Lead/ethanol interactions. II: pharmacokinetics

The effects of binge alcohol exposure on tooth movement and associated root resorption in rats

BACKGROUND

Considering the increasing prevalence of alcohol use and the growing number of orthodontic patients, some orthodontic patients might engage in binge drinking during treatment. Nevertheless, little is known about the effect of alcohol use on orthodontic treatment.

METHODS

Male Wistar rats were divided into ethanol and control groups (n = 32). The rats received a single daily intraperitoneal injection of 20% (vol/vol) ethanol/saline solution at a dose of 3 g/kg of ethanol or saline for three consecutive days, and no injection was given during the remaining four days each week. All rats received orthodontic appliances to draw the maxillary first molar mesially. The rats were sacrificed at days 14 and 28, respectively. The amount of tooth movement was measured. Root resorption area was evaluated by scanning electron microscope. Hematoxylin and eosin (H&E) staining and tartrate-resistant acid phosphatase (TRAP) staining were conducted. Immunohistochemistry staining was performed to evaluate the expressions of nuclear factor kappa B ligand (RANKL), osteoprotegerin (OPG), and inducible nitric oxide synthase (iNOS).

RESULTS

There were no significant differences in tooth movement and root resorption between ethanol and control groups. The number of TRAP-positive cells was significantly higher in the ethanol group. The expression of RANKL was statistically increased in the ethanol group. In contrast, the expression of OPG was remarkably decreased in rats injected with ethanol. Moreover, the iNOS level was significantly up-regulated in the ethanol group.

CONCLUSION

The tooth movement and root resorption in rats were not affected by binge alcohol exposure.

Effects of Episodic Alcohol Exposure on BMP2 Signaling During Tibia Fracture Healing

OBJECTIVES

To explore how alcohol affects the BMP-2 signaling pathway, which is known to play a critical role in bone and cartilage formation during fracture healing.

METHODS

A rat model was used to demonstrate the detrimental effects of alcohol exposure on tibia fracture healing. Specific components of the BMP-2 pathway were analyzed in fracture callus on days 3, 7, 14, and 21 after fracture via western immunoassays and enzyme-linked immunosorbent assay.

RESULTS

Alcohol exposure before tibia fracture demonstrated attenuation of downstream BMP-2 signaling. The BMP-2 antagonist, Chordin, may be the central component of the BMP-2-related changes demonstrated in this study. Although alcohol affected BMP-related proteins at all time points, it seems that day 14 after fracture is a critical time point for alcohol-related modulation of callus formation in our model.

CONCLUSIONS

This study may provide the scientific basis for further studies addressing whether the application of exogenous BMP-2 in patients with a history of alcohol abuse who sustain long bone fractures may or may not be of benefit.

Interactive effects of prenatal exposure to restraint stress and alcohol on pentylenetetrazol-induced seizure behaviors in rat offspring

Prenatal exposure to stress or alcohol increases vulnerability of brain regions involved in neurobehavioral development and programs susceptibility to seizure. To examine how prenatal alcohol interferes with stress-sensitive seizures, corticosterone (COS) blood levels and pentylenetetrazol (PTZ)-induced seizure behaviors were investigated in rat pups, prenatally exposed to stress, alcohol, or both. Pregnant rats were exposed to stress and saline/alcohol on 17, 18, and 19 days of pregnancy and divided into four groups of control-saline (CS), control-alcohol (CA), restraint stress-saline (RS), and restraint stress-alcohol (RA). In CS/CA groups, rats received saline/alcohol (20%, 2 g/kg, intraperitoneally [i.p.]). In RS/RA groups, rats were exposed to restraint stress by being held immobile in a Plexiglas^® tube (twice/day, 1 h/session), and received saline/alcohol, simultaneously. After parturition, on postnatal days 6 and 15 (P6 & P15), blood samples were collected from the pups to determine COS level. On P15 and P25, PTZ (45 mg/kg) was injected into the rest of the pups and seizure behaviors were then recorded. COS levels increased in pups of the RS group but not in pups of the RA group. Both focal and tonic-clonic seizures were prevalent and severe in pups of the RS group, whereas only focal seizures were prominent in pups of the CA group. However, pups prenatally exposed to co-administration of alcohol and stress, unexpectedly, did not show additive epileptic effects. The failure of pups prenatally exposed to alcohol to show progressive or facilitatory epileptic responses to stressors, indicates decreased plasticity and adaptability, which may negatively affect HPA-axis performance or hippocampal structure/function.

Long-term modulations in the vertebral transcriptome of adolescent-stage rats exposed to binge alcohol

AIMS

Dangerous alcohol consumption practices are common in adolescents, yet little is known about their consequences on attainment of peak bone mass and long-term skeletal integrity. We previously demonstrated that binge alcohol-exposed adolescent rats showed site-specific reductions in accruement of bone mineral density and bone strength, which were incompletely recovered following prolonged alcohol abstinence. Currently, we analysed the vertebral transcriptome of adolescent rats following alcohol treatment and abstinence to identify long-term molecular changes in the lumbar spine.

