1.07, 95% CI 1.02, 1.21). The use of SRIs was associated with an increased risk of bone loss in both men and women. In particular, the association was stronger in recent users. These findings provide population-level evidence for the risk of bone loss associated with SRI exposure and highlight the importance of monitoring the bone health of SRI users.

Melatonin Inhibits Osteoclastogenesis and Bone Loss in Ovariectomized Mice by Regulating PRMT1-Mediated Signaling

Melatonin, a pineal gland hormone, has been suggested to treat postmenopausal osteoporosis due to its inhibitory effect on osteoclast differentiation. We previously reported that protein arginine methyltransferase 1 (PRMT1) was an important mediator of receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. However, the relationship between melatonin and PRMT1 in osteoclast differentiation and estrogen deficiency-induced osteoporosis is unclear. In this study, we investigated the inhibitory mechanisms of melatonin in vitro and in vivo by focusing on PRMT1. Melatonin treatment effectively blocked RANKL-induced osteoclastogenesis by inhibiting PRMT1 and asymmetric dimethylarginine (ADMA) expression. RANKL-induced tumor necrosis factor receptor-associated factor 6 (TRAF6) and the phosphorylation of JNK were also suppressed by melatonin, and TRAF6 siRNA attenuated RANKL-induced p-JNK and PRMT1 production. Melatonin inhibited the transcriptional activity of NF-κB by interfering with the binding of PRMT1 and NF-κB subunit p65 in RANKL-treated bone marrow-derived macrophages. Our results also revealed that melatonin inhibits RANKL-induced PRMT1 expression through receptors-independent pathway. Thus, the anti-osteoclastogenic effect of melatonin was mediated by a cascade of inhibition of RANKL-induced TRAF6, JNK, PRMT1, and NF-κB signaling in melatonin receptors-independent pathway. In vivo, ovariectomy caused significant decreases in bone mineral density, but melatonin treatment alleviated the ovariectomized (OVX)-induced bone loss by inhibiting bone resorption. Furthermore, the expression PRMT1 and TRAP mRNA was upregulated in OVX-femurs, but effectively suppressed by melatonin injection. These findings suggest that melatonin inhibited osteoclast differentiation and estrogen deficiency-induced osteoporosis by suppressing RANKL-induced TRAF6, JNK, PRMT1, and NF-κB signaling cascades in melatonin receptors-independent pathway.

Evaluation of the Association of Early Implant Failure With Local, Environmental, and Systemic Factors: A Retrospective Study

PURPOSE

This study aimed to assess the association of early implant failure (EIF) with demographic, local, environmental, and systemic factors.

METHODS

Clinical charts of 594 individuals with 2,537 dental implants were assessed. EIF was characterized by implant loss before and up to the abutment connection. Logistic regression analysis was used to verify the association between EIF and local, environmental, and systemic factors at the individual and implant levels. The chosen level of significance was 5%.

RESULTS

EIF occurred in 144 implants (5.68%) and in 97 individuals (16.3%). At the individual level, smoking habits (odds ratio [OR] = 2.54; 95% confidence interval [CI] = 1.00 to 6.47; P = .05), absence of postoperative antibiotic therapy (OR = 2.73; CI = 1.22 to 6.13; P = .02), and bone augmentation (OR = 1.83; CI = 1.17 to 2.85; P = .01) were significantly associated with EIF. At the implant level, smoking habits (OR = 2.90; CI = 1.60 to 5.26, P < .001), absence of postoperative antibiotic therapy (OR = 2.77; CI = 1.36 to 5.63, P = .005), postoperative complications (OR = 28.35; CI = 6.79 to 118.45, P < .001), implant length ≤8.5 mm (OR = 1.79; CI = 1.07 to 2.99; P = .03), and diameter <3.75 mm (OR = 1.65; CI = 1.08 to 2.52, P = .02) were associated with EIF. Age, sex, alcohol abuse, diabetes, hypertension, and long-term medication use were not associated with EIF at both individual and implant levels (P ≥ .12).

CONCLUSIONS

Smoking habits, absence of antibiotic therapy, bone augmentation, postoperative complications, implant diameter <3.75 mm, and implant length ≤8.5 mm were associated with EIF. Clinicians should be aware of these associations that should be controlled for when feasible. Future cohort studies are required to confirm the risk factors.

Implant survival in patients with neuropsychiatric, neurocognitive, and neurodegenerative disorders: A meta-analysis

Neurologic disorders impede oral hygiene measures and routine clinical follow-up, along with the various drugs used may jeopardise oral health and the peri- implant tissue health. A total of 7 studies were considered eligible for the current systematic review. The overall estimated effect was categorized as significant where P < 0.05. Funnel plot was used to assess the publication bias within the studies. Difference in means was used as principal summary measure. P value <0.05 was considered as statistically significant. 1069 implants survived in test group and 4677 implants survived in control group (odds ratio: 2.58, 95% CI: 1.93-3.43) indicating significant success in patient without any disorders or taking medications for these disorders. Subgroup analysis was done to check the implant survival rate in patients taking selective serotonin reuptake inhibitors (SSRI) compared with SSRI non-users. Subgroup analysis showed that SSRI non-users had higher implant survival rate than patients taking SSRI (odds ratio: 2.45, 95% CI: 1.82-3.31). Serotonin significantly inhibits bone mineralization and osteoblast differentiation. The presence of any form of neuropsychiatric or neuromuscular disorders precludes proper oral hygiene and may contribute towards implant failure.

