The atypical anti-psychotic clozapine decreases bone mass in rats in vivo

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.

Does clozapine really affect bone mineral density? An experimental study

Purpose

The aim of this study was to investigate the effect of clozapine use on bone tissue by applying computerized tomography, dual-energy X-ray absorptiometry, and histological and biomechanical analyses in an experimental rat model.

Methods

Sixteen female Wistar Albino rats were included in this study. These animals were divided into two groups: the control group and the clozapine group. The animals in the clozapine group received 10 mg/kg clozapine, and the animals in the control group received tap water by oral gavage daily for 28 days. After sacrification, the femurs of the rats were used for radiologic, histologic, dual-energy X-ray absorptiometry, and biomechanical evaluations.

Results

Although the mean values of the clozapine group were higher in terms of histological, bone mineral density, and biomechanical evaluations, the statistical analyses were not significantly different.

Conclusion

Clozapine use did not affect bone density in the rats. Clozapine can be the preferred treatment for patients with schizophrenia to avoid osteoporosis. It will be necessary to conduct further long-term follow-up and controlled studies in animals and humans to confirm these findings.

Factors That Predict 1-Year Incident Hip and Non-Hip Fractures for Home Care Recipients: A Linked-Data Retrospective Cohort Study

OBJECTIVES

The purpose of our study was to identify factors that predict 1-year incident hip and major osteoporotic non-hip fractures (ie, wrist, spine, pelvis, humerus) for home care recipients while accounting for the competing risk of death.

DESIGN

We conducted a retrospective cohort study with linked population data.

SETTING AND PARTICIPANTS

All home care recipients in Ontario, Canada, receiving services for more than 6 months with an admission assessment between April 1, 2011, and March 31, 2015, were included.

METHODS

Clinical data from the Resident Assessment Instrument Home Care were linked to fracture data from the Discharge Abstract Database and the National Acute Care Reporting System. Competing risk proportional hazard regressions using the Fine and Grey method were performed to model the association between potential risk factors and fracture.

RESULTS

Previous fall, previous fracture, cognitive impairment, unsteady gait, alcohol use, tobacco use, and Parkinson disease were consistently associated with all fracture types. Cognitive impairment (hazard ratio 2.09; 95% confidence interval 1.86-2.36) and wandering [1.66 (1.06-1.27)] were most predictive of hip fractures and being female [1.86 (1.76-1.98)] and experiencing a previous fracture [1.86 (1.76-1.98)] were most predictive of non-hip fractures. Risk factors unique to non-hip fractures as compared with hip fractures were locomotion ability outdoors and psychotropic medication use.

CONCLUSIONS AND IMPLICATIONS

Our results indicate that, in addition to typical fracture risk factors, home care recipients have unique characteristics that increase their risk. Fracture risk assessment tools and subsequent prevention strategies should be modified to accurately identify home care recipients at risk for imminent 1-year fracture.

Atypical antipsychotics induce human osteoblasts apoptosis via Wnt/β-catenin signaling

Background

There is evidence that atypical antipsychotics (APs) increase risk of osteoporosis in schizophrenia patients, however the mechanism is unclear. The aim of the study was to explore the molecular mechanisms about Wnt/β-catenin signal pathway underlying the osteal side effects of APs.

Methods

We cultured human osteoblast cell line hFob1. 19 (OB) treatments with olanzapine, risperidone, amisulpride, aripiprazole or resveratrol in vitro. OB cells viability was detected by cell viability assay. OB cells apoptosis was analyzed by flow cytometry (FCM). Further apoptosis-related marker and β-catenin expression was analyzed by Western blot and Immunofluorescence analysis.

Results

Compared with the control group, proliferation of OB cells decreased and apoptosis rates of OB cells increased significantly in APs group (p < 0.05). There were a reduced level of Bcl-2, Mcl-1 (antiapoptotic marker) and an elevated level of Bax, Cleaved-Caspase3 (proapoptotic marker) in APs group (p < 0.05). Simultaneously, β-catenin expression decreased in cytoplasm and nucleus (p < 0.05). Compared with the just APs group, the apoptosis rates decreased and β-catenin expression increased significantly in resevratrol combined with APs group (p < 0.05). Correlation analysis showed positive correlation between β-catenin expression and the apoptotic rate in OB cells (r = − 0.515, p < 0.05).

Conclusions

APs cause OB cells apoptosis relating to Wnt/β-catenin signaling while resevratrol could reverse this phenomenon. Our study could lay the foundation for overcoming the APs-induced osteal side effects to improve the life quality of schizophrenia patients.

