A selective review of glutamate pharmacological therapy in obsessive-compulsive and related disorders

From tugs to treatments: a systematic review on pharmacological interventions for trichotillomania

BACKGROUND

Trichotillomania (TTM) is a psychiatric disorder with dermatological consequences, characterized by recurrent hair pulling. It affects 1-3% of the population, and often coexists with other psychiatric disorders, leading to emotional distress. Effective management of TTM can be challenging because of underdiagnosis, symptom heterogeneity and stigma. Pharmacological interventions, including selective serotonin reuptake inhibitors and N-acetyl cysteine (NAC) are commonly used.

OBJECTIVES

To assess the existing literature on pharmacotherapy for TTM and identify potential avenues for future research and treatment advancements.

METHODS

A systematic review of the literature was performed using PubMed and Scopus databases within the past 10 years (PROSPERO: CRD42023454009). Included studies assessed pharmacotherapy for TTM and provided insights into current evidence and potential directions for future research and treatment advancements.

RESULTS

In total, 23 articles were identified that met inclusion criteria. The most successful interventions were NAC, aripiprazole and monoamine oxidase inhibitors. NAC was identified as the most impressive adjunctive therapy to selective serotonin reuptake inhibitors and behavioural therapies in treatment through its mechanism of decreased glutamate-induced excitatory neuronal damage, with adjunctive antioxidant properties. Most of the other therapeutics that were identified require further research and controlled trials to validate their findings.

CONCLUSIONS

Even if successful therapeutic outcomes are achieved, it is important to consider the patient's comorbidities and to combine pharmacological interventions with behavioural therapy interventions to comprehensively manage TTM.

Sense of agency and its disturbances: A systematic review targeting the intentional binding effect in neuropsychiatric disorders

Sense of agency (SoA) indicates a person's ability to perceive her/his own motor acts as actually being her/his and, through them, to exert control over the course of external events. Disruptions in SoA may profoundly affect the individual's functioning, as observed in several neuropsychiatric disorders. This is the first article to systematically review studies that investigated intentional binding (IB), a quantitative proxy for SoA measurement, in neurological and psychiatric patients. Eligible were studies of IB involving patients with neurological and/or psychiatric disorders. We included 15 studies involving 692 individuals. Risk of bias was low throughout studies. Abnormally increased action-outcome binding was found in schizophrenia and in patients with Parkinson's disease taking dopaminergic medications or reporting impulsive-compulsive behaviors. A decreased IB effect was observed in Tourette's disorder and functional movement disorders, whereas increased action-outcome binding was found in patients with the cortico-basal syndrome. The extent of IB deviation from healthy control values correlated with the severity of symptoms in several disorders. Inconsistent effects were found for autism spectrum disorders, anorexia nervosa, and borderline personality disorder. Findings pave the way for treatments specifically targeting SoA in neuropsychiatric disorders where IB is altered.

CREB: A Promising Therapeutic Target for Treating Psychiatric Disorders

Psychiatric disorders are complex, multifactorial illnesses. It is challenging for us to understand the underlying mechanism of psychiatric disorders. In recent years, the morbidity of psychiatric disorders has increased yearly, causing huge economic losses to the society. Although some progress, such as psychotherapy drugs and electroconvulsive therapy, has been made in the treatment of psychiatric disorders, including depression, anxiety, bipolar disorder, obsessive-compulsive and autism spectrum disorders, antidepressants and psychotropic drugs have the characteristics of negative effects and high rate of relapse. Therefore, researchers continue to seek suitable interventions. cAMP response element binding protein (CREB) belongs to a protein family and is widely distributed in the majority of brain cells that function as a transcription factor. It has been demonstrated that CREB plays an important role in neurogenesis, synaptic plasticity, and neuronal growth. This review provides a 10-year update of the 2013 systematic review on the multidimensional roles of CREB-mediated transcriptional signaling in psychiatric disorders. We also summarize the classification of psychiatric disorders and elucidate the involvement of CREB and related downstream signalling pathways in psychiatric disorders. Importantly, we analyse the CREB-related signal pathways involving antidepressants and antipsychotics to relieve the pathological process of psychiatric disorders. This review emphasizes that CREB signalling may have a vast potential to treat psychiatric disorders like depression. Furthermore, it would be helpful for the development of potential medicine to make up for the imperfection of current antidepressants and antipsychotics.