Clinical Decision Making for Primary Peri-Implantitis Prevention: Practical Applications

FOCUSED CLINICAL QUESTION

When planning dental implant therapy, what risk-reduction strategies allow practitioners to select patients, sites, and restorative plans that decrease the incidence of peri-implant disease?

SUMMARY

With a marked increase in the number of patients receiving dental implants to treat partial or complete edentulism, it follows that the prevalence of peri-implant mucositis and peri-implantitis have increased. Risks associated with implant therapies may vary based upon underlying local, environmental, surgical, patient, prosthetic, and fixture-related factors. Furthermore, an emphasis on preventative measures and maintenance should be undertaken to avoid development and progression of peri-implant diseases. Thorough risk assessment, proper treatment planning, and early diagnosis and intervention are critical in the absence of definitive data of long-term success of treatments for peri-implant condition. Given the difficulty in intervention once peri-implantitis is established, identification of risk factors and development of treatment plans to address those factors before dental implant therapy is critical to the long-term health and success of dental implants.

CONCLUSIONS

A patient-centered, evidence based approach to dental implant treatment planning to reduce the risk for peri-implantitis should be undertaken. Systematic diagnosis of disease state(s) and evaluation of the etiologic and modifying risk factors for peri-implant diseases can yield more optimal outcomes to reduce peri-implantitis rates.

Long-term follow-up of full-arch immediate implant-supported restorations in edentulous jaws: a clinical study

BACKGROUND

This study aims to show the long-time stability of straight and tilted implants loaded immediately with a provisional resin bridge followed by a definitive prosthodontic rehabilitation in edentulous jaws despite difficult hygiene conditions postoperatively.

RESULTS

This study included the participation of 23 patients and the restoration of 170 dental implants in 32 edentulous jaws. Patient data was analyzed from the start of treatment with a minimum follow-up period of 6 years in order to determine long-term implant success rates. However, the age of patients at time of surgery significantly affected the BOP to the detriment of younger patients (median 62 years old).

CONCLUSION

Although there was a higher risk of implant failure due to general disease, all the implants in this study survived successfully. As a replacement for a complete dental arch, the reduced number of implants in combination with the avoidance of augmentations reduces treatment costs. The immediate fixed prosthetic restoration of edentulous jaws thus represents a reliable therapeutic alternative to a two- to three-stage procedure. Optimized aftercare including professional teeth cleaning (PTC) (at least twice a year) can minimize the anamnestic effect of smoking, diabetes mellitus, and osteoporosis on BOP and possible bone loss.

Selective serotonin reuptake inhibitors (SSRI) affect murine bone lineage cells

AIMS

Data suggest pharmacological treatment of depression with selective serotonin reuptake inhibitors (SSRI) may impair bone health. Our group has previously modeled compromised craniofacial healing after treatment with sertraline, a commonly prescribed SSRI, and hypothesized potential culprits: alterations in bone cells, collagen, and/or inflammation. Here we interrogate bone lineage cell alterations due to sertraline treatment as a potential cause of the noted compromised bone healing.

MAIN METHODS

Murine pre-osteoblast, pre-osteoclast, osteoblast, and osteoclast cells were treated with clinically relevant concentrations of the SSRI. Studies focused on serotonin pathway targets, cell viability, apoptosis, differentiation, and the osteoblast/osteoclast feedback loop.

KEY FINDINGS

All cells studied express neurotransmitters (e.g. serotonin transporter, SLC6A4, SSRI target) and G-protein-coupled receptors associated with the serotonin pathway. Osteoclasts presented the greatest native expression of Slc6a4 with all cell types exhibiting decreases in Slc6a4 expression after SSRI treatment. Pre-osteoclasts exhibited alteration to their differentiation pathway after treatment. Pre-osteoblasts and osteoclasts showed reduced apoptosis after treatment but showed no significant differences in functional assays.

RANKL

OPG mRNA and protein ratios were decreased in the osteoblast lineage. Osteoclast lineage cells treated with sertraline demonstrated diminished TRAP positive cells when pre-exposed to sertraline prior to RANKL-induced differentiation.

SIGNIFICANCE

These data suggest osteoclasts are a likely target of bone homeostasis disruption due to sertraline treatment, most potently through the osteoblast/clast feedback loop.

Neural regulation of the contractility of nutrient artery in the guinea pig tibia

