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Previous reports have shown that during chronic inflammation, the tryptophan (TRP)-kynurenine (KYN) pathway plays a pivotal role in the onset of depression. The aim of this study was to investigate the characteristics of the serum TRP-KYN pathway metabolite profile in high-risk subjects of major depressive disorder (HRMDD) defined by depression scores. The concentrations of TRP-KYN pathway metabolites {TRP, KYN, 3-hydroxyanthranilic acid (3HAA), 3-hydroxykynurenine (3HK), kynurenic acid (KYNA) and anthranilic acid (AA)} were assessed in serum from HRMDD, chronic pain disorder patients and healthy controls. In serum from HRMDD, elevated levels of AA and decreased levels of TRP were observed, but the levels of other metabolites were not changed. Furthermore, the change in the AA 2nd /AA 1st ratio in subjects who progressed from a healthy state to a depressive state was correlated with an increase in the CES-D score. The level of IL-1 receptor antagonist (IL-1RA) was negatively correlated with that of AA. Interestingly, we confirmed AA as a possible biomarker for depression-related symptoms, since the metabolite profiles in the chronic pain disorder group and chronic unpredictable mild stress model mice were similar to those in the HRMDD. These results suggest that AA may be an effective marker for HRMDD.

Tryptophan metabolism is important to induce immune tolerance in tumors. To date, 3 types of tryptophan‐metabolizing enzymes have been identified: indoleamine 2,3‐dioxygenase 1 and 2 (IDO1 and IDO2) and tryptophan 2,3‐dioxygenase 2. Numerous studies have focused on IDO1 as its expression is enhanced in various cancers. Recently, IDO2 has been identified as a tryptophan‐metabolizing enzyme that is involved in several immune functions and expressed in cancers such as pancreatic cancer. However, the biological role of IDO2 in the induction of immune tolerance in tumors has not yet been reported. In the present study, we examined the effects of Ido2 depletion on tumor growth in a mouse model of Lewis lung carcinoma by using Ido2‐knockout mice. Ido2‐knockout mice had reduced tumor volumes compared to WT mice. Furthermore, Ido2 depletion altered the tumor microenvironment, such as tryptophan accumulation and kynurenine reduction, leading to enhancement of immune cell invasion. Finally, enzyme‐linked immunospot assay revealed that Ido2 depletion enhanced γ‐interferon secretion in the tumor. In conclusion, Ido2 is an important immune regulator in the tumor microenvironment. Our data indicate that IDO2 is a potential target for cancer treatment and drug development. Indoleamine 2,3‐dioxygenase 2 (Ido2) deletion reduced tumor volumes in a mouse model of Lewis lung carcinoma. Furthermore, Ido2 depletion led to enhancement of immune cell invasion, and γ‐interferon secretion in the tumor. Our data indicate that Ido2 is an important immune regulator in the tumor microenvironment.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by repetitive behaviors, social deficits, and cognitive impairments. Maternal use of valproic acid (VPA) during pregnancy is associated with an increased risk of ASD in offspring. The prevailing pathophysiological hypothesis for ASD involves excitation/inhibition (E/I) imbalances and serotonergic dysfunction. Here, we investigated the association between glutamatergic-serotonergic neuronal interactions and ASD-like behaviors in mice exposed to prenatal VPA. Prenatal VPA exposure induced excessive repetitive self-grooming behavior and impaired social behavior and object recognition memory in young adult period. Prenatal VPA mice showed hyper-glutamatergic function (increase in basal extracellular glutamate levels and CaMKII phosphorylation) and hypo-serotonergic function (decrease in 5-hydroxyindoleacetic acid and stimulation-induced serotonin [5-HT] release, but an increase in 5-HT transporter expression) in the prefrontal cortex. Treatment with a low-affinity NMDA receptor antagonist (memantine), a selective 5-HT reuptake inhibitor (fluoxetine), and a 5-HT 1A receptor agonist (tandospirone) attenuated both the increase in CaMKII phosphorylation and ASD-like behavior of prenatal VPA mice. Opto-genetic activation of the serotonergic neuronal system attenuated impairments in social behavior and object recognition memory in prenatal VPA mice. WAY-100635—a 5-HT 1A receptor antagonist—antagonized the effect of fluoxetine on impaired social behavior and object recognition memory. These results suggest that E/I imbalance and ASD-like behavior are associated with hypo-serotonergic receptor signaling through 5-HT 1A receptors in prenatal VPA mice.

