Search

All-optical methods that provide deeper understanding of neural activity are currently being developed. Optogenetics is a biological technique useful to control neuronal activity or life phenomena using light. Microbial rhodopsins are light-activated membrane proteins used as optogenetic tools. Microbial rhodopsins such as channelrhodopsin2 (ChR2) consist of seven-pass transmembrane proteins with a covalently bound retinal. Light absorption is followed by photoisomerization of the all-trans retinal to a 13-cis configuration and subsequent conformational changes in the molecule, with consequent permeability of the channel structure to ions. Recent studies have reported the discovery of microbial rhodopsins with novel functions. Microbial rhodopsin diversity has also increased. We describe the characteristics of microbial rhodopsins used as optogenetic tools and the latest research in this domain.

Two-photon calcium imaging is widely used to observe neural activity in animal brains. Improvements in two-photon microscopy and calcium indicators in recent years have led to higher sensitivity, faster speed, and larger field-of-view imaging, which have facilitated observation of large-scale neuronal activity in three dimensions on a micrometer to millimeter scale. In this paper, we describe these novel two-photon imaging techniques and their applications to neuroscience.

Accurate identification of regions that show activity changes in response to functional expression is necessary to understand the mechanisms underlying functional expression in the brain. Quantitative activity-induced manganese-enhanced magnetic resonance imaging (qAIM-MRI) is a noninvasive whole-brain activity history imaging method used for this purpose. Notably, qAIM-MRI is a pseudo-Ca 2+ imaging method that uses Mn 2+ as a surrogate marker for Ca 2+ . In this paper, I describe the principles, applications, and limitations of qAIM-MRI.

Positron emission tomography (PET) refers to a noninvasive imaging modality that enables ultrahigh-sensitivity quantitative evaluation of the spatiotemporal dynamics of targeted molecules within living organisms from outside the body. In this review, we explain the principles of PET imaging technology and the basic properties of ultrahigh sensitivity and quantifiability. Furthermore, we have outlined PET imaging-based integrated approaches to elucidate the fundamental neurobiological mechanisms underlying neuropsychiatric activity, as well as the usefulness of PET imaging in pharmacokinetic analysis and theranostics during drug development.

Two-photon excitation microscopy enables in vivo deep-tissue imaging within organisms. This technique is based on two-photon excitation, a nonlinear optical process that uses near-infrared light for excitation, resulting in high tissue permeability. Notably, two-photon excitation occurs only near the focal plane; therefore, minimally invasive tomographic images can be obtained. Owing to these features, two-photon excitation microscopy is currently widely used in medical and life-science research, particularly in the domain of neuroscience for in vivo visualization of deep tissues. However, the use of long-wavelength excitation light in two-photon excitation microscopy has resulted in a larger focused spot size and relatively low spatial resolution, which is a limitation of this technique for further applications. Recent studies have described super-resolution microscopy techniques applied to two-photon excitation microscopy in an attempt to observe living organisms "as they are in their natural state" with high spatial resolution. We have also addressed this topic using an optical approach (two-photon stimulated emission depletion microscopy) and an image analysis approach (two-photon super-resolution radial fluctuation). Here, we describe these approaches together with a discussion of our recent accomplishments.

Humans have a highly developed retina and obtain approximately 80% of their external information from vision. Photoreceptor cells, which are located in the outermost layer of the neuroretina and recognize light signals, are highly specialized sensory cilia that share structural and functional features with primary cilia. Genetic disorders of the retina or photoreceptor cells are termed inherited retinal diseases (IRDs) and are caused by variants in one of more than 280 genes identified to date. Among the genes responsible for IRDs, many are shared with those responsible for ciliopathies. In studies of inherited diseases, mouse models are commonly used due to their advantages in breeding, handling, and relative feasibility in creating pathological models. On the other hand, structural, functional, and genetic differences in the retina between mice and humans can be a barrier in IRD research. To overcome the limitations of mouse models, larger vertebrate models of IRDs can be a useful research subject. In particular, canines have retinas that are structurally and functionally similar and eyes that are anatomically comparable to those of humans. In addition, due to their unique veterinary clinical surveillance and genetic background, naturally occurring canine IRDs are more likely to be identified than in other large animals. To date, pathogenic mutations related to canine IRDs have been identified in more than 30 genes, contributing to the understanding of pathogeneses and to the development of new therapies. This review provides an overview of the roles of the canine IRD models in ciliopathy research.

