Dopamine Dynamics in the Amygdala Influence Emotional Changes in the Early Stage of Systemic Inflammatory Response Syndrome in Rats

SUMMARY: Systemic inflammatory response syndrome (SIRS) is a potentially fatal reaction to various forms of tissue damage and infections that cause damage to various organs. Furthermore, the brain is damaged earlier than other organs, resulting in diffuse brain dysfunction. The central clinical symptom of SIRS is delirium and emotional changes are involved in disease development. Although the amygdala is known to play a major role, the mechanisms underlying emotional changes in the early stages of SIRS have not been elucidated. Therefore, changes to dopamine levels in the amygdala were observed using an in vivo model of lipopolysaccharide (LPS)- induced SIRS to clarify the biochemical mechanisms activated in the early stages of SIRS. Extracellular dopamine was collected from the amygdala of free moving rats via microdialysis and then analyzed by high-performance liquid chromatography. In addition, emotional changes were assessed with the open field and sucrose preference tests. In the LPS group, dopamine release in the amygdala increased remarkably immediately after LPS administration, peaking at 120 min. Thereafter, dopamine release temporarily decreased, but then significantly increased again after 180 min. The present results suggest that diffuse brain dysfunction in the early stages of SIRS may involve altered dopamine levels in the amygdala.

El síndrome de respuesta inflamatoria sistémica (SRIS) es una reacción potencialmente fatal a diversas formas de daño tisular e infecciones que causan injuria a varios órganos. Además, el cerebro se daña antes que otros órganos, lo que provoca una disfunción cerebral difusa. El síntoma clínico central del SIRS es el delirio y los cambios emocionales están involucrados en el desarrollo de la enfermedad. Aunque se sabe que la amígdala desempeña un papel importante, no se han dilucidado los mecanismos que subyacen a los cambios emocionales en las primeras etapas del SRIS. Por lo tanto, en el estudio se provocaron cambios en los niveles de dopamina en la amígdala utilizando un modelo in vivo de SRIS inducido por lipopolisacáridos (LPS) para dilucidar los mecanismos bioquímicos activados en las primeras etapas del SRIS. La dopamina extracelular se recogió de la amígdala de ratas en movimiento libre mediante microdiálisis y luego se analizó mediante cromatografía líquida de alta resolución. Además, se evaluaron los cambios emocionales con las pruebas de campo abierto y de preferencia de sacarosa. En el grupo de LPS, la liberación de dopamina en la amígdala aumentó de manera notable inmediatamente después de la administración de LPS, alcanzando un máximo a los 120 minutos. A partir de entonces, la liberación de dopamina disminuyó temporalmente, pero luego volvió a aumentar significativamente después de 180 min. Los resultadosactuales sugieren que la disfunción cerebral difusa en las primeras etapas del SIRS puede implicar niveles alterados de dopamina en la amígdala.

Effect of intermittent subchronic MK-801 administration on dopamine synthesis capacity and responsiveness in the prefrontal cortex.

AIM: The therapeutic potential of N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists, particularly ketamine, in mood disorders, is linked to their modulation of dopamine dynamics in the medial prefrontal cortex (mPFC). However, conflicting effects of distinct NMDAR antagonists, like ketamine and phencyclidine, on mPFC dopamine levels stem from variances in their receptor affinity profiles. This study investigates the impact of intermittent subchronic administration of an NMDAR antagonist on dopamine synthesis capacity and responsiveness within the mPFC, focusing on Dizocilpine (MK-801), a highly selective NMDAR antagonist. METHODS: In vivo microdialysis and high-performance liquid chromatography assessed extracellular dopamine levels in the mPFC following subchronic MK-801 treatment. Locomotor activity was measured using a computed video tracking system. RESULTS: Intermittent subchronic MK-801 administration, followed by a 24-h withdrawal, preserved both dopamine synthesis capacity and responsiveness to MK-801 challenge in the mPFC. However, altered locomotor activity was observed, deviating from previous findings indicating impaired dopamine synthesis and responsiveness in the mPFC with twice-daily subchronic NMDAR antagonist treatment. CONCLUSION: These findings offer crucial biochemical insights into the diverse impacts of NMDAR antagonists on dopamine dynamics and the distinct therapeutic mechanisms associated with ketamine in depression treatment. However, further investigation is imperative to pinpoint potential inconsistencies stemming from variances in drug type, dosage, or administration frequency.

