Moderate alcohol consumption suppresses bone turnover in adult female rats

Effect of alcohol consumption on bone mineral density and hormonal parameters in physically active male soldiers

BACKGROUND

Previous studies on the influence of alcohol intake and smoking on bone mineral density (BMD) in men are inconsistent and the effect of these variables on BMD in physically active men is yet to be explored.

OBJECTIVE

To investigate the influence of alcohol intake and smoking on BMD in a cohort of males with well-defined lifestyle conditions.

DESIGN

Men from the armed forces (n=400) having uniform and defined routines were enrolled. BMD was measured by DXA and participants were grouped according to lifestyle variables. Hormonal parameters were measured by immunoassays.

RESULTS

Participants with intake of >24 g/wk of alcohol had significantly higher BMD at femur compared to non-alcohol consumers (p=0.0001) and a linear increase in mean femoral BMD over increasing categories of alcohol intake (p(trend)<0.0001) was observed. Smoking was negatively associated with femoral BMD. In multiple regression analysis, age, BMI, alcohol consumption and smoking were independent predictors of femoral BMD, explaining 10.6% variance. At lumbar spine, age, height and BMI were independent predictors, explaining 9.4% variance in BMD. The concentrations of total testosterone, free testosterone, bioavailable testosterone and PTH were low (p<0.0001) whereas estradiol (p=0.02), free and bioavailable estradiol (p<0.001) were high in alcohol consumers compared to non-consumers. In multiple regression analysis alcohol intake and height explained 5.5% variance in estradiol(.)

CONCLUSIONS

In physically active men with well-defined lifestyle conditions, alcohol consumption was associated with higher femoral BMD, the effect of alcohol is complex and is probably partly mediated by influencing the sex steroid levels.

Alcohol alters whole body composition, inhibits bone formation, and increases bone marrow adiposity in rats

Chronic alcohol abuse is a risk factor for osteoporosis and sarcopenia, but the long-term effects of alcohol on the immature musculoskeletal system are less clear. The present investigation in growing rats was designed to determine the effects of alcohol consumption on body composition, muscle mass, and bone mass, architecture, and turnover.

INTRODUCTION

Few studies have focused on the long-term effects of drinking on bone and muscle during skeletal maturation.

METHODS

Alcohol was included in the diet of 4-week-old male Sprague-Dawley rats (35% caloric intake) for 3 months. The controls were fed an isocaloric alcohol-free liquid diet ad libitum. A second study was performed in which the controls were pair-fed to the alcohol-fed animals.

RESULTS

Compared to ad libitum-fed age-matched controls, alcohol-fed rats weighed less and had lower lean mass, fat mass, and percent body fat. In addition, they had lower slow- and fast-twitch muscle mass, lower total body bone mineral content and bone mineral density, and lower cancellous bone volume in the lumbar vertebra and proximal tibia. The effects of alcohol consumption on body composition were reduced when compared to the pair-fed control diet, indicating that caloric restriction was a comorbidity factor. In contrast, the effects of alcohol to decrease bone formation and serum leptin and IGF-I levels and to increase bone marrow adiposity appeared independent of caloric restriction.

CONCLUSIONS

The skeletal abnormalities in growing alcohol-fed rats were due to a combination of effects specific to alcohol consumption and alcohol-induced caloric restriction.

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.

Ethanol and stress activate catecholamine synthesis in the adrenal: effects on bone

Ethanol consumption and mental stress activate the sympathetic nervous system, which can adversely affect bone. We compared six groups of 10 young adult rats, three with and three without 2 h daily restraint stress. Two groups consumed food and water ad libitum, two received food and 6% (w/v) ethanol as drinking water, and two received the amount of food consumed by ethanol rats the previous day plus water ad libitum (pairfed). After 6 weeks, rats were killed. Plasma, femurs, lumbar vertebrae, and adrenals were harvested. Femoral dimensions were measured and biomechanical properties were tested by three-point bending. Plasma osteocalcin, vertebral osteocalcin mRNA levels, and adrenomedullary tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyl transferase (PNMT) mRNA levels were quantified. Daily restraint decreased weight gain and femoral length compared to dietary controls, and appeared to partially preserve bone strength, especially in calorie-restricted pairfed rats. Femoral strength was significantly affected by treatment in that bones of pairfed controls were weakest, ethanol drinkers were intermediate, and ad libitum restrained were strongest. Femoral yield load, displacement, and work at yield load were negatively correlated with TH and DBH mRNA levels, but not PNMT, suggesting a negative influence of norepinephrine. Plasma osteocalcin and dry weight of lumbar 3-5 vertebrae were unaffected; however, osteocalcin mRNA in second lumbar vertebrae was positively correlated with TH, DBH, and PNMT levels. Ethanol consumption at this level had little effect on femur morphology or strength. In contrast, the data suggested possible stimulation rather than inhibition of vertebral bone formation.