A photoreceptor is a specialized neuron that is responsible for the conversion of light into an electrical signal. Photoreceptors are classified into rods and cones, and both photoreceptors possess light-sensing ciliary organelles called outer segments (OSs), anchored in the cells by a microtubule-based axoneme. The OS consists of a stack of disc membranes, which are abundant for the retinal phototransduction proteins such as rhodopsin. Recently, modern protein synchronization techniques using in vivo transfection in rodents revealed that rhodopsin transits through Rab11-positive recycling endosomes, preferentially entering the OS in the dark. Moreover, Peripherin-2 (PRPH2, also called retinal degeneration slow, RDS), a photoreceptor-specific tetraspanin protein essential for the morphogenesis of disc membranes, is delivered to the OS following complementary to that of rhodopsin. Various PRPH2 disease-causing mutations have been found in humans, and most of the mutations in the cytosolic C-terminus of PRPH2 are linked to cone-dominant macular dystrophies. It has been shown that the late endosome is the waystation that sorts newly synthesized PRPH2 into the cilium. The multiple C-terminal motifs of PRPH2 regulate its late endosome and ciliary targeting through ubiquitination and binding to an Endosomal Sorting Complexes Required for Transport (ESCRT) component, Hrs. These findings suggest that the late endosomes play an important role in the biosynthetic pathway of ciliary proteins and can be a new therapeutic target for the diseases caused by ciliary defects.

The primary cilium, an antenna-like structure of cell membrane, detects various signals and regulates cellular functions such as proliferation and differentiation. The impairment of primary cilium is associated with the etiologies of diseases including cancer, obesity, and congenital anomalies. In this review, novel functions of trichoplein, a suppressor of ciliogenesis, on the regulation of adipose progenitors and fibro-adipogenic progenitors are focused. Trichoplein-knockout mice show resistance to high-fat diet-induced obesity and accelerated regeneration after skeletal muscle injury. The primary cilia of adipose progenitors from trichoplein-knockout mice are elongated, leading to the inhibitions of the accumulation of lipid raft to the base of primary cilia and the phosphorylation of AKT. The primary cilia of fibro-adipogenic progenitors from trichoplein-knockout mice are also elongated, causing the increased expression of IL-13 through IL-33 receptor signaling. These mechanisms are involved in the resistance to diet-induced obesity and improved regeneration. These findings suggest that targeting the primary cilia of specific cells may be a novel therapeutic approach through modulating cellular functions.

Primary cilia are immotile cilia assembled from the centriole-derived basal body, and they protrude on the cell surface in almost all cell types during the cell cycle G 0 phase. Due to the diffusion barrier at the ciliary base, cilia harbor selective G protein-coupled receptors, growth factor receptors, and ion channels on their membrane. Thus, cilia act as sensory organelles, regulating the proliferation and differentiation of the cells and promoting the formation and maturation of various organs including bone, brain, and kidney. It has been unveiled that malformation and dysregulation of cilia cause organ dysplasia, so-called ciliopathy, thus research on primary cilia has become active during the past 20 years. Research on the roles of cilia in bone formation and its regulatory mechanisms have also progressed. It is widely recognized that cilia of preosteoblasts receive hedgehog and promote differentiation of the cells to osteoblasts, resulting in the formation of skulls and long bones. Recently, it has been shown that a membrane-associated protein 4.1G is important in ciliogenesis, hedgehog signaling, and osteoblast differentiation in neonatal bone formation. In this review, we would like to summarize the roles of primary cilia in bone formation and their regulatory mechanisms including the contribution of 4.1G.