Efficacy and safety of 5-hydroxytryptamine-3 (5-HT3) receptor antagonists in augmentation with selective serotonin reuptake inhibitors (SSRIs) in the treatment of moderate to severe obsessive-compulsive disorder: a systematic review and meta-analysis of randomized clinical trials

Obsessive-compulsive disorder (OCD) is the fourth most common mental disorder, and selective serotonin reuptake inhibitors (SSRIs) are the cornerstone of its pharmacological treatment. About 40-60% of the cases are treatment-refractory, and this makes searching for second-line treatment necessary. 5-Hydroxytryptamine-3 (5-HT3) antagonists are among the many medications that have been used in augmentation with SSRIs. In this systematic review and meta-analysis, we assessed the efficacy and safety of 5-HT3 receptor antagonists in augmentation with SSRIs in treating moderate to severe OCD. We searched PubMed, Web of Science, Scopus, Cochrane library, and Google Scholar for relevant trials published up to December 2022. The effect size was the mean difference in Yale-Brown obsessive compulsive scale (Y-BOCS) scores before and after receiving 5-HT3 receptor antagonist drugs in augmentation with SSRIs in moderate to severe OCD patients. We included 6 randomized-controlled trails (RCTs) with 334 patients assessing the effect of the augmentation of SSRIs with ondansetron, granisetron, and tropisetron on treating moderate to severe OCD. Our results were in favor of the experimental group in total (Z = 8.37, P < 0.00001), in the compulsion subgroup (Z = 5.22, P < 0.00001), and in the obsession subgroup (Z = 8.33, P < 0.00001). They are well-tolerated, and have mild side effects and do not result in withdrawal. Augmentation of 5-HT3 antagonists with SSRIs can be beneficial in treating moderate to severe OCD. Further multi-center trials under adequate conditions in longer periods are needed to help come up with a comprehensive action plan.

Double-Blind Placebo-Controlled Study of Memantine in Trichotillomania and Skin-Picking Disorder

OBJECTIVE

Trichotillomania and skin-picking disorder are underrecognized and often disabling conditions in which individuals repeatedly pull at their hair or pick at their skin, leading to noticeable hair loss or tissue damage. To date there is a severe paucity of evidence-based treatments for these conditions. In this study, the authors sought to determine whether memantine, a glutamate modulator, is more effective than placebo in reducing hair-pulling and skin-picking behavior.

METHODS

One hundred adults with trichotillomania or skin-picking disorder (86 women; mean age, 31.4 years [SD=10.2]) were enrolled in a double-blind trial of memantine (dosing range, 10-20 mg/day) or placebo for 8 weeks. Participants were assessed with measures of pulling and picking severity. Outcomes were examined using a linear mixed-effects model. The prespecified primary outcome measure was treatment-related change on the NIMH Trichotillomania Symptom Severity Scale, modified to include skin picking.

RESULTS

Compared with placebo, memantine treatment was associated with significant improvements in scores on the NIMH scale, Sheehan Disability Scale, and Clinical Global Impressions severity scale in terms of treatment-by-time interactions. At study endpoint, 60.5% of participants in the memantine group were "much or very much improved," compared with 8.3% in the placebo group (number needed to treat=1.9). Adverse events did not differ significantly between the treatment arms.

CONCLUSIONS

This study found that memantine treatment resulted in statistically significant reductions in hair pulling and skin-picking symptoms compared with placebo, with relatively high efficacy (based on number needed to treat), and was well tolerated. The glutamate system may prove to be a beneficial target in the treatment of compulsive behaviors.

