Ryanodine receptors are involved in the improvement of depression-like behaviors through electroconvulsive shock in stressed mice.

BACKGROUND: Electroconvulsive therapy (ECT) is effective for treating depression. However, the mechanisms underlying the antidepressant effects of ECT remain unknown. Depressed patients exhibit abnormal Ca2+ kinetics. Early stages of the intracellular Ca2+ signaling pathway involve the release of Ca2+ from the endoplasmic reticulum (ER) via Ca2+ release channels. OBJECTIVE: We considered that depression may be improved via ECT-induced normalization of intracellular Ca2+ regulation through the Ca2+ release channels. The current study aimed to investigate the effects of ECT on two Ca2+ release channels, ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors (IP3Rs). METHODS: A mouse depression-like model subjected to water immersion with restraint stress was administered electroconvulsive shock (ECS) therapy. Their depression-like status was behaviorally and histologically assessed using forced swimming tests, novelty-suppressed feeding tests, and by evaluating neurogenesis in the hippocampal dentate gyrus, respectively. A RyRs blocker, dantrolene, was administered prior to ECS, and the changes in depression-like conditions were examined. RESULTS: The protein expressions of RyR1 and RyR3 significantly increased in the hippocampus of the mouse model with depression-like symptoms. This increase was attenuated as depression-like symptoms were reduced due to ECS application. However, pre-injection with dantrolene reduced the antidepressant effects of ECS. CONCLUSIONS: A significant increase in RyRs expression in a depression-like state and exacerbation of depression-like symptoms by RyRs inhibitors may be caused by RyRs dysfunction, suggesting overexpression of RyRs is a compensatory effect. Normalization of RyRs expression levels by ECS suggests that ECT normalizes the Ca2+ release via RyRs. Thus, normalizing the function of RyRs may play an important role in the therapeutic effect of ECT.

Association between previous high-dose antipsychotic therapy and brexpiprazole discontinuation after the initiation of brexpiprazole in patients with schizophrenia or schizoaffective disorder.

The objective of this study was to identify the factors associated with brexpiprazole discontinuation after initiating brexpiprazole in patients with schizophrenia or schizoaffective disorder. All patients with schizophrenia or schizoaffective disorder who were started on brexpiprazole in our institution between May 2018 and April 2019 were retrospectively screened. The continuation rate of brexpiprazole during a follow-up period of 16 weeks was examined. Multivariate Cox regression analysis was conducted to identify predictors of brexpiprazole discontinuation. During the follow-up period, 52 out of 120 patients (43.4%) discontinued brexpiprazole. Thirty-three subjects discontinued due to a lack of efficacy, eight more due to intolerability and a further 11 for other reasons. The continuation rate of brexpiprazole among patients who were previously on high-dose antipsychotics (chlorpromazine-equivalent doses > 800 mg) was significantly lower than that in those who were previously on low-dose antipsychotics (chlorpromazine-equivalent doses ≤ 800 mg). The Cox regression analysis showed that only having been subject to a high dose of their previous antipsychotics was independently associated with an increased risk of brexpiprazole discontinuation (P < 0.001). Patients who were previously on high-dose antipsychotics discontinued brexpiprazole mainly due to inefficacy. Previous high-dose antipsychotic therapy is an independent risk factor for brexpiprazole discontinuation in patients with schizophrenia or schizoaffective disorder.

Hyaluronic acid is present on specific perineuronal nets in the mouse cerebral cortex.

In the central nervous system (CNS), extracellular matrix (ECM) molecules comprise more than 20% of the volume and are involved in neuronal plasticity, synaptic transmission, and differentiation. Perineuronal nets (PNNs) are ECM molecules that highly accumulate around the soma of neurons. The components of the ECM in the CNS include proteins, proteoglycans, and glycosaminoglycans. Although hyaluronic acid (HA) is considered a constituent element of PNNs, the distribution of HA in the cortex has not been clarified. To elucidate the cortical region-specific distribution of HA, we quantitatively analyzed HA binding protein (HABP)-positive PNNs in the mature mouse cerebral cortex. Our findings revealed that HABP-positive PNNs are present throughout the mouse cortex. The distribution of many HABP-positive PNNs differed from that of Wisteria floribunda agglutinin-positive PNNs. Furthermore, we observed granular-like HABP-positive PNNs in layer 1 of the cortex. These findings indicate that PNNs in the mouse cortex show region-dependent differences in composition. HABP-positive PNNs in layer 1 of the cortex may have different functions such as neuronal differentiation, proliferation, and migration unlike what has been reported for PNNs so far.