Malfunction of the basal ganglia leads to movement disorders such as Parkinson's disease, dystonia, Huntington's disease, dyskinesia, and hemiballism, but their underlying pathophysiology is still subject to debate. To understand their pathophysiology in a unified manner, we propose the "dynamic activity model", on the basis of alterations of cortically induced responses in individual nuclei of the basal ganglia. In the normal state, electric stimulation in the motor cortex, mimicking cortical activity during initiation of voluntary movements, evokes a triphasic response consisting of early excitation, inhibition, and late excitation in the output stations of the basal ganglia of monkeys, rodents, and humans. Among three components, cortically induced inhibition, which is mediated by the direct pathway, releases an appropriate movement at an appropriate time by disinhibiting thalamic and cortical activity, whereas early and late excitation, which is mediated by the hyperdirect and indirect pathways, resets on-going cortical activity and stops movements, respectively. Cortically induced triphasic response patterns are systematically altered in various movement disorder models and could well explain the pathophysiology of their motor symptoms. In monkey and mouse models of Parkinson's disease, cortically induced inhibition is reduced and prevents the release of movements, resulting in akinesia/bradykinesia. On the other hand, in a mouse model of dystonia, cortically induced inhibition is enhanced and releases unintended movements, inducing involuntary muscle contractions. Moreover, after blocking the subthalamic nucleus activity in a monkey model of Parkinson's disease, cortically induced inhibition is recovered and enables voluntary movements, explaining the underlying mechanism of stereotactic surgery to ameliorate parkinsonian motor signs. The "dynamic activity model" gives us a more comprehensive view of the pathophysiology underlying motor symptoms of movement disorders and clues for their novel therapies.

Alveolar soft part sarcoma(ASPS)is a rare malignant tumor whose origin is unidentified, arising from deep soft tissue and affecting adolescents and young adults. ASPS is characterized by its abundant vascular network forming alveolar structures, and demonstrates frequent hematogenous metastasis. An ASPSCR1-TFE3 fusion gene derived from t(X;17)chromosome translocation is detected as a disease gene in all cases, and the ASPSCR1-TFE3 protein causes abnormal transcriptional regulation. We generated a mouse model for ASPS by introducing ASPSCR1-TFE3 into mouse embryonic mesenchymal cells. In the model, tumor angiogenesis and alveolar structures of human ASPS were reproduced, revealing pericyte-rich blood vessels and metastatic processes with pericytic encapsulation of tumor cell nests. ASPSCR1-TFE3 is frequently associated with active enhancers and super-enhancers, and angiogenesis-related enhancers were significantly diminished by the loss of ASPSCR1- TFE3. Angiogenesis-associated enhancers and important target genes, Rab27a, Sytl2, Pdgfb and Vwf were identified by epigenetic CRISPR screening. Rab27a and Sytl2 facilitates trafficking of cytoplasmic vesicles containing angiogenic factors such as Pdgfb and Vwf, resulting in pericyte-rich vascular structures in ASPS. These studies highlight the importance of the Rab27/Sytl axis as a novel drug target in cancer.

The gut microbiome is involved in host physiology, including nutrition, metabolism, and immunity. It was recently known that dysbiosis of the gut microbiome has been implicated in several human diseases such as inflammatory bowel disease. It is altered by environmental factors such as diet, habit and lifestyle and has been directly and indirectly linked to the development and progression of colorectal cancer(CRC). Fusobacterium(F.)nucleatum, which causes periodontal disease, has been shown to play an important role in the initiation and development of CRC, although not as clearly as Helicobacter(H.) pylori in gastric cancer. Therefore, gut bacteria hold promise as a potential therapeutic approach to prevent or treat CRC. Although its clinical usefulness has not yet been demonstrated, future research such as metagenomics may open new avenues for CRC treatment with gut bacteria. Here, we reviewed the role of the gut microbial community in the development, progression, and prevention of colorectal carcinogenesis.

In recent years, the human microbiota, especially the gut microbiota, has been attracting attention in various fields, and it is one of the topics in the field of oncology. The human microbiota is known to act directly or indirectly on host immunity, and the gut and lung microbiota influence each other through the"gut-lung axis". It has been suggested that dysbiosis, a condition in which the symbiosis of the human microbiota is disrupted, induces lung inflammation and various respiratory diseases, and is also implicated in the immune microenvironment of lung cancer. It is also widely known that the gut microbiota modulates the efficacy of cancer immunotherapy, a major pillar of lung cancer treatment, and many clinical trials targeting the gut microbiota, such as fecal microbiome transplantation and biotics intervention, are currently being conducted. In the future, research on lung carcinogenesis mechanisms and lung cancer treatment focusing on the human microbiota will become increasingly active.

