Increased susceptibility of aging kidney to ischemic injury: identification of candidate genes changed during aging, but corrected by caloric restriction.

Aging is associated with an increased incidence and severity of acute renal failure. However, the molecular mechanism underlying the increased susceptibility to injury remains undefined. These experiments were designed to investigate the influence of age on the response of the kidney to ischemic injury and to identify candidate genes that may mediate this response. Renal slices prepared from young (5 mo), aged ad libitum (aged-AL; 24 mo), and aged caloric-restricted (aged-CR; 24 mo) male Fischer 344 rats were subjected to ischemic stress (100% N(2)) for 0-60 min. As assessed by biochemical and histological evaluation, slices from aged-AL rats were more susceptible to injury than young counterparts. Importantly, caloric restriction attenuated the increased susceptibility to injury. In an attempt to identify the molecular pathway(s) underlying this response, microarray analysis was performed on tissue harvested from the same animals used for the viability experiments. RNA was isolated and the corresponding cDNA was hybridized to CodeLink Rat Whole Genome Bioarray slides. Subsequent gene expression analysis was performed using GeneSpring software. Using two-sample t-tests and a twofold cut-off, the expression of 92 genes was changed during aging and attenuated by caloric restriction, including claudin-7, kidney injury molecule-1 (Kim-1), and matrix metalloproteinase-7 (MMP-7). Claudin-7 gene expression peaked at 18 mo; however, increased protein expression in certain tubular epithelial cells was seen at 24 mo. Kim-1 gene expression was not elevated at 8 or 12 mo but was at 18 and 24 mo. However, changes in Kim-1 protein expression were only seen at 24 mo and corresponded to increased urinary levels. Importantly, these changes were attenuated by caloric restriction. MMP-7 gene expression was decreased at 8 mo, but an age-dependent increase was seen at 24 mo. Increased MMP-7 protein expression in tubular epithelial cells at 24 mo was correlated with the gene expression pattern. In summary, we identified genes changed by aging and changes attenuated by caloric restriction. This will facilitate investigation into the molecular mechanism mediating the age-related increase in susceptibility to injury.

Adult-onset alcohol consumption induces osteopenia in female rats.

BACKGROUND: Alcohol is a known risk factor for osteopenia and fracture in humans, and its effects on the skeleton have been studied extensively in animal models. Almost all studies of rats, however, have begun rats on alcohol diets while the animals were young and still growing. The purpose of the current study was to examine the effects of alcohol consumption on rats that began drinking alcohol as adults, so that the confounding effects of growth might be minimized. METHODS: Nine-month-old female Sprague-Dawley rats were studied for two durations (8 and 14 weeks). The following diet groups were used for both durations: alcohol (n = 7), in which rats were fed a liquid diet containing ethanol (8.1% v/v; Lieber-DeCarli method); pair-fed (n = 7), in which rats were fed a caloric-equivalent liquid diet matched to the alcohol-fed animals; and pellet (n = 6), in which rats consumed standard rat chow and water. A cessation protocol was also used in which alcohol- and pair-fed groups were fed liquid diets for 8 weeks and then given pellet chow and water for 6 weeks, with pair feeding maintained during the cessation period. RESULTS: Only minor effects developed in the rats in the 8-week group, but after 14 weeks, the cancellous bone of the proximal tibia was severely osteopenic in the alcohol-fed animals. The bone volume and trabecular number were both significantly lower in the alcohol-fed animals than in the pair-fed and pellet-fed control animals and also lower than in the alcohol-fed animals in the 8-week group. Mechanical properties of the cancellous bone in the distal femur also were significantly diminished in the 14-week alcohol-fed group. Composition and mechanical properties of the cortical bone in the femur diaphysis were largely unaffected, but the yield stress was significantly lower in the 14-week alcohol-fed group than in the 8-week alcohol-fed group. No significant effects were found in the cessation groups with regard to almost all parameters measured. CONCLUSIONS: Our study results demonstrate that chronic adult-onset alcohol consumption leads to significantly diminished cancellous bone properties and that these effects depend on the duration of alcohol use.

The mechanical properties of cancellous bone in the proximal tibia of ovariectomized rats.