N-acetylcysteine in the treatment of compulsive sexual behavior disorder: A case series

Although compulsive sexual behavior disorder (CSBD) is a relatively common disorder with an estimated prevalence of at least 3%, clinicians currently have limited evidence and no FDA-approved drugs to guide their treatment of this condition. N-acetylcysteine (NAC), an amino acid that seems to restore extracellular levels of glutamate in the nucleus accumbens, has previously demonstrated efficacy in treating multiple psychiatric disorders, including substance use disorders and putative behavioral addictions. However, no study has assessed the use of NAC (or any other glutamatergic agent, for that matter) in the treatment of CSBD. Here, we present data from a case series of 8 male patients with CSBD treated with NAC in routine clinical practice in a specialty outpatient clinic. Of these 8 patients, all of whom had previously been treated for CSBD with medications, therapy, or both, 5 had marked clinical improvement (&gt;35% improvement on a modified version of Yale-Brown Obsessive Compulsive Scale) on NAC, and 3 showed minimal or no improvement (&lt;15%). These findings suggest that NAC may be a potentially promising, well-tolerated treatment option for patients with CSBD, including those who have failed more traditional therapies.

Dramatic Improvement of Trichotillomania with 6 Months of Treatment With N-Acetylcysteine

We present a case of a 17-year-old male with recurrent hair twirling resulting in patchy alopecia, who improved dramatically on N-acetylcysteine (NAC). Trichotillomania is characterized by repetitive hair pulling, twisting, or twirling and can vary from a mild habit to an impulse-control disorder. Standard treatment for pediatric trichotillomania includes cognitive behavioral therapy or medical therapy with selective serotonin reuptake inhibitors. NAC is a more recently utilized, safe, and well-tolerated over-the-counter supplement with some evidence of benefit for habitual skin and hair disorders. For this patient, we recommended 600 mg twice daily, increasing to 1200 mg twice daily as tolerated. After 6 months, our patient reported decreased desire to twirl his hair and his hair had almost completely regrown. Pediatricians who see patients with trichotillomania or other habitual disorders can consider treating these patients with NAC given its potential benefits and favorable side effect profile.

Glutamatergic medications as adjunctive therapy for moderate to severe obsessive-compulsive disorder in adults: a systematic review and meta-analysis

BACKGROUND

Obsessive-compulsive disorder (OCD) is among the most disabling neuropsychiatric conditions characterized by the presence of repetitive intrusive thoughts, impulses, or images (obsessions) and/or ritualized mental or physical acts (compulsions). Serotonergic medications, particularly Selective Serotonin Reuptake Inhibitors (SSRIs), are the first-line treatments for patients with OCD. Recently, dysregulation of glutamatergic system has been proposed to be involved in the etiology of OCD. We designed this systematic review and meta-analysis to evaluate clinical efficacy of glutamatergic medications in patients with OCD, according to the guidelines of Cochrane collaboration.

METHOD

We searched Medline, Scopus, and Cochrane library without applying any language filter. Two of the authors independently reviewed search results for irrelevant and duplicate studies and extracted data and assessed methodological quality of the studies. We transformed data into a common rubric and calculated a weighted treatment effect across studies using Review Manager.

RESULTS

We found 476 references in 3 databases, and after exclusion of irrelevant and duplicate studies, 17 studies with total number of 759 patients with OCD were included. In the present review we found evidence for several drugs such as memantine, N-acetylcysteine (NAC), Minocycline, L-carnosine and riluzole. Glutamaterigic drug plus SSRIs were superior to SSRI+ Placebo with regard to Y-BOCS scale [standardized mean difference (SMD = - 3.81 95% CI = - 4.4, - 3.23).

CONCLUSION

Augmentation of glutamatergic medications with SSRIs are beneficial in obsessive-compulsive patients, no harmful significant differences in any safety outcome were found between the groups.