Effects of low-dose parathyroid hormone on bone mass, turnover, and ectopic osteoinduction in a rat model for chronic alcohol abuse

Parathyroid hormone (PTH) is used clinically in osteoporotic patients to increase bone mass by enhancing bone formation. PTH therapy is not uniformly effective at all skeletal sites and "life-style" factors may modulate the skeletal response to PTH. Alcohol may represent one of these factors. Chronic alcohol abuse is associated with osteoporosis and impaired fracture healing. Therefore, the present study investigated the effects of alcohol on the bone anabolic response to a dose of PTH similar to a human therapeutic dose 1) during normal cancellous and cortical bone growth and turnover, and 2) in a model of demineralized allogeneic bone matrix (DABM)-induced osteoinduction. Three-month-old male Sprague Dawley rats were fed a Lieber-DeCarli liquid diet with 35% of the calories derived from ethanol. The controls were pair-fed an alcohol-free isocaloric diet containing maltose-dextran. Following adaptation to the liquid diets, the rats were implanted subcutaneously with DABM cylinders prepared from cortical bone of rats fed normal chow. The rats were subsequently treated daily with PTH (1 microg/kg/d sc, 5 d/week) or vehicle and measurements on bone and DABM implants performed 6 weeks later. Total bone mass was evaluated on the day of necropsy using DXA. Tibiae were processed for histomorphometry. Bone mass and architecture in tibial diaphysis and DABM implants were evaluated by muCT. PTH treatment increased whole body bone mineral content (BMC) and bone mineral density (BMD). The hormone also increased bone formation and bone area/tissue area in the proximal tibial metaphysis. In contrast, PTH treatment had no effect on periosteal bone formation and minimal effects on DABM-induced osteoinduction. Alcohol consumption decreased whole body BMC. Alcohol also decreased cancellous as well as cortical bone formation and bone mass in tibia and impaired DABM-mediated osteoinduction. There was no interaction between PTH treatment and alcohol consumption for any of the endpoints evaluated. Our results indicate that the bone anabolic response to a therapeutic dose of PTH in the rat is largely confined to cancellous bone. In contrast, alcohol consumption inhibits bone formation at all sites. Furthermore, alcohol inhibits osteoinduction and reduces periosteal and cancellous bone formation, irrespective of therapeutic PTH administration. Based on the animal model, our findings suggest that alcohol consumption could impair the beneficial effects of PTH therapy in osteoporosis.

Association of Harris lines and shorter stature with ethanol consumption during growth

Ethanol consumption may impair bone growth. Transverse radiopaque lines (Harris lines) have been interpreted as manifestations of bone growth arrest due to nutritional stress. It is possible that ethanol consumption during growth leads to Harris lines formation and to a shorter stature. Plain X-ray film of the right tibia was performed to 175 individuals, who were inquired about ethanol consumption, periods of perceived hunger, and protracted illness during growth period (from birth to 18 years of age). Stature was also recorded. Men who drank during growth showed a shorter stature than those who did not (t=3.65, P<.001). Differences were not statistically significant among women (t=0.95). Neither periods of perceived hunger nor illness were associated to differences in stature. Ethanol consumption during growth showed a significant association with the presence of Harris lines (chi(2)=15, P<.001, Odds Ratio [OR]=3.39, confidence interval [CI]=1.81-6.33), an association which was more marked between having two or more Harris lines and drinking during growth (chi(2)=23.19, P<.001, OR=6.04, CI=2.79-13.11) or having three or more lines and drinking during growth (chi(2)=15.93, P<.001, OR=7.41, CI=2.47-22.21). Periods of perceived hunger during growth were also related to the presence of two or more Harris lines (chi(2)=4.66, P=.031, OR=2.055, CI=1.065-3.965), but no association was observed between illness and Harris lines, two or more Harris lines, and three or more Harris lines. Multivariate analysis showed that only ethanol consumption during growth period was associated with Harris lines.

Association of gene polymorphisms with intervertebral disc degeneration and vertebral osteophyte formation

STUDY DESIGN

Cross-sectional cohort study of elderly people.

OBJECTIVES

To examine the factors influencing osteophyte formation without lumbar disc degeneration and to estimate the implications of osteophytes from the viewpoint of low back pain and gene polymorphisms.

SUMMARY OF BACKGROUND DATA

The degenerative changes that occur in the intervertebral discs are the point of departure of osteophyte formation. Several studies on factors associated with genetic susceptibility to spinal osteophyte formation, such as VDR and TGF-beta1. However, there are no detailed studies concerning osteophytes not accompanied with disc degeneration.

METHODS

A total of 387 elderly persons were recruited, and disc degeneration and osteophyte formation were evaluated. The cases with osteophyte formation were classified into 3 groups: osteophyte formation with disc height narrowing (n = 217), osteophyte formation without disc height narrowing (n = 99), and control group defined as the cases without osteophyte formation (n = 71). Twelve genotypes were characterized. Correlations between these degenerative factors and the polymorphisms were analyzed.