Negative experiences during adolescence, such as social isolation (SI), bullying, and abuse, increase the risk of psychiatric diseases in adulthood. However, the pathogenesis of psychiatric diseases induced by these factors remain poorly understood. In adolescents, stress affects the intestinal homeostasis in the gut-brain axis. This study determined whether adolescent SI induces behavioral abnormalities by disrupting colonic function. Adolescent mice exposed to SI exhibit spatial cognitive deficits and microglial activation in the hippocampus (HIP). SI decreased the differentiation of mucin-producing goblet cells, which was accompanied by alterations in the composition of the gut microbiota, particularly the depletion of mucin-feeding bacteria. Treatment with rebamipide, which promotes goblet cell differentiation in the colon, attenuated SI-induced spatial cognitive deficits and microglial activation in the HIP and decreased cystine, a downstream metabolite of homocysteine. Treatment with cystine ameliorated SI-induced spatial cognitive deficits and increased microglial C-C motif chemokine ligand 7 (CCL7) levels in the HIP. Inhibition of CCL7 receptors by antagonists of CC motif chemokine receptors 2 (CCR2) and 3 (CCR3) in the HIP prevented spatial cognitive deficits induced by SI. Infusion of CCL7 into the HIP following microglial ablation with clodronate liposome induced spatial cognitive deficits. These findings suggest that adolescent SI decreases serum cystine levels by damaging the colonic goblet cells, resulting in spatial cognitive deficits by triggering microglial activation in the HIP. Our results indicate that increased CCL7 expression in hippocampal microglia may contribute to spatial cognitive deficits by activating CCR2 and CCR3.

Major depressive disorder (MDD) is the most prevalent and serious psychiatric disease involving inflammation. Loureirin C and Xanthoceraside are extracts of dragon’s blood and Xanthoceras sorbifolia Bunge, respectively, which have neuroprotective and anti-inflammatory properties. In this study, we examined whether Loureirin C and Xanthoceraside attenuated depression-like behaviors and inflammation induced by chronic unpredicted mild stress (CUMS) in mice. Adult C57BL/6 J mice exposed to CUMS for 4 weeks showed depression-like behaviors characterized by hyperactivity in a novel environment, decreased interaction time in the social interaction test, prolongation of eating latency in the novelty suppressed feeding test, and increased immobility in the forced swimming test. CUMS increased the expression of interleukin-17 (IL-17) in the prefrontal cortex (PFC). One week after exposure to CUMS, the mice were treated with Loureirin C (0.64 mg/kg) or Xanthoceraside (1.28 mg/kg) once a day for 3 weeks during CUMS. Loureirin C and Xanthoceraside significantly attenuated CUMS-induced behavioral impairment. Furthermore, both Loureirin C and Xanthoceraside prevented IL-17 expression induced by CUMS in the PFC. This data suggests that Loureirin C and Xanthoceraside have antidepressant-like properties that may be associated with the inhibition of IL-17 expression.

Background Stress during the adolescent period influences postnatal maturation and behavioral patterns in adulthood. Adolescent stress-induced molecular and functional changes in neurons are the key clinical features of psychiatric disorders including schizophrenia. Objective In the present study, we exposed genetically vulnerable mice to isolation stress to examine the molecular changes in the glutamatergic system involving N -methyl- d -aspartate (NMDA) receptors via dopaminergic disturbance in the prefrontal cortex (PFc). Results We report that late adolescent stress in combination with Disrupted-in-Schizophrenia 1 ( DISC1 ) genetic risk elicited alterations in glutamatergic neurons in the PFc, such as increased expression of glutamate transporters, decreased extracellular levels of glutamate, decreased concentration of d -serine, and impaired activation of NMDA-Ca 2+ /calmodulin kinase II signaling. These changes resulted in behavioral deficits in locomotor activity, forced swim, social interaction, and novelty preference tests. The glutamatergic alterations in the PFc were prevented if the animals were treated with an atypical antipsychotic drug clozapine and a dopamine D1 agonist SKF81297, which suggests that the activation of dopaminergic neurons is involved in the regulation of the glutamatergic system. Conclusion Our results suggest that adolescent stress combined with dopaminergic abnormalities in the PFc of genetically vulnerable mice induces glutamatergic disturbances, which leads to behavioral deficits in the young adult stage.

Dopamine is a key neurotransmitter that regulates attention through dopamine D1 and D2-receptors in the prefrontal cortex (PFC). We previously developed an object-based attention test (OBAT) to evaluate attention in mice. Disruption of the dopaminergic neuronal system in the PFC induced attentional impairment in the OBAT. However, previous studies have not systematically examined which specific brain regions are associated with the blockade of PFC dopamine D1 and D2-receptors in the OBAT. In this study, we investigated the association of dopamine D1 and D2-receptors in the PFC with attention and neuronal activity in diverse brain regions. We found that both dopamine D1 and D2-receptor antagonists induced attentional impairment in the OBAT by bilateral microinjection into the PFC of mice, suggesting that both dopamine D1 and D2-receptors were associated with attention in the OBAT. Our analysis of the neuronal activity as indicated by c-Fos expression in 11 different brain regions showed that based on the antagonist types, there was selective activation of several brain regions. Overall, this study suggests that both dopamine D1 and D2-receptors play a role in attention through different neuronal circuits in the PFC of mice.