Capturing the Effects of Domestication on Vocal Learning Complexity

Domesticated and vocal learning species can serve as informative model organisms for the reduction of reactive aggression and emergence of speech in our lineage. Amidst mounting evidence that domestication modifies vocal repertoires across different species, we focus on the domesticated Bengalese finch, which has a more complex song than the wild-type white-rumped munia. Our explanation for this effect revolves around the glutamate neurotransmitter system. Glutamate signaling (i) is implicated in birdsong learning, (ii) controls dopamine activity in neural circuits crucial for vocal learning, (iii) is disproportionately targeted in the evolution of domesticates, and (iv) regulates stress responses and aggressive behaviors attenuated under domestication. We propose that attenuated excitation of stress-related neural circuits potentiates vocal learning via altered dopaminergic signaling.

Pregabalin augmentation for resistant obsessive-compulsive disorder: a double-blind placebo-controlled clinical trial

BACKGROUND AND OBJECTIVE

Glutamate dysfunction has been shown to be associated with pathophysiology of obsessive-compulsive disorder (OCD). Our objective is to survey the effects of pregabalin (a glutamate-modulating agent) as an augmenting treatment for resistant OCD.

PATIENTS AND METHODS

In this 12-week double-blind placebo-controlled clinical trial, 56 patients with resistant OCD were randomly allocated to receive either pregabalin or placebo plus their current medication (sertraline). Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was used to evaluate the outcomes. Adverse effects were also registered.

RESULTS

Of the 56 patients with resistant OCD who were randomly allocated in 2 groups of pregabalin (n = 28) and placebo group (n = 28), 42 patients (22 in pregabalin group and 20 in placebo group) completed the trial. Throughout the trial, the mean score decreased from 26.13± 7.03 to 8.81 ± 3.47 in the pregabalin group (p < 0) and from 26.85 ± 4.34 to 17.63 ± 4.22 in the placebo group (p < 0). At the end of trial, 16 (57.14%) patients in the pregabalin group and 2 (7.14%) patients in the placebo group showed more than 35% decline in YBOCS (p < .01). The pregabalin group showed good tolerability and safety.

CONCLUSIONS

Our study revealed that pregabalin, as an augmenting medication, is more effective than placebo in the treatment of patients with resistant OCD.

Effect of Jian-Pi-Zhi-Dong Decoction on the Amino Acid Neurotransmitters in a Rat Model of Tourette Syndrome and Comorbid Anxiety Disorder

Amino acid neurotransmitters have been shown to correlate with Tourette syndrome (TS) and its comorbidities. In this study, we investigated the effects of Jian-Pi-Zhi-Dong Decoction (JPZDD), a formula containing 10 different Chinese medical herbs, on amino acid neurotransmitters in rats. We established a rat model of Tourette syndrome and comorbid anxiety with an iminodipropionitrile injection plus uncertain empty water bottle stimulation for 3 weeks. Then the rats were randomly divided into four groups: control group and model group were gavaged with saline, while the remaining two treatment groups were gavaged with fluoxetine hydrochloride or JPZDD for four consecutive weeks. We recorded the behaviors of the rats with TS and comorbid anxiety by stereotypy recording, open field test, and elevated plus maze. We observed mitochondrial changes with transmission electron microscopy. We measured the content of glutamate (GLU) and γ-aminobutyric acid (GABA) both in the serum and striatum and the expression of their receptors by Western blot and real-time polymerase chain reaction. The study revealed that JPZDD was effective in alleviating the behavioral symptoms of both tic and anxiety in the rat model groups. These results might be associated with the increase in GABA levels and decrease in GLU levels in the serum, as well as an increase in striatal GABA level by the activation of GABA receptors Type A (GABAAR). JPZDD treatment also reversed the mitochondrial dysfunction both in the striatum and cortex in affected animals.