RESULTS

The prevalence of low back pain was significantly greater in the group of osteophyte formation with disc height narrowing than the other 2 groups. In the polymorphism of alcohol dehydrogenase (ADH2), prevalence of osteophyte formation without disc height narrowing was less in His/Arg (odds ratio = 0.57, P = 0.041) and Arg/Arg (odds ratio = 0.41, P = 0.18) than His/His.

CONCLUSIONS

Patients with osteophyte formation preceding intervertebral disc narrowing had a lower risk of low back pain compared with those without osteophytes. The 47Arg polymorphism in the ADH2 may act to suppress osteophyte formation unaffected by disc degeneration.

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.

Quantitative Microcomputed Tomography Assessment of Intratrabecular, Intertrabecular, and Cortical Bone Architecture in a Rat Model of Severe Renal Osteodystrophy

OBJECTIVE

To determine the effects of renal osteodystrophy (ROD) on bone microarchitecture in growing rats.

METHODS

A total of 24 rats underwent 5/6 nephrectomy (NX) and were fed a high-phosphorus diet to induce ROD; another 6 underwent sham NX. In vitro microcomputed tomography images (GEMS, London, Ontario, Canada) were obtained in the femoral metaphysis and midshaft.

RESULTS

Trabecular and cortical bone volume/total volume (BV/TV) were significantly lower in NX specimens because of pores within the trabeculae and along the endosteal surface. Topological analysis using component labeling in 3-dimensions verified that trabecular pores connected to the marrow space. After the trabecular pores were filled using a morphological filter, trabecular thickness was significantly increased in NX. In contrast, cortical thickness was significantly decreased in NX compared with controls; however, after filling the endocortical pores, thickness did not differ.

CONCLUSIONS

The ROD resulted in decreased cortical and trabecular BV/TV, increased porosity, and increased trabecular thickness. Advanced image processing algorithms demonstrated the effects of cortical and trabecular porosity on BV/TV and structure in ROD.

Moderate alcohol consumption and increased bone mineral density: potential ethanol and non-ethanol mechanisms

Mounting epidemiological evidence indicates an association between the moderate ingestion of alcoholic beverages and higher bone mineral density (v. abstainers). More limited findings provide some evidence for translation of this association into reduced fracture risk, but further studies are required. Here, these data are reviewed and caveats in their assimilation, comparison and interpretation as well as in the use and application of bone health indices are discussed. Whilst it is concluded that evidence is now strong for the moderate alcohol-bone health association, at least in relation to bone mineral density, mechanisms are less clear. Both ethanol and non-ethanol components have been implicated as factors that positively affect bone health in the light of moderate consumption of alcoholic beverages, and four particular areas are discussed. First, recent findings suggest that moderate ethanol consumption acutely inhibits bone resorption, in a non-parathyroid hormone- and non-calcitonin-dependent fashion, which can only partly be attributed to an energy effect. Second, critical review of the literature does not support a role for moderate ethanol consumption affecting oestrogen status and leading to a knock-on effect on bone. Third, Si is present at high levels in certain alcoholic beverages, especially beer, and may have a measurable role in promoting bone formation. Fourth, a large body of work indicates that phytochemicals (e.g. polyphenols) from alcoholic beverages could influence bone health, but human data are lacking. With further work it is hoped to be able to model epidemiological observations and provide a clear pathway between the magnitude of association and the relative contribution of these mechanisms for the major classes of alcoholic beverage.

Binge alcohol treatment increases vertebral bone loss following ovariectomy: compensation by intermittent parathyroid hormone

BACKGROUND

Postmenopausal estrogen deficiency and alcohol abuse are known risk factors for osteoporosis. Previous studies of the combined effect of alcohol and ovariectomy on bone loss using chronic alcohol-feeding models have not demonstrated additional alcohol-induced bone loss in ovariectomized (OVX) animals. Binge alcohol treatment causes rapid bone loss in male rats. We hypothesized that binge alcohol would cause additional bone loss in OVX rats.

METHODS

Ninety-six adult (400 g) female Sprague-Dawley rats (48 sham-operated and 48 OVX, pair fed) were randomly divided into 4 treatment groups: (a) saline-treated, (b) binge alcohol-treated (3 g/kg alcohol as a 20% weight to volume alcohol/saline solution, intraperitoneal (IP), 3 times per week), (c) parathyroid hormone (PTH)-treated (80 microg/kg, SC, 5 d/wk), and (d) binge alcohol plus PTH. Rats were treated for either 2 or 4 weeks. Following treatment periods, blood was collected for alcohol concentration (BAC) measurements; lumbar vertebrae were removed for bone mineral density (BMD) levels, trabecular microarchitecture assessment, and vertebral compressive strength analysis.