Effects of chronic haloperidol treatment on the expression of fear memory and fear memory extinction in the cued fear-conditioned rats.

AIM: Impairments in emotional memory are frequently observed in several mental disorders, highlighting their significance as potential therapeutic targets. Recent research on the cued fear conditioning model has elucidated the neural circuits involved in fear memory processing. However, contradictory findings have been reported concerning the role of dopamine and the impact of dopamine D2 receptor (D2R) antagonists. There is notably limited knowledge regarding the clinical utility of chronic D2R antagonist treatments. This study aimed to uncover how such treatments affect fear memory processing. METHODS: We utilized a cued fear conditioning rat model and conducted chronic haloperidol treatment for 14 days. Subsequently, to investigate the effect of chronic haloperidol treatment on fear-conditioned memory expression and extinction, we observed freezing behavior under exposure to a conditioned stimulus for 14 days. RESULTS: Chronic haloperidol treatment suppressed freezing time on the fear memory expression. In contrast, a single haloperidol administration enhanced the freezing time on fear memory expression and delayed extinction. CONCLUSION: The results of this study suggest that chronic administration of antipsychotic drugs affects fear memory processing differently from single-dose administration. This indicates that the effects of chronic D2R antagonist treatment are distinct from the nonspecific effects of the drugs. This study provides fundamental insights that may contribute to our understanding of therapeutic mechanisms for fear memory disorders related to D2R in the future.

Association of the Stanford Integrated Psychosocial Assessment for Transplant and 1-Year Outcome of Living Kidney Transplantation in Japan.

BACKGROUND: Because most kidney transplantations in Japan are performed on the basis of living donors, after-transplant outcomes should achieve optimum results, overcoming participants' possible reduced adherence. OBJECTIVE: To investigate the association between the Japanese version of the Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT-J) and outcomes, 1 year after the patient's living kidney transplant (LKT). METHODS: The prospective cohort study was undertaken at Tokyo Women's Medical University Hospital from January 2020 to July 2021, with a 1-year follow-up period. The SIPAT-J assesses 18 psychosocial risk factors: (1) Patient's Readiness Level and Illness Management (SIPAT A), (2) Social Support System Level of Readiness (SIPAT B), (3) Psychological Stability and Psychopathology (SIPAT C), and (4) Lifestyle and Effect of Substance Use (SIPAT D). The evaluators, a psychiatrist and 3 clinical psychologists, conducted an independent, blinded application of the SIPAT-J using participants' medical records. The study focused on physical composite outcomes, psychiatric outcomes, and nonadherent behaviors. RESULTS: The participants were 173 LKT recipients (median age [interquartile range], 51 [38-59]); 67.1% were male and 67.1% were employed. The median (interquartile range) SIPAT scores were SIPAT A [7 (5-9)], SIPAT B [7 (5-9)], SIPAT C [2 (0-4)], SIPAT D [3 (3-4)], and SIPAT total [20 (16-23)]. The physical composite outcome was 25 (14.5%), psychiatric outcome 9 (5.2%), and nonadherent behavior 17 (9.8%). SIPAT C (odds ratio = 1.34, 95% confidence interval = 1.06-1.72, P = 0.02) was significantly associated with the psychiatric outcome. SIPAT B (odds ratio = 1.49, 95% confidence interval = 1.12-1.98, P = 0.01) and SIPAT total (odds ratio = 1.13, 95% confidence interval = 1.03-1.24, P = 0.01) were significantly associated with nonadherent behaviors. There was no significant association between the SIPAT and physical composite outcomes. CONCLUSION: This study is the first to examine the association between SIPAT and physical and psychiatric outcomes 1 year after LKT, controlling for follow-up periods and factors other than SIPAT. Comprehensive psychosocial assessment before LKT and early identification of factors that may negatively affect transplant success can allow targeted interventions to be implemented and increase the likelihood of favorable recipient outcomes.

Family functioning before kidney transplantation from living-related donors: Perspectives of donors and recipients in Japan.

