Effects of Parathyroid Hormone on Bone Formation in a Rat Model for Chronic Alcohol Abuse

Six months of voluntary alcohol consumption in male cynomolgus macaques reduces intracortical bone porosity without altering mineralization or mechanical properties

Chronic heavy alcohol consumption is a risk factor for low trauma bone fracture. Using a non-human primate model of voluntary alcohol consumption, we investigated the effects of 6 months of ethanol intake on cortical bone in cynomolgus macaques (Macaca fascicularis). Young adult (6.4 ± 0.1 years old, mean ± SE) male cynomolgus macaques (n = 17) were subjected to a 4-month graded ethanol induction period, followed by voluntary self-administration of water or ethanol (4 % w/v) for 22 h/d, 7 d/wk. for 6 months. Control animals (n = 6) consumed an isocaloric maltose-dextrin solution. Tibial response was evaluated using densitometry, microcomputed tomography, histomorphometry, biomechanical testing, and Raman spectroscopy. Global bone response was evaluated using biochemical markers of bone turnover. Monkeys in the ethanol group consumed an average of 2.3 ± 0.2 g/kg/d ethanol resulting in a blood ethanol concentration of 90 ± 12 mg/dl in longitudinal samples taken 7 h after the daily session began. Ethanol consumption had no effect on tibia length, mass, density, mechanical properties, or mineralization (p > 0.642). However, compared to controls, ethanol intake resulted in a dose-dependent reduction in intracortical bone porosity (Spearman rank correlation = -0.770; p < 0.0001) and compared to baseline, a strong tendency (p = 0.058) for lower plasma CTX, a biochemical marker of global bone resorption. These findings are important because suppressed cortical bone remodeling can result in a decrease in bone quality. In conclusion, intracortical bone porosity was reduced to subnormal values 6 months following initiation of voluntary ethanol consumption but other measures of tibia architecture, mineralization, or mechanics were not altered.

The effects of MIR137HG genetic polymorphisms on the susceptibility of alcohol-induced osteonecrosis of the femoral head in a Chinese male population

BACKGROUNDS

Osteonecrosis of the femoral head (ONFH) is one of the common and complicated diseases in the orthopedic clinic. Previous studies indicate that genetic factors play a crucial role in the occurrence of ONFH. This case-control study aimed to investigate the associations of MIR137HG genetic polymorphisms with the alcohol-induced ONFH risk.

METHODS

A total of 731 participants were recruited to detect the effect of MIR137HG SNPs on the alcohol-induced ONFH risk in a Chinese male population. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to evaluate the associations. Multifactor dimensionality reduction (MDR) was used to analyze the SNP-SNP interaction with the alcohol-induced ONFH risk.

RESULTS

Our study showed that rs7549905 played a protective role in alcohol-induced ONFH risk (OR 0.57, p = 0.045). Stratified analysis indicated that rs9440302 was associated with an increased risk of patients aged >45 years (OR 2.00, p = 0.038), and rs7549905 showed a reduced risk in patients aged ≤ 45 years (OR 0.43, p = 0.023). In addition, we found that rs9440302 and rs7554283 exhibited a significantly increased susceptibility of III-IV grade alcohol-induced ONFH patients (OR 2.34, p = 0.003; OR 2.13, p = 0.011, respectively). We also observed that rs12138817 was related to an increased risk in patients with >21 months of course (OR 1.77, p = 0.043). Interestingly, rs17371457 showed a significant correlation with low-density lipoprotein-cholesterol (p = 0.040).

CONCLUSION

Our study suggests that MIR137HG genetic variants are associated with the alcohol-induced ONFH susceptibility in a Chinese male population, which may give scientific evidence for exploring molecular mechanisms of the alcohol-induced ONFH.

Effects of Alcohol and Estrogen Receptor Blockade Using ICI 182,780 on Bone in Ovariectomized Rats

BACKGROUND

Estrogen signaling is essential for the sexual dimorphism of the skeleton, is required for normal bone remodeling balance in adults, and may influence the skeletal response to alcohol. High levels of alcohol consumption lower bone mass in ovary-intact but not ovariectomized (ovx) rats. However, the extremely rapid rate of bone loss immediately following ovx may obscure the effects of alcohol. We therefore determined (i) whether heavy alcohol consumption (35% caloric intake) influences bone in sexually mature ovx rats with established cancellous osteopenia and (ii) whether ICI 182,780 (ICI), a potent estrogen receptor signaling antagonist, alters the skeletal response to alcohol.