Classical evidence for neural mechanisms of attention resulted from findings that attention to sensory signals modulated sensory neuronal responses in both humans and non-human animals. These findings led scientists to propose a variety of sophisticated information-processing and mathematical models of attention. Recent advances in neuroimaging and studies including hemispatial neglect and attention deficits in patients have also facilitated understanding of neural mechanisms of attention in terms of functional specialization and large-scale brain network. Here, we reviewed neural mechanisms of attention from classical literature up to recent advances.

Visual search is a useful experimental paradigm investigating various aspects of attention. For efficient search, participants must avoid revisiting previously viewed objects. Inhibitory tagging and inhibition of return are phenomena related to this process, but their neural mechanisms are yet to be elucidated. Recent studies have shown that the rate of revisit behavior during visual search correlates with working memory capacity. This suggests that top-down signals from the frontal executive system alter the priority map that guides attention and eye movements. With this in mind, we have developed a novel visual search paradigm with many identical distractors and an evaluation model that assesses multiple parameters of working memory. The model incorporated memory capacity, memory decay, and utility rate, and when applied to data obtained from experimental animals, these parameters could be reliably evaluated. Furthermore, using the behavioral paradigm and model, we found that systemic administration of subanesthetic dose of ketamine decreased utility rate and memory capacity, while nicotine administration increased utility rate. Since our behavioral paradigm does not require complex instruction, it can be applied to a variety of patients in future clinical studies.

The aggregation of α-synuclein (α-syn), associated with Parkinson's disease (PD) extends from the peripheral autonomic nervous system to the cerebral cortex, indicating a neural circuit-based mechanism of spread. However, recent studies, have proposed alternative propagation routes beyond neural pathways, including transmission via bodily fluids, such as the blood. This notion expands our understanding of PD progression, underscoring the complexity of α-syn spread and its implications in disease management and therapeutic strategies.

Diabetes stands as the predominant cause of peripheral neuropathy, and diabetic neuropathy (DN) is an early-onset and most frequent complication of diabetes. Distal symmetric polyneuropathy is the major form of DN; however, various patterns of nerve injury can manifest. Growing evidence suggests that hyperglycemia-related metabolic disorders in neurons, Schwann cells, and vascular endothelial cells play a major role in the development and progression of DN; however, its pathogenesis and development of disease-modifying therapies warrant further investigation. Herein, recent studies regarding the possible pathogenic factors of DN (polyol and other collateral glycolysis pathways, glycation, oxidative stress, Rho/Rho kinase signaling pathways, etc.) and therapeutic strategies targeting these factors are introduced.

This chapter outlines the cerebrovascular developmental anatomy with emphasis on the internal carotid artery(ICA), which is important for optimal endovascular treatment of cerebrovascular system disorders. Gene expression, neural crest cells, and pharyngeal arches play key roles in the embryonic development of the carotid arteries. Evolutionary inheritance in vertebrates contributes to the formation, regression, and segmental structure of these arteries. We present examples of current mutations with regard to their segmental nature; ICA mutations are discussed primarily with regard to their developmental origin from the first to third pharyngeal arches and the role of the ductus caroticus. This comprehensive review highlights the importance of understanding the developmental and anatomical nuances of the ICA to aid with accurate diagnosis and management of vascular anomalies in the clinical setting. We have focused on the complexity associated with ICA mutations, particularly those associated with the third pharyngeal arch and the need for a solid foundation of developmental and anatomical knowledge to accurately identify and interpret their significance in the adult phenotype.