The "mature rat model" is an effective and often-used surrogate for studying mechanisms and characteristics of estrogen-deficient osteopenia. The purpose of this study was to extend our understanding of this animal model to include the mechanical properties of cancellous bone in the proximal tibia. Female Sprague-Dawley rats were divided into two groups (n=13 each) at 14 weeks of age: an ovariectomized group (OVX) and a sham-operated control group (sham). The study terminated after a duration of 5 weeks. Specimens 2 mm long were cut from the proximal tibial metaphysis just below the growth plate and tested using two methods: (1) "whole-slice" compression, in which the entire specimen is loaded between two larger flat platens and (2) "reduced-platen" compression (RPC), which uses platens sized and aligned to load only the cancellous bone in the center of the sample. Three-point bending tests also were conducted on the femur. The short duration of estrogen deficiency yielded only minimal differences (< 10%) in femoral cortical bone but dramatic reductions (approximately 60%) in cancellous bone properties as determined by the RPC method. Ultimate stress was 7.23 MPa +/- 1.97 MPa for OVX versus 18.1 MPa +/- 5.21 MPa for sham; and elastic modulus was 252 MPa +/- 104 MPa for OVX versus 603 MPa +/- 180 MPa for sham. These changes in mechanical properties are similar in many respects to the dramatic effects reported in histomorphometric studies. For the whole-slice method, differences in mechanical properties between the two groups were not as large because the test directly loads both cancellous and cortical bone, and the latter is not affected as severely by estrogen deficiency. In this case, ultimate stress and elastic modulus were only 30% (or less) lower for the OVX group.

Long-term alcohol consumption in the rat affects femur cross-sectional geometry and bone tissue material properties.

BACKGROUND: Alcohol consumption previously has been demonstrated to reduce the density and strength of cortical bone of young, actively growing rats. Osteoblast activity and trabecular bone volume were also significantly lower. A germane question arising from these studies is whether the detrimental effects would persist into adulthood. To address this issue, a long-term study was undertaken with animals that consumed alcohol throughout their life and into old age. METHODS: One-month-old female Sprague-Dawley rats were divided into three diet groups: alcohol-fed, pair-fed, and chow-fed. The alcohol-fed animals received a modified Lieber-DeCarli diet that contained 35% ethanol-derived calories. The pair-fed group served as a caloric-equivalent control, and the chow-fed animals served as a completely untreated control. Animals were euthanized after five time periods on the diets that represented three stages of the life span: young (3 months), adult (6, 9, 12 months), and aged (18 months). The left femur was isolated and mechanically tested in 3-point bending for mechanical properties. RESULTS: In the young animals, alcohol consumption produced dramatic reductions in both extrinsic (whole bone) and intrinsic (tissue material) properties, which is consistent with results from previous studies on growing rats. For the adult animals, however, the alcohol groups were only slightly lower and the differences were not statistically significant. The aged animals showed diminished properties due to alcohol, but only for the intrinsic material properties. The extrinsic properties remained similar to controls as a result of greater radial expansion in the femur diaphysis. Despite the cross-sectional areas being the same, this expansion gave rise to higher cross-sectional moment of inertia values in the alcohol animals. The thickness of the cortical wall was lowest in the alcohol group at all time points. CONCLUSIONS: Long-term alcohol consumption produced two major effects in the oldest animals studied: the quality of the cortical bone tissue was diminished, as evidenced by reduced elastic modulus and ultimate strength values, and the bone seemed to compensate for this by expanding the cross-section to produce larger cross-sectional moment of inertia values. The reduced bone tissue quality is consistent with the lower ash percent values in the alcohol animals, but other factors such as the quality of the collagen and mineral crystal may also be important contributors.

Long-term alcohol consumption increases matrix metalloproteinase-2 activity in rat aorta.

Altered degradation of extracellular matrix (ECM) underlies vascular remodeling, a hallmark in the pathogenesis of cardiovascular diseases including hypertension and aneurysmal dilatation. Although alcohol is recognized as a risk factor for certain cardiovascular disease states, its role in vascular remodeling has not been completely explored. We studied the effect of chronic alcohol consumption on upregulation of the enzymatic activity of matrix metalloproteinase-2 (MMP-2) as a possible pathway for large vessel remodeling. For this purpose, female rats were placed on one of three diets: a modified Lieber-DeCarli liquid diet containing 35% ethanol-derived calories, a pair-fed liquid diet with ethanol replaced by isocaloric maltose-dextrin, or a standard rat pellet. Weekly blood alcohol concentration averaged 117+/-7.9 mg/dl for the alcohol-fed rats. At 2, 4, and 72 weeks, aortas were removed and processed for measuring MMPs activity by gelatin zymography. Aortic extracts from rats on long-term (72 weeks), but not the short-term (2 and 4 weeks), alcohol diets showed increased MMP-2 activity. Furthermore, histochemical analysis of the aortas showed distinct disruption of the elastic fibers only in the 72 weeks alcohol-fed rats, compared to the control animals. These observations demonstrate that long-term alcohol consumption up-regulates MMP-2 activity, which is coincident with the alteration of aortic ECM composition through the degradation of vascular elastin components.