METHODS

Three weeks following ovx, rats were randomized into 5 groups, (i) baseline, (ii) control + vehicle, (iii) control + ICI, (iv) ethanol (EtOH) + vehicle, or (v) EtOH + ICI, and treated accordingly for 4 weeks. Dual-energy X-ray absorptiometry, microcomputed tomography, blood measurements of markers of bone turnover, and gene expression in femur and uterus were used to evaluate response to alcohol and ICI.

RESULTS

Rats consuming alcohol had lower bone mass and increased fat mass. Bone microarchitecture of the tibia and gene expression in femur were altered; specifically, there was reduced accrual of cortical bone, net loss of cancellous bone, and differential expression of 19/84 genes related to bone turnover. Furthermore, osteocalcin, a marker of bone turnover, was lower in alcohol-fed rats. ICI had no effect on weight gain, body composition, or cortical bone. ICI reduced cancellous bone loss and serum CTX-1, a biochemical marker of bone resorption; alcohol antagonized the latter 2 responses. Neither alcohol nor ICI affected uterine weight or gene expression.

CONCLUSIONS

Alcohol exaggerated bone loss in ovx rats in the presence or absence of estrogen receptor blockade with ICI. The negligible effect of alcohol on uterus and limited effects of ICI on bone in alcohol-fed ovx rats suggest that estrogen receptor signaling plays a limited role in the action of alcohol on bone in a rat model for chronic alcohol abuse.

Isoquercitrin, a flavonoid glucoside, exerts a positive effect on osteogenesis in vitro and in vivo

Isoquercitrin (quercetin-3-O-β-d-glucopyranoside) possess various pharmacological effect as a biologically active compound. The aim of the present study was to investigate its potential effects on the proliferation and osteoblastic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) in vitro and bone formation in the mid-palatal suture during rapid maxillary expansion (RME) in vivo. Cell proliferation of rat BMSCs was detected by cell-counting kit- 8 (CCK-8) assay. Alkaline phosphatase (ALP) activity assay and alizarin red staining were used to evaluate osteogenic differentiation of BMSCs. Furthermore, the expression levels of osteogenesis-related genes including runt-related transcription factor 2 (Runx2), bone sialoprotein (BSP) and activating transcription factor 6 (ATF6) were measured by real-time RT-PCR. In vivo, thirty-six male 6-week-old Wistar rats with or without suture expansion receive systemic administration of isoquercitrin or saline solution. Micro-CT, HE and Masson staining were used to compare the morphological changes between the groups. Bone morphogenetic protein 2 (BMP2) expression in the suture was detected using immunohistochemical staining. Our results showed that isoquercitrin significantly promoted cell proliferation, ALP activity and mineral deposition in the range from 0.01 to 1 μM. Moreover, the expression levels of Runx2, BSP and ATF6 were also upregulated. The measurement of micro-CT imaging and histological examinations demonstrated that daily oral administration of isoquercitrin (10 mg/kg) increased bone formation compared to the other groups. Furthermore, the expression level of BMP2 was also augmented in the presence of isoquercitrin. Consequently, those findings showed that isoquercitrin exerts stimulatory effects on osteogenesis in vitro and in vivo, suggesting that isoquercitrin could be a potential candidate for preventing relapse following RME within palatal sutures.

Alcohol: A Simple Nutrient with Complex Actions on Bone in the Adult Skeleton

BACKGROUND

Alcohol is an important nonessential component of diet, but the overall impact of drinking on bone health, especially at moderate levels, is not well understood. Bone health is important because fractures greatly reduce quality of life and are a major cause of morbidity and mortality in the elderly. Regular alcohol consumption is most common following skeletal maturity, emphasizing the importance of understanding the skeletal consequences of drinking in adults.

METHODS

This review focuses on describing the complex effects of alcohol on the adult skeleton. Studies assessing the effects of alcohol on bone in adult humans as well as skeletally mature animal models published since the year 2000 are emphasized.