Nutrient arteries provide the endosteal blood supply to maintain bone remodelling and energy metabolism. Here, we investigated the distribution and function of perivascular nerves in regulating the contractility of the tibial nutrient artery. Changes in artery diameter were measured using a video tracking system, while the perivascular innervation was investigated using fluorescence immunohistochemistry. Nerve-evoked phasic constrictions of nutrient arteries were suppressed by phentolamine (1 μM), an α-adrenoceptor antagonist, guanethidine (10 μM), a blocker of sympathetic transmission, or fluoxetine (10 μM), a serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitor. In arteries pretreated with guanethidine, residual nerve-evoked constrictions were abolished by a high concentration of propranolol (10 μM) that is known to inhibit 5-HT receptors, or ketanserin (100 nM), a 5-HT₂ receptor antagonist, but not SB207216 (1 μM), an antagonist of 5-HT₃ and 5-HT₄ receptors. Bath-applied 5-HT (100 nM) induced arterial constriction that was suppressed by propranolol (10 μM) or ketanserin (100 nM). Nerve-evoked arterial constrictions were enhanced by spantide (1 μM), a substance P (SP) receptor antagonist, or L-nitro arginine (L-NA; 100 μM), an inhibitor of nitric oxide synthase (NOS). Immunohistochemistry revealed 5-HT-positive nerves running along the arteries that are distinct from perivascular sympathetic or substance P-positive primary afferent nerves. For the first time, functional serotonergic nerves are identified in the tibial nutrient artery of the guinea pig. Thus, it appears that tibial nutrient arterial calibre is regulated by the balance between sympathetic and serotonergic vasoconstrictor nerves and vasodilator afferent nerves that release substance P-stimulating endothelial nitric oxide (NO) release.

The teratogenic effects of sertraline in mice

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs), which include paroxetine (Paxil), sertraline (Zoloft), fluoxetine (Prozac), citalopram (Celexa), and escitalopram (Lexapro), are the most common antidepressants prescribed to pregnant women. There is considerable debate in the literature regarding the developmental toxicities of SSRIs individually, and as a class.

METHODS

It is considered unethical to perform developmental toxicity studies on pregnant women, but rodent and nonrodent species provide laboratory-controlled experimental models to examine the toxicity of SSRI exposure during pregnancy. The Embryo-Fetal Developmental Toxicity Study was conducted with sertraline in mice, Crl:CD1 (lCR), during the period of organogenesis.

RESULTS

Increased resorption rates, lower fetal weight, and increased percentage of fetuses with visceral and skeletal abnormalities were found in the intermediate and high sertraline dose groups. In addition to incomplete ossification of treated animals, eleven sertraline exposed fetuses, two in group 2 (5 mg/kg), five in group 3 (25 mg/kg), and four in group 4 (60 mg/kg), had cleft palate (CP). This malformation was not observed in any controls. Only the highest dose of sertraline was found to be maternally toxic, as evidenced by significantly lower weight gain during pregnancy.

CONCLUSION

These data indicate that in utero exposure to sertraline at 25 and 60 mg/kg was embryotoxic, teratogenic, and fetotoxic in mice. The incidence of CP observed in groups 3 and 4 (2.99% and 2.5%, respectively) were higher than the maximum range value noted in historical controls and indicate sertraline is a teratogen in ICR mice.

The effect of selective serotonin reuptake inhibitors on the human mandible

OBJECTIVES

Selective serotonin reuptake inhibitors (SSRI) are a group of drugs that selectively and strongly block the serotonin transporter. Aim of this study was to evaluate the mandibular bone structure of patients who are using SSRIs with fractal analysis and panoramic morphometric indices [mandibular cortical width (MCW), panoramic mandibular index (PMI) and Klemetti index (KI)] and to compare with control group.

METHODS

Patients who declared using SSRIs for more than six months had been included in the study group. In total, 212 dental panoramic radiographs (DPR) were assessed. For fractal analysis; three regions of interest (ROIs) were determined: ROI1 and ROI2 were chosen within trabecular bone, ROI3 was selected from cortical bone. MCW, PMI, and KI were obtained from DPRs. The study group was categorized into five subgroups of various SSRIs. The fractal dimension (FD) values and panoramic morphometric indices of these subgroups were also compared.

RESULTS

There was no significant difference between the groups for age and gender (p = 0.57, p = 0.5). There were significant differences in the mean FD values between the study and control groups both for the ROI1 and ROI2 (p < 0.01, p < 0.01). There was no significant difference between the groups for the mean FD value of ROI3, MCW, PMI and KI (p = 0.93, p = 0.98, p = 0.74, p = 0.06). There were no significant differences for all the values between the SSRI subgroups (p = 0.52, p = 0.7, p = 0.76, p = 0.24, p = 0.31, p = 0.08) CONCLUSIONS: Trabecular rich sites of the mandible were found to be affected by SSRI usage.

Breast Cancer: Lifestyle, the Human Gut Microbiota/Microbiome, and Survivorship

Patients with a current diagnosis of breast cancer are enjoying dramatic cure rates and survivorship secondary to an increase in awareness, earlier detection, and more effective therapies. Although strategies such as Breast Cancer Awareness Month in October focus on early detection, lifestyle changes are seldom discussed other than dietary concerns and physical activity. Lifestyle modifications centered on diet and exercise have been demonstrated to affect overall disease-free survival in breast cancer. Since the early 2000s, the role of the human gut microbiota and its relation to breast cancer has become a major area of interest in the scientific and medical community. We live and survive owing to the symbiotic relationship with the microorganisms within us: the human microbiota. Scientific advances have identified a subset of the gut microbiota: the estrobolome, those bacteria that have the genetic capability to metabolize estrogen, which plays a key role in most breast cancers. Recent research provides evidence that the gut microbiome plays a substantial role in estrogen regulation. Gut microbiota diversity appears to be an essential component of overall health, including breast health. Future research attention should include a more extensive focus on the role of the human gut microbiota in breast cancer.