METHODS

Sixty male adolescent Sprague-Dawley rats were assigned to one of six treatment groups receiving binge alcohol (3 g/kg) or saline i.p., 3 consecutive days (acute binge), 4 consecutive weekly (3-day) binge cycles (chronic binge) or 4 weekly binge cycles followed by a 30-day abstinence period (chronic binge with abstinence). Following treatment, lumbar vertebrae were assayed for global transcriptional changes using gene array technology.

RESULTS

Analysis of the adolescent rat vertebral transcriptome identified clusters of binge alcohol-sensitive genes displaying differential expression patterns starting before bone damage was seen and persisting after alcohol treatment was discontinued. Functional grouping of these gene clusters identified candidate cellular pathways affected following acute and chronic binge treatment, as well as pathways remaining modulated following abstinence.

CONCLUSIONS

These results demonstrate that binge alcohol exposure can produce disruptions of normal bone gene expression patterns in the adolescent rat that persist well beyond the period of active intoxication. This data may have relevance to peak bone mass attainment and future risk of skeletal disease in adolescents engaging in repeated binge-drinking episodes.

Binge alcohol-induced bone damage is accompanied by differential expression of bone remodeling-related genes in rat vertebral bone

Binge alcohol-related bone damage is prevented by concurrent administration of bisphosphonates, suggesting an activation of bone resorption with patterned alcohol exposure. Although chronic alcohol abuse is known to cause osteopenia, little is known about the effects of binge drinking on bone metabolism. We examined the effects of binge alcohol exposure on the relationship between bone damage and modulation of bone remodeling-specific gene expression profiles. Our hypothesis was that bone damage observed in young adult rats after binge alcohol exposure is associated with differential expression of bone remodeling-related gene expression. We further hypothesized that this differential gene expression specific to bone remodeling (bone resorption or formation related) would be influenced by the duration of binge alcohol exposure. Binge alcohol (3 g/kg, i.p.) was administered on 3 consecutive days each week, for 1 or 4 weeks, to adult male rats. Matched control animals were injected with an equal volume of isotonic saline. Lumbar vertebrae, L4-5, were analyzed for the presence of bone damage by quantitative computed tomography and compressive strength analysis. Total RNA was isolated from an adjacent vertebrae (L3), and whole transcriptome gene expression data were obtained for each sample. The expression levels of a subset of bone formation and resorption-associated differentially expressed genes were validated by quantitative reverse transcriptase-polymerase chain reaction. Bone loss was not observed after 1 week of treatment but was observed after four binge alcohol cycles with a 23% decrease in cancellous bone mineral density and 17% decrease in vertebral compressive strength compared with control values (P < 0.05). We observed that the duration of binge alcohol treatment influenced the modulation of expression profiles for genes that regulate the bone formation process. The expression of key bone formation-related marker genes such as osteocalcin and alkaline phosphatase were significantly reduced (P < 0.05) after acute binge alcohol exposure, and expression of regulators of osteoblast activity such as bone morphogenetic proteins and parathyroid hormone receptor displayed significantly (P < 0.05) decreased differential expression. The expression of sclerostin, a key canonical Wnt inhibitory protein, was significantly increased after acute binge alcohol treatment. The expression of important regulators of osteoclast maturation and activity such as NF-kappabeta (nuclear factor kappabeta) ligand (RANKL) and interleukin-6 were significantly increased (P < 0.05) by binge alcohol, and osteoprotegerin levels were significantly decreased (P < 0.05) in vertebral bone. These results show that expression patterns of several key bone remodeling genes are significantly perturbed by binge alcohol treatment, suggesting that perturbation of gene expression associated with bone remodeling may be one mechanism contributing to the disruption of bone mass homeostasis and subsequent bone loss observed after binge alcohol exposure in rodents.

Binge alcohol treatment of adolescent rats followed by alcohol abstinence is associated with site-specific differences in bone loss and incomplete recovery of bone mass and strength