My colleagues and I previously found a subset of neutrophil-like Ly6C hi monocytes, named "regulatory monocytes", that expand in the bone marrow during the late phase of inflammation. Regulatory monocytes migrate to injured tissue where they promote tissue repair. Unlike classical Ly6C hi monocytes, regulatory monocytes arise from GMP through proNeu1, which was previously thought to be committed to becoming neutrophils. G-CSF not only stimulates neutrophil differentiation but also drives the expansion of regulatory monocytes in the absence of inflammatory stimuli. The human parallel to mouse regulatory monocytes was found in the peripheral blood CD14 hi CD16 lo monocyte fraction. These monocytes can be distinguished from classical CD14 hi CD16 lo monocytes by neutrophil marker CXCR1 expression. Like mouse regulatory monocytes, human CXCR1 + monocytes arise from neutrophil progenitors in response to G-CSF. CXCR1 + CD14 hi CD16 lo monocytes suppressed the proliferation of syngeneic T cells in vitro, which suggests an immunosuppressive phenotype. Overall, these findings indicate that the process of differentiation of regulatory monocytes from progenitors of neutrophil lineage is maintained across humans and mice, and may aid in resolution of excess inflammation.

Myelodysplastic syndrome (MDS) is a refractory cancer that arises from hematopoietic stem cells and predominantly affects elderly adults. In addition to driver gene mutations, which are also found in clonal hematopoiesis in healthy elderly people, systemic inflammation caused by infection or collagen disease has long been known as an extracellular factor in the pathogenesis of MDS. Wild-type HSCs have an "innate immune memory" that functions in response to infection and inflammatory stress, and my colleagues and I used an infection stress model to demonstrate that the innate immune response by the TLR-TRIF-PLK-ELF1 pathway is similarly critical in impairment of hematopoiesis and dysregulation of chromatin in MDS stem cells. This revealed that not only are MDS stem cells expanded by the TRAF6-NF-kB pathway, the innate immune response is also involved in generating MDS stem cells. In this review, I will present research findings related to "innate immune memory," one of the pathogenic mechanisms of blood cancer, and discuss future directions for basic pathological research and potential therapeutic development.

Adipose tissue plays a central metabolic role in systemic energy metabolism via nutrient exchange and secretion of adipose-derived hormones and cytokines. Adipose tissue dysfunction increases the risk of developing conditions, including type 2 diabetes, coronary artery disease, stroke, and cancer, ultimately shortening healthy lifespan. Maintaining adipose tissue functions has recently garnered attention as a means to extend healthy life expectancy. We previously developed a T-cell activation-inhibitory assay, which facilitates efficient selection of candidate substances for extending healthy lifespan. Using this assay, we identified two candidate substances: Cynandione A (CA), a major component of Cynanchum wilfordii, and N-caffeoyltryptophan (NCT) found in coffee. This review summarizes recent findings regarding the effect of CA and NCT on adipocyte (the primary cells in adipose tissue) function, and their potential contribution to extending healthy life expectancy.

Mysids are small crustaceans that are closely related to shrimp/prawns and crabs but not subject to food allergen labeling requirements for raw materials. In the past, a processed food that contained Japanese smelt (wakasagi) was suspected of producing a false-positive result in shrimp/prawn and crab allergen test because of the presence of consumed mysids. However, there was no reported methods to confirm mysid presence. Therefore, we developed a PCR method to detect mysids. The developed PCR method had high specificity for a mysid species, with no amplification observed from samples of shrimp, crab, krill, mantis shrimp, or the meat of Japanese smelt. In addition, DNA extracted from the internal organs of Japanese smelt was amplified by this PCR method, and sequencing revealed mysid DNA. This confirmed that mysids remained in the internal organs of Japanese smelt following consumption. This PCR method for mysid detection even amplified Japanese smelt-containing processed food samples that were suspected to have produced a false-positive result in shrimp/prawn and crab ELISA. Thus, this PCR method would enable to detect such false positives are caused by mysid contamination.