Binge drinking and bone metabolism in a young actively growing rat model.

BACKGROUND: Chronic alcohol consumption has been demonstrated to be deleterious to bone health. However, binge drinking is the prevalent form of drinking in young people, which was the impetus for the present study to determine the effect of week-end and week-long binge drinking on bone health in a young actively growing animal model. METHODS: Four-week-old, female, Sprague-Dawley rats were given the amount of 5% alcohol by gavage to be equivalent to a 63 kg woman drinking six beers a day for either 2 or 5 consecutive days per week. RESULTS: There were no changes in the 5-day binge animals, but the 2-day binge animals were hypocalcemic. Similarly, 2-day binge animals had slightly increased bone chemistry and histomorphometric values for both tibia and femur, but only femur length, dry weight, and ash weight as well as femur density, presented either as g/ml or ash weight per unit volume, were increased by a statistically significant level. Cross-section periosteal Mineral Apposition Rate (MAR) was significantly decreased in the 2-day alcohol fed animals. CONCLUSIONS: Actively growing rats given 5% alcohol by gavage for 2 days per week have an increased bone length, bone weight, and bone density. The interpretation of these results must be viewed with great caution because studies of chronic alcohol consumption, and many studies of acute drinking, clearly indicate deleterious effects of alcohol on bone health. Those fed alcohol for 5 days per week showed no change.

Osteopenia due to chronic alcohol consumption by young actively growing rats is not completely reversible.

Our project was conducted to determine if the deleterious effects of chronic alcohol consumption on growing bone are reversible if the adolescent stops drinking. Four-week old, female, Sprague-Dawley rats were housed and maintained in an AAALAC-accredited facility. Six animals each were placed on alcohol-fed (35% ethanol-derived calories), pair-fed or chow-fed diets for 2 or 4 weeks. A recovery group of six animals was alcohol-fed for 2 weeks followed by an additional 2 weeks of chow feeding. This group was pair-fed to an additional group of six animals that received liquid diet, pair fed to the recovery group for 2 weeks followed by 2 weeks on a pair-fed chow diet. Blood alcohol concentrations averaged 309 +/- 9 mg/dl. Morphological parameters of the femur, such as length, diameter, and volume were smaller in alcohol treated animals at both 2 and 4 weeks of feeding. Femur length and volume of recovery alcohol-fed animals were more than either 2- or 4-week alcohol-fed animals, but they were not as great as the same-age 4-week pair-fed or chow-fed animals. Diameter was similar to the 4-week alcohol-fed, but less than the chow-fed. Femur density was reduced at all time periods in the alcohol-fed animals. The recovery alcohol-fed animals had greater density than the 2-week alcohol, but not the 4-week alcohol-fed animals. They did not, however, reach 4-week chow- or pair-fed levels. Tibia BV/TV was reduced in the 2- and 4-week alcohol- and pair-fed animals. BV/TV was greater in the recovery animals than either 2- or 4-week alcohols, but not as great as the chow-fed animals. At 2 weeks, calorie deprivation caused a reduction in insulin-like growth factor-1 (IGF-1) that was reduced even more by alcohol. By 4 weeks, the calorie deprivation was no longer seen, but alcohol continued to reduce the values. Two weeks of alcohol followed by 2 weeks of chow diet returned the IGF-1 values to almost normal, but significantly different levels. The apparent improvement was probably due to continued growth of the young bones and not a regaining of bone lost during alcohol consumption.

Effect of alcohol consumption on adult and aged bone: composition, morphology, and hormone levels of a rat animal model.