RESULTS

Peak binge BACs averaged 300 mg/dL. Alcohol and OVX decreased cancellous BMD: alcohol and OVX treatment in combination caused additional cancellous BMD loss and significant cortical BMD reductions. Compressive strength was also decreased by OVX and alcohol. Combination treatment resulted in further declines in bone strength. Micro-CT analysis revealed a significant effect of combined OVX and alcohol treatment resulting in decreased trabecular bone volume/total volume (BV/TV). Intermittent PTH administration compensated for losses of BMD, compressive strength, and restored BV/TV deficits caused by OVX, alcohol, or their combination.

CONCLUSIONS

Bone loss following OVX can be significantly increased by concurrent binge alcohol treatment. The effects of alcohol and OVX are compensated by concurrent intermittent treatment with PTH. These results suggest that postmenopausal women who abuse alcohol may place their skeleton at additional risk for osteoporotic fracture.

Alcohol-induced bone loss and deficient bone repair

BACKGROUND

Chronic consumption of excessive alcohol eventually results in an osteopenic skeleton and increased risk for osteoporosis. Alcoholics experience not only increased incidence of fractures from falls, but also delays in fracture healing compared with non-alcoholics. In this review the term "alcohol-induced bone disease" is used to refer to these skeletal abnormalities. Alcohol-induced osteopenia is distinct from osteoporoses such as postmenopausal osteoporosis and disuse osteoporosis. Gonadal insufficiency increases the rate of bone remodeling, whereas alcohol decreases this rate. Thus, histomorphometric studies show different characteristics for the bone loss that occurs in these two disease states. In particular, alcohol-induced osteopenia results mainly from decreased bone formation rather than increased bone resorption. Human, animal and cell culture studies of the effects of alcohol on bone strongly suggest alcohol has a dose-dependent toxic effect on osteoblast activity. The capacity of bone marrow stromal cells to differentiate into osteoblasts has a critical role in the cellular processes involved in the maintenance of the adult human skeleton by bone remodeling. Chronic alcohol consumption suppresses osteoblastic differentiation of bone marrow cells and promotes adipogenesis. In fracture healing, the effect of alcohol is to suppress synthesis of an ossifiable matrix, possibly due to inhibition of cell proliferation and maldifferentiation of mesenchymal cells in the repair tissue. This results in the deficient bone repair observed in animal studies, characterized by repair tissue of lower stiffness, strength and mineral content. Current knowledge of cellular effects and molecular mechanisms involved in alcohol-induced bone disease is insufficient to develop interventional strategies for its prevention and treatment.

OBJECTIVES

The objectives of this review are 1) to identify the characteristics of alcohol-induced bone loss and deficient bone repair as revealed in human and animal studies, 2) to determine the current understanding of the cellular effects underlying both skeletal abnormalities, and 3) to suggest directions for future studies to resolve current ambiguities regarding the cellular basis of alcohol-induced bone disease.

Serum osteoprotegerin and RANKL levels in chronic alcoholic liver disease

OBJECTIVES

Osteoprotegerin (OPG) is a decoy receptor that binds RANK-ligand (RANKL) and prevents osteoclast activation. Oestrogens, androgens, corticosteroids, parathyroid hormone (PTH), vitamin D, and several cytokines exert their effects on bone modulating the OPG/RANKL system. Since these substances become altered in chronic alcoholic liver disease, we investigated the OPG/RANKL system in alcoholic liver disease, its relation with bone mineral density (BMD) and with several hormones and cytokines.

METHODS

Serum OPG, RANKL, C-terminal cross-linking telopeptide of type 1 collagen, osteocalcin, insulin-like growth factor 1 (IGF-1), 1,25 dihydroxyvitamin D, IL-6, tumour necrosis factor (TNF)-alpha, PTH, estradiol, free testosterone and corticosterone were measured in 77 male alcoholic patients, 25 of them cirrhotics. All these patients underwent assessment of BMD at lumbar spine and left hip by a Hologic QDR-2000 (Waltham, MA) bone densitometer. Nineteen non-drinkers male sanitary workers of similar age served as controls.

