Relationship between non-functional masticatory activity and central dopamine in stressed rats

Effect of dopaminergic agonist group of drugs in treatment of sleep bruxism: A systematic review

STATEMENT OF PROBLEM

Various factors are responsible for sleep bruxism; however, whether the dopaminergic agonist group of drugs is effective in the treatment of sleep bruxism is unclear.

PURPOSE

The purpose of this systematic review was to evaluate the effect of the dopaminergic agonist group of drugs in controlling sleep bruxism in comparison with no treatment or placebo-controlled treatment.

MATERIAL AND METHODS

Two electronic databases, PubMed and Cochrane Central, were searched by using the keywords bruxism, sleep bruxism, dopamine, and dopamine agonist. After screening titles and abstracts, only those articles which met predefined inclusion criteria were selected for full-text assessment. Clinical trials using the dopaminergic agonist group of drugs as a treatment approach to sleep bruxism were included.

RESULTS

The literature search yielded a total of 64 articles from the 2 electronic databases (PubMed, 53; Cochrane Central, 11). After removal of the duplicates (n=8), the initial screening of titles and abstracts was performed by 2 independent reviewers, removing 46 articles. A total of 10 articles were selected for full-text reading, and 4 studies were included for qualitative analysis.

CONCLUSIONS

Levodopa (L-DOPA) and Bromocriptine showed decrease in root mean square value in electromyography per bruxism burst (P<.001) and 20% to 30% reduction of bruxism episodes during sleep in 2 different studies. However, treatment with bromocriptine led to conflicting result in another study in terms of frequency of bruxism episodes and amplitude of muscle contractions in electromyography (EMG). Bruxism bursts and episodes were also not significantly improved with another dopaminergic agonist group of drugs, Pramipexole (P>.001). Based on the limited evidence and conflicting results, significant conclusions cannot be generated, and further studies are required.

Antidepressants and movement disorders: a postmarketing study in the world pharmacovigilance database

BACKGROUND

Antidepressants-induced movement disorders are rare and imperfectly known adverse drug reactions. The risk may differ between different antidepressants and antidepressants' classes. The objective of this study was to assess the putative association of each antidepressant and antidepressants' classes with movement disorders.

METHODS

Using VigiBase®, the WHO Pharmacovigilance database, disproportionality of movement disorders' reporting was assessed among adverse drug reactions related to any antidepressant, from January 1967 to February 2017, through a case/non-case design. The association between nine subtypes of movement disorders (akathisia, bruxism, dystonia, myoclonus, parkinsonism, restless legs syndrome, tardive dyskinesia, tics, tremor) and antidepressants was estimated through the calculation first of crude Reporting Odds Ratio (ROR), then adjusted ROR on four potential confounding factors: age, sex, drugs described as able to induce movement disorders, and drugs used to treat movement disorders.

RESULTS

Out of the 14,270,446 reports included in VigiBase®, 1,027,405 (7.2%) contained at least one antidepressant, among whom 29,253 (2.8%) reported movement disorders. The female/male sex ratio was 2.15 and the mean age 50.9 ± 18.0 years. We found a significant increased ROR for antidepressants in general for all subtypes of movement disorders, with the highest association with bruxism (ROR 10.37, 95% CI 9.62-11.17) and the lowest with tics (ROR 1.49, 95% CI 1.38-1.60). When comparing each of the classes of antidepressants with the others, a significant association was observed for all subtypes of movement disorders except restless legs syndrome with serotonin reuptake inhibitors (SRIs) only. Among antidepressants, mirtazapine, vortioxetine, amoxapine, phenelzine, tryptophan and fluvoxamine were associated with the highest level to movement disorders and citalopram, paroxetine, duloxetine and mirtazapine were the most frequently associated with movement disorders. An association was also found with eight other antidepressants.

CONCLUSIONS

A potential harmful association was found between movement disorders and use of the antidepressants mirtazapine, vortioxetine, amoxapine, phenelzine, tryptophan, fluvoxamine, citalopram, paroxetine, duloxetine, bupropion, clomipramine, escitalopram, fluoxetine, mianserin, sertraline, venlafaxine and vilazodone. Clinicians should beware of these adverse effects and monitor early warning signs carefully. However, this observational study must be interpreted as an exploratory analysis, and these results should be refined by future epidemiological studies.

Long-term follow-up of a patient with venlafaxine-induced diurnal bruxism treated with an occlusal splint: A case report

BACKGROUND

Bruxism is a jaw-muscle activity characterized by the clenching or grinding of teeth. It can be divided into nocturnal bruxism and diurnal bruxism (DB). DB secondary to antidepressants is rare and refractory. Reports associated with antidepressant-induced DB are mostly anecdotal without long-term follow-up. The effect of drug intervention on antidepressant-induced DB is still contested. We herein report the first case of successful treatment of venlafaxine-induced DB with an occlusal splint.

CASE SUMMARY

This case report describes detailed 7-year follow-up of a patient with venlafaxine-induced DB treated with an occlusal splint. The patient who complained about involuntary daytime tooth grinding after taking venlafaxine for a period of 4 mo and was diagnosed with venlafaxine-induced DB. Subsequently, an occlusal splint with modified bilateral buccal-pterygoid pads was used to treat his tooth grinding and to protect the dental structures from tooth wearing. The patient reported remission of symptoms after several months of treatment. His grinding activity was gradually and stably controlled after 2 years, with an almost complete recovery from DB after 6 years.