To determine the effect of life-long alcohol consumption on the adult and aged rat model, 4-week-old, female Sprague-Dawley rats were divided into three diet groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin substituted calories supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Proximal tibiae (primarily cancellous bone) and femora (primarily cortical bone) were removed for analysis after 3, 6, 9, 12, or 18 months on the diets. Serum was collected for analysis of calcium levels, the calcium regulating hormones; parathyroid hormone, 25-hydroxyvitamin D, calcitonin, corticosterone, estradiol, testosterone, and IGF-1. Creatinine, SGOT/AST, and SGPT/ALT levels were measured to determine kidney and liver integrity. Previous studies, with young animals, showed that chronic alcohol consumption during the age of bone development reduced bone density and bone mass in both cortical and cancellous bone. The present study demonstrates that these reductions last throughout life, whereas morphological values, such as length and diameter, attain control levels. Calcium regulating hormones and sex hormones are essentially normal and do not appear to be the primary causative agent for adult alcohol-induced osteopenia, but it appears to be due to a more direct effect of alcohol on bone cells.

The vastus medialis oblique muscle and its relationship to patellofemoral joint deterioration in human cadavers.

Patellofemoral joint deterioration (PFJD) is frequently seen in physical therapy clinics and represents a significant problem for both patients and rehabilitation clinicians. The vastus medialis oblique (VMO) muscle is reported to be the primary stabilizer of the patella during knee extension. Most studies and treatment protocols emphasize strengthening of the VMO as the nonsurgical treatment of choice for patients with PFJD. The purpose of this study was to determine whether any relationship exists between the morphology of the VMO and the presence and severity of PFJD in human cadavers. Dissection of 374 vastus medialis (VM) muscles and patellofemoral joints was performed on 229 human cadaver lower limbs to determine what relationships exist between gender, VMO features, and PFJD. Patellofemoral joint deterioration was determined by direct visual observation and assigned a score based on severity of joint deterioration present. Two-way chi-square tests were performed to determine the relationships between cadaver gender, the presence of VMO features, and the presence and severity of PFJD. Linear regression was performed to determine whether any correlation existed between the VMO fiber angle and the severity of PFJD. A one-way analysis of variance was performed to determine whether any differences existed between the VMO fiber angle and the PFJD groups. No statistically significant relationships, correlation, or differences existed in any of the tests performed between cadaver gender, VMO features, and presence or severity of PFJD. The presence or severity of PFJD in human cadavers is not related to either gender or VMO morphologic features. The results of this study do not support the premise that a more distal insertion of the VMO onto the patella of the VMO will have any effect on the presence or severity of PFJD.

Alcohol consumption inhibits osteoblastic cell proliferation and activity in vivo.

To better understand the effect of alcohol consumption on the bone remodeling process in vivo, we used a rodent animal model system to compare osteoblast activity and number in alcohol-fed, pair-fed, and chow-fed animals. Adult, virgin female Sprague-Dawley rats were assigned to alcohol-fed, pair-fed, and chow groups based on weights. Alcohol animals were fed a liquid diet containing 35% ethanol-derived calories for 6 weeks. Pair-fed animals were matched to test animals on the basis of initial weight and fed an isocaloric diet equivalent to that consumed by the alcohol-matched animals on the previous day with alcohol replaced by maltose-dextrin. Right tibias were fixed and embedded in methyl methacrylate for sectioning. Sections (5 microm) were stained for cement lines and packets were measured using histomorphometric techniques on a BioQuant morphometric system. Alcohol-fed animals exhibited statistically significant decreases in the amount of bone surface containing active osteoblasts and a decrease in mean wall thickness. Osteocalcin values were significantly reduced from pair-fed levels and slightly, but not significantly, reduced from chow-fed animals.

Magnesium levels in alcohol-treated rodents using different consumption paradigms.

To develop an animal model system that examines magnesium (Mg) deficiency associated with chronic alcohol consumption, we tried to reproduce a Mg-deficient state, caused by alcohol consumption, in rats using different alcohol consumption experimental designs. Serum and bone samples were collected from 2-day binge (high BACs achieved by intubating a 5% ethanol solution 2 consecutive days/week), 5-day binge, moderate drinking, and adolescent (4-week-old rats, equivalent to late teen/early adult humans) alcohol consumption projects. Mg content was measured using color spectrophotometry. Alcohol-fed animals consumed a liquid diet containing 0.38 g/kg/day ethanol in the moderate project and 35% ethanol-derived calories in the adolescent drinking project. Animals in the two binge drinking projects were intubated with 12 g/kg/day of ethanol in a 5% solution. When looked at acutely and chronically, no consistent deficiencies in Mg were seen. The lack of a chronic Mg deficiency in rats may indicate a different mechanism of action than observed in humans.

Effect of alcohol consumption on adult and aged bone: a histomorphometric study of the rat animal model.