INTRODUCTION: In Japan, approximately 90% of kidney transplantations involve living donors who are relatives. Selection of a living donor from potential family member donors could affect the entire family. However, reports focusing on preliving-related kidney transplant (LRKT) family functioning are lacking. Family functioning comprises ways that family members communicate and cooperate with each other. The Family Assessment Device (FAD) was used to measure family functioning from the perspective of donors and recipients just prior to LRKT. METHOD: A total of 122 donor-recipient pairs (244 participants in total) who planned to have LRKT were recruited consecutively from July 2020 to July 2021 and included in the analysis. RESULTS: There was no significant difference in FAD scores between donors and recipients, with approximately 20% of both groups reporting poor family functioning. Differences in family functioning according to types of relatives were shown in recipients. The rate of poor family functioning was significantly lower in the spouse group than in the parent-to-child group (recipient: 6.6%, 29.3%; donor: 8.2%, 34.1%, respectively). However, agreement regarding good or poor family functioning assessment was high in the parent-to-child pairs and low in the spouse pairs. DISCUSSION: Most LRKT donors and recipients reported good family functioning; however, some perceived poor family functioning. Evaluations by donors did not always align with that of recipients, especially among spouse pairs. It is important to treat them as independent entities. Preoperative assessment to connect them with appropriate support can enhance recovery after LRKT. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Characterization of the stanford integrated psychosocial assessment for transplant for heart, liver, and kidney transplant candidates in Japan.

BACKGROUND: The Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT) is a comprehensive psychosocial assessment proven useful for predicting the outcomes of organ transplantation that is expected to be useful in Japan. However, the characteristics of organ-specific SIPAT scores for organ transplant recipient candidates in Japan are unclear and, to date, the SIPAT has not been properly utilized in clinical practice. The purpose of this study was to present basic data that can be used to establish the relation between SIPAT scores and post-transplantation psychosocial outcomes as well as organ-specific outcomes. METHODS: This study included 167 transplant recipient candidates (25 heart, 71 liver, and 71 kidney) who completed a semi-structured interview based on the Japanese version of SIPAT (SIPAT-J) prior to transplantation. The differences between organs in terms of SIPAT scores and differences in SIPAT scores based on demographic data were comparatively analyzed. RESULTS: The total SIPAT scores were higher for liver recipient candidates than for heart recipient candidates (P = .019). Regarding the subscales, SIPAT B (social support system) scores were higher for liver and kidney recipient candidates than for heart recipient candidates (P = .021), whereas SIPAT C (psychological stability and psychopathology) scores were higher for liver recipient candidates than for kidney recipient candidates (P = .002). Recipient candidates with a history of psychiatric treatment and those who were unemployed had higher SIPAT scores, regardless of the transplant organ, than recipient candidates without a history of psychiatric treatment and those who were employed (P < .001, P = .016, respectively). CONCLUSIONS: There were notable differences in the total SIPAT-J and subscale scores among the liver, heart, and kidney recipient candidates. Each organ was associated with specific psychosocial issues that should be addressed before transplantation. Interventions such as information provision and patient education based on SIPAT assessment results for each organ may improve recipient post-transplant outcomes.

Guidelines for diagnosis and treatment of depression in older adults: A report from the Japanese Society of mood disorders.

The Committee for Treatment Guidelines of Mood Disorders, Japanese Society of Mood Disorders, published a Japanese guideline for the treatment of late-life depression in 2020. Based on that guideline, the present guideline was developed and revised to incorporate the suggestions of global experts and the latest published evidence. In the diagnosis of late-life depression, it is important to carefully differentiate it from bipolar disorders, depressive states caused by physical and organic brain disease, drug effects, and dementia, and to determine the comorbidity between late-life depression and dementia. It is necessary to fully understand the clinical characteristics and psychosocial background of late-life depression, evaluate the patient's condition, and provide basic interventions based on these factors. Problem-solving therapy, reminiscence therapy/life review therapy, and behavioral activation therapy, and other forms of psychotherapy can reduce depressive symptoms. In terms of pharmacotherapy, newer antidepressants or non-tricyclic antidepressants are recommended for late-life depression, and it is recommended that the efficacy of least the minimal effective dosage should first be determined. Switching antidepressants and aripiprazole augmentation can be used to treatment-resistant therapy. Electroconvulsive therapy and repetitive transcranial magnetic stimulation have demonstrated usefulness for late-life depression. Exercise therapy, high-intensity light therapy, and diet therapy also show some effectiveness and are useful for late-life depression. Continuation therapy should be maintained for at least 1 year after remission.

Psychosocial Assessment of Transplant Candidates: Inter-rater Reliability and Concurrent Validity of the Japanese Version of the Stanford Integrated Psychosocial Assessment for Transplantation.