A Psycho-Behavioral Perspective on Modelling Obsessive-Compulsive Disorder (OCD) in Animals: The Role of Context

Obsessive-compulsive disorder is a heterogeneous and debilitating condition, characterized by intrusive thoughts and compulsive repetition. Animal models of OCD are important tools that have the potential to contribute significantly to our understanding of the condition. Although there is consensus that pre-clinical models are valuable in elucidating the underlying neurobiology in psychiatric disorders, the current paper attempts to prompt ideas on how interpretation of animal behavior can be expanded upon to more effectively converge with the human disorder. Successful outcomes in psychopharmacology involve rational design and synthesis of novel compounds and their testing in well-designed animal models. As part of a special journal issue on OCD, this paper will 1) review the psychobehavioral aspects of OCD that are of importance on how the above ideas can be articulated, 2) briefly elaborate on general issues that are important for the development of animal models of OCD, with a particular focus on the role and importance of context, 3) propose why translational progress may often be less than ideal, 4) highlight some of the significant contributions afforded by animal models to advance understanding, and 5) conclude by identifying novel behavioral constructs for future investigations that may contribute to the face, predictive and construct validity of OCD animal models. We base these targets on an integrative approach to face and construct validity, and note that the issue of treatment-resistance in the clinical context should receive attention in current animal models of OCD.

Combination Therapy of Serotonin Reuptake Inhibitors and Memantine for Obsessive- Compulsive Disorder: A Meta-Analysis of Double-Blind, Randomized, Placebo-Controlled Trials

We performed a meta-analysis to determine whether combination therapy with serotonin reuptake inhibitors (SRIs) and memantine (MEM) was beneficial for the treatment of obsessive- compulsive disorder. This study included three double-blind, randomized, placebo-controlled trials. MEM+SRI was superior to placebo+SRI with regard to response rate [primary outcome, n = 97; risk ratio = 0.22; 95% confidence intervals (CI) = 0.12-0.42; p < 0.00001; I2 = 0%; number needed to treat = 2], the Yale- Brown Obsessive- Compulsive Scale total [standardized mean difference (SMD) = - 4.56; 95% CI = - 8.50, - 0.62; p = 0.02], obsession subscale (SMD = - 4.39; 95% CI = - 5.94, - 2.85; p < 0.00001), and compulsion subscale score (SMD = - 4.60; 95% CI = - 7.64, - 1.55; p = 0.003). No significant differences in any safety outcome were found between the groups.

No Association of Variants of the NPY-System With Obsessive-Compulsive Disorder in Children and Adolescents

Obsessive-compulsive disorder (OCD) causes severe distress and is therefore counted by the World Health Organisation (WHO) as one of the 10 most impairing illnesses. There is evidence for a strong genetic underpinning especially in early onset OCD (eoOCD). Though several genes involved in neurotransmission have been reported as candidates, there is still a need to identify new pathways. In this study, we focussed on genetic variants of the Neuropeptide Y (NPY) system. NPY is one of the most abundant neuropeptides in the human brain with emerging evidence of capacity to modulate stress response, which is of high relevance in OCD. We focussed on tag-SNPs of NPY and its receptor gene NPY1R in a family-based approach. The sample comprised 86 patients (children and adolescents) with eoOCD with both their biological parents. However, this first study on genetic variants of the NPY-system could not confirm the association between the investigated SNPs and eoOCD. Based on the small sample size results have to be interpreted as preliminary and should be replicated in larger samples. However, also in an additional GWAS analysis in a large sample, we could not observe an associations between NPY and OCD. Overall, these preliminary results point to a minor role of NPY on the stress response of OCD.