RESULTS

Light to moderate alcohol consumption is generally reported to be beneficial, resulting in higher bone mineral density (BMD) and reduced age-related bone loss, whereas heavy alcohol consumption is generally associated with decreased BMD, impaired bone quality, and increased fracture risk. Bone remodeling is the principal mechanism for maintaining a healthy skeleton in adults and dysfunction in bone remodeling can lead to bone loss and/or decreased bone quality. Light to moderate alcohol may exert beneficial effects in older individuals by slowing the rate of bone remodeling, but the impact of light to moderate alcohol on bone remodeling in younger individuals is less certain. The specific effects of alcohol on bone remodeling in heavy drinkers are even less certain because the effects are often obscured by unhealthy lifestyle choices, alcohol-associated disease, and altered endocrine signaling.

CONCLUSIONS

Although there have been advances in understanding the complex actions of alcohol on bone, much remains to be determined. Limited evidence implicates age, skeletal site evaluated, duration, and pattern of drinking as important variables. Few studies systematically evaluating the impact of these factors have been conducted and should be made a priority for future research. In addition, studies performed in skeletally mature animals have potential to reveal mechanistic insights into the precise actions of alcohol and associated comorbidity factors on bone remodeling.

Effects of low-level laser therapy on changes in inflammation and in the activity of osteoblasts in the expanded premaxillary suture in an ovariectomized rat model

BACKGROUND AND OBJECTIVE

Osteoporosis is a progressive systemic skeletal disease characterized by reduced bone mass/density and microarchitectural deterioration of bone tissue. Bone formation initially exceeds bone resorption, but by the third decade, such formation is reversed, resulting in a net loss of bone mass. This resorption, in turn, increases bone fragility and susceptibility to fracture. This study aimed to evaluate the effects of low-level laser therapy (LLLT) on bone regeneration in the expanded premaxillary suture in an ovariectomized rat model.

METHODS

Thirty-two 12-week-old female Wistar albino rats were used in the experiment. All of the animals underwent ovariectomy 3 months before the experiment. Expansion appliances were affixed to the maxillary incisors for the expansion of premaxillary sutures. The premaxillary sutures of the laser group were exposed to 5 J/cm(2) laser energy, and no treatment was performed for the controls. All the rats in both groups were euthanized on either the 7th day (n=8) [end of expansion period; Laser Group 1(LG1) and Control Group 1 (CG1)] or the 17th day (n=8) [end of retention period; Laser Group 2 (LG2) and Control Group 2 (CG2)], respectively, for histological assessment.

RESULTS

Histological findings indicated that the LG1 group showed a significantly higher number of osteoblasts than did the CG1 group (p=0.028). The CG1 and CG2 groups showed a significantly higher number of osteoclasts than did the LG1 and LG2 groups, respectively (p=0.005), (p=0.032). The LG2 group exhibited a capillary increase similar to that of the other groups, without statistically significant differences.

CONCLUSIONS

On the basis of our methodology and results, we conclude that low-level laser associated with rapid maxillary expansion influences bone regeneration in sutures, thereby accelerating healing, even in ovariectomized rats. We found that LLLT decreased osteoclastic activity in the ovariectomized rats. Therefore, preventing osteoporosis necessitates further investigations to clarify the effect of LLLT on postmenopausal patients.

Preventive effects of siRNA targeting PPARγ gene on steroid-induced osteonecrosis in rabbits

PURPOSES/AIM: Glucocorticoid steroids can induce expression of PPARγ gene and enhance adipogenesis by bone marrow mesenchymal stem cells (BMSCs), which may result in osteonecrosis of the femoral head. Currently, there are no medications available to prevent steroid-induced osteonecrosis. We hypothesized that siRNA targeting PPARγ gene may prevent steroid-induced adipogenesis and osteonecrosis in rabbit. The purpose of this study was to evaluate the preventive effects of siRNA targeting PPARγ gene on steroid-induced adipogenesis and osteonecrosis.

METHODS

Forty-eight healthy New Zealand rabbits were randomized into four groups with Group M treated with dexamethasone only, Group S with dexamethasone and a recombinant adenovirus shuttle vector carrying siRNA targeting PPARγ gene, Group Con with dexamethasone and a vector carrying irrelative sequence, and Group N with no treatment serving as control. Expressions of the PPARγ, osteocalcin and Runx2 genes, as well as histopathologic changes were evaluated.