BACKGROUND: The Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT) is a comprehensive instrument developed to provide a standardized, objective, and evidence-based psychosocial evaluation of the main pretransplant psychosocial risk factors that may influence transplant outcomes. OBJECTIVE: Because established assessment procedures or standardized tools designed to perform pre-solid organ transplant psychosocial evaluation are currently unavailable in Japan, the present study aimed to develop and preliminarily validate the Japanese version of the SIPAT. METHODS: First, the Japanese version of the SIPAT was developed using standard forward-back-translation procedures. Then, the Japanese versions of the SIPAT and the Japanese version of Psychosocial Assessment of Candidates for Transplant were retrospectively and blindly applied to 107 transplant cases by 4 independent raters. RESULTS: The interrater reliability of the scores obtained with the Japanese version of the SIPAT was excellent (Pearson's correlation coefficient = 0.86). The concurrent validity of the SIPAT to the Psychosocial Assessment of Candidates for Transplant for each examiner was substantial (Spearman's rank correlation coefficient = -0.66). CONCLUSION: These findings suggest that the Japanese version of the SIPAT is a promising and reliable instrument. Further research is required to test the predictive validity of the Japanese version of the SIPAT.

Prevalence of Circadian Rhythm Sleep-Wake Disorder in Outpatients with Schizophrenia and Its Association with Psychopathological Characteristics and Psychosocial Functioning.

The prevalence of circadian rhythm sleep-wake disorder (CRSWD) among patients with schizophrenia is not clear. The effect of comorbid CRSWD on such patients has also not been fully evaluated yet. Outpatients with schizophrenia in the maintenance phase who visited Tokyo Women's Medical University Hospital between April 2018 and March 2019 participated in this study. The Brief Psychiatric Rating Scale (BPRS), the Clinical Global Impressions-Severity Illness Scale (CGI-S), Global Assessment of Functioning (GAF), World Health Organization Disability Assessment Schedule II, Insomnia Severity Index (ISI), and Morningness-Eveningness Questionnaire (MEQ) were administered, and the patient responses with and without CRSWD were compared. Of the 105 patients with schizophrenia, 19 (18.1%) had CRSWD. There were trends toward higher BPRS and lower GAF scores in the CRSWD group than in the non-CRSWD group, although these did not reach statistical significance following a false discovery rate correction. Among the BPRS subitems, the anxiety scores were significantly higher in the CRSWD group than in the non-CRSWD group (p < 0.01). CRSWD was highly prevalent among patients with schizophrenia in the maintenance phase. Comorbidities of CRSWD may affect psychopathological characteristics and psychosocial functioning.

Clinical Factors Associated with New-Onset Glucose Intolerance among Patients with Schizophrenia during Clozapine Treatment: All-Case Surveillance in Japan.

Clozapine (CLZ), an antipsychotic with a unique mechanism of action, is known to be superior to any other antipsychotic for schizophrenia. However, CLZ is also known to be associated with the development of lethal side effects, which include agranulocytosis and glucose intolerance (GI). Regular measurement and registration of blood test results have been mandatory for all CLZ users; however, these risks may still prevent therapists from prescribing CLZ. While CLZ-induced agranulocytosis has been well documented, CLZ-induced GI in the real world has not been fully investigated. Therefore, in this study, we used data registered in monitoring systems to investigate background factors associated with new-onset GI after CLZ administration and changes in HbA1c levels during CLZ treatment. Data of all patients with schizophrenia who were using CLZ from July 29, 2009 to January 20, 2016 were used for the analysis. Of the 3,746 patients enrolled in the study, 92 (2.5%) had GI at baseline; of the remaining 3,654 patients, 428 (11.7%) developed new-onset GI. Multivariate logistic regression analysis revealed that the development of new-onset GI was significantly associated with older age, higher baseline HbA1c levels, and longer treatment duration. In patients with GI at baseline, HbA1c levels were maintained or improved over 18 months, while in the other patients, CLZ administration gradually elevated HbA1c levels. The findings of this study suggest that, although adequate monitoring and intervention is required, CLZ induction and maintenance therapy may be safe, even for patients with impaired glucose tolerance.

Clozapine-induced agranulocytosis in Japan: Changes in leukocyte/neutrophil counts before and after discontinuation of clozapine.