Expression of aggrecan components in perineuronal nets in the mouse cerebral cortex.

Specific regions of the cerebral cortex are highly plastic in an organism's lifetime. It is thought that perineuronal nets (PNNs) regulate plasticity, but labeling for Wisteria floribunda agglutinin (WFA), which is widely used to detect PNNs, is observed throughout the cortex. The aggrecan molecule-a PNN component-may regulate plasticity, and may also be involved in determining region-specific vulnerability to stress. To clarify cortical region-specific plasticity and vulnerability, we qualitatively analyzed aggrecan-positive and glycosylated aggrecan-positive PNNs in the mature mouse cerebral cortex. Our findings revealed the selective expression of both aggrecan-positive and glycosylated aggrecan-positive PNNs in the cortex. WFA-positive PNNs expressed aggrecan in a region-specific manner in the cortex. Furthermore, we observed variable distributions of PNNs containing WFA- and aggrecan-positive molecules. Together, our findings suggest that PNN components and their function differ depending on the cortical region, and that aggrecan molecules may be involved in determining region-specific plasticity and vulnerability in the cortex.

Juvenile stress induces behavioral change and affects perineuronal net formation in juvenile mice.

BACKGROUND: Many neuropsychiatric disorders develop in early life. Although the mechanisms involved have not been elucidated, it is possible that functional abnormalities of parvalbumin-positive interneurons (PV neurons) are present. Several previous studies have shown that juvenile stress is implicated in the development of neuropsychiatric disorders. We aimed to clarify the effects of juvenile stress on behavior and on the central nervous system. We investigated behavioral abnormalities of chronically-stressed mice during juvenilehood and the effect of juvenile stress on PV neurons and WFA-positive perineuronal nets (PNNs), which are associated with vulnerability and plasticity in the mouse brain. RESULTS: Due to juvenile stress, mice showed neurodevelopmental disorder-like behavior. Juvenile stressed mice did not show depressive-like behaviors, but on the contrary, they showed increased activity and decreased anxiety-like behavior. In the central nervous system of juvenile stressed mice, the fluorescence intensity of WFA-positive PNNs decreased, which may signify increased vulnerability. CONCLUSION: This study suggested that juvenile stressed mice showed behavioral abnormalities, resembling those seen in neuropsychiatric disorders, and increased brain vulnerability.

Empathic behavior according to the state of others in mice.

INTRODUCTION: Empathic behavior is essential for social activities in social animals. Therefore, lack of empathy is a feature of several neuropsychiatric disorders. However, the underlying mechanisms of empathy and which animals possess it remain unclear. In this study, we investigated whether mice show empathic behavior. METHODS: We tested mice for empathy-like behaviors toward conspecifics who were distressed. We investigated behavioral changes in cage-mate or stranger mice. RESULTS: When the conspecific mice were in a painful state, subject mice showed preferential approach behavior toward them, presumably recognizing the state. Both visual information and olfactory information are indispensable for this empathic behavior. CONCLUSIONS: These results suggest that the mouse recognizes the emotional state of the conspecific and engages in social interaction. The results of this study are useful for the elucidation of the causal mechanisms involved in neuropsychiatric disorders and may contribute in the development of novel treatment targets.

Two-year effectiveness of risperidone and aripiprazole in the maintenance treatment of patients with recent-onset or chronic schizophrenia and related psychotic disorders: a retrospective multicenter study.

This study aimed to assess the comparative effectiveness of risperidone (RIS) versus aripiprazole (ARP) in patients with recent-onset or chronic schizophrenia during maintenance treatment and to examine the interaction between illness duration and the effectiveness of the treatment. All adult patients with schizophrenia and related disorders discharged from four psychiatric hospitals between 2006 and 2012 were screened and the 2-year continuation rates of monotherapy using RIS or ARP after discharge were examined retrospectively. The treatment continuation of the two drugs in patients with recent-onset (illness duration <5 years) or chronic schizophrenia (illness duration ≥5 years) and the moderator effect of illness duration on the effectiveness of the treatment were analyzed. Of 328 patients, 233 received RIS and 95 received ARP. No significant difference was found between the two drugs in the treatment continuation for the entire sample. However, there was a significant difference favoring ARP in the recent-onset subgroup mainly because of differences in tolerability, whereas RIS tended to present better outcomes in patients with chronic illness. Furthermore, there was a significant variation in the effectiveness of the treatment between recent-onset and chronic schizophrenia. Our results suggest that illness duration is an important moderator in terms of the long-term effectiveness of the two drugs.