Cigarette smoking during pregnancy is associated with various disabilities in the offspring such as attention deficit/hyperactivity disorder, learning disabilities, and persistent anxiety. We have reported that nicotine exposure in female mice during pregnancy, in particular from embryonic day 14 (E14) to postnatal day 0 (P0), induces long-lasting behavioral deficits in offspring. However, the mechanism by which prenatal nicotine exposure (PNE) affects neurodevelopment, resulting in behavioral deficits, has remained unclear. Here, we report that PNE disrupted the proliferation of neuronal progenitors, leading to a decrease in the progenitor pool in the ventricular and subventricular zones. In addition, using a cumulative 5-bromo-2'-deoxyuridine labeling assay, we evaluated the rate of cell cycle progression causing the impairment of neuronal progenitor proliferation, and uncovered anomalous cell cycle kinetics in mice with PNE. Accordingly, the density of glutamatergic neurons in the medial prefrontal cortex (medial PFC) was reduced, implying glutamatergic dysregulation. Mice with PNE exhibited behavioral impairments in attentional function and behavioral flexibility in adulthood, and the deficits were ameliorated by microinjection of D-cycloserine into the PFC. Collectively, our findings suggest that PNE affects the proliferation and maturation of progenitor cells to glutamatergic neuron during neurodevelopment in the medial PFC, which may be associated with cognitive deficits in the offspring.

Background Although the number of frozen-thawed blastocysts transfer is increasing worldwide, the live birth rate following blastocyst transfer using assisted reproductive technology remains at 30–60%. Thus, improving the pregnancy rate per transfer is an urgent issue. In a previous retrospective study, we evaluated the use of granulocyte-macrophage colony-stimulating factor (GM-CSF)-containing medium for recovery culture to improve the outcomes of frozen-thawed blastocyst transfers. The results demonstrated that the live birth rates increased by approximately 10% following recovery culture in the GM-CSF-containing culture medium. This study aims to prospectively evaluate whether GM-CSF-containing blastocyst recovery culture following thawing increases live birth. Methods This is a multicenter, randomized, parallel-group, active-controlled, single-blind trial. The recruitment target is 750 participants meeting the criteria. Enrolled patients are randomized 1:1 to the GM-CSF-containing culture medium group (test group) or the non-GM-CSF-containing culture medium group (control group). The blastocyst recovery culture after warming was defined as an intervention in this study; frozen-thawed blastocysts will be cultured for 3–7 h in GM-CSF-containing medium (test group) or medium without GM-CSF (control group) followed by blastocyst transfer. The primary outcome will be live birth. We will also evaluate embryo transfer outcomes as secondary efficacy endpoints and evaluate perinatal and neonatal outcomes as a safety endpoint. Discussion This is the first large-scale prospective study to investigate the efficacy of a GM-CSF-containing medium for frozen-thawed blastocyst transfer. The study findings will provide evidence regarding the efficiency of GM-CSF-containing medium for blastocyst recovery culture after warming. Trial registration Japan Registry of Clinical Trials jRCT1040240159. Registered on January 6, 2025

Rationale We previously reported that prenatal treatment with phencyclidine (PCP) induces glutamatergic dysfunction in the prefrontal cortex (PFC), leading to schizophrenia-like behavioral deficits in adult mice. However, little is known about the prenatal effect of PCP treatment on other types of neurons. Objectives We focused on γ-aminobutyric acid (GABA)-ergic interneurons and evaluated the effect of prenatal PCP exposure on the neurodevelopment of GABAergic interneurons in the PFC. Methods PCP was administered at the dose of 10 mg/kg/day to pregnant dams from embryonic day 6.5 to 18.5. After the pups were reared to adult, we analyzed their GABAergic system in the PFC using immunohistological, biochemical, and behavioral analyses in adulthood. Results The prenatal PCP treatment decreased the density of parvalbumin-positive cells and reduced the expression level of glutamic acid decarboxylase 67 (GAD67) and GABA content of the PFC in adults. Additionally, prenatal PCP treatment induced behavioral deficits in adult mice, such as hypersensitivity to PCP and prepulse inhibition (PPI) deficits. These behavioral deficits were ameliorated by pretreatment with the GABA B receptor agonist baclofen. Furthermore, the density of c-Fos-positive cells was decreased after the PPI test in the PFC of mice treated with PCP prenatally, and this effect was ameliorated by pretreatment with baclofen. Conclusions These findings suggest that prenatal treatment with PCP induced GABAergic dysfunction in the PFC, which caused behavioral deficits.