Social isolation induces schizophrenia-like behavior potentially associated with HINT1, NMDA receptor 1, and dopamine receptor 2

HINT1 promotes neuronal apoptosis and triggers schizophrenia-like behavior in rats

This study aims to investigate the mechanism by which Histidine triad nucleotide-binding protein 1 (HINT1) promotes hippocampal neuronal apoptosis, triggering schizophrenia (SZ)-like behavior in rats. By establishing a rat SZ-like model, we assessed learning, memory, emotional response, and cognitive function through the Morris Water Maze, auditory startle response, and open field tests. HINT1 expression in the hippocampus was analyzed via RT-PCR and Western blot. We also created a HINT1 overexpression model in hippocampal neuronal cells to analyze its effects on cell proliferation and apoptosis. This analysis was conducted using the CCK-8 assay and flow cytometry, along with the quantification of apoptosis-related proteins and neurotrophic factors. Our findings indicated that the SZ-like model rats exhibited diminished learning and memory abilities, altered emotional reactions, and impaired cognitive functions, alongside a notable increase in HINT1 mRNA and protein levels. HINT1 overexpression was observed to inhibit hippocampal neuronal cell proliferation and promote apoptosis, with an increase in the expression of pro-apoptotic proteins and a decrease in neurotrophic factors. These results suggest HINT1's role in the onset and development of SZ-like behavior through its upregulation and induction of apoptosis in hippocampal neuronal cells, underlining its potential as a therapeutic target.

HINT1 Gene Polymorphisms, Smoking Behaviour, and Personality Traits: A Haplotype Case-Control Study

The factors influencing the development and maintenance of nicotine dependence are numerous and complex. Recent studies indicate that smokers exhibit distinct genetic predispositions to nicotine dependence. We aimed to analyse (1) the association between rs2551038 and cigarette smoking, (2) the association of between the rs3864236-rs2526303-rs2551038 haplotype and cigarette smoking, and (3) the personality traits measured by the NEO Five-Factor Inventory in cigarette users and never-smokers. No significant differences were present in the frequency of rs2551038 genotypes and alleles in the studied cigarette users compared to the control group. Cigarette users, compared to the control group, had higher scores on the NEO-FFI Extraversion scale (p = 0.0011), and lower scores were obtained by the cigarette users for the NEO-FFI Openness (p = 0.0060), Agreeability (p ≤ 0.000), and Conscientiousness (p ≤ 0.000) scales. There was a significant positive Pearson's linear correlation between the age and the Fagestrom test (r = 0.346; p < 0.0001) and the NEO-FFI Openness scale (r = 0.180; p < 0.0001) in the group of cigarette users. We observed significant linkage disequilibrium between rs2526303 and rs3864236 (D' = 0.3581; p < 2.2204 × 10-16) and between rs2526303 and rs2551038 (D' = 0.9993; p < 2.2204 × 10-16) in the tested sample. The sex-stratified haplotype analysis revealed that in the group of male never-smokers, the GTC haplotype was significantly more frequent than in the group of cigarette users (38% vs. 22%; p = 0.0039). The presented study reveals significant differences in personality trait scores between cases and controls. Moreover, the sex-stratified analysis showed significant differences in haplotype distribution. These results underscore the interplay between genetic predisposition, sex, and personality in nicotine-using individuals.

The HINT1 Gene rs2526303 Polymorphism and Its Association with Personality Traits in Cigarette Smokers

The development of a substance use disorder (SUD) is a multifaceted process influenced by both genetic and environmental factors. Recent research has suggested the potential involvement of the HINT1 gene in various aspects of plasticity, mood regulation, anxiety-like behaviour, and stress-coping mechanisms. Moreover, personality traits are also recognised to be instrumental in developing substance dependency. Given these considerations, our study investigated the associations among cigarette smoking, personality traits, and the rs2526303 polymorphism. Additionally, we investigated the interactions between personality traits and rs2526303 in the HINT1 gene. The study group comprised 531 volunteers: 375 cigarette users (mean age = 29.42 ± 10.72; F = 49%, M = 51%) and 156 never-smokers (mean age = 26.93 ± 10.09; F = 79%, M = 21%). Genotyping was conducted using the real-time PCR method, and the NEO Five-Factor Personality Inventory and State-Trait Anxiety Inventory were administered. There were no statistically significant differences in the frequency of rs2526303 genotypes and alleles in the cigarette user group compared to the control group. Compared to the control group, the cigarette users obtained higher scores in the assessment of the NEO-FFI Extraversion scale and lower results for the NEO-FFI Openness, Agreeableness, and Conscientiousness scales. Additionally, there was a statistically significant effect of rs2526303 genotype interaction and cigarette-using status on the conscientiousness scale. These outcomes collectively suggest a notable association between cigarette smoking and specific dimensions of personality, particularly highlighting differences in extraversion, openness, agreeableness, and conscientiousness. Furthermore, the detected interaction effect involving rs2526303 concerning conscientiousness signifies a complex interplay between genetic factors and smoking behaviour.