RESULTS

Serum OPG levels were higher in patients (12.66 +/- 6.44 pmol/l) than in controls (6.59 +/- 1.58 pml/l, P < 0.005), especially in cirrhotics (15.97 +/- 7.03 pmol/l) vs non-cirrhotics (10.96 +/- 5.45 pmol/l, P < 0.001). Patients also showed higher telopeptide levels (0.60 +/- 0.36 vs 0.20 +/- 0.10 nmol/100 ml, P < 0.001), less IGF-1 [median = 192, interquartile range (IQR) = 46.7-175.99 ng/ml vs 150, IQR = 118.8-239.4 ng/ml, P < 0.001], vitamin D (25.5, IQR = 18.25-35 pg/ml vs 77.89, IQR = 57.48-98.53 pg/ml, P < 0.001) and osteocalcin (1.8, IQR = 1-3.6 ng/ml vs 6.04, IQR = 4.63-8.20 ng/ml, P < 0.001) than controls, but no differences in PTH and RANKL. Patients also showed lower Z-scores than controls at trochanter (-0.36 +/- 1.10 vs 0.26 +/- 0.87 in controls, P = 0.026), intertrochantereal area (-0.56 +/- 1.16 vs 0.46 +/- 1.01, P = 0.001), and total hip (-0.44 +/- 1.12 vs 0.42 +/- 1, P = 0.003). TNF-alpha levels were higher in patients (7.40, IQR = 4.30-17.80 pg/ml) than in controls (5.10, IQR = 4.40-8 pg/ml, P = 0.009), especially in cirrhotics (median = 13.90, IR = 6.10-21.10 pg/ml). OPG levels showed strong correlations with TNF-alpha (rho = 0.57, P < 0.001) and IL-6 (r = 0.62, P < 0.001), but not with BMD. Estradiol levels (31.83 +/- 13.11 pg/ml) were higher and free testosterone lower (13.62 +/- 11.96 pg/ml) in patients than in controls (20.36 +/- 3.08 and 18.19 +/- 4.68 pg/ml, respectively, P < 0.001 in both cases).

CONCLUSION

OPG is raised in alcoholics, especially in cirrhotics, showing no relationship with decreased BMD. Also, raised TNF and IL-6 were observed, and were strongly, directly related with OPG levels. Since TNF and IL-6 enhance bone resorption, their relation with OPG suggests a protective effect of raised OPG on bone loss.

The effect of dietary taurine supplementation on plasma and liver lipid concentrations and mineral metabolism in rats fed alcohol

The purpose of this study was to investigate the effect of dietary taurine supplementation on plasma and liver lipid concentrations and plasma and urine Ca, Mg, Se, Zn concentrations in alcohol-consuming (15% of energy/d) rats. Thirty-two male rats (Sprague-Dawley) were divided into 4 groups and fed experimental diets (non-alcohol+control diet, non-alcohol+taurine, alcohol+control diet, alcohol+taurine) for six weeks. The level of taurine supplementation was 1.5 g/100 g diet. There were no significant differences in the body weight gain and total calorie intake between the control and alcohol groups, but the food efficiency ratio was higher in the control group. The concentrations of plasma total cholesterol, triglyceride, and HDL-cholesterol were higher in the alcohol group, while the levels were apparently reduced in the groups fed taurine. Glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities were not significantly influenced by alcohol (15% of energy) consumption and dietary taurine supplementation. The plasma concentrations of Ca, Mg, Se, and Zn were not affected by alcohol consumption or dietary taurine supplementation. Only the urinary excretion of Se significantly increased by alcohol consumption, which was decreased by dietary taurine supplementation. These results indicate that taurine exerted some beneficial effects on hypocholesterlemia, hypotriglyceridemia and urinary Se excretion caused by alcohol consumption.

Bone mass and strength: phenotypic and genetic relationship to alcohol preference in P/NP and HAD/LAD rats

BACKGROUND

The association between moderate alcohol intake and elevated bone mineral density observed in several epidemiologic studies might result from common genetic pathway regulating both phenotypes. In this study, we determined whether there is a relationship between alcohol preference and high bone mass or strength and whether bone mass-regulating genes segregate during selective breeding of alcohol preferring rats.

METHODS

Six different lines of male rats with high or low preference for alcohol consumption were used in this study. The high alcohol preference lines are alcohol-preferring (P), high-alcohol-drinking 1 (HAD1), and high-alcohol-drinking 2 (HAD2), and their corresponding low alcohol preference lines are alcohol-nonpreferring (NP), low-alcohol-drinking 1 (LAD1), and low-alcohol-drinking 2 (LAD2). Bone mass phenotypes were determined using dual energy x-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and biomechanics in long bones and lumbar vertebrae from rats at 3 and 6 months of age.

RESULTS

P rats had significantly higher bone mass and strength compared with NP rats, mainly due to higher cortical bone in long bones and lumbar vertebrae. HAD2 rats also had significantly higher bone mass compared with LAD2 rats, but mostly due to increased trabecular bone leading to increased strength only in lumbar vertebra. Conversely, HAD1 rats had significantly lower bone mass and strength compared with LAD1 rats in long bones. The vertebral bone mass and strength did not differ between HAD1 and LAD1 rats.

CONCLUSIONS

This study demonstrated that preference for alcohol consumption had no consistent relationship with high bone mass or strength, as each alcohol-preferring rat line had their unique bone mass phenotypes. However, genes regulating bone mass and strength appear to segregate with alcohol preference genes in P and HAD rat lines, suggesting that alcohol preferring rat lines may be useful for identifying genes that regulate bone mass and structure.