Age-dependent and region-specific alteration of parvalbumin neurons and perineuronal nets in the mouse cerebral cortex.

Cognitive function declines with age. Such function depends on γ-oscillation in the frontal cortex. Pyramidal neurons, and the parvalbumin-expressing interneurons (PV neurons) that control them, are important for the generation of γ-oscillation. The mechanism by which cognitive function declines is unclear. Perineuronal nets (PNNs) mainly surround the soma and proximal dendrites and axon segments of PV neurons in the cerebral cortex. Previous evidence indicates that PNNs inhibit neural plasticity. If this is true, an increase in the number of neurons surrounded by PNNs or in the thickness or density of the PNNs around neurons could decrease plasticity in the cortex. To determine if an aging-related change in cortical PNNs occurs, we examined the influence of aging on PV neurons and whether Wisteria floribunda agglutinin-positive PNNs differ depending on the cortical area. The results showed that the number of PV neurons/mm2 did not change in many areas of the cortex as mice aged. In contrast, the number of neurons in the sensory cortex surrounded by PNNs increased as mice aged. Thus, with age, PNN density increases in some cortical areas but not in others. In addition, the expression level of PV protein in PV neurons decreased with aging in the whole cortex. We suggest that decreased expression of PV protein impairs fast spiking in PV neurons. We propose that PNNs surround more neurons as age increases. This aging-related increase in PNNs decreases plasticity in the cerebral cortex and reduces cognitive function. The first step in investigating this proposal would be to determine if PNN density increases with age.

Postnatal development of GABAergic interneurons and perineuronal nets in mouse temporal cortex subregions.

In human neuropsychiatric disorders, there are functional and anatomical abnormalities of GABAergic interneurons in each temporal cortex subregion. Furthermore, accumulation of amyloid-ß is observed in the temporal cortex in the early stages of Alzheimer's disease. Each subregion of the temporal cortex has an important role in coordinating the input and output of the hippocampus. When subregions of the temporal cortex are impaired, memory and learning ability decrease. GABAergic interneurons control excitatory neurons, forming the cortico-cortical and cortico-hippocampal networks. However, in temporal cortex subregions, details of the distribution and developmental processes of GABAergic interneurons and perineuronal nets (PNNs) have not been elucidated. Here we examined the development of GABAergic interneurons and PNNs in mouse temporal cortex subregions. Results indicate that temporal cortex GABAergic interneurons have developmental stages different to those of the primary sensory cortex. In addition, the density of PNNs in the temporal cortex is lower than that in the sensory cortex. Furthermore, we found that the Wisteria floribunda agglutinin-reactive extracellular matrix molecule is present in the upper level of layer 1 of the temporal cortex. These results support the idea that mouse temporal cortex subregions develop differently from other cortical regions and have region-specific characteristics after maturation. The present study results suggested that the structure of the temporal cortex is significantly different from the sensory cortex and that temporal cortex may be highly vulnerable to neuropsychiatric and neurodegenerative disorders.

Optimal Dosing of Risperidone and Olanzapine in the Maintenance Treatment for Patients With Schizophrenia and Related Psychotic Disorders: A Retrospective Multicenter Study.