CONCLUSION

The maxillary buccal-pterygoid splint can be used as a noninvasive approach to treat venlafaxine-induced DB.

The functional link between tail-pinch-induced food intake and emotionality and its possible role in stress coping in rats

Tail pinch facilitates eating in rats. We investigated an unidentified link between tail-pinch-induced eating behavior and individual emotionality in male Sprague-Dawley rats. Anxiety-like behavior was assessed on the elevated plus maze (EPM) and in the open field test (OFT). Tail-pinch-induced eating was observed as follows: After a 30-min habituation period, the tail pinch was applied for 5 min, followed by a 30-min recovery period. During the habituation and recovery periods, rats were allowed to access food ad libitum. During the recovery period, 14 of 24 rats ate more food than during the habituation period. Thus, we named them "high responders" and the others as "low responders". The food intake was significantly greater, while the times spent in the open arms in the EPM and in the center area in the OFT were significantly shorter in high responders than in low responders. This result suggests that the rats consuming more food after mild stress have higher anxiety.

The relationship between bruxism, sleep quality, and headaches in schoolchildren

[Purpose] Present study aimed to evaluate the relationship between sleep bruxism and headache in school children. [Subjects and Methods] This study was conducted with 103 children aged 3-6 years. The exclusion criteria were early tooth loss, dental appliance was used, physical or psychological limitations, chronic disease and continuous medication. Sleep bruxism was diagnosed based on an indication by parents of the occurrence of teeth clenching/grinding and incisor/occlusal tooth wear, following the criteria of the American Academy of Sleep Medicine. Sleep quality was evaluated by a questionnarie, detailing the child's sleep characteristics. [Results] Forty-nine children (47.6%) were diagnosed with sleep bruxism. Those with sleep bruxism were 3.25-fold more likely to present headache. Children whose parents were separated had a significantly greater frequency of sleep bruxism and primary headache. The relative risk of exhibiting primary headache was 13.1 among children with sleep bruxism whose parents were separated. [Conclusion] Children with SB demonstrated a greater risk of having primary headache and those whose parents were separated had a greater chance of having headache. Only sleep bruxism was associated with headache, clenching the teeth during waking hours was not correlated with primary headache.

Methylphenidate-induced awake bruxism: a case report

Methylphenidate (MPH) is a stimulant that is commonly used in the treatment of attention-deficit/hyperactivity disorder in children and adults. Several reports are available regarding the relationship of MPH use and sleep bruxism. We report the case of a 9-year-old boy who presented with severe awake bruxism after his second dose of sustained release form of MPH treatment, which was confirmed on rechallenge. This is the first report of its kind showing such relationship in the literature.

Psychotropic drugs and bruxism

INTRODUCTION

Sleep and awake bruxism is defined as 'a parafunctional activity including clenching, bracing, gnashing, and grinding of the teeth'. Some evidence suggests that bruxism may be caused by, or associated with, alterations in the CNS neurotransmission. Several classes of psychotropic drugs interfering with CNS activity may potentially contribute to bruxism. Thus, the purpose of this study was to examine relevant peer-reviewed papers to identify and describe the various classes of psychotropic substances that may cause, exacerbate or reduce bruxism as the result of their pharmacological action in CNS neurons.

AREAS COVERED

A literature search from 1980 to the present was performed using PubMed database. The term 'bruxism' was used in association with 'psychotropic', 'dopamine (DA)', 'serotonin', 'histamine', 'antipsychotics', 'antidepressants', 'antihistaminergics' and 'stimulants'.

EXPERT OPINION

Studies on the effects of DA agonists (Levo-DOPA, psychostimulants) and antagonists (antipsychotics) identified a central role of DA in the pathogenesis of pharmacologically induced bruxism. Important information from studies on drugs acting on serotonin neurotransmission (antidepressants) was recognized. Other mechanisms involving different neurotransmitters are emerging. This is the case of antihistaminergic drugs which may induce bruxism as a consequence of their disinhibitory effect on the serotonergic system.

The effects of anandamide signaling enhanced by the FAAH inhibitor URB597 on coping styles in rats

RATIONALE

Coping styles are fundamental characteristics of behavior that affect susceptibility to, and resilience during, mental and physical illness. Shifts from passive to active coping are considered therapeutic goals in many stress-related disorders, but the neural control of coping is poorly understood. Based on earlier findings, we hypothesized that coping styles are influenced by endocannabinoids.

OBJECTIVES

Here, we tested whether FAAH inhibition by URB597 affects behaviors aimed at controlling a critical situation and the degree to which environmental stimuli influence behavior i.e., we studied the impact of URB597 on the two main attributes of coping styles.

METHODS

Rats were tested in the tail-pinch test of coping and in the elevated plus-maze test that was performed under highly divergent conditions.

RESULTS

Under the effects of URB597, rats focused their behavior more on the discomfort-inducing clamp in the tail-pinch test, i.e., they coped with the challenge more actively. In the elevated plus-maze, URB597-treated rats demonstrated an autonomous behavioral control by reducing both "wariness" induced by aversive conditions and "carelessness" resulting from favorable conditions.

CONCLUSIONS

URB597 treatment-induced behavioral changes indicated a shift towards active coping with challenges. This behavioral change appears compatible with the previously suggested role of endocannabinoids in emotional homeostasis. Albeit further studies are required to characterize the role of endocannabinoids in coping, these findings suggest that the enhancement of endocannabinoid signaling may become a therapeutic option in emotional disorders characterized by passive coping (e.g., anxiety and depression) and in physical diseases where active coping is therapeutically desirable.