The adult and aged skeleton exist in a time when osteoporosis and age-related bone loss is at a maximum, and it is modified by lifestyle factors such as alcohol. To determine the effect of life-long alcohol consumption on the adult and aged rat model, 4-week-old female Sprague-Dawley rats were divided into three diet groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin substituted calories supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Proximal tibiae were removed and prepared for histomorphometric analysis after 3, 6, 9, 12, or 18 months on the diets. Previous studies, with young animals, showed that chronic alcohol consumption during the age of bone development reduced bone volume and trabecular number in cancellous bone. The present study demonstrates that these reductions last throughout life. The rate of bone formation is reduced in alcohol-fed animals, but most bone cell parameters are relative normal, except for wall thickness, indicating a reduced osteoblast activity.

Alcohol's harmful effects on bone.

Long-term alcohol consumption can interfere with bone growth and replacement of bone tissue (i.e., remodeling), resulting in decreased bone density and increased risk of fracture. These effects may be exerted directly or indirectly through the many cell types, hormones, and growth factors that regulate bone metabolism. Alcohol consumption during adolescence reduces peak bone mass and can result in relatively weak adult bones that are more susceptible to fracture. In adults, alcohol consumption can disrupt the ongoing balance between the erosion and the remodeling of bone tissue, contributing to alcoholic bone disease. This imbalance results in part from alcohol-induced inhibition of osteoblasts, specialized cells that deposit new bone. Some evidence suggests that moderate drinking may decrease the risk of fracture in postmenopausal women.

Moderate alcohol consumption does not augment bone density in ovariectomized rats.

Moderate levels of alcohol consumption have been reported to have a beneficial effect on bone mineral density in postmenopausal women. The objective of this study was to examine the effect of a moderate level of alcohol consumption on bone density in a rigorously controlled animal model of osteoporosis. Ovariectomized and nonovariectomized rats were placed on standard lab pellets with free access to deionized water ad libitum. Alcohol-treated animals were given 0.38 g/kg of alcohol daily by intubation in the mid-afternoon and free access to standard lab pellets for 6 weeks. The amount of the alcohol solution was calculated daily to give the human equivalent of 2 glasses of wine/day. Pair-fed control animals were given, on the following day, an equal volume of the diet consumed by individual ethanol-fed rats. They received daily intubation solutions, with the ethanol replaced by isocaloric and isovolumetric amounts of maltose-dextrin. Chow-fed control animals received no intubations and were given access to standard lab pellets ad libitum. Ovariectomized animals had increased weight and decreased femur density and bone volume per total volume. They also had decreased total trabecular area, trabecular area, and number, as well as increased trabecular separation. Significant differences were found between the ovariectomized and nonovariectomized animals in the parameters under discussion, but there were no differences between diet groups. No beneficial effects were found after daily alcohol treatments.

Prevalence and morphology of the vastus medialis oblique muscle in human cadavers.

BACKGROUND: The vastus medialis (VM) muscle has been described as being composed of two separate divisions: the vastus medialis longus (VML) proximally and the vastus medialis oblique (VMO) distally. The VML is reported to directly contribute to knee extension, while the VMO provides medial stabilization of the patella during knee extension. Despite the prevalence of literature describing the morphology and function of the VMO as an individual muscle, very little literature exists which actually substantiates the existence of the VMO as a separate, distinct muscle from the VML. The purpose of this study was to examine a sufficiently large sample of human cadavers to quantify and substantiate the existence of the VMO as a separate, distinct muscle from the VML, and to establish a statistical parameter representative of a normal adult population. METHODS: Three hundred seventy-four adult human cadaver lower extremities were dissected, exposing the entire anterior thigh from the anterior superior iliac spine to the tibial tubercle. Examination of the cadavers included goniometric measurement of the fiber angles of the VML and VMO, determination of the existence and location of a fascial plane, and determination of the maximum VM fiber angle in all cadaver specimens. Descriptive statistics were performed on all fiber angle measurements and frequency of fascial plane presence. Analysis of variance was performed on the maximal VM fiber angle between muscles with and without a definitive fascial plane. Intrarater reliability tests were performed on all measures to ensure the reliability and increase the validity of all of the measurements taken. RESULTS: A statistical parameter for the appearance of VMO features as originally defined was set at 21.65% of the sample. No statistically significant differences existed in the maximal VM fiber angle between the groups demonstrating the presence or absence of a VM fascial plane. None of the cadavers possessed an aponeurotic sheet of epimysium anatomically separating the VMO from the VML. CONCLUSIONS: This study supports earlier research reporting a difference in fiber orientation between the proximal and distal VM fibers; however, contrary to statements in published literature, the VMO does not appear to be an anatomically separate structure from the VML inherent throughout the human population. The results of this study do not support the concept that the VMO and VML exist as anatomically separate structures in a sample of human cadavers.