Selective Serotonin Reuptake Inhibitor Use and Hip Fracture Risk Among Patients on Hemodialysis

RATIONALE & OBJECTIVE

Use of selective serotonin reuptake inhibitors (SSRIs) has been associated with hip fracture risk in the general population. This study examined this relationship among patients with kidney failure treated by hemodialysis, a unique high-risk subpopulation, within which the impact of SSRIs on hip fracture risk remains unexplored.

STUDY DESIGN

Case-control study.

SETTINGS & PARTICIPANTS

Eligible cases of hip fracture among maintenance hemodialysis patients between January 1, 2009, and September 30, 2015, were identified using the US Renal Data System. Each case was matched on index date with 10 eligible controls. To be eligible, study participants needed to have more than 1 year of Medicare Parts A and B coverage and more than 3 years of Part D coverage. For a separate examination of new short-term SSRI exposure, we selected cases and controls with more than 18 months of Part D coverage and no prior antidepressant use for 1 year.

EXPOSURE

During the 3-year Part D coverage period, use of SSRIs characterized as any (≥1 prescription filled), low, moderate, and high use (<20%, 20%-<80%, and≥80% of days covered by filled prescriptions, respectively).

OUTCOME

We selected cases using International Classification of Diseases, Ninth Revision codes 820.xx and 821.xx. In addition to 1 of these codes tied to a hospitalization, we required a corresponding surgical procedural code within 7 days of diagnosis.

ANALYTIC APPROACH

Conditional logistic regression to estimate unadjusted and multivariable-adjusted ORs and 95% CIs.

RESULTS

We identified 4,912 cases and 49,120 controls. SSRI use was associated with increased hip fracture risk (adjusted OR, 1.25; 95% CI, 1.17-1.35). Risk for fracture was estimated for any, low, moderate, and high SSRI use: adjusted conditional ORs were 1.25 (95% CI, 1.17-1.35), 1.20 (95% CI, 1.08-1.32), 1.31 (95% CI, 1.18-1.43), and 1.26 (95% CI, 1.12-1.41), respectively. The association between hip fracture events and SSRI use was also seen in the examination of new short-term use (adjusted OR, 1.43; 95% CI, 1.23-1.67).

LIMITATIONS

Biomarkers of mineral bone disorder were not captured and accounted for in this analysis.

CONCLUSIONS

We demonstrated an association between increased hip fracture risk and both long- and new short-term SSRI use. The stronger association with new short-term use may suggest an acute mechanism potentially related to falls.

The effects of tranylcypromine on osteoclastogenesis in vitro and in vivo

Identification of anti-osteoclastogenic agents is important for the treatment of bone loss diseases that feature excessive osteoclast (OC) activity and bone resorption. Tranylcypromine (TCP), an irreversible inhibitor of monoamine oxidase (MAO), has been used as an antidepressant and anxiolytic agent in the clinical treatment of mood and anxiety disorders. TCP has been discovered to exert anabolic effect on osteoblasts, and MAO-A has also been verified as an important mediator in prostate cancer cells to accelerate osteoclastogenesis. In current study, we were focused on TCP and MAO-A effects on osteoclastogenesis. As illustrated by tartrate-resistant acid phosphatase staining, TCP was capable of inhibiting osteoclastogenesis induced by receptor activators of the NF-κB ligand (RANKL) in bone marrow-derived macrophage cells without any cytotoxicity. It was also shown to effectively suppress bone resorption of OCs. The subsequent study revealed that TCP inhibited osteoclastogenesis-related genes in a time-dependent manner through protein kinase B (AKT)-mediated mechanism followed by the nuclear factor of activated T cells, cytoplasmic 1 (NFATc1)-c-fos pathway. And TCP could overcome the osteoclastogenic effects of AKT activator SC79. In addition, our results indicated that the expression and catalytic activity of MAO-A were up-regulated by RANKL stimulation and down-regulated by TCP in vitro and in vivo. Furthermore, the effects of MAO-A knockdown on OC differentiation indicated that MAO-A played an important role in osteoclastogenesis in vitro and might contribute to the inhibitory effects of TCP. And AKT, NFATc1, and c-fos were involved in the MAO-A pathway. Notably, our in vivo study reflected that TCPs were capable of restoring the bone loss in LPS-induced calvaria osteolysis and estrogen deficiency-induced osteoporosis models. Thus, our current work provided a potential option for the treatment of bone loss diseases and highlighted the important role of MAO-A in osteoclastogenesis as well.-Liu, Z., Yang, K., Yan, X., Wang, T., Jiang, T., Zhou, Q., Qi, J., Qian, N., Zhou, H., Chen, B., Huang, P., Guo, L., Zhang, X., Xu, X., Jiang, M., Deng, L. The effects of tranylcypromine on osteoclastogenesis in vitro and in vivo.

Serotonin and orthodontic tooth movement

Peripheral serotonin continuously reveals its unexpected involvements in many organ functions. In bone tissue, there is an increasing evidence for a local serotonergic system affecting the cellular and molecular actors involved in bone turnover. During orthodontic treatment, tooth movement relies on bone remodeling, itself a result of the inflammatory process triggered by application of orthodontic forces to the teeth. Nowadays, many adults proceed to an orthodontic treatment, it therefore seems important to consider physiological growth-related factors and external factors as medications that may influence adverse effects and efficacy of orthodontic treatment techniques. In this review, we focus on peripheral serotonin mechanism of regulation of bone remodeling during orthodontic movement. We discuss the differential effect of serotonin on alveolar bone inflammation that may open new strategies in orthodontics.