Handling prevents and reverses cognitive deficits induced by sub-chronic phencyclidine in a model for schizophrenia in rats

Treatments for schizophrenia are not effective in ameliorating cognitive deficits. Therefore, novel therapies are needed to treat cognitive impairments associated with schizophrenia (CIAS), which are modelled in rats through administration of sub-chronic phencyclidine (scPCP). We have previously shown that enrichment via voluntary exercise prevents and reverses impairments in novel object recognition (NOR) in this model. The present study aimed to investigate if handling could prevent delay-induced NOR deficits and prevent and reverse scPCP-induced NOR deficits. Two cohorts of adult female Lister Hooded rats were used. In experiment one, handling (five minutes/day, five days/week for two weeks), took place before scPCP administration (2 mg/kg, i.p. twice-daily for seven days). NOR tests were conducted at two, four, and seven weeks post-handling with a one-minute inter-trial interval (ITI) and at five weeks post-dosing with a six-hour ITI. In experiment two, rats were handled after scPCP administration and tested immediately in the one-minute ITI NOR task and again at two weeks post-handling. In both handling regimens, the scPCP control groups failed to discriminate novelty, conversely the scPCP handled groups significantly discriminated in this task. In the 6 h ITI test, vehicle control and scPCP control failed to discriminate novelty; however, the vehicle handled and scPCP handled groups did significantly discriminate. Handling rats prevented and reversed scPCP-induced deficits and prevented delay-induced NOR deficits. These findings add to evidence that environmental enrichment is a viable treatment for cognitive deficits in rodent tests and models of relevance to schizophrenia, with potential to translate into effective treatments for CIAS.

Association between childhood trauma and white matter deficits in first-episode schizophrenia

OBJECTIVE

This study aimed to investigate the relationship between childhood trauma (ChT) and white matter (WM) deficits in first-episode schizophrenia (FES).

METHODS

A total of 103 individuals with FES and 206 healthy control individuals (HCs) were enrolled and assessed based on ChT Questionnaire (CTQ) and Positive and Negative Symptoms Scale (PANSS). Diffusion tensor imaging was acquired on a Signa 3.0 T scanner. Map of fractional anisotropy (FA) was analyzed using Tract-Based Spatial Statistics. Hierarchical logistic regression analyses were used to examine associations of sociodemographic characteristics, total CTQ scores, and WM deficits.

RESULTS

Compared with the HCs group, the FES group showed significantly lower FA in several WM bundles (left anterior thalamic radiation, left inferior frontal-occipital fasciculus, left cingulum, forceps major, and forceps minor), and the mean FA value in these WM bundles was inversely related to the total CTQ score. In addition, a higher CTQ score may increase the risk of schizophrenia, while higher FA values may decrease the risk of schizophrenia.

CONCLUSION

This study demonstrates that individuals with FES evince widespread cerebral WM abnormalities and that these abnormalities were associated with ChT. These results provide clues about the neural basis and potential biomarkers of schizophrenia.

Correlates of Social Isolation in Forensic Psychiatric Patients with Schizophrenia Spectrum Disorders: An Explorative Analysis Using Machine Learning

The detrimental effects of social isolation on physical and mental health are well known. Social isolation is also known to be associated with criminal behavior, thus burdening not only the affected individual but society in general. Forensic psychiatric patients with schizophrenia spectrum disorders (SSD) are at a particularly high risk for lacking social integration and support due to their involvement with the criminal justice system and their severe mental illness. The present study aims to exploratively evaluate factors associated with social isolation in a unique sample of forensic psychiatric patients with SSD using supervised machine learning (ML) in a sample of 370 inpatients. Out of >500 possible predictor variables, 5 emerged as most influential in the ML model: attention disorder, alogia, crime motivated by ego disturbances, total PANSS score, and a history of negative symptoms. With a balanced accuracy of 69% and an AUC of 0.74, the model showed a substantial performance in differentiating between patients with and without social isolation. The findings show that social isolation in forensic psychiatric patients with SSD is mainly influenced by factors related to illness and psychopathology instead of factors related to the committed offences, e.g., the severity of the crime.

Sonic hedgehog pathway as a new target of atypical antipsychotics: Revisiting of amisulpride and aripiprazole effects in a rat model of schizophrenia

OBJECTIVES

Schizophrenia is a chronic mental illness presented by cognitive deficits that precede its positive and negative symptoms. Sonic hedgehog (Shh)-pathway contributes to its pathophysiology. Shh has a role in neurogenesis as it regulates proliferation and survival of neural cells. In this study, effects of the anti-psychotics Amisulpride and/or Aripiprazole on the Shh-pathway and its relation to cognitive functions and neurogenesis in a rat model of schizophrenia were tested.

METHODS

60 male Wistar rats were allocated into the following groups: control, socially isolated, amisulpride and/or aripiprazole-treated groups. Rats were then subjected to behavioral, biochemical, and histopathological tests to assess the impact of these drugs on Shh-pathway.

KEY FINDINGS

Cognitive-dysfunction was evidenced in socially isolated group in novel object, three-chamber, and Morris water maze tests, associated by disorganised Shh-pathway proteins levels concentrations, increased glial fibrillary acidic protein (GFAP)-stained astrocytes. Treated groups favorably reversed these changes evidenced by increased Shh, transmembrane patched-1 and smoothened, glioma-associated-oncogene (GLI)-1 levels, dopamine-1 receptors and brain derived neurotrophic factor, and decreased GLI-3 protein, GFAP immune reaction in astrocytes and inflammatory markers compared to socially isolated group.

