Changes in levels of cortical metabotropic glutamate 2 receptors with gender and suicide but not psychiatric diagnoses

New pharmacotherapies to tackle the unmet needs in bipolar disorder: a focus on acute suicidality

INTRODUCTION

Suicidal behavior is relatively frequent in patients with bipolar disorder (BD) and constitutes their most frequent cause of death. Suicide rates remain high in patients with BD despite adherence to guidelines recommending lithium as first line, and/or antidepressants, antipsychotics, psychotherapy, psychosocial interventions, and electroconvulsive therapy. Hence the need to identify more effective and rapid anti-suicide interventions.

AREAS COVERED

To tackle the unmet needs of pharmacotherapy, we investigated the PubMed database on 24-25 January 2024 using strategies like ('acute suicid*'[ti] OR 'suicide crisis syndrome' OR 'acute suicidal affective disturbance') AND (lithium[ti] OR clozapine[ti]), which obtained 3 results, and ('acute suicid*'[ti] OR 'suicide crisis syndrome' OR 'acute suicidal affective disturbance') AND (ketamine[ti] OR esketamine[ti] OR NMDA[ti] OR glutamat*[ti]), which yielded 14 results. We explored glutamatergic abnormalities in BD and suicide and found alterations in both. The noncompetitive NMDS antagonist ketamine and its S-enantiomer esketamine reportedly decrease acute suicidality.

EXPERT OPINION

Intranasal esketamine or subcutaneous ketamine, single-bolus or intravenous, and possibly other glutamate receptor modulators may improve suicidal behavior in patients with unipolar and bipolar depression. This may be achieved through prompt remodulation of glutamate activity. The correct use of glutamatergic modulators could reduce acute suicidality and mortality in patients with BD.

Metabotropic glutamate receptors and cognition: From underlying plasticity and neuroprotection to cognitive disorders and therapeutic targets

Metabotropic glutamate (mGlu) receptors are G protein-coupled receptors that play pivotal roles in mediating the activity of neurons and other cell types within the brain, communication between cell types, synaptic plasticity, and gene expression. As such, these receptors play an important role in a number of cognitive processes. In this chapter, we discuss the role of mGlu receptors in various forms of cognition and their underlying physiology, with an emphasis on cognitive dysfunction. Specifically, we highlight evidence that links mGlu physiology to cognitive dysfunction across brain disorders including Parkinson's disease, Alzheimer's disease, Fragile X syndrome, post-traumatic stress disorder, and schizophrenia. We also provide recent evidence demonstrating that mGlu receptors may elicit neuroprotective effects in particular disease states. Lastly, we discuss how mGlu receptors can be targeted utilizing positive and negative allosteric modulators as well as subtype specific agonists and antagonist to restore cognitive function across these disorders.

Suicidal Behavior and Its Relationship with Postmortem Forensic Toxicological Findings

Suicide affects all sociodemographic levels, age groups, and populations worldwide. The factors that can increase the risk of suicidal tendencies are widely studied. The aim of this study was to analyze the types and combinations of toxics found in fatal suicide victims with different suicide mechanisms. A total of 355 autopsies were retrospectively studied, and 26 toxics were determined and related to mechanisms of suicide. Hanging (55%), drug overdose (22.7%), and jumping from a height (17.8%) were most represented suicide mechanisms with positive toxicology. Hanging was the most represented in men (50.3%; p = 0.019), while jumping from a height was more represented in women (29.7%, p = 0.028). Drugs of abuse were the most frequent toxics found in men (55.5%; p < 0.001), while medicines were the most frequent type found in women (70.3%, p < 0.001). Alcohol, nordiazepam, cocaine, and venlafaxine were the most consumed toxics. Benzodiazepines and venlafaxine were found in suicides involving drug overdose, hanging, and jumping from a height. In conclusion, most suicides were associated with drug abuse in men. Hanging was more represented in men and jumping from a height in women. Alcohol was present in combination with other toxics and medicines. The toxicological analysis is fundamental to understanding consumption patterns and establishing strategies and protocols for detecting and preventing suicide.

Sex Differences in Psychosis: Focus on Animal Models

Most psychiatric illnesses, such as schizophrenia, show profound sex differences in incidence, clinical presentation, course, and outcome. Fortunately, more recently the literature on sex differences and (to a lesser extent) effects of sex steroid hormones is expanding, and in this review we have focused on such studies in psychosis, both from a clinical/epidemiological and preclinical/animal model perspective. We begin by briefly describing the clinical evidence for sex differences in schizophrenia epidemiology, symptomatology, and pathophysiology. We then detail sex differences and sex hormone effects in behavioral animal models of psychosis, specifically psychotropic drug-induced locomotor hyperactivity and disruption of prepulse inhibition. We expand on the preclinical data to include developmental and genetic models of psychosis, such as the maternal immune activation model and neuregulin transgenic animals, respectively. Finally, we suggest several recommendations for future studies, in order to facilitate a better understanding of sex differences in the development of psychosis.