Impact of selective serotonin reuptake inhibitors in the veteran population: 10-year risk outcomes

AIM

To evaluate the comparative risk of hip fracture or osteoporosis among US Veterans based on selective serotonin reuptake inhibitor (SSRI) exposure.

PATIENTS & METHODS

A retrospective cohort study of eligible US Veterans Health Administration patients enrolled in 2003-2004 was performed to examine SSRIs' 2-, 5- and 10-year impact on bone health using multiple logistic regression.

RESULTS

Veterans on SSRIs were found to be 56.7% more likely over a 10-year period to suffer a hip fracture (risk ratio: 1.567; 95% CI: 1.464-1.676) and 34.6% more likely to develop osteoporosis (risk ratio: 1.346; 95% CI: 1.319-1.374) when compared with those who were SSRI naive.

CONCLUSION

SSRI usage was associated with greater risk of hip fracture and osteoporosis over a 10-year period in the veteran population, with similar effect sizes to smaller studies.

Medication-related dental implant failure: Systematic review and meta-analysis

OBJECTIVES

The aim of this systematic review was to investigate the association between the intake of systemic medications that may affect bone metabolism and their subsequent impact on implant failures.

MATERIAL AND METHODS

Electronic and manual literature searches were conducted. Implant failure (IF) was the primary outcome, while biological/mechanical and the causes/timing associated with IF were set as secondary outcomes. Meta-analyses for the binary outcome IF and odds ratio were performed to investigate the association with medications.

RESULTS

A final selection of 17 articles was screened for qualitative assessment. As such, five studies focused on evaluating the association of implant failure and non-steroidal anti-inflammatory drugs (NSAIDs), two on selective serotonin reuptake inhibitors (SSRIs), two on proton pump inhibitors (PPIs), seven on bisphosphonates (BPs), and one on anti-hypertensives (AHTNs). For PPIs, the fixed effect model estimated a difference of IF rates of 4.3%, indicating significantly higher IF rates in the test compared to the control group (p < 0.5). Likewise, for SSRIs, the IF was shown to be significantly higher in the individuals taking SSRIs (p < 0.5) as estimated a difference of 7.5%. No subset meta-analysis could be conducted for AHTNs medications as only one study fulfilled the inclusion criteria, which revealed an increased survival rate of AHTN medication. None of the other medications yielded significance.

CONCLUSIONS

The present systematic review showed an association of PPIs and SSRIs with an increased implant failure rate. Hence, clinicians considering implant therapy should be aware of possible medication-related implant failures.

Impacts of Psychological Stress on Osteoporosis: Clinical Implications and Treatment Interactions

The significant biochemical and physiological effects of psychological stress are beginning to be recognized as exacerbating common diseases, including osteoporosis. This review discusses the current evidence for psychological stress-associated mental health disorders as risk factors for osteoporosis, the mechanisms that may link these conditions, and potential implications for treatment. Traditional, alternative, and adjunctive therapies are discussed. This review is not intended to provide therapeutic recommendations, but, rather, the goal of this review is to delineate potential interactions of psychological stress and osteoporosis and to highlight potential multi-system implications of pharmacological interventions. Review of the current literature identifies several potentially overlapping mechanistic pathways that may be of interest (e.g., glucocorticoid signaling, insulin-like growth factor signaling, serotonin signaling) for further basic and clinical research. Current literature also supports the potential for cross-effects of therapeutics for osteoporosis and mental health disorders. While studies examining a direct link between osteoporosis and chronic psychological stress are limited, the studies reviewed herein suggest that a multi-factorial, personalized approach should be considered for improved patient outcomes in populations experiencing psychological stress, particularly those at high-risk for development of osteoporosis.

Evaluation of jawbone morphology and bone density indices in panoramic radiographs of selective serotonin reuptake inhibitor users: a preliminary study

OBJECTIVES:

To assess the influence of selective serotonin reuptake inhibitor (SSRI) use on jawbone and bone mineral density by retrospective analysis of panoramic radiographs.

METHODS:

Radiographic and clinical records were sourced from the Division of Orthodontics and TMJD, Eastman Institute for Oral Health, University of Rochester. Randomly selected adults (20-65 years) were categorized into: "Active" (with history of SSRI use of >6 months) and a "Control" group. Panoramic indices: Klemetti index (KI), panoramic mandibular index, antegonial notching index, condylar pathology, mandibular cortical width (MCW)⁠ and mean ramus height were recorded. Frequency-weighted Χ2 tests and multinomial regression controlling for age and gender were applied to categorical indices (KI, condylar pathology, antegonial notching index). Multivariate generalized linear modeling was applied to mean ramus height, MCW and panoramic mandibular index. Multiple regression analyses determined: (a) panoramic indices that best predicted SSRI use, and (b) independent predictors of KI category.