Skin-Picking Disorder: A Guide to Diagnosis and Management

Skin-picking disorder, also known as excoriation disorder or psychogenic skin excoriations, is an obsessive-compulsive and related disorder that is classified with other body-focused repetitive-behavior disorders in the most recent edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Skin-picking disorder is associated with significant comorbidity and psychosocial dysfunction. The disorder has a female predominance across studies, and the average age of onset is variable but commonly in adolescence and adulthood. A full clinical and dermatologic examination and multidisciplinary approach is important in the diagnosis of this condition. There is no specific or recommended treatment option, but cognitive-behavioral therapy, particularly habit-reversal therapy and acceptance and commitment therapy have shown promise. Various pharmacological interventions have also been described to treat this condition in case reports and open and controlled trials. Specific classes of agents implemented include selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors, antipsychotics, and glutaminergic-modulating agents. SSRIs and N-acetylcysteine have been shown to be the most effective of the pharmacological interventions.

Feline hyperaesthesia syndrome with self-trauma to the tail: retrospective study of seven cases and proposal for an integrated multidisciplinary diagnostic approach

CASE SERIES SUMMARY

This was a retrospective study on the clinical features and response to treatment in seven cats with feline hyperaesthesia syndrome (FHS) and tail mutilation. FHS is a poorly understood disorder characterised by skin rippling over the dorsal lumbar area, episodes of jumping and running, excessive vocalisation, and tail chasing and self-trauma. The majority of the cats were young, with a median age of 1 year at the onset of clinical signs, male (n = 6) and with access to the outdoors (n = 5). Multiple daily episodes of tail chasing and self-trauma were reported in five cats, with tail mutilation in four cats. Vocalisation during the episodes (n = 5) and rippling of lumbar skin (n = 5) were also reported. Haematology, serum biochemistry, Toxoplasma gondii and feline immunodeficiency virus/feline leukaemia virus serology, MRI scans of brain, spinal cord and cauda equina, cerebrospinal fluid analysis and electrodiagnostic tests did not reveal any clinically significant abnormalities. A definitive final diagnosis was not reached in any of the cats, but hypersensitivity dermatitis was suspected in two cases. A variety of medications was used alone or in combination, including gabapentin (n = 6), meloxicam (n = 4), antibiotics (n = 4), phenobarbital (n = 2), prednisolone (n = 2) and topiramate (n = 2); ciclosporin, clomipramine, fluoxetine, amitriptyline and tramadol were used in one cat each. Clinical improvement was achieved in six cases; in five cats complete remission of clinical signs was achieved with gabapentin alone (n = 2), a combination of gabapentin/ciclosporin/amitriptyline (n = 1), gabapentin/prednisolone/phenobarbital (n = 1) or gabapentin/topiramate/meloxicam (n = 1).

RELEVANCE AND NOVEL INFORMATION

This is the first retrospective study on a series of cats with FHS. The diagnostic work-up did not reveal any significant abnormalities of the central or peripheral nervous system; dermatological and behavioural problems could not be ruled out. We propose an integrated multidisciplinary diagnostic pathway to be used for the management of clinical cases and for future prospective studies.

Trichotillomania: a good response to treatment with N-acetylcysteine

Trichotillomania is considered a behavioral disorder and is characterized by the recurring habit of pulling one's hair, resulting in secondary alopecia. It affects 1% of the adult population, and 2 to 4.4% of psychiatric patients meet the diagnostic criteria. It can occur at any age and is more prevalent in adolescents and females. Its occurrence in childhood is not uncommon and tends to have a more favorable clinical course. The scalp, eyebrows and eyelashes are the most commonly affected sites. Glutamate modulating agents, such as N-acetylcysteine, have been shown to be a promising treatment. N-acetylcysteine acts by reducing oxidative stress and normalizing glutaminergic transmission. In this paper, we report a case of trichotillomania with an excellent response to N-acetylcysteine.

Glutamate Genetics in Obsessive-Compulsive Disorder: A Review

OBJECTIVE

Obsessive-compulsive disorder (OCD) is common and debilitating with patients exhibiting persistent intrusive thoughts (obsessions), repetitive ritualistic behaviours (compulsions) and anxiety. While it is known that OCD is highly heritable, the specific genetic risk factors for OCD are still largely unknown. The etiology of OCD has also not been fully elucidated but there is growing evidence that glutamate signaling dysfunction in the cortico-striatal-thalamo-cortical (CSTC) circuitry plays a role in its pathogenesis.