CONCLUSION

Amisulpride and/or aripiprazole have a favorable role in turning on Shh-pathway with subsequent beneficial cognitive and neurogenesis effects.

Social isolation among older veterans: findings from the National Health and Aging Trends Study

OBJECTIVES

Social isolation is a critical public health issue that affects multiple domains of well-being among older adults, but little is known about social isolation among older military veterans. As such, the purpose of this study was to estimate the prevalence of social isolation among older veterans and to examine risk factors for social isolation among older veterans.

METHOD

Data were derived from Round 1 of the National Health and Aging Trends Study, which is an annual, longitudinal panel survey of Medicare beneficiaries aged 65 and older. The sample included 1,683 veterans, who were primarily White and male. Weighted logistic regression models were used to predict severe social isolation (having no social participation) and social isolation (having only one source of social participation) among older veterans, while controlling for age, sex, race, marital status, education, income, and metropolitan residency.

RESULTS

After accounting for other predictors, results show that veterans who are 85 and older, male, White, unmarried or unpartnered, with lower educational attainment and lower income are greatly at risk of both severe social isolation and social isolation.

CONCLUSION

The results of this study support past research showing that veterans with limited social and economic capital are at great risk of experiencing adverse outcomes in older adulthood, including social isolation. Interventions should therefore aim to improve social connectedness among this population and should address the risk-factors that contribute to social isolation among older veterans.

Relationships between social withdrawal and facial emotion recognition in neuropsychiatric disorders

BACKGROUND

Emotion recognition constitutes a pivotal process of social cognition. It involves decoding social cues (e.g., facial expressions) to maximise social adjustment. Current theoretical models posit the relationship between social withdrawal factors (social disengagement, lack of social interactions and loneliness) and emotion decoding.

OBJECTIVE

To investigate the role of social withdrawal in patients with schizophrenia (SZ) or probable Alzheimer's disease (AD), neuropsychiatric conditions associated with social dysfunction.

METHODS

A sample of 156 participants was recruited: schizophrenia patients (SZ; n = 53), Alzheimer's disease patients (AD; n = 46), and two age-matched control groups (SZc, n = 29; ADc, n = 28). All participants provided self-report measures of loneliness and social functioning, and completed a facial emotion detection task.

RESULTS

Neuropsychiatric patients (both groups) showed poorer performance in detecting both positive and negative emotions compared with their healthy counterparts (p < .01). Social withdrawal was associated with higher accuracy in negative emotion detection, across all groups. Additionally, neuropsychiatric patients with higher social withdrawal showed lower positive emotion misclassification.

CONCLUSIONS

Our findings help to detail the similarities and differences in social function and facial emotion recognition in two disorders rarely studied in parallel, AD and SZ. Transdiagnostic patterns in these results suggest that social withdrawal is associated with heightened sensitivity to negative emotion expressions, potentially reflecting hypervigilance to social threat. Across the neuropsychiatric groups specifically, this hypervigilance associated with social withdrawal extended to positive emotion expressions, an emotional-cognitive bias that may impact social functioning in people with severe mental illness.

COVID-19 Induced New-onset Psychosis: A Case Report from Oman

Neurobehavioral impairment associated with COVID-19 infection has been recently documented in the literature. COVID-19 infection has also been associated with an increased risk for developing psychiatric symptoms, including rare reports on psychosis. We report a case of a 46-year-old male with no significant medical, family, and psychiatric history admitted to the hospital with COVID-19-related psychosis. Possible contributory factors for his condition are discussed, including the relationship between infections and the brain circuitry, inadvertent iatrogenic effects of pharmaceuticals used to manage COVID-19, as well as diathesis-stress associated with the tribulation of the prevailing pandemic.

The SEEKING Drive and Its Fixation: A Neuro-Psycho-Evolutionary Approach to the Pathology of Addiction

Neuro-ethological studies conducted by Panksepp and his colleagues have provided an understanding of how the activity of the mesolimbic dopaminergic (ML DA) system leads to the emotional disposition to SEEK/Explore, which is involved in all appetitive motivated behavior and mental activity. In pathological addiction phenomena, this emotional disposition “fixes” itself on certain obsessive-compulsive habits, losing its versatility and its natural predisposition to spontaneous and unconditioned activation. Overall, the result is a consistent disinterest in everything that is not the object of addiction. From a neuro-psycho-evolutionary point of view, the predisposition to develop addictive behavior can be attributed to a loss of “functional autonomy” of the SEEKING/Explorative disposition. Indeed, as shown by animal and human studies, the tendency to be conditioned by situations and contexts that provide an immediate reward can be closely related to a deficit in the tonic endogenous activity of the ML DA-SEEKING system.