RESULTS:

64 SSRI users and 48 Controls were assessed. SSRI users had significantly higher odds of having worse KI status than normal [mildly to moderately eroded cortex: odds ratio (OR) = 2.926, 95% CI (1.07-8.04) and severely eroded cortex: OR = 19.86, 95% CI (3.91-100.69)], more frequent flat condylar anatomy (right side: p = 0.009, left side: p < 0.001) but greater ramus height (p = 0.001) and mandibular cortical width (p = 0.032). Age, gender, SSRI use each significantly impacted KI. Only SSRI use significantly impacted condylar pathology, ramus height and MCW. KI category (OR = 1.3) was the best panoramic predictor of SSRI use. Conversely, KI category C3 was significantly predicted by SSRI use (OR = 31.2, p = 0.002), female gender (17.5, p = 0.006), and severe antegonial notching (OR = 1289, p < 0.001).

CONCLUSIONS:

SRRI use was significantly associated with worse panoramic morphometric indices: KI, condylar pathology, ramus height, and MCW, where KI was its strongest predictor. Worse KI was independently predicted by SSRI use.

Peripartum dietary supplementation of a small-molecule inhibitor of tryptophan hydroxylase 1 compromises infant, but not maternal, bone

Long-term effects of breastfeeding on maternal bone are not fully understood. Excessive maternal bone loss stimulated by serotonin signaling during lactation may increase bone fragility later in life. We hypothesized that inhibiting nonneuronal serotonin activity by feeding a small-molecule inhibitor of the rate-limiting enzyme in serotonin synthesis [tryptophan hydroxylase 1 (TPH1)] would preserve maternal bone postweaning without affecting neonatal bone. Chow supplemented with the small-molecule TPH1 inhibitor LP778902 (~100 mg/kg) or control chow was fed to C57BL/6 dams throughout pregnancy and lactation, and blood was collected on days 1 and 21 of lactation. Dams returned to a common diet postweaning and were aged to 3 or 9 mo postweaning. Pups were euthanized at weaning. The effect of TPH1 inhibition on dam and pup femoral bone was determined by micro-computed tomography. Peripartum dietary supplementation with LP778902 decreased maternal serum serotonin concentrations ( P = 0.0007) and reduced bone turnover, indicated by serum NH2-terminal propeptide of type I collagen ( P = 0.01) and COOH-terminal collagen cross-links ( P = 0.02) concentrations, on day 21 of lactation. Repressed bone turnover from TPH1 inhibition was not associated with structural changes in maternal femur at 3 or 9 mo postweaning. By contrast, neonates exposed to peripartum LP778902 demonstrated differences in trabecular and cortical femoral bone compared with pups from control dams, with fewer ( P = 0.02) and thinner ( P = 0.001) trabeculae as well as increased trabecular spacing ( P = 0.04). Additionally, cortical porosity was increased ( P = 0.007) and cortical tissue mineral density was decreased ( P = 0.005) in pups of LP778902-treated dams. Small-molecule TPH1 inhibitors should be carefully considered in pregnant and lactating women, given potential risks to neonatal bone development.

The effects of fluoxetine on the human adipose-derived stem cell proliferation and differentiation

Fluoxetine is one of the most commonly used antidepressants. Fluoxetine could prevent the mesenchymal stem cell differentiation in lung fetus of rat. Moreover, the mesenchymal stem cells are also present in adult tissues. Therefore, in the current study, we aimed to investigate the effects of fluoxetine (FLX) on both proliferation and adipogenic/osteogenic differentiation of human adipose-derived stem cells (ADSCs). After culturing of human ADSCs, these cells were treated with two concentrations of FLX (10 and 20 μm). Then, cells were differentiated by adding osteogenic and adipogenic media. The effect of FLX on human ADSCs proliferation was evaluated by MTT assay. Fluoxetine role on adipogenic and osteogenic differentiation of human ADSCs was analyzed by oil red and alizarin red staining and RT-PCR reaction. According to MTT assay, FLX showed a time- and concentration-dependent proliferation response and eventually decreased human ADSCs proliferation. RT-PCR analysis indicated that FLX significantly diminished the expression of osteogenesis-related genes such as RUNX2 and alkaline phosphatase (ALP). Data also revealed a significant reduction in the expression of peroxisome proliferator-activated receptor γ (PPARγ) and fatty acid-binding protein (FABP) (specific genes of adipogenic lineage). In addition, FLX decreased mineralized matrix and the amount of lipid droplets in human ADSCs by staining methods. Our observation demonstrated that the effects of FLX may be time-dependent. This drug possesses an increasing phase in proliferation and survival of human ADSCs (first 24 h) following a decreasing phase (after 48 h). Moreover, FLX could attenuate both osteogenic and adipogenic differentiation of human ADSCs.