The effect of a simultaneous dietary administration of xylitol and ethanol on bone resorption

Our previous studies have shown that dietary xylitol supplementation diminishes bone resorption in rats, as well as protects against ovariectomy-induced increase of bone resorption during experimental osteoporosis. Interestingly, ethanol, when given simultaneously with xylitol, is known to increase blood concentration of xylitol. On the other hand, ethanol, when given alone, has been shown to increase bone resorption. The aim of the present study was to evaluate the effects of a simultaneous dietary administration of 10% xylitol and 10% ethanol on bone resorption. Bone resorption was determined using measurement of urinary excretion of hydrogen 3 (3H) radioactivity in 3H-tetracycline prelabeled rats. Already 4 days after the beginning of dietary supplementations, excretion of 3H was about 15% lower in the xylitol group (diet supplemented with 10% xylitol) and about 25% lower in the xylitol-ethanol group (diet supplemented with 10% xylitol and 10% ethanol) as compared to the controls. The excretion of 3H in these groups remained smaller than that of the controls throughout the entire study period of 40 days. The excretion of 3 H in the xylitol-ethanol group remained also smaller than that of the xylitol group. Bone mineral density and bone mineral content were determined with a peripheral quantitative computed tomography (pQCT) system from the rat tibiae at the end of the experiment. Trabecular bone mineral density and trabecular bone mineral content were significantly greater in the xylitol group and in the xylitol-ethanol group compared to the controls. They were also greater in the xylitol-ethanol group as compared to the xylitol group. Cortical bone mineral density and cortical bone mineral content did not differ significantly between the groups. In conclusion, a simultaneous dietary supplementation with 10% xylitol and 10% ethanol seems to diminish bone resorption and to increase trabecular bone mineral density and trabecular bone mineral content in rats. These effects seem to be stronger than the effects induced by 10% xylitol supplementation alone.

The role of nitric oxide on bone metabolism in ovariectomized rats following chronic ethanol intake

This experimental study was designed to examine the effect of nitric oxide (NO) on bone metabolism in ovariectomized rats following chronic ethanol treatment. Chronic ethanol intake was produced by gradual substitution (within 3 weeks) of tap water in diet with 5,10,15 and finally 20% of ethanol. Thereafter, the rats were maintained under these conditions for a duration of 4 months. The rats were divided into two groups. The first group received sham operation (SHAM) and the rats in Group II were ovariectomized (OVX). Five weeks after the SHAM and ovariectomy, the rats were treated with ethanol for 4 months. After this period of ethanol administration, the NOS inhibitor N(W)-nitro-L-arginine methyl ester (L-NAME) was given for three weeks along with ethanol to the same rats. Serum interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, NO, calcium (Ca), phosphorous (P), parathyroid hormone (PTH), 25 HydroxyvitaminD3 [25(OH)D3], alkaline phosphatase (ALP), bone alkaline phosphatase (b-ALP), alanine amino transferase (ALT), aspartate amino transferase (AST), gamma-glutamyltransferase (GGT) levels were measured in different stages of the experiment. IL-1beta, IL-6, TNFalpha and NO levels increased after ethanol administration in SHAM and OVX rats. The decrease in serum Ca was significant while the changes in P, PTH and 25 (OH)D3 levels were not. ALP and b-ALP levels were significantly decreased; ALT, AST and GGT levels were significantly increased. In ovariectomized and SHAM rats, administration of L-NAME together with ethanol, produced a significant increase in IL-1beta, IL-6 and TNFalpha levels. In this group, Ca and P levels were significantly increased, PTH and 25 (OH)D3 levels were significantly decreased. Also, there was a significant decrease in ALT, AST, ALP, b-ALP, and GGT levels. NO increase due to alcohol intake may function as a protective mechanism preventing bone resorption in cases of estrogen insufficiency.

The effects of binge alcohol exposure on bone resorption and biomechanical and structural properties are offset by concurrent bisphosphonate treatment

BACKGROUND

Chronic alcohol consumption reduces bone mass and strength, increasing fracture risk for alcohol abusers. Mechanisms underlying this vulnerability involve modulation of bone remodeling. Direct effects of alcohol on bone formation have been documented; those on bone resorption are less well studied. Skeletal effects of exposure to high blood alcohol concentrations (BAC's) attained during binge drinking have not been studied. We examined the effects of repeated binge-like alcohol treatment on bone resorption, bone mineral density and vertebral compressive strength in adult male rats treated with the aminobisphosphonate, risedronate.

METHODS

A binge alcohol exposure model was developed using intraperitoneal (IP) injection to administer a 20% (vol/vol) alcohol/saline solution (3 g/kg, 1X/day) on four consecutive days for 1, 2 or 3 weeks in 400 g rats, with and without weekly risedronate treatment (0.5 mg/kg, 1X/week). Total serum deoxypyridinoline (Dpd) a crosslink of bone type collagen released during resorption was measured by ELISA. Bone mineral density (BMD) was measured using peripheral quantitative computed tomography (pQCT). Vertebral compressive strength was determined using an Instron materials testing machine. Trabecular integrity was analyzed by computer-aided trabecular analysis system (TAS).