RESULTS

The levels of PPARγ gene expression were decreased while the levels of osteocalcin and Runx2 gene expression were increased in rabbits treated with dexamethasone and recombinant adenovirus shuttle vector carrying siRNA targeting PPARγ gene (Group S), compared to rabbits treated either with dexamethasone alone (Group M) or with both dexamethasone and a vector carrying irrelative sequence (Group Con). The marrow necrosis, adipocyte hypertrophy and proliferation, diminished hematopoiesis, thinner and sparse trabeculae, and increased empty osteocyte lacunae in the femoral head were observed in Group M and Group Con rabbits. However, no such changes were seen in Group S rabbits that were treated with dexamethasone and a recombinant adenovirus shuttle vector carrying siRNA targeting PPARγ gene.

CONCLUSION

siRNA targeting PPARγ gene can inhibit adipogenic differentiation of BMSCs and prevent steroid-induced osteonecrosis in rabbit. The inhibition of bone-marrow adipogenesis and concomitant enhancement of osteogenesis with RNAi may provide a novel approach to the prevention of steroid-induced osteonecrosis.

Effects of alcohol on skeletal response to growth hormone in hypophysectomized rats

Chronic alcohol abuse is an established risk factor for osteoporosis. However, the precise mechanisms for the bone loss are largely unknown. Alcohol decreases skeletal expression of insulin-like growth factor-I (IGF-I), an important growth hormone (GH)-regulated skeletal growth factor. Therefore, we investigated the effects of alcohol on the skeletal response to GH in male Sprague-Dawley rats made GH-deficient by hypophysectomy (HYPOX). Four groups of sexually mature (3-month-old) rats were studied: pituitary-intact (control), HYPOX, HYPOX + GH, and HYPOX + alcohol + GH. All animals were transferred to a liquid diet 6 days following surgery. The alcohol-fed group was adapted to a graded increase in alcohol beginning 11 days following surgery. GH or vehicle was administered during the final 8 days of study and all animals were sacrificed 25 days following surgery. HYPOX resulted in cessation of body weight gain and tibial growth. Compared to controls, longitudinal bone growth and cancellous bone formation were lower following HYPOX. The latter was associated with lower mineralizing perimeter/bone perimeter. Bone marrow adiposity was higher following HYPOX. Compared to HYPOX, GH treatment increased body weight gain and bone formation rate, and decreased bone marrow adiposity. In contrast to the effects of GH treatment without alcohol, bone marrow adiposity did not differ between HYPOX and alcohol-fed GH-treated HYPOX rats. Alcohol did not alter GH-induced weight gain or increases in serum IGF-I levels, but significantly impaired the effects of GH on tibial growth and cancellous bone formation. We conclude that the detrimental skeletal effects of alcohol abuse observed in this experiment are mediated, at least in part, by skeletal resistance to GH.

Stress fracture and military medical readiness: bridging basic and applied research

PURPOSE

Military recruits and distance runners share a special risk of stress fracture injury. Recent efforts by US and Israeli military-sponsored researchers have uncovered important mechanisms and practical low-cost interventions. This article summarizes key findings relevant to prevention of stress fracture, including simple strategies to identify and to mitigate risk.

METHODS

Published research supported through the Bone Health and Military Medical Readiness research program and related military bone research was analyzed for contributions to preventing stress fracture in military recruits and optimizing bone health.

RESULTS

Thousands of military recruits helped test hypotheses about predictors of risk, safer exercise regimens, and rest, nutrition, gait training, and technology interventions to reduce stress fracture risk. Concurrent cellular, animal, and human laboratory studies were used to systematically investigate mechanisms of mechanical forces acting on bone and interactions through muscle, hormonal and genetic influences, and metabolism. The iterative and sometimes simultaneous process of basic discovery and field testing produced new knowledge that will provide safer science-based physical training.

DISCUSSION

Human training studies evaluating effects on bone require special commitment from investigators and funders due to volunteer compliance and attrition challenges. The findings from multiple studies indicate that measures of bone elasticity, fragility, and geometry are as important as bone mineral density in predicting fracture risk, with applications for new measurement technologies. Risk may be reduced by high intakes of calcium, vitamin D, and possibly protein (e.g., milk products). Prostaglandin E2, insulin-like growth factor 1, and estrogens are important mediators of osteogenesis, indicating reasons to limit the use of certain drugs (e.g., ibuprofen), to avoid excessive food restriction, and to treat hypogonadism. Abnormal gait may be a correctable risk factor. Brief daily vibration may stimulate bone mineral accretion similar to weight-bearing exercise. Genetic factors contribute importantly to bone quality, affecting fracture susceptibility and providing new insights into fracture healing and tissue reengineering.