We previously demonstrated that alcohol-fed adolescent rats exhibit reductions in lumbar spine bone mineral density (BMD) and vertebral body height, suggesting that chronic alcohol consumption has negative consequences for skeletal development during adolescence. Binge alcohol consumption is common in adolescents and young adults, yet little is known about its consequences on skeletal integrity or the attainment of peak bone mass. We used a previously validated binge alcohol exposure model to test the hypothesis that binge alcohol treatment of adolescent rats would be associated with distinct temporal and site-specific bone loss profiles, with incomplete recovery from bone loss following a period of alcohol abstinence. Seventy-two male adolescent Sprague-Dawley rats were assigned to one of six treatment groups (n=12/group) receiving binge alcohol (3 g/kg) or saline intraperitoneal, 3 consecutive days (acute binge), 4 consecutive weekly (3-day) binge cycles (chronic binge), or 4 weekly binge cycles followed by a 30-day abstinence period without alcohol or saline injections (chronic binge with abstinence). Cancellous BMD was determined by quantitative computed tomography and compressive strength determined by biomechanical testing. Serum testosterone and osteocalcin levels were measured by enzyme-linked immunosorbent assay. Tibial cancellous BMD was significantly reduced by 25% (P<.05) after both acute and chronic binge alcohol treatment and vertebral cancellous BMD was significantly reduced by 15% (P<.05) after chronic binge exposure. Vertebral compressive strength was also significantly decreased by 31% (P<.05) after chronic binge alcohol treatment. Tibial cancellous BMD returned to control levels after the 30-day alcohol abstinence period, but vertebral cancellous BMD remained 15% below control values (P<.05) 30 days after termination of binge alcohol exposures. Serum osteocalcin levels were significantly decreased following acute binge alcohol exposure (P<.05). These results show that binge alcohol exposure can produce both short- and long-term skeletal damage in the adolescent rat. These data might have relevance to peak bone mass attainment and future risk of skeletal disease in adolescents and young adults who engage in repeated binge-drinking episodes.

Identification of novel bone-specific molecular targets of binge alcohol and ibandronate by transcriptome analysis

BACKGROUND

Our laboratory established that binge alcohol-related bone damage is prevented by aminobisphosphonates, suggesting bone resorption increases following binge exposure. We examined the effects of binge alcohol and antiresorptive therapy on the relationship between bone damage and modulation of the vertebral transcriptome, in an attempt to determine how alcohol-induced bone damage and its prevention modulate bone-related biological pathways.

METHODS

Male Sprague-Dawley rats were assigned to 1 of 6 treatment groups (n = 12/group). (C1) saline ip 3 d/wk for 1 week, (A1) binge alcohol, 3 g/kg, ip 3 d/wk for 1 week, (C4) saline ip, 3 d/wk for 4 weeks, (A4) binge alcohol, ip, 3 g/kg 3 d/wk for 4 weeks, (I4) ibandronate, saline ip 3 d/wk for 4 weeks, plus a single ip injection of ibandronate at 120 microg/animal, and (AI4) binge alcohol plus ibandronate as above. After 1 or 4 weeks, adjacent lumbar vertebrae were assayed for bone damage or transcriptional changes.

RESULTS

Bone loss was not observed after 1 week of binge alcohol treatment. After 4 weeks, binge alcohol decreased vertebral BMD by 23% (p < 0.05) and compressive strength by 18% compared to saline controls (p < 0.05). Concurrent ibandronate prevented bone loss, increasing these parameters by 145 and 134% respectively compared to binge alcohol. (p < 0.05). Analysis of the vertebral transcriptome identified gene clusters specific for acute and chronic binge alcohol-related bone damage. Acute binge alcohol modulated the expression of integrin signaling-specific genes, while chronic binge alcohol modulated canonical Wnt signaling gene expression. Ibandronate normalized the expression of approximately 20% of the genes affected by chronic binge alcohol, allowing the identification of a unique subset of alcohol-sensitive, ibandronate-responsive genes.

CONCLUSIONS

Identification of bone-specific gene expression clusters associated with acute and chronic binge alcohol treatment allowed for the identification of cellular pathways affected by binge treatment with known involvement in bone remodeling (Integrin, Canonical Wnt signaling) not previously identified as alcohol-sensitive. This data provides a basis for a plausible mechanistic explanation for the known detrimental effects of alcohol on bone formation and resorption.

Vitamin D and ibandronate prevent cancellous bone loss associated with binge alcohol treatment in male rats