Abnormal gene expression of BDNF, but not BDNF-AS, in iPSC, neural stem cells and postmortem brain samples from bipolar disorder

BACKGROUND

Brain-derived neurotrophic factor (BDNF) antisense RNA (BDNF-AS) was identified as naturally conserved non-coding antisense RNA that suppresses the transcription of BDNF.

METHODS

We measured the expression of BDNF mRNA and BDNF-AS mRNA in iPSC and NSC from bipolar disorder (BD) patients and healthy control subjects, and postmortem brain samples such as the corpus callosum, the Brodmann area (BA8), and BA46 from BD patients and age- and sex-matched controls.

RESULTS

The expression of BDNF mRNA in iPSC from BD patients (n = 6) was significantly lower than that of control subjects (n = 4) although the expression of BDNF mRNA in NSC from BD patients was significantly higher than that of control subjects. In contrast, there were no changes in the expression of BDNF-AS mRNA in both iPSC and NSC between two groups. The expression of BDNF mRNA in the BA46 from BD patients (n = 35) was significantly lower than that of controls (n = 34) although the expression of BDNF mRNA in the corpus callosum and BA8 was not different between two groups (n = 15). In contrast, there were no changes in expression of BDNF-AS mRNA in the three brain regions between two groups. Interestingly, there were significant positive correlations between BDNF mRNA expression and BDNF-AS mRNA expression in the postmortem brain samples.

LIMITATIONS

Sample sizes are relatively low.

CONCLUSIONS

Our data suggest that abnormalities in the expression of BDNF, but not BDNF-AS, play a role in the pathogenesis of BD.

Cortical expression of the RAPGEF1 gene in schizophrenia: investigating regional differences and suicide

Rap guanine nucleotide exchange factor 1 (RAPGEF1) is involved in cell adhesion and neuronal migration. Previously we found lower RAPGEF1 mRNA levels in Brodmann's area (BA) 9 in subjects with schizophrenia compared to controls. This study aimed to determine whether RAPGEF1 expression was altered in other brain regions implicated in schizophrenia and whether this was associated with suicide. Using qPCR, we measured the levels of RAPGEF1 in post-mortem BA 8 and 44 from 27 subjects with schizophrenia and 26 non-psychiatric control subjects. To address the effect of antipsychotic treatments, Rapgef1 mRNA levels were measured in the cortex from rats treated with typical antipsychotic drugs. There was no difference in RAPGEF1 normalised relative expression levels in BA 8 or 44. However, in BA 8, schizophrenia subjects had higher raw Ct RAPGEF1 levels compared to controls. There were higher RAPGEF1 levels in suicide completers compared to non-suicide schizophrenia subjects in BA 8. Rapgef1 expression levels in the rat cortex did not vary with antipsychotic treatment. Our findings suggest changes in RAPGEF1 expression may be limited to the dorsolateral prefrontal cortex from subjects with schizophrenia. Further investigation of the function of RAPGEF1 may lead to a greater understanding of the pathophysiology of schizophrenia.

Gender Differences Related to Spirituality, Coping Skills and Risk Factors of Suicide Attempt: A Cross-Sectional Study of French Adolescent Inpatients

Background: Suicide attempts in adolescence represent a major public health concern, since these behaviors are associated with psychosocial burden and an increased risk of suicide. This cross-sectional study aimed to explore possible gender differences related to protective and risk factors in adolescents who have attempted suicide. Methods: Participants were French adolescents hospitalized for attempt suicide in five French pediatric departments. The participants were evaluated on 12 instruments measuring individual risk and protective factors. Results: Our sample included 320 adolescents aged 13-17 years (M = 14.43, SD = 1.29), of whom 82% were female and 35% were repeat attempters. Boys had greater difficulties at school and used more lethal means such as strangulation. We failed to find any differences between the two groups as regards the main Axis I psychiatric diagnoses. Boys tend to use more non-productive coping skills such as tension reduction or wishful thinking and girls use more reference to other strategies such as seeking social support. Although spirituality scores were low overall sample, they were significantly higher among girls. Conclusions: In the end, we find little difference between the two groups in terms of risk factors. However, we have shown gender differences in spirituality and some coping strategies. These results should be taken into consideration when designing suicide prevention programs.