Does the Intake of Selective Serotonin Reuptake Inhibitors Negatively Affect Dental Implant Osseointegration? A Retrospective Study

The success of osseointegration is influenced by several factors that affect bone metabolism and by certain systemic medications. Selective serotonin reuptake inhibitors (SSRIs) have been previously suggested to be among these medications. This study aims to investigate the association between systemic intake of SSRIs and failure of osseointegration in patients rehabilitated with dental implants. A retrospective cohort study was conducted, including a total of 2055 osseointegrated dental implants in 631 patients (109 implants in 36 SSRI \users and 1946 in 595 nonusers). Predictor and outcome variables were SSRI intake and osseointegration failure, respectively. The data were analyzed with Mann–Whitney test or Fisher exact test accordingly. Both patient-level and implant-level models were implemented to evaluate the effect of SSRI exposure on the success of osseointegration of dental implants. Median duration of follow-up was 21.5 months (range = 4–56 months) for SSRI users and 23 months (range –60 months) for nonusers (P = .158). Two of 36 SSRI users had 1 failed implant each; thus, the failure rate was 5.6%. Eleven nonusers also had 1 failed implant each; thus, the failure rate was 1.85%. The difference between the 2 groups failed to reach statistical significance at patient and implant levels (P = .166, P = .149, respectively). The odds of implant failure were 3.123 times greater for SSRI users compared with nonusers. Patients using SSRIs were found to be 3.005 times more likely to experience early implant failure than nonusers. The results of this study suggest that SSRIs may lead to increase in the rate of osseointegration failure, although not reaching statistical significance.

LP533401 restores bone health in 5/6 nephrectomized rats by a decrease of gut-derived serotonin and regulation of serum phosphate through the inhibition of phosphate co-transporters expression in the kidneys

LP533401 is an orally bioavailable small molecule that inhibits tryptophan hydroxylase-1, an enzyme responsible for the synthesis of gut-derived serotonin (GDS). Recently, we showed that increased GDS in rats with chronic kidney disease (CKD) affected bone strength and metabolism. We tested the hypothesis that treatment with LP533401 could reverse CKD-induced bone loss in uremia. Sixteen weeks after 5/6 nephrectomy, rats were randomized into untreated (CKD), treated with vehicle (VEH) and LP533401 at a dose of 30 or 100 mg/kg daily for 8 weeks. Treatment with LP533401 decreased serotonin turnover and restored bone mineral status, microarchitecture, and strength in CKD rats to the values observed in the controls. In parallel with the reduction of serotonin, serum phosphate levels also decreased, particularly in the LP533401, 100 mg/kg group. The mechanism underlying this phenomenon resulted from decreased expression of the renal VDR/FGF1R/Klotho/Npt2a/Npt2c axis, leading to elevated phosphate excretion in the kidneys. The elevated urinary phosphate excretion resulted in improved bone mineral status and strength in LP533401-treated rats. Unexpectedly, the standard VEH used in this model was able to reduce renal VDR/FGF1R/Klotho/Npt2a expression, leading to a compensatory increase in Npt2c mRNA levels, secondary disturbances in phosphate-regulated hormones and partial improvement in the mineral status of the trabecular bone. The decrease of serotonin synthesis together with the simultaneous reduction of renal Npt2a and Npt2c expression in rats treated with LP533401, 100 mg/kg led to an increase in 1,25(OH)₂D₃ levels; this mechanism seems to be particularly beneficial in relation to the mineral status of cortical bone.

Metabolism of Phenolic Compounds in LPS-stimulated Raw264.7 Cells Can Impact Their Anti-inflammatory efficacy: Indication of Hesperetin

Raw264.7 is a murine macrophage-like cell line commonly used to study the anti-inflammatory efficacy of natural compounds. However, the impacts of long-time incubation on the tested compounds are often inappropriately ignored. Among 77 natural phenolic compounds (mainly flavonoids), only 36 remain more than 70% after a 15-h incubation in cell culture medium at 37 °C. Interestingly, for those compounds with a relatively good chemical stability, the presence of Raw264.7 cells could accelerate their disappearance in the medium, indicating that cellular metabolism occurred. As a representative phenolic, hesperetin was found to be efficiently metabolized by Raw264.7 cells and the metabolite was identified as a glucuronide in the further investigation. The glucuronidation activity is constitutive in this cell line. At certain concentration levels of hesperetin, the ability of hesperetin to inhibit PGD₂ production in LPS-induced Raw264.7 cells was significantly enhanced by introducing β-glucuronidase, which can hydrolyze hesperetin glucuronide, into the incubation medium. The results indicate that glucuronidation and excretion of hesperetin can significantly impact its bioactivity in Raw264.7 cells.

Serotonin in the gut: Blessing or a curse

Serotonin (5-hydroxytryptamine or 5-HT) once most extensively studied as a neurotransmitter of the central nervous system, is seen to be predominantly secreted in the gut. About 95% of 5-HT is estimated to be found in gut mainly within the enterochromaffin cells whereas about 5% is found in the brain. 5-HT is an important enteric signaling molecule and is well known for playing a key role in sensory-motor and secretory functions in the gut. In recent times, studies uncovering various new functions of gut-derived 5-HT indicate that many more are yet to be discovered in coming days. Recent studies revealed that 5-HT plays a pivotal role in immune cell activation and generation/perpetuation of inflammation in the gut. In addition to its various roles in the gut, there are now emerging evidences that suggest an important role of gut-derived 5-HT in other biological processes beyond the gut, such as bone remodeling and metabolic homeostasis. This review focuses to briefly summarize the accumulated and newly updated role of 5-HT in the maintenance of normal gut physiology and in the pathogenesis of inflammation in the gut. The collected information about this multifaceted signaling molecule may aid in distinguishing its good and bad effects which may lead to the development of novel strategies to overcome the unwanted effect, such as in inflammatory bowel disease.