Influence of Family Dynamics on Stigma Experienced by Patients With Schizophrenia: Mediating Effect of Quality of Life

Background: Stigma is a barrier to schizophrenia recovery; thus, screening the factors that affect stigma experienced by patients with schizophrenia and exploring the interactions between each factor are critical for improved treatment. The purpose of this study was to demonstrate the relationship between quality of life (QoL), family dynamics, and stigma in patients with schizophrenia. Methods: A total of 447 participants with schizophrenia were recruited in the study, namely, 281 community patients and 166 inpatients. Three scales, Schizophrenia Quality of Life Scale (SQLS), Self-rating Scale of Systemic Family (SSFD), and Stigma Scale for Mental Illness (SSMI), were, respectively, used to evaluate three variables: QoL, family dynamics, and stigma. The correlations between each factor in these three scales were evaluated by Spearman's rank correlation analysis. A mediation model was constructed to investigate whether QoL mediated the relationship between stigma and family dynamics. Results: Correlation analysis revealed that most variables in these three scales correlated significantly with each other. Mediational regression analyses indicated that the degree of stigma was affected by family dynamics; that is, good family dynamics predicted less stigma. Surprisingly, we found that a worse QoL was associated with less stigma, and this led to good family dynamics being related to a worse QoL. These findings further suggested that QoL had a mediating effect on the relationship between family dynamics and stigma. Conclusions: This study suggested that more attention should be focused on the multifactorial influence of stigma on patients with schizophrenia. Integrated and personalized interventions regarding QoL and family dynamics can be tailored for patients with schizophrenia to reduce self-stigma.

Combined Low Dose of Ketamine and Social Isolation: A Possible Model of Induced Chronic Schizophrenia-Like Symptoms in Male Albino Rats

While animal models for schizophrenia, ranging from pharmacological models to lesions and genetic models, are available, they usually mimic only the positive symptoms of this disorder. Identifying a feasible model of chronic schizophrenia would be valuable for studying the possible underlying mechanism and to investigate emerging treatments. Our hypothesis starts from the observation that combining ketamine with isolation could result in long-lasting neuro-psychological deficits and schizophrenia-like features; thus, it could probably be used as the first model of chronic schizophrenia that emphasizes the characteristic of having a multifactorial etiology. By the means of this study, we investigated the effects of ketamine administration combined with isolation in inducing schizophrenia-like symptoms in male albino rats and the brain reactive oxygen species levels. Our results showed that the number of lines crossings in the open field test, the number of open arm entries in the elevated plus maze, and the spontaneous alternations percentage in the Y-maze were significantly lower in the ketamine + isolation group compared to both the control and ketamine + social housing group (p < 0.05). Furthermore, the ketamine + isolation intervention significantly increased the MDA levels and decreased the GPx levels both in the hippocampus and the cortex of the rats. In addition, our premise of creating a model capable of exhibiting both positive and negative symptoms of schizophrenia was also based on adding the aripiprazole treatment to a group of rats. Therefore, we compared the ketamine + social isolation group with the ketamine + social isolation + aripiprazole group in order to attempt to discover if the antipsychotic drug would significantly decrease the potential positive schizophrenia-like symptoms induced by social isolation and ketamine. Given that we obtained significant results, we cautiously presume that this might be an important step in developing our animal model capable of illustrating both positive and negative symptoms of schizophrenia. This study could be a first step towards the creation of a complex animal model capable of exhibiting the multifactorial origin and manifestation of schizophrenia.

Juvenile social isolation leads to schizophrenia-like behaviors via excess lactate production by astrocytes

Repeated early environmental deprivation is regarded as a typical paradigm to mimic the behavioral abnormalities and brain dysfunction that occur in psychiatric disorders. Previously, we reported that social isolation could disrupt prepulse inhibition (PPI) in Sprague-Dawley (SD) rats, producing the typical characteristics of a schizophrenia animal model. Based on further analysis of previous proteomic and transcriptomic data, a disrupted balance of glucose metabolism was found in the prefrontal cortex (PFC) of isolated rats. Subsequently, in the first experiment of this study, we investigated the effects of juvenile social isolation (postnatal days (PND) 21-34) on PPI and lactate levels in PND56 rats. Compared with the social rearing group, rats in the isolated rearing group showed disrupted PPI and increased lactate levels in the PFC. In the second experiment, at PND55, the model rats were acutely injected with a glycogen phosphorylase inhibitor (4-dideoxy-1,4-imino-darabinitol, DAB) or control saline in the bilateral PFC. Our data showed that acute DAB administration (50 pmol, 0.5 μl) significantly improved the disrupted PPI and decreased the levels of oxidative phosphorylation (OXPHOS)-related mRNAs as well as lactate. In summary, our results suggested that excess astrocytic lactate production was involved in the impairment of auditory sensory gating of isolated rats, which may contribute to the metabolic pathogenesis of schizophrenia.

Prenatal MAM treatment altered fear conditioning following social isolation: Relevance to schizophrenia

Adolescent social isolation (SI) might change the trajectory of brain development. In the present study, we investigated the effect of short-term adolescent SI on fear memory, anxiety and protein levels in the adult medial prefrontal cortex of rats prenatally treated with methylazoxymethanol, MAM-E17 model of schizophrenia. The animals were maintained in standard housing (SH) or social isolation (P30-P40, SI) conditions. Behavioural tests (trace or delay fear conditioning, light/dark box) were performed in late adolescence and early adulthood. The results showed that MAM treatment did not alter fear memory, which was investigated with the use of either trace or delay fear conditioning, at any age, and SI decreased the fear response in adult control animals only under trace conditioning. Neither MAM nor SI influenced anxiety-related behaviour measured in the light/dark box. A proteomics study showed that both MAM and SI changed the protein levels related to synapse maturation and cytoskeletal organization, energy transfer and metabolic processes. Prenatal or adolescent environmental factors are able to change the expression of proteins that are correlated with behavioural impairments. Moreover, SI reversed some alterations in proteins induced by MAM. Thus, normally developing brains showed different responses to adolescent SI than those with altering courses of MAM administration.