METHODS

We conducted a focused review of recent literature on the role of glutamate genes in OCD.

RESULTS

There have been several recent discoveries in the SAPAP (DLGAP) family, SLC1A1, and GRIN/GRIK families of proteins related to OCD.

CONCLUSION

There is growing evidence supporting a role for genetic variation leading to dysfunctional glutamate signaling in OCD. Based on this new evidence we hypothesize that sustained glutamatergic neurotransmission in key areas of the brain may be contributing to the etiology of OCD.

Integrated mass spectrometry imaging and omics workflows on the same tissue section using grid-aided, parafilm-assisted microdissection

BACKGROUND

In spite of the number of applications describing the use of MALDI MSI, one of its major drawbacks is the limited capability of identifying multiple compound classes directly on the same tissue section.

METHODS

We demonstrate the use of grid-aided, parafilm-assisted microdissection to perform MALDI MS imaging and shotgun proteomics and metabolomics in a combined workflow and using only a single tissue section. The grid is generated by microspotting acid dye 25 using a piezoelectric microspotter, and this grid was used as a guide to locate regions of interest and as an aid during manual microdissection. Subjecting the dissected pieces to the modified Folch method allows to separate the metabolites from proteins. The proteins can then be subjected to digestion under controlled conditions to improve protein identification yields.

RESULTS

The proof of concept experiment on rat brain generated 162 and 140 metabolite assignments from three ROIs (cerebellum, hippocampus and midbrain/hypothalamus) in positive and negative modes, respectively, and 890, 1303 and 1059 unique proteins. Integrated metabolite and protein overrepresentation analysis identified pathways associated with the biological functions of each ROI, most of which were not identified when looking at the protein and metabolite lists individually.

CONCLUSIONS

This combined MALDI MS imaging and multi-omics approach further extends the amount of information that can be generated from single tissue sections.

GENERAL SIGNIFICANCE

To the best of our knowledge, this is the first report combining both imaging and multi-omics analyses in the same workflow and on the same tissue section.

Excoriation (skin-picking) disorder: a systematic review of treatment options

Although pathological skin-picking has been documented in the medical literature since the 19th century, it has only recently been included as a distinct entity in psychiatric classification systems. In the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition and the proposed International Classification of Diseases, Eleventh Revision, excoriation (skin-picking) disorder (ED), also known as neurotic excoriation, psychogenic excoriation, or dermatillomania), is described as recurrent picking of skin, leading to skin lesions and significant distress or functional impairment. ED is listed as one of the obsessive-compulsive and related disorders, given its overlap with conditions such as trichotillomania (hair-pulling disorder). Arguably, its inclusion and delineation in the diagnostic nomenclature will lead to increased awareness of the condition, more research, and ultimately in treatment advances. This systematic review aims to provide readers with an up-to-date view of current treatment options for ED. A MEDLINE search of the ED treatment literature was conducted to collate relevant articles published between 1996 and 2017. The findings indicate that a number of randomized controlled trails on ED have now been published, and that current management options include behavioral therapy (habit reversal or acceptance-enhanced behavior therapy), and medication (selective serotonin reuptake inhibitors or N-acetyl cysteine).

