Effect of 15% Alcohol Dependence on Alveolar Bone Loss and TNF-α Secretion in Wistar Rats

Chronic Ethanol Consumption Induces Osteopenia via Activation of Osteoblast Necroptosis

Chronic high-dose alcohol consumption impairs bone remodeling, reduces bone mass, and increases the risk of osteoporosis and bone fracture. However, the mechanisms underlying alcohol-induced osteoporosis are yet to be elucidated. In this study, we showed that excess intake of ethyl alcohol (EtOH) resulted in osteopenia and osteoblast necroptosis in mice that led to necrotic lesions and reduced osteogenic differentiation in bone marrow mesenchymal stem cells (BMMSCs). We found that EtOH treatment led to the activation of the RIPK1/RIPK3/MLKL signaling, resulting in increased osteoblast necroptosis and decreased osteogenic differentiation and bone formation both in vivo and in vitro. We further discovered that excessive EtOH treatment-induced osteoblast necroptosis might partly depend on reactive oxygen species (ROS) generation; concomitantly, ROS contributed to necroptosis of osteoblasts through a positive feedback loop involving RIPK1/RIPK3. In addition, blocking of the RIPK1/RIPK3/MLKL signaling by necrostatin-1 (Nec-1), a key inhibitor of RIPK1 kinase in the necroptosis pathway, or antioxidant N-acetylcysteine (NAC), an inhibitor of ROS, could decrease the activation of osteoblast necroptosis and ameliorate alcohol-induced osteopenia both in vivo and in vitro. Collectively, we demonstrated that chronic high-dose alcohol consumption induced osteopenia via osteoblast necroptosis and revealed that RIPK1 kinase may be a therapeutic target for alcohol-induced osteopenia.

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.

Ethanol binge drinking exposure affects alveolar bone quality and aggravates bone loss in experimentally-induced periodontitis

Background

Periodontitis is a multifactorial inflammatory disease of tooth supporting tissues caused by oral biofilms, influenced by environmental and genetic factors, among others. Ethanol consumption has been considered a factor that enhances alveolar bone loss, especially in high doses. The present study aims to investigate the changes promoted by ethanol binge drinking per se or associated with ligature-induced periodontal breakdown on alveolar bone loss.

Materials and methods

Thirty-two Wistar rats were randomly allocated into four groups: control (C), ethanol (3g/kg/day; 3 days On-4 days Off protocol by gavage for 28 days, EtOH), experimental periodontitis (EP) and experimental periodontitis plus ethanol administration (EP+EtOH). On day 14^th, periodontitis was induced by ligatures that were placed around the lower first molars. On day 28^th, the animals were euthanized and mandibles were submitted to stereomicroscopy for exposed root area analysis and micro-computed tomography (micro-CT) for the evaluation of alveolar bone loss and microstructural parameters.

Results

The results revealed that ligature-induced alveolar bone loss is aggravated by ethanol binge drinking compared to controls (1.06 ± 0.10 vs 0.77 ± 0.04; p<0.0001). In addition, binge drinking per se altered the alveolar bone quality and density demonstrating a reduction in trabecular thickness, trabecular number parameter and bone density percentual. Periodontal disorder plus ethanol binge drinking group also demonstrated reduction of the quality of bone measured by trabecular thickness.

Conclusions

In conclusion, intense and episodic ethanol intake decreased alveolar bone quality in all microstructural parameters analyzed which may be considered a modifying factor of periodontitis, intensifying the already installed disease.