OBJECTIVES: This study aims to determine the optimal tolerability dose ranges of risperidone (RIS) and olanzapine (OLZ) administered during schizophrenia maintenance phase. METHODS: Two-year continuation rates of prescription at discharge were examined using a retrospective cohort study method. Adult patients with schizophrenia and related psychotic disorders, receiving antipsychotic monotherapy with RIS or OLZ at discharge, were included. The primary outcome measures were the time to treatment discontinuation and 2-year continuation rates at 4 modal dose ranges of each drug. We estimated the optimal tolerability dose ranges by comparing the continuation rates at various modal doses. RESULTS: Of 648 patients, 344 received RIS and 304 received OLZ. The RIS 2-year continuation rates at 4 daily modal dose ranges were significantly different (0.5-2.5 mg: 46.0%, 3.0-5.0 mg: 40.0%, 5.5-7.5 mg: 30.0%, and 8.0-10.0 mg: 28.0%), with the difference favoring RIS at lower doses (0.5-5.0 mg) more than higher doses (5.5-10.0 mg). In contrast, there were no significant differences among OLZ 4 modal dose ranges (2.5-7.5 mg: 49.1%, 10.0-15.0 mg: 42.6%, 17.5-22.5 mg: 40.9%, and 25.0-30.0 mg: 39.0%). The time to treatment discontinuation significantly favored OLZ over RIS. However, it did not significantly differ between RIS and OLZ at lower doses. CONCLUSIONS: It is suggested that the optimal tolerability dose range during maintenance treatment is 0.5 to 5.0 mg/d for RIS and 2.5 to 30 mg/d for OLZ, and that RIS at lower doses is comparable with OLZ at lower doses.

Efficacy of second-generation antipsychotics in patients at ultra-high risk and those with first-episode or multi-episode schizophrenia.

AIM: The aim of this study was to examine the speed of response, doses, and safety of treatment with second-generation antipsychotics (SGAs) in patients at ultra-high risk (UHR) compared to those with schizophrenia. METHODS: A 12-week open-label, prospective study of SGAs was performed in UHR patients and those with first-episode schizophrenia (FES) and multi-episode schizophrenia (MES). The subjects were 14-30 years old and were recruited at Zikei Hospital, Okayama, Japan from December 1, 2006 to December 1, 2011. Treatment was carried out in a natural setting in an open-label format, but clinical evaluation was performed blind. The clinical rating scales include the Global Assessment of Functioning (GAF), the Positive and Negative Syndrome Scale (PANSS), and the Clinical Global Impression-Severity scale (CGI-S). RESULTS: UHR (n = 17), FES (n = 23), and MES (n = 21) patients all showed significant improvements on the GAF, PANSS, and CGI-S. However, the UHR patients showed significantly greater improvement on the GAF at weeks 4, 8, and 12 compared to the other groups, and a significantly lower modal dose of SGAs (chlorpromazine equivalent: 183 [201.1] mg/day, mean [SD]) was needed for improvement in the UHR group. Each group was also prescribed anticholinergic agents during the study period and the UHR group had significantly fewer extrapyramidal symptoms (only 6%) compared with the FES group. CONCLUSION: Our findings suggest that UHR patients have a better response to SGAs compared to patients with schizophrenia, and that these drugs can be given safely by minimizing the dosage of SGAs and using anticholinergic agents.

Characteristics and outcomes of school refusal in Hiroshima, Japan: proposals for network therapy.

The authors conducted a study on children undergoing treatment at major school refusal treatment centers in Hiroshima Prefecture. On the whole, school refusal in the prefecture was found to peak between 13 and 14 years of age. By age group, the main reason for school refusal in elementary school group was parent-child relationship with separation anxiety. Given additional problems such as neglect at home and complicated social situations in their schools, junior high school students were found to present diverse symptoms from introversion and self-analysis to extroversion, neglect of studies, and delinquency. Among high school students, there were more cases suffering withdrawal and schizophrenia spectrum disorders. The major task regarding treatment seems to lie in how to treat complex cases combining different problems. We summarized herein the studies we have carried out and propose a model for a network therapy system based on functional liaisons between treatment centers. With this system, a child psychiatric medical facility plays the part of a liaison center for the overall network system.

Clonazepam augmentation of antidepressants: does it distinguish unipolar from bipolar depression?

BACKGROUND: The authors compared the effect of clonazepam supplement treatment on unipolar depression and bipolar depression. METHODS: A total of 38 protracted depression patients with unipolar depression (n = 19) or bipolar depression (n = 19) were treated with 3.0 mg clonazepam for 4 weeks. RESULTS: In the unipolar depression group, 84.2% of the subjects fulfilled the response criteria (at least an 80% reduction in their HDRS score). However, in the bipolar depression group, only 10.5% of them fulfilled these criteria. CONCLUSIONS: The difference in responses between the two groups supposes that the underlying abnormality in unipolar depression is not the same as that in bipolar depression. This trial also supposed that clonazepam can play active role in the treatment of protracted depression in patients with unipolar depression. LIMITATIONS: This finding was made in an open study, and the effect on clonazepam alone was not established.