Mental Symptoms and Stress of Hospitalized Schizophrenia Patients With 2019 Novel Coronavirus Disease: An Observation Study

Background: The 2019 novel coronavirus disease (COVID-19) is an extremely rapidly spreading respiratory infection caused by SARS-CoV-2. Many schizophrenic patients were infected with COVID-19 in Wuhan City, Hubei Province. This study took hospitalized schizophrenia patients with COVID-19 as the research subjects and observed the changes in psychopathology and stress of patients with COVID-19 and the accompanying social isolation. Methods: To sort and isolate potential COVID-19-infected patients, an isolated ward was set up from January 30, 2020, to March 30, 2020. Schizophrenia patients with COVID-19 were referred to this ward, and long-term hospitalized cases were included in this study. The Positive and Negative Syndrome Scale and Perceived Stress Scale were used to evaluate the severity of mental symptoms and psychological stress in the early stage of the outbreak of COVID-19, after the diagnosis of COVID-19 and after recovery. At the time of diagnosis, we also extracted the patient's routine blood, biochemical and other indicators and asked the patient's perception of COVID-19. Results: 21 hospitalized schizophrenia patients with COVID-19 were recruited in this study. The changes in PANSS scores were not significant (p = 0.225 baseline vs. diagnosed, p = 0.399 cured vs. diagnosed). The CPSS scores increased significantly after diagnosis and transfer to the isolation ward (p < 0.001 baseline vs. diagnosed, p < 0.001 cured vs. diagnosed). The course of schizophrenia was a protective factor of stress levels to cases (t = -3.25, p = 0.006), and patients' perception of COVID-19 was a risk factor (t = 2.48, p = 0.038). The final multiple linear regression model was statistically significant (F = 8.16, p < 0.001). Conclusion: Hospitalized schizophrenia patients with COVID-19 had increased stress levels and negative symptoms but alleviated positive symptoms after medical isolated treatment. This reminds us that in the face of major epidemics, we must specifically alleviate the psychological burden at the peak of the epidemic and improve the prognosis of patients after the epidemic.

Long-Term Impacts of Post-weaning Social Isolation on Nucleus Accumbens Function

Adolescence is a period of incredible change, especially within the brain's reward circuitry. Stress, including social isolation, during this time has profound effects on behaviors associated with reward and other neuropsychiatric disorders. Because the Nucleus Accumbens (NAc), is crucial to the integration of rewarding stimuli, the NAc is especially sensitive to disruptions by adolescent social isolation stress. This review highlights the long-term behavioral consequences of adolescent social isolation rearing on the NAc. It will discuss the cellular and molecular changes within the NAc that might underlie the long-term effects on behavior. When available sex-specific effects are discussed. Finally by mining publicly available data we identify, for the first time, key transcriptional profiles induced by adolescence social isolation in genes associated with dopamine receptor 1 and 2 medium spiny neurons and genes associated with cocaine self-administration. Together, this review provides a comprehensive discussion of the wide-ranging long-term impacts of adolescent social isolation on the dopaminergic system from molecules through behavior.

Epigenetic-mediated N-methyl-D-aspartate receptor changes in the brain of isolated reared rats

Aim: We investigated: Grin1, Grin2a, Grin2b DNA methylation; NR1 and NR2 mRNA/protein in the prefrontal cortex (PFC); and hippocampus of male Wistar rats exposed to isolation rearing. Materials & methods: Animals were kept isolated or grouped (n = 10/group) from weaning for 10 weeks. Tissues were dissected for RNA/DNA extraction and N-methyl-D-aspartate receptor subunits were analyzed using quantitative reverse transcription (RT)-PCR, ELISA and pyrosequencing. Results: Isolated-reared animals had: decreased mRNA in PFC for all markers, increased NR1 protein in hippocampus and hypermethylation of Grin1 in PFC and Grin2b in hippocampus, compared with grouped rats. Associations between mRNA/protein and DNA methylation were found for both brain areas. Conclusion: This study indicates that epigenetic DNA methylation may underlie N-methyl-D-aspartate receptor mRNA/protein expression alterations caused by isolation rearing.

Improving treatments for psychotic disorders: beyond cognitive behaviour therapy for psychosis

More effective treatments for people with psychotic disorders are urgently required. Here, we make three suggestions for progress: 1. Targeting the disorders' core phenomenological features ('phenomenological phenotype'), 2. Addressing social disconnection, isolation and loneliness, and 3. Leveraging 'hot' cognitions and using symptom capture approaches that combine psychotherapy with advances in technology and neuroscience.