Alcohol consumption by young actively growing rats: a study of cortical bone histomorphometry and mechanical properties.

Alcohol consumption by young actively growing rats has been previously demonstrated to decrease cortical and cancellous bone density, to reduce trabecular bone volume, and to inhibit bone growth at the epiphyseal growth plate. This study addresses the action of alcohol on cortical bone growth using histomorphometric techniques and on mechanical properties by three-point bending. Four-week-old, female Sprague-Dawley rats were divided into three groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin-substituted calories were supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Femora were removed for analysis after 2, 4, 6, or 8 weeks on the diets. Cortical bone area, bone formation rates, and mineral apposition rates were reduced in the alcohol-fed animals. Bone stiffness, strength, and energy absorbed to fracture were significantly lower in the alcohol-fed animals. This distinctive alcohol effect was revealed to be caused by lower quality bone tissue as reflected by lower elastic moduli and yield strengths.

Alcohol, osteoporosis, and bone regulating hormones.

The mechanism of the production of ethanol-associated osteopenia seems to be a direct effect of alcohol on bone cells and an indirect or modulating effect through mineral regulating hormones such as vitamin D metabolites, parathyroid hormone, and calcitonin. The modulating effects of these hormones on bone and mineral metabolism in acute and chronic alcohol consumption is discussed herein.

Alcohol consumption by young actively growing rats: a histomorphometric study of cancellous bone.

Alcohol consumption by young actively growing rats has been previously demonstrated to decrease bone density. This study addresses the mechanism of alcohol action on the early phases of bone growth and development using histomorphometric techniques. Four-week-old, female Sprague-Dawley rats were divided into three groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin-substituted calories were supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Proximal tibiae, including epiphyseal growth plate, were removed for analysis after 2, 4, 6, or 8 weeks on the diets. Trabecular volume and number were greatly reduced in the alcohol-fed animals; however, bone formation rates and mineralization rates were normal. Epiphyseal growth rate and proliferation rate were essentially stopped in the alcohol-fed animals.

Alcohol consumption inhibits bone growth and development in young actively growing rats.

Adolescence is an age of widespread alcohol abuse, but the effect of alcohol consumption on bone formation has not been studied in the young population. This study addresses the effect of alcohol on the early phases of bone growth and development in an animal model. Four-week-old, female Sprague-Dawley rats were divided into three groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin substituted calories supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Proximal tibiae (primarily cancellous bone) and femora (primarily cortical bone) were removed for analysis after 2, 4, 6, or 8 weeks on the diets. Serum was collected for analysis of calcium levels, osteocalcin, corticosterone, growth hormone, parathyroid hormone, and 25-hydroxyvitamin D. The most rapid weight gain occurred between 6 and 8 weeks of age, it was significantly delayed in alcohol and pair-fed animals. Almost all morphological parameters of bone were lower in the alcohol groups. No significant difference in serum calcium levels, osteocalcin, or growth hormone levels were found, and small difference in calciotropic hormone levels was found between groups. The results indicated that chronic alcohol consumption during the age of bone development reduces bone density and peak bone mass in both cortical and cancellous bone. The mechanism whereby this effect occurs is not fully understood, but, our results suggest that the negative impact of alcohol on growing bone is not due to the secondary effects of altered bone mineral regulating hormones.

The relationship of nutritional copper to the development of postmenopausal osteoporosis in rats.

Factors that influence tissue copper concentration include age, diet, hormones, and pregnancy. In this study we altered diet independently, hormone (estrogen) independently, and various combinations of diet and hormone in animals of the same age to study the effects of ovariectomy complicated with dietary copper deficiency; a deficiency that has been demonstrated to cause bone defects. Sprague-Dawley rats were placed on various combinations of copper deficient or enriched diets before and/or after ovariectomy to determine if copper deficiency aggravated osteoporosis and if return to a copper-adequate diet alleviated it. In this study, ovariectomy did induce an osteopenia that was characterized by decreased trabecular bone. This osteopenia was slightly more severe with copper deficiency, but was not necessarily alleviated by the return of normal copper levels to the diet.