Decreased bone mass and bone strength can result from excess alcohol consumption in humans and alcohol treatment in the rat. Although the specific mechanism is unknown, the damaging effects of alcohol abuse modulate the bone remodeling cycle and increase bone turnover. Chronic alcohol consumption models have shown an inhibition of bone formation. We previously reported that binge alcohol treatment increases bone resorption and that alcohol-induced damage can be prevented by treatments with intermittent parathyroid hormone and bisphosphonates. In this study, we hypothesized that an effective dose of vitamin D (cholecalciferol) or a single dose of ibandronate would prevent bone loss caused by binge alcohol treatment in male rats. Forty-eight adult (450 gram) male Sprague-Dawley rats were randomly assigned to 6 treatment groups (n=8): (a) saline i.p., 3 days/week (C); (b) binge alcohol, 3 g/kg i.p., 3 days/week (A); (c) vitamin D, 5,000 IU/kg daily s.c. (D); (d) binge alcohol and vitamin D (AD); (e) ibandronate (120 microg, given as a single i.p. injection (I)); and (f) alcohol and ibandronate (AI) . After 4 weeks of treatment, proximal tibia and L3 and L4 vertebrae were analyzed for bone mineral density (BMD) by quantitative computerized tomography and compressive strength-to-failure using an Instron materials testing machine. Type I collagen cross-linked c-telopeptide, calcium, and 25-OH vitamin D levels were measured in serum collected at the time of sacrifice. Binge alcohol significantly decreased cancellous BMD by 58% in tibia and 23% in lumbar spine (p<0.05). Binge alcohol treatment decreased L3 and L4 compressive strength-to-failure by 21% (p<.05). Treatment with vitamin D at 5,000 IU/kg/day prevented alcohol-induced bone loss, significantly increasing both tibial and vertebral cancellous BMD values (161% increase in tibia and 40% increase in vertebra, respectively, p<0.05) compared to alcohol alone groups. Pre-treatment with the single dose of 120 microg ibandronate prevented alcohol-induced bone loss, increasing cancellous BMD by 186% in tibiae and by 46% in vertebrae compared to the alcohol alone group (p<0.05). In summary, binge alcohol-induced tibial and vertebral bone loss can be prevented using an effective dose of vitamin D or a single dose of ibandronate even during high blood alcohol concentrations that have been shown to impair osteoblast functions and increase bone resorption.

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.

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.

Simultaneous administration of diethylphthalate and ethyl alcohol and its toxicity in male Sprague-Dawley rats

Phthalate esters have been implicated as xenoestrogens. One among them is di-ethylphthalate (DEP), which is used as plasticizer, detergent base, and binder in incense sticks and after-shave lotions. DEP is one of the contaminants of freshwater and marine ecosystems. Incense stick workers are occupationally exposed to DEP and some workers are chronic alcoholics. Therefore, a study was undertaken to evaluate the interactive toxicity of DEP with ethyl alcohol (EtOH) in young male Sprague-Dawley rats. The rats were given 50 ppm DEP (w/v), 5% EtOH (v/v) and a combined dose of 50 ppm DEP (w/v)+EtOH (5% v/v) in water ad libitum for a period of 120 days and were maintained on normal diet. Control animals received normal diet and plain water. During the treatment rats were weighed every week and water consumption per day was measured. After the completion of treatment, liver weight/body weight, liver weight, body weight, serum enzymes and other biochemical parameters were assessed. It was found that there was no significant change observed in body weight, liver weight, liver weight/body weight and water consumption. It was observed that there was a significant decrease in liver aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in EtOH, DEP and EtOH+DEP treated rats in the order of EtOH>DEP>EtOH+DEP as compared with control. Serum AST, ALT, acid phosphatase (ACP), alkaline phosphatase (ALP), succinate dehydrogenase (SDH) and liver ACP showed significant increase in DEP and EtOH+DEP treated rats in the order of DEP>EtOH+DEP as compared with control and EtOH treated rats. On the contrary, there was no significant change in liver ALP levels in treated rats. There was significant increase in liver SDH, glycogen, total triglyceride, total cholesterol and lipid peroxidation in DEP and EtOH+DEP treated rats, but no significant changes in the serum SDH, glucose and total triglyceride levels. Serum total cholesterol levels in DEP and EtOH+DEP treated rats were significantly high as compared to control and EtOH treated rats. These results show that there is no interaction of DEP with EtOH but DEP alone leads to severe impairment of lipid metabolism coupled with toxic injury to the liver as evident from significantly altered lipid and enzyme levels in the liver and serum. Long term simultaneous exposure to DEP and EtOH may have severe implications for humans who are occupationally exposed to these two xenobiotics.

Lead/ethanol interactions. I: rate-depressant effects

Adult male rats were exposed to a diet containing 500 ppm added lead as lead acetate (group lead-diet) or a control diet containing no added chemicals (group control-diet) for 61 days prior to commencing fixed-ratio 32 (FR 32) lever press training for water reinforcement. After steady state responding was achieved, all animals received serial administrations of acute doses of ethanol prior to the daily training session. Specifically, lead-diet and control-diet rats received i.p. injections of .25, .5, .75, 1.0, and 1.25 g/kg ethanol, in ascending order, alternating daily with injections of saline. The results revealed a dose-dependent rate-depressant effect, with higher doses of ethanol producing more behavioral suppression than lower doses for both groups. In addition, at the dose of 1.0 g/kg it was observed that the suppressive effects of ethanol on schedule-controlled responding were reduced among lead-treated animals relative to controls. These data are discussed in terms of lead-induced attenuation of the pharmacologic effects of ethanol.