OBJECTIVE: To determine the prevalence, background factors, and progression of and recovery from clozapine-induced agranulocytosis in Japan. METHODS: Data on treatment-resistant schizophrenia patients registered with the Clozaril Patient Monitoring Service (CPMS) between July 29, 2009 and January 20, 2016 were extracted. Patients with a neutrophil count <500/mm3 were defined as having agranulocytosis, and those with a leukocyte count <3,000/mm3 or a neutrophil count <1,500/mm3 but not meeting the criteria for agranulocytosis were defined as having leukopenia/neutropenia. RESULTS: Of 3,746 patients, agranulocytosis and leukopenia/neutropenia were observed in 38 (1.0%) and 182 (4.9%) patients, respectively. Age was significantly higher in the agranulocytosis group (p < .001). Decreased leukocyte counts 1 week prior to discontinuation were observed only in the agranulocytosis group. The median number of days to recovery from agranulocytosis and leukopenia/neutropenia was 10 and 4, respectively, with more variation in the latter. CONCLUSIONS: Although some patients with leukopenia/neutropenia might carry less pathologic significance, the results of this study reconfirmed the importance of regular blood monitoring for preventing agranulocytosis.

Escitalopram attenuates fear stress-induced increase in amygdalar dopamine following methamphetamine-induced sensitisation: Implications of fine-tuning action of selective serotonin reuptake inhibitors on emotional processing.

Serotonin reuptake inhibitors modulate the serotonergic pathways of the nervous system and are widely used for treating psychiatric conditions such as anxiety and depression. The dopaminergic system is related to the development of these conditions. Previous studies on methamphetamine-sensitised rats (behavioural models of stress vulnerability) have shown increased release of dopamine in response to conditioned stress in the amygdala. This biochemical abnormality was proposed to underlie the pathophysiology of stress vulnerability. However, the effect of serotonin reuptake inhibitors on dopamine levels and its consequent impact on emotional processing is unclear. Here we examined the acute effect of escitalopram, a highly selective serotonin reuptake inhibitor, on fear-related behaviour, baseline dopamine release and dopamine release in response to conditioned fear stress in the amygdala of model rats. Male Sprague-Dawley rats received 2 mg/kg/day, s.c. of methamphetamine for 10 days to sensitise them to the drug, and a fear conditioning paradigm was instituted to model psychological stress. Dopamine changes in the amygdala in response to systemic administration of escitalopram followed by conditioned fear stress were measured using microdialysis and high-performance liquid chromatography. Baseline dopamine release in the amygdala was increased by escitalopram in non-sensitised rats but not in methamphetamine-sensitised rats. Escitalopram attenuated dopamine release in response to the fear-conditioned stimulus in both sensitised and non-sensitised rats. The extent of suppression in methamphetamine-sensitised rats (- 90%) was greater than that in non-sensitised rats (- 48%). These findings suggest that serotonin reuptake inhibitors indirectly stabilise the dopaminergic pathway and modulate emotional processing in the amygdala.

Diazepam suppresses the stress-induced dopaminergic release in the amygdala of methamphetamine-sensitized rat.

Although the benzodiazepine class of drugs has proven useful in treating anxiety symptoms, recent studies yield no consistent empirical support for their use in treating psychiatric disorders. However, animal studies using a fear conditioning paradigm have suggested that benzodiazepines facilitate fear memory extinction, dependent on treatment timing and subject conditions. However, we have no data on the effect of subject conditions. The purpose of this study was to investigate whether the effect of benzodiazepines depends on hypersensitivity to fear-memory processing. We examined the effect of diazepam, a benzodiazepine, on the extracellular dopamine level in the left amygdala of methamphetamine-sensitized, fear-conditioned model rats, using microdialysis and high-performance liquid chromatography. In this model, the dopamine level in the amygdala excessively increases in response to a fear-conditioned stimulus; the phenomenon has been proposed as a biological marker for hypersensitivity to fear-memory processing. Diazepam inhibited this excessive increase. The extent of the inhibitory effect was greater in the sensitized condition. Diazepam alone increased amygdalar dopamine levels under physiological conditions but not under sensitized conditions. Diazepam did not shorten freezing time in any group. These results suggest that diazepam modulates amygdala dopamine with state dependence and that amygdalar dopamine fine-tuning accounts for part of the therapeutic effect of benzodiazepines on fear memory processing. Further investigation is required to identify patients suitable for treatment with benzodiazepines. This is the first report on the pharmacodynamic effects of benzodiazepine on the amygdalar dopamine basal level and on fear memory processing.