Chronic ethanol intake inhibits in vitro osteogenesis induced by osteoblasts differentiated from stem cells

The study investigated whether chronic ethanol (ETH) intake and subsequent ETH exposure of cell cultures affects osteoblast differentiation by evaluating key parameters of in vitro osteogenesis. Rats were treated with 5-20% (0.85-3.43 mm) ETH, increasing by 5% per week for a period of 4 weeks (habituation), after which the 20% level was maintained for 15 days (chronic intake). Bone-marrow stem cells from control (CONT) or ETH-treated rats were cultured in osteogenic medium which was either supplemented (ETH) or not supplemented (CONT) with 1.3 mm ethanol. Thus, four groups relating to rat treatment/culture supplementation were evaluated: (1) CONT/CONT, (2) ETH/CONT, (3) CONT/ETH and (4) ETH/ETH. Cell morphology, proliferation and viability, total protein content, alkaline phosphatase (ALP) activity and bone-like nodule formation were evaluated. Chronic ethanol intake significantly reduced both food and liquid consumption and body weight gain. No difference was seen in cell morphology among treatments. Cell number was affected at 7 and 10 days as follows: CONT/CONT = CONT/ETH < ETH/CONT = ETH/ETH. Doubling time between 3 and 10 days was greater in groups of CONT animals: ETH/ETH = ETH/CONT < CONT/ETH = CONT/CONT. Cell viability and ALP activity were not affected by either animal treatment or culture exposure to ethanol. At day 21, the total protein content was affected as follows: ETH/ETH = CONT/ETH < ETH/CONT = CONT/CONT. Bone-like nodule formation was affected as follows: ETH/ETH < CONT/ETH < ETH/CONT < CONT/CONT. These results show that chronic ethanol intake, followed by the exposure of osteoblasts to ethanol, inhibited the differentiation of osteoblasts, as indicated by an increased proliferation rate and reduced bone-like nodule formation.

Alcohol-induced disruption of endocrine signaling

This article contains the proceedings of a symposium at the 2006 ISBRA meeting in Sydney Australia, organized and cochaired by Martin J. Ronis and Thomas M. Badger. The presentations were (1) Effect of long-term ethanol consumption on liver injury and repair, by Jack R. Wands; (2) Alcohol-induced insulin resistance in liver: potential roles in regulation of ADH expression, ethanol clearance, and alcoholic liver disease, by Thomas M. Badger; (3) Chronic gestational exposure to ethanol causes brain insulin and insulin-like growth factor resistance, by Suzanne M de la Monte; (4) Disruption of IGF-1 signaling in muscle: a mechanism underlying alcoholic myopathy, by Charles H. Lang; (5) The role of reduced plasma estradiol and impaired estrogen signaling in alcohol-induced bone loss, by Martin J. Ronis; and (6) Short-term influence of alcohol on appetite-regulating hormones in man, by Jan Calissendorff.

Intermittent exposure to ethanol vapor affects osteoblast behaviour more severely than estrogen deficiency does in vitro study on rat osteoblasts

With rising rates of alcohol consumption acute and chronic damage from alcohol is expected to increase all over the world. Habitual excessive alcohol consumption is associated with pathological effects on bone. The aim of the present in vitro study was to investigate comparatively the proliferation and synthetic activity of osteoblasts (OB) isolated from the trabecular bone of rats previously exposed to 7-week intermittent exposure to ethanol vapor, sham-aged rats and long-term estrogen deficient rats. Cell proliferation (WST1) and synthesis of alkaline phosphatase (ALP), osteocalcin (OC), collagen I (CICP), transforming growth factor beta1 (TGF-beta1), interleukin-6 (IL-6), tumor necrosis factor alfa (TNFalpha) were measured at 3, 7 and 14 days of culture. Osteoblast proliferation rate and TGF-beta1, IL-6 and TNFalpha syntheses were significantly affected by alcohol exposure. Estrogen deficiency and alcohol consumption share many common pathophysiological mechanisms of damage to bone, but alcohol affects OB proliferation and TNFalpha synthesis significantly more than menopause does. Therefore, these in vitro data suggest that alcohol has even more deleterious effects on bone than estrogen deficiency does.