Effects of NMDA receptor antagonists on probability discounting depend on the order of probability presentation

Risky decision making can be measured using a probability-discounting procedure, in which animals choose between a small, certain reinforcer and a large, uncertain reinforcer. Recent evidence has identified glutamate as a mediator of risky decision making, as blocking the N-methyl-d-aspartate (NMDA) receptor with MK-801 increases preference for a large, uncertain reinforcer. Because the order in which probabilities associated with the large reinforcer can modulate the effects of drugs on choice, the current study determined if NMDA receptor ligands alter probability discounting using ascending and descending schedules. Sixteen rats were trained in a probability-discounting procedure in which the odds against obtaining the large reinforcer increased (n=8) or decreased (n=8) across blocks of trials. Following behavioral training, rats received treatments of the NMDA receptor ligands MK-801 (uncompetitive antagonist; 0, 0.003, 0.01, or 0.03mg/kg), ketamine (uncompetitive antagonist; 0, 1.0, 5.0, or 10.0mg/kg), and ifenprodil (NR2B-selective non-competitive antagonist; 0, 1.0, 3.0, or 10.0mg/kg). Results showed discounting was steeper (indicating increased risk aversion) for rats on an ascending schedule relative to rats on the descending schedule. Furthermore, the effects of MK-801, ketamine, and ifenprodil on discounting were dependent on the schedule used. Specifically, the highest dose of each drug decreased risk taking in rats in the descending schedule, but only MK-801 (0.03mg/kg) increased risk taking in rats on an ascending schedule. These results show that probability presentation order modulates the effects of NMDA receptor ligands on risky decision making.

Graphene Oxide Nanosheets Reshape Synaptic Function in Cultured Brain Networks

Graphene offers promising advantages for biomedical applications. However, adoption of graphene technology in biomedicine also poses important challenges in terms of understanding cell responses, cellular uptake, or the intracellular fate of soluble graphene derivatives. In the biological microenvironment, graphene nanosheets might interact with exposed cellular and subcellular structures, resulting in unexpected regulation of sophisticated biological signaling. More broadly, biomedical devices based on the design of these 2D planar nanostructures for interventions in the central nervous system require an accurate understanding of their interactions with the neuronal milieu. Here, we describe the ability of graphene oxide nanosheets to down-regulate neuronal signaling without affecting cell viability.

Effect of Jian-Pi-Zhi-Dong Decoction on striatal glutamate and γ-aminobutyric acid levels detected using microdialysis in a rat model of Tourette syndrome

BACKGROUND

Jian-Pi-Zhi-Dong Decoction (JPZDD) is a dedicated treatment of Tourette syndrome (TS). The balance of neurotransmitters in the cortico-striato-pallido-thalamo-cortical network is crucial to the occurrence of TS and related to its severity. This study evaluated the effect of JPZDD on glutamate (Glu) and γ-aminobutyric acid (GABA) and their receptors in a TS rat model.

MATERIALS AND METHODS

Rats were divided into four groups (n=12 each). TS was induced in three of the groups by injecting them with 3,3'-iminodipropionitrile for 7 consecutive days. Two model groups were treated with tiapride (Tia) or JPZDD, while the control and the remaining model group were gavaged with saline. Behavior was assessed by stereotypic score and autonomic activity. Striatal Glu and GABA contents were detected using microdialysis. Expressions of N-methyl-D-aspartate receptor 1 and GABAA receptor (GABAAR) were observed using Western blot and real-time polymerase chain reaction.

RESULTS

Tia and JPZDD groups had decreased stereotypy compared with model rats; however, the JPZDD group showed a larger decrease in stereotypy than the Tia group at a 4-week time point. In a spontaneous activity test, the total distance of the JPZDD and Tia groups was significantly decreased compared with the model group. The Glu levels of the model group were higher than the control group and decreased with Tia or JPZDD treatment. The GABA level was higher in the model group than the control group. Expressions of GABAAR protein in the model group were higher than in the control group. Treatment with Tia or JPZDD reduced the expression of GABAAR protein. In the case of the mRNA expression, only Tia reduced the expression of N-methyl-D-aspartate receptor 1, compared with the model group.

CONCLUSION

JPZDD could alleviate impairments in behavior and dysfunctional signaling by downregulating GABAAR in the striatum. We suggest that this acts to maintain the balance of Glu and GABA.