Analysis of Clozapine Use and Safety by Using Comprehensive National Data From the Japanese Clozapine Patient Monitoring Service.

OBJECTIVE: The aim of this study was to investigate clozapine use and its associated adverse effects in patients in Japan. METHODS: We analyzed data recorded from July 2009 to January 2016 (N = 3780 patients) in the Clozaril Patient Monitoring Service, which was established in Japan in 2009 and includes all Japanese patients who have been prescribed clozapine. RESULTS: The treatment discontinuation rate was 23.9% (869/3780 cases). The average ± SD treatment duration was 234.9 ± 306.9 days (median, 115 days), and the average ± SD dosage was 186.41 ± 151.6 mg/d. The estimated treatment continuation rates resulting from all-cause discontinuation were 78.2 after 1 year and 72.9% after 2 years of treatment. The incidence of neutropenia/leucopenia was 5.4% (206/3780 cases). The average ± SD dose before discontinuation was 233.36 ± 168.15 mg (median, 200 mg; range, 4-600 mg). The incidence of glucose intolerance was 15.4% (583/3780 cases). Of 3780 patients, 98 (2.67%) developed glucose intolerance before and after taking clozapine administration, whereas 485 patients (12.8%) developed glucose intolerance after taking clozapine. The average ± SD time from treatment initiation to new onset of glucose intolerance was 382.2 ± 420.2 days (median, 216 days; range, 4-2053 days). CONCLUSIONS: The data obtained in this study, particularly regarding the incidence of clozapine-induced adverse events, will enable the optimal and safe use of clozapine in Japanese patients with treatment-resistant schizophrenia.

Therapeutic effects of diclofenac, pregabalin, and duloxetine on disuse-induced chronic musculoskeletal pain in rats.

The aim of this study was to clarify the mechanism of disuse-induced muscle hyperalgesia through the evaluation of the pharmacological behaviour of muscle hyperalgesia profiles in chronic post-cast pain (CPCP) rats with acute and chronic-phase mirror-image muscle hyperalgesia treated with diclofenac (NSAID), pregabalin (an inhibitor of Ca2+ channel α2δ), and duloxetine (SNRI). After 2 weeks of cast immobilization, the peak cross-sectional area and muscle wet weight of the ipsilateral soleus and gastrocnemius muscles decreased more significantly in CPCP rats than in untreated rats. Histological findings revealed disuse-induced muscle atrophy in CPCP rats. The blood biochemical parameters of CPCP rats in acute and chronic phases did not differ significantly from those of untreated rats. The diclofenac and pregabalin-treated groups exhibited no improvement in acute or chronic muscle hyperalgesia. In contrast, the duloxetine-treated group exhibited an improvement in acute muscle hyperalgesia, but showed no apparent effect on chronic muscle hyperalgesia on ipsilateral or contralateral sides. However, the chronic muscle hyperalgesia was reversed by intrathecal administration of DAMGO (a µ-opioid receptor agonist). The results suggest that chronic muscle hyperalgesia in CPCP rats did not result from an inflammatory mechanism, and there is only a low probability that it's caused by a neuropathic mechanism.

Dopamine dynamics during emotional cognitive processing: Implications of the specific actions of clozapine compared with haloperidol.

Clozapine has improved efficacy relative to typical antipsychotics in schizophrenia treatment, particularly regarding emotional symptoms. However, the mechanisms underlying its therapeutic benefits remain unclear. Using a methamphetamine-sensitised rat model, we measured changes in dopamine levels in the amygdalae in response to a fear-conditioned cue, serving as a biochemical marker of emotional cognitive processing disruption in psychosis, for analysing the biochemical mechanisms associated with the clinical benefits of clozapine. We also compared how clozapine and haloperidol affected basal dopamine levels and phasic dopamine release in response to the fear-conditioned cue. Extracellular dopamine was collected from the amygdalae of freely moving rats via microdialysis and was analysed by high-performance liquid chromatography. Clozapine or haloperidol was injected during microdialysis, followed by exposure to the fear-conditioned cue. We analysed the ratio of change in dopamine levels from baseline. Haloperidol treatment increased the baseline dopamine levels in both non-sensitised and sensitised rats. Conversely, clozapine only increased the basal dopamine levels in the non-sensitised rats, but not in the sensitised rats. Although both antipsychotics attenuated phasic dopamine release in both the non-sensitised and sensitised rats, the attenuation extent was greater for clozapine than for haloperidol under both dopaminergic conditions. Our findings indicate that stabilized dopamine release in the amygdalae is a common therapeutic mechanism of antipsychotic action during emotional processing. However, the specific dopaminergic state-dependent action of clozapine on both basal dopamine levels and stress-induced dopamine release may be the underlying mechanism for its superior clinical effect on emotional cognitive processing in patients with schizophrenia.