Frailty and Social Isolation: Comparing the Relationship between Frailty and Unidimensional and Multifactorial Models of Social Isolation

Objective: The aim of the study was to compare uni- and multidimensional models of social isolation to improve the specificity of determining associations between social isolation and frailty. Methods: The study included participants aged ≥60 years from the English Longitudinal Study of Ageing assessed for social isolation and frailty (frailty index and Fried phenotype) over a 4-year period. Factor analysis assessed whether social isolation was multidimensional. Multiple regression analysis was used to assess specificity in associations between social isolation and frailty over time. Results: Social isolation comprises social isolation from nuclear family, other immediate family, and wider social networks. Over time, social isolation from a wider social network predicted higher frailty index levels, and higher frailty index and Fried phenotype levels predicted greater social isolation from a wider social network. Discussion: Social isolation is multidimensional. The reciprocal relationship between social isolation from wider social networks and accumulating frailty deficits, and frailty as a clinical syndrome influencing social isolation from social networks is discussed.

Reward Circuitry and Motivational Deficits in Social Anxiety Disorder: What Can Be Learned From Mouse Models?

Social anxiety disorder (SAD) is a common and serious psychiatric condition that typically emerges during adolescence and persists into adulthood if left untreated. Prevailing interventions focus on modulating threat and arousal systems but produce only modest rates of remission. This gap in efficacy suggests that most mainstream treatment concepts do not sufficiently target core processes involved in the onset and maintenance of SAD. This idea has further driven the development of new theoretical models that target dopamine (DA)-driven reward circuitry and motivational deficits that appear to be systematically altered in SAD. Most of the available data linking systemic alterations in DA neurobiology to SAD in humans, although abundant, remains at the level of correlational evidence. Accordingly, the purpose of this brief review is to critically evaluate the relevance of experimental work in rodent models that link details of DA function to symptoms of social anxiety. We conclude that, despite certain systematic limitations inherent in animal models, these approaches provide useful insights into human biomarkers of social anxiety including that (1) adolescence may serve as a critical period for the convergence of neurobiological and environmental factors that modify future expectations about social reward through experience dependent changes in DA-ergic circuitry, (2) females may show unique susceptibility to social anxiety symptoms when encountering relational instability that influences DA-related neural processes, and (3) separate from fear and arousal systems, the functional neurobiology of central DA systems contribute uniquely to susceptibility and maintenance of anhedonic factors relevant to human models of SAD.

Ketamine administration induces early and persistent neurochemical imbalance and altered NADPH oxidase in mice

Administration in adulthood of subanaesthetic doses of ketamine, an NMDA receptor (NMDA-R) antagonist, is commonly used to induce psychotic-like alterations in rodents. The NADPH oxidase (NOX) derived-oxidative stress has been shown to be implicated in ketamine-induced neurochemical dysfunctions and in the loss of parvalbumin (PV)-positive interneurons associated to the administration of this NMDA receptor antagonist in adult mice. However, very few data are available on the effects of early ketamine administration and its contribution to the development of long-term dysfunctions leading to psychosis. Here, by administering a subanaesthetic dose of ketamine (30 mg/kg i.p.) to mice at postnatal days (PNDs) 7, 9 and 11, we aimed at investigating early neurochemical and oxidative stress-related alterations induced by this NMDA-R antagonist in specific brain regions of mice pups, i.e. prefrontal cortex (PFC) and nucleus accumbens (NAcc) and to assess whether these alterations lasted until the adult period. To this purpose, we evaluated glutamatergic, glutamine and GABAergic tissue levels, as well as PV amount in the PFC, both two hours after the last ketamine injection (PND 11) and at 10  weeks of age. Dopamine (DA) tissue levels and DA turnover were also evaluated in the NAcc at the same time points. Levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a reliable biomarker of oxidative stress, as well as of the free radical producers NOX1 and NOX2 enzymes, were also assessed in both PFC and NAcc of ketamine-treated pups and adult mice. Ketamine-treated pups showed increased cortical levels of glutamate (GLU) and glutamine, as well as similar GABA amount compared to controls, together with an early reduction of cortical PV levels. In the adult period, the same was observed for GLU and PV, whereas GABA levels were increased and no changes in glutamine amount were detected. Ketamine administration in early life induced a decrease in DA tissue levels and an increase of DA turnover which were also detectable at 10 weeks of age. These alterations were accompanied by 8-OHdG elevations in both PFC and NAcc at the two considered life stages. The expression of NOX1 was significantly reduced in these brain regions following ketamine administration at early life stages, while, in the adult period, significant elevation of this enzyme was observed. Levels of NOX2 were found increased at both time points. Our results suggest that an early increase of NOX2-derived oxidative stress may contribute to the development of neurochemical imbalance in PFC and NAcc, induced by ketamine administration. Modifications of NOX1 expression might represent, instead, an early response of the developing brain to a neurotoxic insult, followed by a later attempt to counterbalance ketamine-related detrimental effects.

