Activation of the VpdmVGLUT1-VPM pathway contributes to anxiety-like behaviors induced by malocclusion

Can fluoxetine influence orthodontic tooth movement? A systematic review and meta-analysis of studies on animal models

INTRODUCTION

Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine adversely affect bone mineral density (BMD) and turnover, thereby increasing the risk of fractures. The objective of the present systematic review and meta-analysis was to evaluate studies on animal models that assessed whether fluoxetine can influence orthodontic tooth movement (OTM).

MATERIAL AND METHODS

Indexed databases (PubMed/Medline, EMBASE, Cochrane Library, Scopus and ISI Web of Knowledge) and Google Scholar were searched without time and language barriers up to and including June 2024. Original studies that assessed the influence of fluoxetine on OTM were included. Letters to the Editor, reviews, commentaries, perspectives and, in-vitro/ex-vivo studies were excluded. Study selection, and risk of bias (RoB) and quality assessments were assessed. Quantitative assessment (meta-analysis) was also performed using fixed-effects and random effects models.

RESULTS

Four studies performed on male rats were included. Rats in the experimental group underwent OTM with adjunct fluoxetine injections at concentrations ranging between 10-20mg/kg. Orthodontic forces applied ranged between 25-60grams. Three studies reported that fluoxetine does not influence OTM. All studies had a high RoB. Three studies demonstrated low certainty (weak) and two showed very low certainty of evidence. In the meta-analysis, the pooled SMD using a random effects model was 0.05 (95% CI: -0.42 to 0.52), indicating no significant overall effect of fluoxetine on OTM. The analysis revealed substantial heterogeneity across the included studies.

CONCLUSION

Further well-designed and power-adjusted prospective studies are needed to elucidate the role of SSRIs on OTM.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42024563793.

Whole-brain long-range connectivity of glutamatergic, GABAergic, parvalbumin-expressing and somatostatin-expressing neurons in mouse somatosensory cortex

Understanding the composition of cortical circuits at the whole-brain scale is crucial. However, the specific ways in which particular neuronal types in the primary somatosensory cortex (SSp) establish connections with upstream and downstream brain regions remain unclear. In this study, we used whole-brain imaging technology with submicron resolution to systematically reveal the long-range connectivity patterns of glutamatergic, GABAergic, parvalbumin-expressing (PV+), and somatostatin-expressing (SOM+) neurons in the SSp. Our results show that while glutamatergic, GABAergic, PV+ , and SOM+ neurons receive similar upstream afferent, specific thalamic subregions showed numerically stronger afferent to GABAergic, PV+ , and SOM+ neurons compared to glutamatergic neurons. Additionally, glutamatergic neurons exhibit a more complex collateral projection pattern in subcortical axonal pathways compared to PV+ neurons. These findings elucidate the long-range connectivity patterns of specific neuronal types in the SSp, offering new insights into the cell-type-specific mechanisms of sensory information processing.

Separable Microneedle Patch Integrated with the Dictamnine-Loaded Copper MOF Nanozyme for Atopic Dermatitis Treatment

Atopic dermatitis (AD) is a chronic inflammatory skin disorder marked by skin thickening, severe pruritus, lesions, and emotional disturbances, including anxiety and depression-like behavior. Current treatments primarily rely on localized therapies, which can lead to adverse effects such as hyperglycemia and Cushing's syndrome with repeated use. To address these issues, we developed a hyaluronic acid-based separable microneedle patch (Dic@pCu-HA MN), integrating polydopamine-coordinated copper-based metal-organic frameworks (pCu-MOFs) and the anti-inflammatory agent dictamnine (Dic), for synergistic management of AD and its neuropsychiatric comorbidities. pCu-MOFs exhibited dual functionality as nanocargo for hydrophobic Dic (encapsulation efficiency: 84.62 ± 2.14%) and multienzyme mimics that efficiently scavenge reactive oxygen species (ROS) (superoxide radical scavenging: 63.85 ± 0.34%). In vitro release studies demonstrated ROS-responsive Dic release of 86.80 ± 4.83% over 48 h under AD pathology-mimicking conditions. In a 1-Chloro-2,4-dinitrochlorobenzene (DNCB)-induced AD mouse model, the Dic@pCu-HA MN significantly reduced oxidative stress (8-OHdG: 85.1 ± 7.0% decrease), suppressed pro-inflammatory cytokines (IL-4: 70.0 ± 7.8% decrease vs control), and restored skin barrier integrity. By modulating the HPA axis, the system attenuated neuroinflammation and alleviated itching (scratching frequency: 40.1 ± 41.3% reduction) and depression-like behavior (time in the bright box: 96.6 ± 156.2% increase). This combined therapeutic approach not only offers a comprehensive strategy for AD management but also provides potential benefits for addressing inflammatory skin disorders and their neuropsychiatric sequelae.