Antipsychotic drug exposure and risk of fracture: a systematic review and meta-analysis of observational studies

To investigate the extent to which exposure to first-generation and second-generation antipsychotics (APs) is associated with an increased risk of fractures, with a particular focus on hip fractures, and to ascertain the risk associated with exposure to individual drugs. We included observational studies that reported data on fractures in individuals exposed to APs compared with unexposed individuals or individuals with previous exposure. We extracted information on study design, source of data, population characteristics, outcomes of interest, matching and confounding factors, and used a modified version of the Newcastle-Ottawa Scale to judge study risk of bias. We pooled adjusted estimates of relative effects to generate pooled odds ratios (ORs) and their 95% confidence interval (CI) using a random-effects model. We rated the quality of evidence using the GRADE approach. Of 36 observational studies, 29 proved to have a low risk of bias and seven were found to have a high risk of bias. The risk of hip fracture (OR: 1.57, 95% CI: 1.42-1.74, low quality of evidence) and of any fracture (OR: 1.17, 95% CI: 1.04-1.31, very low quality of evidence) increased with exposure to APs, with similar increases in risk in the first generation and second generation. The risk was similar among different diagnostic categories. The few studies that provided data were insufficient to allow inferences on individual drugs. AP exposure in unselected populations was associated with a 57% increase in the risk of hip fractures and a 17% increase in the risk of any fractures. Between-study heterogeneity limits the confidence in this estimate.

Access to the CNS: Biomarker Strategies for Dopaminergic Treatments

Despite substantial research carried out over the last decades, it remains difficult to understand the wide range of pharmacological effects of dopaminergic agents. The dopaminergic system is involved in several neurological disorders, such as Parkinson's disease and schizophrenia. This complex system features multiple pathways implicated in emotion and cognition, psychomotor functions and endocrine control through activation of G protein-coupled dopamine receptors. This review focuses on the system-wide effects of dopaminergic agents on the multiple biochemical and endocrine pathways, in particular the biomarkers (i.e., indicators of a pharmacological process) that reflect these effects. Dopaminergic treatments developed over the last decades were found to be associated with numerous biochemical pathways in the brain, including the norepinephrine and the kynurenine pathway. Additionally, they have shown to affect peripheral systems, for example the hypothalamus-pituitary-adrenal (HPA) axis. Dopaminergic agents thus have a complex and broad pharmacological profile, rendering drug development challenging. Considering the complex system-wide pharmacological profile of dopaminergic agents, this review underlines the needs for systems pharmacology studies that include: i) proteomics and metabolomics analysis; ii) longitudinal data evaluation and mathematical modeling; iii) pharmacokinetics-based interpretation of drug effects; iv) simultaneous biomarker evaluation in the brain, the cerebrospinal fluid (CSF) and plasma; and v) specific attention to condition-dependent (e.g., disease) pharmacology. Such approach is considered essential to increase our understanding of central nervous system (CNS) drug effects and substantially improve CNS drug development.

Haloperidol affects bones while clozapine alters metabolic parameters - sex specific effects in rats perinatally treated with phencyclidine

Background

The presentation of schizophrenia (SCH) symptoms differs between the sexes. Long-term treatment with antipsychotics is frequently associated with decreased bone mineral density, increased fracture risk and metabolic side effects. Perinatal phencyclidine (PCP) administration to rodents represents an animal model of SCH. The aim of this study was to assess the effects of chronic haloperidol and clozapine treatment on bone mass, body composition, corticosterone, IL-6 and TNF-α concentrations and metabolic parameters in male and female rats perinatally treated with PCP.

Methods

Six groups of male and six groups of female rats (n = 6-12 per group) were subcutaneously treated on 2nd, 6th, 9th and 12th postnatal day (PN), with either PCP (10 mg/kg) or saline. At PN35, one NaCl and PCP group (NaCl-H and PCP-H) started receiving haloperidol (1 mg/kg/day) and one NaCl and PCP group (NaCl-C and PCP-C) started receiving clozapine (20 mg/kg/day) dissolved in drinking water. The remaining NaCl and PCP groups received water. Dual X-ray absorptiometry measurements were performed on PN60 and PN98. Animals were sacrificed on PN100. Femur was analysed by light microscopy. Concentrations of corticosterone, TNF-α and IL-6 were measured in serum samples using enzyme-linked immunosorbent assay (ELISA) commercially available kits. Glucose, cholesterol and triacylglycerol concentrations were measured in serum spectrophotometrically.

Results

Our results showed that perinatal PCP administration causes a significant decrease in bone mass and deterioration in bone quality in male and female rats. Haloperidol had deleterious, while clozapine had protective effect on bones. The effects of haloperidol on bones were more pronounced in male rats. It seems that the observed changes are not the consequence of the alterations of corticosterone, IL-6 and TNF-α concentration since no change of these factors was observed. Clozapine induced increase of body weight and retroperitoneal fat in male rats regardless of perinatal treatment. Furthermore, clozapine treatment caused sex specific increase in pro-inflammatory cytokines.