Effects of parathyroid hormone (1-34) on tibia in an adult rat model for chronic alcohol abuse

Chronic alcohol abuse is a risk factor for osteoporosis in men. Human recombinant parathyroid hormone (1-34) (PTH) therapy increases bone mass in patients with osteoporosis. The purpose of the present study was to determine whether PTH is effective in increasing bone formation and bone mass in a rat model for established osteopenia caused by chronic alcohol abuse. Eight-month-old male Sprague Dawley rats were fed the Lieber-DeCarli liquid diet in which 35% of the calories were derived from either maltose-dextran or ethanol. Measurements were performed 16 weeks later to establish the magnitude of bone changes in the rats fed alcohol. High dose PTH (80 microg/kg/day) was administered 5 days/week for 6 weeks to establish the differential efficacy of hormone therapy on bone formation in alcohol consuming and alcohol withdrawn rats. The effects of alcohol and PTH on cancellous and cortical bone mass, architecture and turnover were determined by densitometry and histomorphometry. Rats fed alcohol had reduced bone mineral contents and densities, cancellous and cortical bone areas and cancellous bone formation rates compared to pair-fed controls. Following the withdrawal of alcohol, indices of bone formation increased compared to baseline values. PTH treatment increased bone mineral content and density, bone formation rates, cortical bone area, cancellous bone area and trabecular number and thickness, but several indices of bone formation were reduced in the presence of continued alcohol consumption. These results suggest that alcohol consumption, in addition to inducing bone loss, may reduce the efficacy of PTH therapy to reverse osteoporosis.

Dose-response effects of intermittent PTH on cancellous bone in hindlimb unloaded rats

HLU suppressed bone formation and resulted in bone loss in the tibial metaphysis of 6-month-old male rats. A human therapeutic dose of intermittent PTH (1 microg/kg/day) prevented the skeletal changes associated with HLU.

INTRODUCTION

Skeletal unloading of skeletally mature rats results in trabecular thinning in the proximal tibial metaphysis, which is in part caused by a decrease in bone formation. We examined the efficacy of PTH in preventing the detrimental skeletal effects that occur with hindlimb unloading (HLU).

MATERIALS AND METHODS

Six-month-old male Fisher 344 rats were HLU and treated with vehicle or recombinant human PTH(1-34) at 1, 5, 20, or 80 microg/kg/day for 2 weeks. The bone response was measured by microCT analysis of bone structure, histomorphometric analysis of static and dynamic bone parameters, and Northern blot analysis of mRNA levels for bone matrix proteins. The PTH-treated HLU animals were compared with vehicle-treated HLU and pair-fed normal weight-bearing controls.

RESULTS

Unloading resulted in a decrease in cancellous bone volume that was caused in part by a dramatic 83% decrease in bone formation. All dose rates (1-80 microg/kg/day) of human PTH(1-34) significantly increased bone formation rates compared with vehicle-treated HLU controls. There was a dose response, and the highest dose rate of the hormone increased bone formation compared with normal weight-bearing rats by 708% (p < 0.0001). The increases in bone formation were accompanied by increases in mRNA levels for type 1 collagen, osteocalcin, and osteonectin. Also, treatment with PTH resulted in increases in mineral apposition rate and double-labeled perimeter, but the latter was disproportionally increased at high dose rates. A therapeutic dose of PTH (1 microg/kg/day) prevented disuse-induced trabecular thinning, whereas high-dose PTH (80 microg/kg/day) increased trabecular thickness compared with normal weight-bearing rats.

CONCLUSIONS

These findings reveal that administration of a therapeutic dose of PTH to HLU rats prevents the decrease in bone formation and trabecular thinning, whereas high dose rates of the hormone increase bone formation and trabecular thickness to values that exceed normal values.

Alcohol-induced adipogenesis in a cloned bone-marrow stem cell

BACKGROUND

Alcohol has been shown to be associated with osteoporosis and osteonecrosis in patients and in animal models. Recent studies have demonstrated that alcohol contributes to abnormal lipid metabolism in the stromal cells of bone marrow, but the mechanisms have not been defined. The purpose of this study was to evaluate the effects of alcohol on the differentiation of a stem cell that was cloned from bone marrow.

METHODS

D1 cells (cloned bone-marrow stem cells from a BALB/c mouse) were treated either with increasing concentrations of ethanol (0.09, 0.15, and 0.21 mol/L) or without alcohol to serve as controls. Morphologic features of the cells were monitored with use of a phase-contrast microscope. Alkaline phosphatase activity was determined with use of a colorimetric assay. The expression of genes that are indicators of adipogenesis [422(aP2), PPARgamma] and osteogenesis (osteocalcin) was evaluated using Northern blot and reverse transcription-polymerase chain reaction assays.