RESULTS

Peak BAC's averaged 308.5 +/- 12 mg/dL; average BAC was 258.6 +/- 28.7 mg/dL at time of euthanasia. No significant effects of treatment were observed after 1 or 2 weeks of binge alcohol exposure. At 3 weeks of alcohol treatment serum Dpd was significantly increased (205%, p < 0.05) over controls. Bone mineral density (BMD) in cancellous bone of distal femur and lumbar spine were significantly decreased (34% and 21% respectively, p < 0.01) after 3 weeks of binge treatment. Vertebral (L4) compressive strength (maximum load sustained before failure) also decreased (27%, p < 0.05) after 3 binge alcohol cycles. Risedronate maintained the Dpd level (p < 0.01), BMD (p < 0.001) and vertebral structural biomechanical properties (p < 0.01) of binge-treated rats at control levels (E vs ER). Indices of trabecular architectural integrity [Trabecular bone volume/tissue volume (BV/TV), bone area (BAR) and trabecular separation (Tb.Sp)] analyzed at week 3 showed (BV/TV) and (BAR) were significantly reduced in alcohol-binged rats (p < 0.01), while (Tb.Sp) was significantly increased (p < 0.01). Risedronate also maintained the trabecular architectural indices of binge-treated rats at control levels (E versus ER, p < 0.01).

CONCLUSIONS

In adult male rats, BAC's reflective of those attained during alcoholic binge drinking may affect the skeleton in part by stimulating bone resorption, an effect mitigated by risedronate.

Effect of Duration of Alcohol Consumption on Calcium and Bone Metabolism During Pregnancy in the Rat

BACKGROUND

Little is known about the consequences of drinking during pregnancy for the long-term health of the mother. Alcohol (ethanol) has been shown to disrupt calcium (Ca) homeostasis and is known to have deleterious effects on bone. During pregnancy, bone turnover is increased to maintain Ca homeostasis; therefore, pregnancy may be a time of life when maternal bone is particularly susceptible to the effects of ethanol. This study investigated the effect of duration of ethanol consumption on Ca homeostasis and bone during pregnancy in the rat.

METHODS

Rats were fed ethanol (36% ethanol-derived calories) in liquid diets for 3 (21 days gestation only) or 6 (3 weeks before and throughout 21 days gestation) weeks. Maternal blood was analyzed for Ca (total and ionized Ca [iCa]), the Ca-regulating hormones (parathyroid hormone [PTH], 1,25(OH)2D, calcitonin), and osteocalcin (a marker for bone formation). Bone was analyzed for ash (mineral) content.

RESULTS

Dams consuming ethanol (E dams) had decreased blood Ca levels (total and iCa) at both 3 and 6 weeks, but iCa was lower in E dams after 6 compared with 3 weeks. Importantly, ethanol seemed to interfere with the normal compensatory response to these decreased Ca levels. In contrast to pair-fed controls, serum PTH levels actually were decreased, 1,25(OH)2D levels failed to increase, and calcitonin levels were increased in ethanol-consuming dams, regardless of duration. Moreover, ethanol decreased bone formation, as indicated by serum osteocalcin levels, after both 3 and 6 weeks consumption, and after 6 weeks, the ash content of bone also was decreased. In addition, a relationship was found between the blood alcohol concentration (BAC) and some measures of Ca and bone metabolism. Serum 1,25(OH)2D and osteocalcin levels varied inversely, whereas serum calcitonin varied directly with BAC, suggesting that time of sampling after drinking may be an important variable for interpreting ethanol's effects on Ca and bone metabolism. In all rats, serum osteocalcin levels varied directly with PTH and 1,25(OH)2D levels.

CONCLUSIONS

Ethanol consumption during pregnancy impaired Ca homeostasis in the dam, regardless of duration of consumption, and resulted in decreased bone formation and ash content of bone. Significant relationships among the Ca-regulating hormones, BAC, and osteocalcin support the hypothesis that ethanol's effects on the Ca-regulating hormones may mediate some of its effects on bone.

Spine bone mineral density and vertebral body height are altered by alcohol consumption in growing male and female rats