Ciguatera poisoning (CP) is one of the most frequent seafood poisonings across the globe. CP results from the consumption of fish flesh that has accumulated principal toxins known as ciguatoxins (CTXs), and it mainly occurs in tropical and subtropical regions. In Japan, incidents of CP have been reported primarily from Okinawa and Amami Islands in the subtropical area. Meanwhile, there have also been reports from Mainland sporadically. Since the amount of CTXs contained in fish flesh is extremely low, a highly sensitive detection method by LC-MS/MS is required. But the currently reported detection method is applicable only to specific equipment, and many laboratories have difficulty to respond CP. In this study, to prepare for the risk of nationwide CP, we researched a universal analytical method for CTXs based on LC-MS/MS. Using a water/acetonitrile mobile phase supplemented with lithium hydroxide and formic acid gave rise to prominent peaks of the stable [M+Li]+ions. As the [M+Li]+ions did not produce valid product ions even with high collision energy, the [M+Li]+ions of each analog were set for both precursor and product ions ([M+Li]+>[M+Li]+) and monitored under the multiple reaction monitoring (MRM) mode. With the method described above, analyses of nine CTX congeners were carried out. The limit of detection (LOD, S/N>5) and quantitation (LOQ, S/N>10) were estimated as 0.005-0.030 ng/mL and 0.010-0.061 ng/mL, respectively. When the 1 mL of extract solution is prepared from 5 g of the fish tissue, the LOD and LOQ will be at 0.001-0.006 μg/kg and 0.002-0.012 μg/kg, respectively. This result indicates that we could detect the required level of 0.175 μg/kg CTX1B equivalent in fish flesh which is recommended for safe consumption in Japan. This method is considered to be a universal analytical method without depending on the specific equipment. Thus it could contribute to improving the CP investigations in nationwide laboratories.

The complement and coagulation systems are ancestrally related mechanisms of serine protease-induced protein activation. Recent studies have shown that the complement system enhances platelet aggregation by activating platelets and vascular endothelial cells. This system is also involved in the expression of tissue factor, which induces the coagulation reaction. Activated platelets and coagulation factors are also known to activate the complement system. In diseases involving the complement system, such as paroxysmal nocturnal hemoglobinuria, autoimmune hemolytic anemia, and atypical hemolytic uremic syndrome, excessive activation of this system contributes to complement-mediated thrombosis. The anti-C5 antibody eculizumab has shown a remarkable thromboprophylactic effect in these complement diseases. The recent surge in development of new anti-complement agents has raised expectations for the advancement of treatments and preventive measures for thrombosis associated with complement disorders. This review outlines the crosstalk between these two systems, and describes the mechanisms of several diseases featuring both thrombosis and complement activation.

Aplastic anemia is a syndrome characterized by reduced hematopoietic stem cells, bone marrow hypoplasia, and pancytopenia, and is often considered a T-cell-mediated autoimmune disease. It is predominantly treated with hematopoietic stem cell transplantation and immunosuppressive therapy with anti-human thymocyte immunoglobulin (ATG) and cyclosporine. Only rabbit ATG was previously available in Japan, but equine ATG was recently approved for use in 2023. Thrombopoietin receptor agonists available in Japan are oral eltrombopag and injectable romiplostim. In hematopoietic stem cell transplantation for aplastic anemia, a conditioning regimen of reduced-dose cyclophosphamide and fludarabine has been used to reduce cardiotoxicity. Human leukocyte antigen haploidentical stem cell transplants have also been developed, and their use in patients without a donor is increasingly reported. Future advancements in novel drugs and transplantation therapies could revolutionize the management of aplastic anemia.

Inclisiran sodium (Brand name: LEQVIO ® for s.c. injection syringe 300 ‍mg, hereinafter referred to as inclisiran), a small interfering ribonucleic acid (siRNA) product that targets the mRNA that encodes the proprotein convertase subtilisin/kexin type 9 (PCSK9) protein was approved on September 25, 2023 for the indication of "Familial hypercholesterolemia, hypercholesterolemia" in Japan. Inclisiran is conjugated on the sense strand with triantennary N-acetylgalactosamine to facilitate uptake by hepatocytes. In vitro and in vivo pharmacology studies demonstrated the lowering effects of PCSK9 and LDL-C in hepatocytes and cynomolgus monkeys. It was considered unlikely to cause clinically significant risks due to toxicities arising from complementary binding to non-target RNA sequences (hybridization-dependent off-target effects). Clinical trials conducted globally including Japan in patients with familial hypercholesterolemia and hypercholesterolemia who did not reach the LDL-C target showed that inclisiran sodium 300 ‍mg dosed at Day 1, Day 90 and then every 6 months demonstrated significant LDL-C reduction and the efficacy sustained long. The majority of patients achieved the guideline recommended LDL-C targets. Inclisiran sodium 300 ‍mg was well tolerated and there were no specific safety concerns. Therefore, inclisiran is expected to be a new therapeutic option for the patients with familial hypercholesterolemia and hypercholesterolemia.