RESULTS

The cells treated with ethanol started to accumulate triglyceride vesicles at day seven. The number of adipocytes and the percentage of the area that contained the cells with fat vesicles increased significantly (p < 0.05), and the level of alkaline phosphatase activity diminished with longer durations of exposure to ethanol and with higher concentrations. Analysis of gene expression showed diminished expression of osteocalcin. This occurred without a significant increase in the expression of either the fat-cell-specific gene 422(aP2) or PPARgamma in cells treated with ethanol, suggesting that adipogenesis may occur at a point downstream in the fatty-acid-metabolism pathway.

CONCLUSIONS

Alcohol treatment decreases osteogenesis while enhancing adipogenesis in a cloned bone-marrow stem cell, indicating that alcohol abuse may be one of the mechanisms leading to osteoporosis and osteonecrosis. This finding explains the clinical observation that there is increased adipogenesis in alcohol-induced osteoporosis and osteonecrosis.

CLINICAL RELEVANCE

The inhibition of bone-marrow adipogenesis and the concomitant enhancement of osteogenesis may provide a novel approach to the prevention or treatment of osteonecrosis and osteoporosis.

Candidate genes, pathways and mechanisms for alcoholism: an expanded convergent functional genomics approach

We describe a comprehensive translational approach for identifying candidate genes for alcoholism. The approach relies on the cross-matching of animal model brain gene expression data with human genetic linkage data, as well as human tissue data and biological roles data, an approach termed convergent functional genomics. An analysis of three animal model paradigms, based on inbred alcohol-preferring (iP) and alcohol-non-preferring (iNP) rats, and their response to treatments with alcohol, was used. A comprehensive analysis of microarray gene expression data from five key brain regions (frontal cortex, amygdala, caudate-putamen, nucleus accumbens and hippocampus) was carried out. The Bayesian-like integration of multiple independent lines of evidence, each by itself lacking sufficient discriminatory power, led to the identification of high probability candidate genes, pathways and mechanisms for alcoholism. These data reveal that alcohol has pleiotropic effects on multiple systems, which may explain the diverse neuropsychiatric and medical pathology in alcoholism. Some of the pathways identified suggest avenues for pharmacotherapy of alcoholism with existing agents, such as angiotensin-converting enzyme (ACE) inhibitors. Experiments we carried out in alcohol-preferring rats with an ACE inhibitor show a marked modulation of alcohol intake. Other pathways are new potential targets for drug development. The emergent overall picture is that physical and physiological robustness may permit alcohol-preferring individuals to withstand the aversive effects of alcohol. In conjunction with a higher reactivity to its rewarding effects, they may able to ingest enough of this nonspecific drug for a strong hedonic and addictive effect to occur.

Skeletal toxicity associated with chronic ethanol exposure in a rat model using total enteral nutrition

Chronic alcohol abuse decreases bone mass, inhibits osteoblast differentiation and function, increases fracture incidence, and delays fracture healing. Four studies were designed to use intragastric ethanol delivery as part of a total enteral nutrition (TEN) system to determine the negative systemic effects of chronic ethanol on 1) the rat skeleton and 2) local rapid bone formation during limb lengthening (distraction osteogenesis, DO). In study 1, three-point bending tests demonstrated that after 75 days of ethanol exposure, the tibiae had significantly lower load to failure versus control diet (p = 0.0006) or ad libitum chow-fed rats (p = 0.0029). Study 2 examined alcohol's effects on the density and cross-sectional area of the proximal tibial metaphysis using peripheral quantitative computed tomography and found that after 25 days of ethanol exposure the trabecular volumetric bone mineral density (p = 0.011) and cortical cross-sectional area (p = 0.011) were lower compared with controls. In study 3, a comparison of distracted tibial radiographs and histological sections demonstrated ethanol-related decreases in both gap mineralization (p = 0.03) and bone column formation (p = 0.01). Histological comparisons in study 4 reproduced the ethanol-related deficits in new bone formation during DO (p = 0.001). These results indicate that the TEN system is a viable model to study ethanol's effects on the skeleton and that chronic ethanol delivery via TEN decreases trabecular bone density, cortical area, and mature bone strength. Also, the DO studies demonstrate, for the first time, that chronic ethanol inhibits rapid bone formation during limb lengthening.