Alcohol, consumed for extended periods by growing male and female rats, impairs osteogenesis and reduces bone size and mass. The skeletal sites of experimental animals commonly chosen for an evaluation of bone mechanical characteristics and architectural properties, bone matrix gene expression, tissue concentrations of growth factors, and bone mineral density (BMD) have been the tibiae and femora. Far less attention has been focused on the spine and the effects of alcohol on vertebral BMD and vertebral body height. Fifteen male and 15 female Sprague-Dawley rats (aged 30 days) were divided into three groups: an alcohol-fed group, matched to a pair-fed non-alcohol isocaloric-fed control group with animals of the same sex, and an ad libitum-fed control group. Alcohol-fed animals received a Lieber-DeCarli liquid diet containing 36% of caloric intake as alcohol; isocaloric pair-fed rats received the same diet without alcohol. After 45 days of feeding, the lumbar spine was removed. The fourth lumbar vertebra from each spine was dissected, and the vertebral body height was measured. Lumbar vertebral body height was significantly reduced by alcohol consumption in both male and female rats compared with findings for either control group. Cancellous and cortical BMD of the vertebral body was determined by peripheral quantitative computed tomography (pQCT). Male and female rats (aged 75 days) in the ad libitum-fed group had similar vertebral body cortical and cancellous BMD, with cortical BMD being greater than cancellous BMD. Lumbar vertebral body cancellous and cortical BMD declined for both male and female rats in response to alcohol consumption for 45 days compared with findings for either control group. More BMD loss occurred from cancellous than from cortical bone in both sexes after chronic alcohol consumption. Chronic alcohol consumption by growing rats results in vertebral growth reduction and vertebral osteopenia.

Alcohol consumption increases periodontitis risk

Alcohol consumption impairs neutrophil, macrophage, and T-cell functions, increasing the likelihood of infections. We examined the association between alcohol consumption and periodontitis, prospectively, among 39,461 male health professionals aged 40 to 75 years and free of periodontitis at the start of follow-up. Alcohol intake was assessed at baseline and updated every 4 years by a food-frequency questionnaire. Periodontal disease status was self-reported and validated against radiographs. Multivariate analysis was adjusted for age, smoking, diabetes, body-mass index, physical activity, time period, and caloric intake. During 406,160 person-years of follow-up, there were 2125 cases of periodontitis. Compared with non-drinkers, the relative risk (95% confidence interval) among men reporting usual alcohol intake of 0.1-4.9 g/day was 1.24 (1.09, 1.42); 5.0 to 14.9 g/day, 1.18 (1.04, 1.35); 15 to 29.9 g/day, 1.18 (1.01, 1.38); and > 30 g/day, 1.27 (1.08, 1.49). The results suggest that alcohol consumption is an independent modifiable risk factor for periodontitis.

Effects of heavy alcohol consumption on the cardiovascular system may be mediated in part by the influence of alcohol-induced depression on the immune system

The harmful effects of heavy alcohol use are well-documented and wide-ranging. Heavy drinking may cause or exacerbate cardiovascular disorders. The author suggests that effects of heavy alcohol consumption on the cardiovascular system may be mediated in part by the influence of alcohol-induced depression on the immune system. This hypothesis is based on the following data: (1) alcohol misuse may cause or exacerbate depression; (2) depressive disorders are associated with increased incidence, morbidity, and mortality of cardiovascular disorders; (3) the immune system may mediate effects of depressive disorders on the cardiovascular system. Further studies are needed to clarify the etiopathogenesis of alcohol-related disorders and develop new treatment modalities.

To drink or not to drink: how are alcohol, caffeine and past smoking related to bone mineral density in elderly women?

OBJECTIVES

To determine relationship between alcohol, caffeine, past smoking and bone mineral density of different skeletal sites in elderly women, accounting for other biological and life-style variables.

METHODS/DESIGN

A cross-sectional study in 136 Caucasian women, mean +/- SD age 68.6 +/- 7.1 years, all healthy and free of medications affecting bones, including estrogen. Bone mineral density (BMD) of multiple skeletal regions and body composition were measured by dual X-ray absorptiometry. Serum vitamin D (25-OHD) and parathyroid hormone (PTH) were analyzed and used as confounders. Calcium (Ca) intake was assessed by food frequency questionnaire. Alcohol and caffeine consumption was assessed by questionnaires determining frequency, amount and source of each. There were no current smokers, but the history of smoking was recorded, including number of years and packages smoked/day. Past physical activity was assessed by Allied Dunbar National Fitness Survey and used as confounder. Statistical significance was considered at p <or= 0.05.

RESULTS

In the correlational analysis, alcohol was positively associated with spine BMD (r = 0.197, p = 0.02), 25-OHD and negatively with PTH. Smoking was negatively related to Ca intake, 25(OH)D and number of reproductive years. In subgroup (stratified by Ca intake) and multiple regression analyses, alcohol (average approximately 0.5-1 drinks/day or approximately 8 g alcohol/day) was favorably associated with BMD of spine and total body. Caffeine (average approximately 2.5 6-fl oz cups/day or 200-300 mg caffeine/day) had negative association with most of the skeletal sites, which was attenuated with higher Ca intake (>or=median, 750 mg/day). The past smokers who smoked on average 24 years of approximately 1 pack cigarettes/day had lower BMD in total body, spine and femur than never-smokers when evaluated in subgroup analyses, and the association was attenuated in participants with >or=median Ca intake. There was no significant association between past smoking and BMD of any skeletal site in multiple regression analyses.

CONCLUSION

The results support the notion that consumption of small/moderate amount of alcohol is positively, while caffeine and past smoking are negatively associated with most of the skeletal sites, which might be attenuated with Ca intake above 750 mg/day.