Elucidation of The Behavioral Program and Neuronal Network Encoded by Dorsal Raphe Serotonergic Neurons.

Elucidating how the brain's serotonergic network mediates diverse behavioral actions over both relatively short (minutes-hours) and long period of time (days-weeks) remains a major challenge for neuroscience. Our relative ignorance is largely due to the lack of technologies with robustness, reversibility, and spatio-temporal control. Recently, we have demonstrated that our chemogenetic approach (eg, Designer Receptors Exclusively Activated by Designer Drugs (DREADDs)) provides a reliable and robust tool for controlling genetically defined neural populations. Here we show how short- and long-term activation of dorsal raphe nucleus (DRN) serotonergic neurons induces robust behavioral responses. We found that both short- and long-term activation of DRN serotonergic neurons induce antidepressant-like behavioral responses. However, only short-term activation induces anxiogenic-like behaviors. In parallel, these behavioral phenotypes were associated with a metabolic map of whole brain network activity via a recently developed non-invasive imaging technology DREAMM (DREADD Associated Metabolic Mapping). Our findings reveal a previously unappreciated brain network elicited by selective activation of DRN serotonin neurons and illuminate potential therapeutic and adverse effects of drugs targeting DRN neurons.

Valproic acid inhibits excess dopamine release in response to a fear-conditioned stimulus in the basolateral complex of the amygdala of methamphetamine-sensitized rats.

Valproic acid, an established antiepileptic and antimanic drug, has recently emerged as a promising emotion-stabilizing agent for patients with psychosis. Although dopamine transmission in the amygdala plays a key role in emotional processing, there has been no direct evidence about how valproic acid acts on the dopaminergic system in the brain during emotional processing. In the present study, we tested the effect of valproic acid on a trait marker of vulnerability to emotional stress in psychosis, which is excess dopamine release in response to a fear-conditioned stimulus (CS) in the basolateral complex of the amygdala of methamphetamine-sensitized rats. Extracellular dopamine was collected from the amygdala of freely moving methamphetamine-sensitized rats by in vivo microdialysis and was measured using high-performance liquid chromatography. During microdialysis, valproic acid was intraperitoneally injected followed by CS exposure. Valproic acid treatment decreased baseline levels of dopamine and also attenuated the excess dopamine release in response to the CS in the amygdala of methamphetamine-sensitized rats. The results prove that valproic acid inhibits spontaneous dopamine release and also attenuates excess dopaminergic signaling in response to emotional stress in the amygdala. These findings suggest that the mechanisms of the emotion-stabilizing effect of valproic acid in psychosis involve modulation of dopaminergic transmission in emotional processing.

[Significance of the pharmacotherapy of schizophrenia in the emotional context processing of cognition].

Emotional disorders and cognitive dysfunctions are important treatment targets in psychiatric clinical settings. The biological mechanisms of emotional disorders have been studied with methods that include fear conditioning, schizophrenia models are studied with methamphetamine-induced reverse tolerance in rats, and dynamic changes in brain neurotransmitters are studied with microdialysis and high-performance liquid chromatography. We combined these methods in order to evaluate dopamine dynamics in the amygdala and the biological bases and relationships of emotional disorder and cognitive dysfunction. Fear-conditioned rats showed freezing behavior and dopamine release in the amygdala in response to conditioned stimuli. Methamphetamine-induced reverse tolerance rats showed increased dopamine release in the amygdala in response to conditioned stimuli. The increased release of dopamine continued after the freezing behavior had ended. This increased and long-lasting dopamine release may reflect abnormal emotional context processing in cognition in schizophrenia. Antipsychotic drugs, such as haloperidol, aripiprazole, and clozapine, suppress this increased release of dopamine in the amygdala in response to conditioned stimuli. These findings suggest that antipsychotic drugs may stabilize abnormal emotional context processing in cognition in this model. We conclude that the significance of pharmacotherapy in schizophrenia is that antipsychotic drugs stabilize the emotional context processing in cognition and adjust the relationship of emotion and cognition.