Paradoxical regulation of iron in hippocampus and prefrontal cortex induces schizophrenic-like symptoms in male rats

Introduction: Social isolation induces schizophrenic-like symptoms. Iron is an essential element for brain functions. The aim of this study is to investigate if the emergence of schizophrenia after social isolation is the result of impaired iron metabolism in the hippocampus and in the prefrontal cortex.Methods and materials: In this study, 42 male Sprague-Dawley rats were randomly divided into six groups: 1) grouped housed (GH), 2) socially isolated (SI), 3) grouped housed + vehicle, 4) grouped housed + morphine, 5) socially isolated + vehicle and 6) socially isolated + morphine. After 14 days of social isolation and group housing, behavioral experiments were performed. Then, the iron in the hippocampus, prefrontal cortex, and serum was assessed.Results: SI rats were more anxious in compared to GH rats. Memory was better in GH rats compared to SI rats. SI rats had more locomotor activity compared to GH rats. Iron was higher in the hippocampus in GH rats compared to SI rats. Paradoxically iron was higher in the prefrontal cortex in SI rats compared to GH rats. In serum, iron was higher in GH rats compared to SI rats.Conclusion: Emergence of schizophrenic-like symptoms is associated with the paradoxical concentration of iron in hippocampus and prefrontal cortex in the isolation period. Further studies are recommended to investigate the possible specific changes in ion transporters and the metabolism of the neurotransmitter that occurs as the result of this paradoxical regulation.

Rosuvastatin improves olanzapine's effects on behavioral impairment and hippocampal, hepatic and metabolic damages in isolated reared male rats

BACKGROUND & AIM

Schizophrenia is a chronic, disabling neurological illness. This study investigated the effect of rosuvastatin (RSU) addition to the antipsychotic drug: olanzapine (OLZ) in treatment of post-weaning isolation rearing (IR) damaging effect and assessed behavioral impairment, metabolic and hepatic abnormalities, oxidative stress, and inflammatory markers.

METHODS

Treatment with OLZ (6 mg/kg, P.O.) and/or RSU (10 mg/kg, I.P.) have been started 6 weeks after isolation. We assessed behavioral tests, serum cortisol level, and hippocampal content of neurotransmitters. In addition, we assessed histopathology, inflammatory and oxidative stress markers of hippocampus, liver and adipose tissue RESULTS: Treatment of IR animals with OLZ, and/or RSU significantly counteracted the changes in hippocampus, liver and adipose tissue induced by post-weaning IR. Co-treatment of IR rats with both OLZ and RSU showed additive effects in some areas like improving both tumor necrosis factor alpha (TNFα) in both hippocampus and liver, histopathology of liver, oxidative stress markers of adipose tissue, β₃ adrenergic receptors (ADRβ₃), serum cortisol and total cholesterol. In addition, RSU alone alleviated the damage of IR rats by the same efficacy as OLZ with more benefit in cognition and exploration.

CONCLUSION

post-weaning IR as a model has behavioral, hippocampal, hepatic and marked metabolic changes more relevant to schizophrenia than drug-induced models. These effects were ameliorated by RSU and/or OLZ that are explained by their antioxidant, anti-inflammatory, anti-stress and anti-hyperlipidemic properties. Interestingly, co-treatment with both drugs showed a better effect.

Long-Term Behavioral Effects of Post-weaning Social Isolation in Males and Females

Adolescence is a developmental period associated with vast neural and behavioral changes which are accompanied by altered sensitivity to stimuli, both stressful and rewarding. Perturbations, especially stressful stimuli, during this period have been shown to alter behavior in adulthood. Social isolation rearing is one such perturbation. This review highlights the long-term behavioral consequences of adolescent social isolation rearing in rodents with a specific focus on anxiety- and addiction-related behaviors. Sex-specific effects are discussed where data are available. We then consider changes in monoaminergic neurotransmission as one possible mechanism for the behavioral effects described. This research on both normative and perturbed adolescent development is crucial to understanding and treating the increased vulnerability to psychiatric disorders seen in humans during this life stage.

The role of the Hint1 protein in the metabolism of phosphorothioate oligonucleotides drugs and prodrugs, and the release of H2S under cellular conditions

Phosphorothioate oligonucleotides (PS-oligos) containing sulfur atom attached in a nonbridging position to the phosphorus atom at one or more internucleotide bond(s) are often used in medicinal applications. Their hydrolysis in cellular media proceeds mainly from the 3'-end, resulting in the appearance of nucleoside 5'-O-phosphorothioates ((d)NMPS), whose further metabolism is poorly understood. We hypothesize that the enzyme responsible for (d)NMPS catabolism could be Hint1, an enzyme that belongs to the histidine triad (HIT) superfamily and is present in all organisms. We previously found that (d)NMPS were desulfurated in vitro to yield (d)NMP and H₂S in a Hint1-assisted reaction. Here, we demonstrate that AMPS/GMPS/dGMPS introduced into HeLa/A549 cells are intracellularly converted into AMP/GMP/dGMP and H₂S. The level of the released H₂S was relative to the concentration of the compounds used and the reaction time. Using RNAi technology, we have shown decreased levels of AMPS/GMPS desulfuration in HeLa/A549 cells with reduced Hint1 levels. Finally, after transfection of a short Rp-d(A_PSA_PSA) oligomer into HeLa cells, the release of H₂S was observed. These results suggest that the metabolic pathway of PS-oligos includes hydrolysis into (d)NMPS (by cellular nucleases) followed by Hint1-promoted conversion of the resulting (d)NMPS into (d)NMP accompanied by H₂S elimination. Our observations may be also important for possible medicinal applications of (d)NMPS because H₂S is a gasotransmitter involved in many physiological and pathological processes.