Conclusion

Taken together our findings confirm that antipsychotics have complex influence on bone and metabolism. Evaluation of potential markers for individual risk of antipsychotics induced adverse effects could be valuable for improvement of therapy of this life-long lasting disease.

Electronic supplementary material

The online version of this article (10.1186/s40360-017-0171-4) contains supplementary material, which is available to authorized users.

Screening for angiogenic inhibitors in zebrafish to evaluate a predictive model for developmental vascular toxicity

Chemically-induced vascular toxicity during embryonic development may cause a wide range of adverse effects. To identify putative vascular disrupting chemicals (pVDCs), a predictive pVDC signature was constructed from 124 U.S. EPA ToxCast high-throughput screening (HTS) assays and used to rank 1060 chemicals for their potential to disrupt vascular development. Thirty-seven compounds were selected for targeted testing in transgenic Tg(kdrl:EGFP) and Tg(fli1:EGFP) zebrafish embryos to identify chemicals that impair developmental angiogenesis. We hypothesized that zebrafish angiogenesis toxicity data would correlate with human cell-based and cell-free in vitro HTS ToxCast data. Univariate statistical associations used to filter HTS data based on correlations with zebrafish angiogenic inhibition in vivo revealed 132 total significant associations, 33 of which were already captured in the pVDC signature, and 689 non-significant assay associations. Correlated assays were enriched in cytokine and extracellular matrix pathways. Taken together, the findings indicate the utility of zebrafish assays to evaluate an HTS-based predictive toxicity signature and also provide an experimental basis for expansion of the pVDC signature with novel HTS assays.

Chronic Psychosocial Stress Impairs Bone Homeostasis: A Study in the Social Isolation Reared Rat

Chronic psychosocial stress is a key player in the onset and aggravation of mental diseases, including psychosis. Although a strong association between this psychiatric condition and other medical co-morbidities has been recently demonstrated, few data on the link between psychosis and bone homeostasis are actually available. The aim of this study was to investigate whether chronic psychosocial stress induced by 4 or 7 weeks of social isolation in drug-naïve male Wistar rats could alter bone homeostasis in terms of bone thickness, mineral density and content, as well as markers of bone formation and resorption (sclerostin, cathepsin K, and CTX-I). We found that bone mineral density was increased in rats exposed to 7 weeks of social isolation, while no differences were detected in bone mineral content and area. Moreover, 7 weeks of social isolation lead to increase of femur thickness with respect to controls, suggesting the development of a hyperostosis condition. Isolated rats showed no changes in sclerostin levels, a marker of bone formation, compared to grouped animals. Conversely, bone resorption markers were significantly altered after 7 weeks of social isolation in terms of decrease in cathepsin K and increase of CTX-I. No alterations were found after 4 weeks of isolation rearing. Our observations suggest that chronic psychosocial stress might affect bone homeostasis, more likely independently from drug treatment. Thus, the social isolation model might help to identify possible new therapeutic targets to treat the burden of chronic psychosocial stress and to attempt alternative therapy choices.

Adverse skeletal effects of drugs - beyond Glucocorticoids

Osteoporotic fractures are an important public health problem with significant individual and societal costs. In addition to the major risk factors for osteoporotic fracture, low bone mineral density (BMD), age, low body weight and history of fracture or falls, some drugs are now considered to be important secondary risk factor for bone loss and fracture, particularly amongst predisposed individuals. Currently available data are often generated from small observational clinical studies, making risk assessment and development of management guidelines difficult. In many cases, the exposed population has a low baseline risk for fracture and additional assessment and treatment may not be necessary. In this review, we focus on drugs other than glucocorticoids identified as potentially causing adverse skeletal effects, summarizing the existing evidence from preclinical and clinical studies, and suggest recommendations for patient management.

Chronic risperidone exposure does not show any evidence of bone mass deterioration in animal model of schizophrenia

BACKGROUND

It has been shown that bone mass is centrally regulated. Thus schizophrenia being a disease of the central nervous system is an interesting model for studying bone. Most second generation antipsychotic drugs including risperidone are used in the treatment of schizophrenia. Weight gain and metabolic disturbances are common side effects.

OBJECTIVE

The aims of this study were to investigate bone mass, body composition and light microscopic pathology examinations of femur in an animal model of schizophrenia (pharmacologically induced by postnatally administered phencyclidine-PCP) and to further examine the effects of chronic treatment with risperidone on these parameters in rats.