Mental Health and Malocclusion: A Comprehensive Review

The purpose of this study is to comprehensively review the relationship between malocclusion and anxiety and depression. While the physical implications of malocclusion are well documented, recent scholarship has shifted focus to examining the direct relationship between malocclusion and both anxiety and depression. It has been hypothesized that individuals with skeletal or dental malocclusion experience a range of psychological sequelae, including diminished quality of life (QoL), reduced oral-health-related quality of life (OHRQoL), increased vulnerability and appearance-related bullying, and impaired body image. Furthermore, these factors are postulated to collectively contribute to overall mental health, with malocclusion potentially serving as a contributing etiological factor in the development of elevated levels of anxiety and depression. Contemporary scholarship has established a complex relationship between dentofacial deviations and the psychological well-being of affected individuals. Evidence shows that malocclusion may contribute to increased depression and anxiety levels in some individuals, influencing their social functioning and treatment-seeking behavior. Dentofacial disharmony has also been associated with altered self-perception, potentially impacting an individual's OHQOL and overall quality of life. While the findings exhibit some inconsistency, a modest body of evidence indicates a possible correlation between pronounced skeletal or dental malocclusion and anxiety and depression. These adverse psychosocial impacts, in turn, contribute to an elevated risk of anxiety and depression, underscoring the far-reaching consequences of malocclusion beyond oral health. Therefore, clinicians need to consider these issues in their treatment plans, incorporating interdisciplinary approaches that address both orthodontic and psychological aspects of patient care.

The neural substrates of bruxism: current knowledge and clinical implications

Bruxism is a complex orofacial behavior that can occur during sleep or wakefulness, characterized by the involuntary grinding or clenching of teeth, involving repetitive activity of the jaw muscles. Its etiology is multifactorial, influenced by genetic, psychological, physiological, and lifestyle factors. While the mild bruxism may not necessitate treatment, severe bruxism can lead to significant consequences, including tooth damage, jaw pain, fatigue, and headaches. The bruxism has been associated with medical conditions, such as stress, anxiety, sleep disorders, and various neurological disorders; however, the exact pathophysiology remains elusive. Although the central nervous system is strongly implicated in the development of bruxism, specific neural substrates have not yet been conclusively established. Furthermore, there is evidence to suggest that individuals with bruxism may exhibit neural plasticity, resulting in the establishment of distinct neural circuitry that control the jaw movements. The application of various neurophysiological techniques in both clinical and pre-clinical studies provides valuable insights into the neural mechanisms underlying bruxism. This review aims to comprehensively examine the current literature on the neural pathways involved in bruxism, with the goal of improving the clinical approach and therapeutics for this condition. A deeper understanding of the neural circuitry controlling bruxism holds the potential to advance future treatment approaches and improve the management of patients with bruxism.

Projections from anteromedial thalamus nucleus to the midcingulate cortex mediate pain and anxiety-like behaviors in mice

Prior research has demonstrated the involvement of the midcingulate cortex (MCC) and its downstream pathway in pain regulation. However, the mechanism via which pain information is conveyed to the MCC remains unclear. The present study utilized immunohistochemistry, chemogenetics, optogenetics, and behavior detection methods to explore the involvement of MCC, anteromedial thalamus nucleus (AM), and AM-MCC pathway in pain and emotional regulation. Chemogenetics or optogenetics methods were employed to activate/inhibit MCCCaMKIIα, AMCaMKIIα, AMCaMKIIα-MCC pathway. This manipulation evokes/relieves mechanical and partial heat hyperalgesia, as well as anxiety-like behaviors. In the complete Freund,s adjuvant (CFA) inflammatory pain model, chemogenetic inhibition of the AMCaMKIIα-MCCCaMKIIα pathway contributed to pain relief. Notably, this study presented the first evidence implicating the AM in the regulation of nociception and negative emotions. Additionally, it was observed that the MCC primarily receives projections from the AM, highlighting the crucial role of this pathway in the transmission of pain and emotional information.

The Cognitive and Emotional Aspect in Fibromyalgia: The Importance of the Orofacial Sphere

Fibromyalgia syndrome (FMS) is a systemic and multifactorial disease of unknown etiology. There are many co-morbidities that the patient presents, making the clinical picture not immediate. Cognitive decline and emotional alteration (anxiety and depression) are found in fibromyalgic patients, as well as temporomandibular joint arthrokinematic disorders, dental malocclusion, and periodontitis. There seems to be a biunivocal relationship between oral and psychiatric dysfunctions in fibromyalgia. The article reviews the information regarding oral health alterations with respect to the patient's cognitive and emotional response, as the most recent information we have raises new hypotheses about the diagnosis of FMS.