The Role of miR-150 in Stress-Induced Anxiety-Like Behavior in Mice

Stress plays a crucial role in several psychiatric disorders, including anxiety. However, the underlying mechanisms remain poorly understood. Here, we used acute stress (AS) and chronic restraint stress (CRS) models to develop anxiety-like behavior and investigate the role of miR-150 in the hippocampi of mice. Corticosterone levels as well as glutamate receptors in the hippocampus were evaluated. We found that anxiety-like behavior was induced after either AS or CRS, as determined by the open-field test (OFT) and elevated plus-maze test (EPM). Increased corticosterone levels were observed in the blood of AS and CRS groups, while the expression of miR-150 mRNA in the hippocampus was significantly decreased. The expressions of GluN2A, GluR1, GluR2, and V-Glut2 in the hippocampus were decreased after either AS or CRS. Hippocampal GAD67 expression was increased by AS but not CRS, and GluN2B expression was decreased by CRS but not AS. Adult miR-150 knockout mice showed anxiety-like behavior, as assessed by the OFT and EPM. The expressions of GluN2A, GluN2B, GluR1, and GluR2 were also downregulated, but the expression of V-Glut2 was upregulated in the hippocampi of miR-150 knockout mice compared with wild-type mice. Interestingly, we found that the miR-150 knockout mice showed decreased dendrite lengths, dendrite branchings, and numbers of dendrite spines in the hippocampus compared with wild-type mice. These results suggest that miR-150 may influence the synaptic plasticity of the hippocampus and play a significant role in stress-induced anxiety-like behavior in adult mice.

Altered Light Conditions Contribute to Abnormalities in Emotion and Cognition Through HINT1 Dysfunction in C57BL/6 Mice

In recent years, the environmental impact of artificial light at night has been a rapidly growing global problem, affecting 99% of the population in the US and Europe, and 62% of the world population. The present study utilized a mouse model exposed to long-term artificial light and light deprivation to explore the impact of these conditions on emotion and cognition. Based on the potential links between histidine triad nucleotide binding protein 1 (HINT1) and mood disorders, we also examined the expression of HINT1 and related apoptosis factors in the suprachiasmatic nucleus (SCN), prefrontal cortex (PFC), nucleus accumbens (NAc) and hippocampus (Hip). Mice exposed to constant light (CL) exhibited depressive- and anxiety-like behaviors, as well as impaired spatial memory, as demonstrated by an increased immobility time in the tail suspension and forced swimming tests, less entries and time spent in the open arms of elevated plus-maze, and less platform site crossings and time spent in the target quadrant in the Morris water maze (MWM). The effects of constant darkness (CD) partially coincided with long-term illumination, except that mice in the CD group failed to show anxiety-like behaviors. Furthermore, HINT1 was upregulated in four encephalic regions, indicating that HINT1 may be involved in mood disorders and cognitive impairments due to altered light exposure. The apoptosis-related proteins, BAX and BCL-2, showed the opposite expression pattern, reflecting an activated apoptotic pathway. These findings suggest that exposure to CL and/or darkness can induce significant changes in affective and cognitive responses, possibly through HINT1-induced activation of apoptotic pathways.

Sauna Bathing and Risk of Psychotic Disorders: A Prospective Cohort Study

OBJECTIVE

Sauna bathing has been suggested to promote mental well-being and relaxation, but the evidence is uncertain with respect to mental disorders. We aimed to assess the association of frequency of sauna bathing with risk of psychosis in the Kuopio Ischemic Heart Disease prospective population-based study.

SUBJECTS AND METHODS

Baseline sauna bathing habits were assessed in 2,138 men aged 42-61 years who had no history of psychotic disorders. Participants were classified into three groups based on the frequency of sauna bathing (once, 2-3, and 4-7 times per week).

RESULTS

During a median follow-up of 24.9 years, 203 psychotic disorders were recorded. A total of 537, 1,417, and 184 participants reported having a sauna bath once a week, 2-3 times, and 4-7 times per week, respectively. In Cox regression analysis adjusted for age, compared to men who had 1 sauna session per week, the hazard ratio (95% confidence intervals) of psychosis for 4-7 sauna sessions per week was 0.23 (0.09-0.58). In a multivariable model adjusted for several risk factors and other potential confounders, the corresponding hazard ratio was 0.21 (0.08-0.52). The association was similar after further adjustment for total energy intake, socioeconomic status, physical activity, and C-reactive protein (0.22 [0.09-0.54]) and was unchanged on additional adjustment for duration of a sauna session and temperature of the sauna bath (0.23 [0.09-0.57]).

CONCLUSION

Our study suggests a strong inverse and independent association between frequent sauna bathing and the future risk of psychotic disorders in a general male population.

HINT1 in Neuropsychiatric Diseases: A Potential Neuroplastic Mediator

Although many studies have investigated the functions of histidine triad nucleotide-binding protein 1 (HINT1), its roles in neurobiological processes remain to be fully elucidated. As a member of the histidine triad (HIT) enzyme superfamily, HINT1 is distributed in almost every organ and has both enzymatic and nonenzymatic activity. Accumulating clinical and preclinical evidence suggests that HINT1 may play an important role as a neuroplastic mediator in neuropsychiatric diseases, such as schizophrenia, inherited peripheral neuropathies, mood disorders, and drug addiction. Though our knowledge of HINT1 is limited, it is believed that further research on the neuropathological functions of HINT1 would eventually benefit patients with neuropsychiatric and even psychosomatic diseases.