METHODS

Four groups of male rats were studied:1) control group-NaCl postnatally administered, n=9; 2) PCP group-postnatal PCP administration to rat pups (on day 2,6,9 and 12), n=6; 3) risperidone group-rats treated with risperidone alone for 9weeks from day 35 (NaCl-RSP group, n=7); 4) PCP rats treated with risperidone for 9weeks from day 35 (PCP-RSP group, n=7). Bone mass and body composition were measured in vivo by dual X ray absorptiometry (areal DXA and fat mass). Light microscopic analysis of the femoral metaphysis was performed in all groups after sacrificing the animals.

RESULTS

Postnatal phencyclidine (PCP) administration to rat pups caused a long lasting reduction of total bone mass versus control animals (aDXA 128±2mg/cm(2) vs 139±5mg/cm(2), p<0.05). Examination of the femoral bone revealed a decrease in the number and thickness of the metaphyseal trabecule and cortical thinning. There was a decrease in total and retroperitoneal fat. Nine weeks of administration of risperidone alone to rats, resulted in significant weight gain and had no effect on bone mass versus control animals (aDXA was 136±7mg/cm(2) vs 139±5mg/cm(2), p>0.05). Furthermore, there were no changes in the light microscopic analysis of femoral metaphysis in comparison with controls. When PCP rats were treated with risperidone, they did not change their body weight nor bone mass versus PCP alone (aDXA 126±2mg/cm(2) vs 128±2mg/cm(2), p>0.05) but intriguingly on examination of the femoral bone an increase in the number and thickness of the metaphyseal trabecule was found (trabecular thickness 0.6±0.1μm vs 0.35±0.1μm, p<0.01).

CONCLUSION

This study shows that in the PCP rat model of schizophrenia bone mass is reduced. When PCP rats were treated with risperidone bone mass remained unchanged but intriguingly and unexpectedly light microscopic examination of femoral metaphysis showed an increase in thickness of metaphyseal trabeculae. The mechanism of risperidone's action on bone remains to be clarified.

Possible mechanisms for the skeletal effects of antipsychotics in children and adolescents

The increasing use of antipsychotics (APs) to treat pediatric psychiatric conditions has led to concerns over the long-term tolerability of these drugs. While the risk of cardiometabolic abnormalities has received most of the attention, preclinical and clinical studies provide preliminary evidence that APs can adversely impact bone metabolism. This would be most concerning in children and adolescents as suboptimal bone accrual during development may lead to increased fracture risk later in life. However, the potential mechanisms of action through which APs may impact bone turnover and, consequently, bone mineral content are not clear. Emerging data suggest that the skeletal effects of APs are complex, with APs directly and indirectly impacting bone cells through modulation of multiple signaling pathways, including those involving dopamine D2, serotonin, adrenergic, and prolactin receptors, as well as by affecting gonadotropins. Determining the action of APs on skeletal development is further complicated by polypharmacy. In children and adolescents, APs are frequently coprescribed with psychostimulants and selective serotonin reuptake inhibitors, which have also been linked to changes in bone metabolism. This review discusses the mechanisms by which APs may influence bone metabolism. Also covered are preclinical and pediatric findings concerning the impact of APs on bone turnover. However, the dearth of clinical information despite the potential public health significance of this issue underscores the need for further studies. The review ends with a call for clinicians to be vigilant about promoting optimal overall health in chronically ill youth with psychopathology, particularly when pharmacotherapy is unavoidable.

Altered cell cycle dynamics in schizophrenia

BACKGROUND

The olfactory mucosa, the organ of smell in the nose, is a neural tissue that regenerates new sensory neurons throughout adult life. Based on this tissue, we previously demonstrated increased mitosis in olfactory biopsy cultures from schizophrenia patients compared with healthy control subjects. In addition, neural stem/progenitor cell cultures (neurosphere-derived cells) from nasal biopsies from individuals with schizophrenia show significantly altered gene and protein expression in key cell cycle control pathways.

METHODS

The aim of this study was to investigate cell cycle dynamics in olfactory neurosphere-derived cells from nine male schizophrenia patients and nine male healthy control subjects. Cell cycles were arrested by serum deprivation after which cell population doubling time, proliferation fraction, and cell cycle period were calculated from cell counts over 96 hours. Cell cycle phase was investigated using flow cytometry. Cell lysates were analyzed for expression of cyclin proteins.

RESULTS

Cell population proliferation rate was increased in schizophrenia through a larger pool of proliferating progenitors and a reduced cell cycle period. All phases of the cell cycle were phase-shifted by 2 hours in the schizophrenia-derived cells, which expressed higher levels of the cyclins D1, E, and A2.

CONCLUSIONS

Our observations indicate that schizophrenia is associated with subtle alterations in cell cycle dynamics, shortening of the cell cycle period, and increased expression of G1/S phase cyclins. We speculate that this underlying diathesis could alter the temporal and spatial cascade of brain development and contribute to an altered neurodevelopmental trajectory in schizophrenia.