Serum serotonin levels and bone in rheumatoid arthritis patients

In rheumatoid arthritis (RA), a disease characterized by bone loss, increased levels of serotonin have been reported. Recent studies have demonstrated a role for circulating serotonin as a regulator of osteoblastogenesis, inhibiting bone formation. Thus, we measured serum serotonin levels (SSL) in a Portuguese sample of 205 RA patients and related these to anthropometric variables, disease parameters, serum bone biomarkers, and bone mineral density (BMD) assessed by dual-energy X-ray absorptiometry at several sites (total proximal femur, lumbar spine, left hand, and left second proximal phalange). SSL were inversely associated with body mass index (BMI) in RA women (r = - 0.218; p = 0.005), independent of exposure to biologics and/or bisphosphonates. Among biologic naïves, there was an inverse association between SSL and osteoprotegerin in RA women (r = - 0.260; p = 0.022). Serum β-CTX and dickkopf-1 were strongly associated with SSL in RA men not treated with bisphosphonates (r = 0.590; p < 0.001/r = 0.387; p = 0.031, respectively). There was also an inverse association between SSL and sclerostin in RA men (r = - 0.374; p < 0.05), stronger among biologic naïve or bisphosphonates-unexposed RA men. In crude models, SSL presented as a significant negative predictor of total proximal femur BMD in RA women as well as in postmenopausal RA women. After adjustment for BMI, disease duration, and years of menopause, SSL remained a significant negative predictor of total proximal femur BMD only in postmenopausal RA women. Our data reinforce a role, despite weak, for circulating serotonin in regulating bone mass in RA patients, with some differences in terms of gender and anatomical sites.

Intestinal microbiota: a potential target for the treatment of postmenopausal osteoporosis

Postmenopausal osteoporosis (PMO) is a prevalent metabolic bone disease characterized by bone loss and structural destruction, which increases the risk of fracture in postmenopausal women. Owing to the high morbidity and serious complications of PMO, many efforts have been devoted to its prophylaxis and treatment. The intestinal microbiota is the complex community of microorganisms colonizing the gastrointestinal tract. Probiotics, which are dietary or medical supplements consisting of beneficial intestinal bacteria, work in concert with endogenous intestinal microorganisms to maintain host health. Recent studies have revealed that bone loss in PMO is closely related to host immunity, which is influenced by the intestinal microbiota. The curative effects of probiotics on metabolic bone diseases have also been demonstrated. The effects of the intestinal microbiota on bone metabolism suggest a promising target for PMO management. This review seeks to summarize the critical effects of the intestinal microbiota and probiotics on PMO, with a focus on the molecular mechanisms underlying the pathogenic relationship between bacteria and host, and to define the possible treatment options.

Is the intake of selective serotonin reuptake inhibitors associated with an increased risk of dental implant failure?

The aim of this retrospective study was to investigate the association between the intake of selective serotonin reuptake inhibitors (SSRIs) and the risk of dental implant failure. Patients were included if they were taking SSRIs only and no other medication, did not present any other systemic condition or compromising habits (bruxism, smoking, snuff), and complied with the use of prophylactic antibiotics for implant surgery. The multivariate generalized estimating equation (GEE) method and multilevel mixed-effects parametric survival analysis were used to test the association between SSRI exposure (predictor variable) and the risk of implant failure (outcome variable), adjusting for several potential confounders (other variables). The total number of implants with information available and meeting the necessary eligibility criteria was 931 (35 failures). These were placed in 300 patients. The implant failure rate was 12.5% for SSRI users and 3.3% for non-users (P=0.007). Kaplan-Meier analysis showed a statistically significant difference in the cumulative survival rate (P<0.001). The multivariate GEE model did not show a statistically significant association between SSRI intake and implant failure (P=0.530), nor did the multilevel model (P=0.125). It is suggested that the intake of SSRIs may not be associated with an increased risk of dental implant failure.

The Diverse Metabolic Roles of Peripheral Serotonin

Serotonin (5-hydroxytryptamine or 5-HT) is a multifunctional bioamine with important signaling roles in a range of physiological pathways. Almost all of the 5-HT in our bodies is synthesized in specialized enteroendocrine cells within the gastrointestinal (GI) mucosa called enterochromaffin (EC) cells. These cells provide all of our circulating 5-HT. We have long appreciated the important contributions of 5-HT within the gut, including its role in modulating GI motility. However, evidence of the physiological and clinical significance of gut-derived 5-HT outside of the gut has recently emerged, implicating 5-HT in regulation of glucose homeostasis, lipid metabolism, bone density, and diseases associated with metabolic syndrome, such as obesity and type 2 diabetes. Although a new picture has developed in the last decade regarding the various metabolic roles of peripheral serotonin, so too has our understanding of the physiology of EC cells. Given that they are scattered throughout the lining of the GI tract within the epithelial cell layer, these cells are typically difficult to study. Advances in isolation procedures now allow the study of pure EC-cell cultures and single cells, enabling studies of EC-cell physiology to occur. EC cells are sensory cells that are capable of integrating cues from ingested nutrients, the enteric nervous system, and the gut microbiome. Thus, levels of peripheral 5-HT can be modulated by a multitude of factors, resulting in both local and systemic effects for the regulation of a raft of physiological pathways related to metabolism and obesity.