Typical monoamine-based antidepressants have significant limitations, including a time lag for therapeutic response and low efficacy (more than one-third of depressed patients fail to respond to multiple antidepressant medications and are considered treatment-resistant). Conversely, ketamine, an N-methyl-D-aspartate receptor antagonist, exhibits rapid and sustained antidepressant actions in patients with treatment-resistant depression. However, clinical use of ketamine is limited due to its serious side effects. Thus, there is a significant need to develop novel ketamine-like antidepressants with fewer side effects. We previously demonstrated that intracerebroventricular infusion of resolvins (RvD1, RvD2, RvE1, RvE2, and RvE3), specialized pro-resolving lipid mediators derived from docosahexaenoic and eicosapentaenoic acids, produce antidepressant-like effects in mouse models of depression. Among resolvins, RvE1 produces the most potent antidepressant-like effects likely via ChemR23 in several mouse models of depression. Local infusion of RvE1 into the medial prefrontal cortex (mPFC) or dorsal hippocampal dentate gyrus (DG) also produces antidepressant-like effects, suggesting that these brain regions are sites of action of RvE1. Additionally, intranasal (i.n.) administration of RvE1 produces antidepressant-like effects through mechanisms similar to ketamine: activity-dependent release of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF), and subsequent mechanistic target of rapamycin complex 1 (mTORC1) activation in the mPFC play a crucial role in the rapid and sustained antidepressant-like actions of i.n. RvE1. Moreover, the antidepressant-like effects of i.n. RvE1 require BDNF and VEGF release, but not mTORC1 activation, in the dorsal DG. These findings suggest that RvE1 can be a promising lead for a novel rapid-acting antidepressant.

The development of genetically-encoded fluorescent probes for the detection of intracellular calcium ions and various neurotransmitters has progressed significantly in recent years, and there is a growing need for techniques that rapidly and efficiently image these signals in the living brain for pharmacological studies of the central nervous system. In this article, we discuss one-photon fluorescence microscopy techniques used for brain activity imaging, particularly wide-field imaging and head-mounted miniaturized microscopy, and introduce their basic principles, recent advances, and applications in pharmacological research. Wide-field calcium imaging is suitable for mesoscopic observation of cortical activity during behavioral tasks in head-fixed awake mice, while head-mounted miniaturized microscopes can be attached to the animal's head to image brain activity associated with naturalistic behaviors such as social behavior and sleep. One-photon microscopy allows for the development of a simple and cost-effective imaging system using an affordable excitation light source such as a light-emitting diode. Its excitation light illuminates the entire field of view simultaneously, making it easy to perform high-speed imaging using a high-sensitivity camera. In contrast, the short wavelength of the excitation light limits the field of observation to areas on or near the brain surface due to its strong light scattering. Moreover, the out-of-focus fluorescence makes it difficult to obtain images with a high signal-to-noise ratio and spatial resolution. The use of one-photon microscopy in brain activity imaging has been limited compared to two-photon microscopy, but its advantages have recently been revisited. Therefore, this technique is expected to become a useful method for pharmacologists to visualize the activity of the living brain.

Major Depressive Disorder (MDD) poses a significant global health burden, with 30-40% patients developing resistance to standard clinical antidepressants, such as selective serotonin reuptake inhibitors and tricyclic antidepressants. In 2016, Carhart-Harris and colleagues reported that psilocybin, the hallucinogenic compound derived from magic mushrooms, exhibits rapid and enduring antidepressant effects in patients with treatment-resistant depression. Subsequent clinical studies have found the therapeutic potential of psilocybin in MDD, depressive episode in bipolar disorder, anorexia, and drug addiction. In 2018 and 2019, the U.S. Food and Drug Administration designated psilocybin as a "breakthrough medicine" for treatment-resistant depression and MDD, respectively. Notably, the side effects of psilocybin are limited to transient and mild issues, such as headache and fatigue, suggesting its safety. In 2023, we published a review on the role of serotonin 5-HT 2A receptors in the antidepressant effects of serotonergic psychedelics (Nihon Yakurigaku Zasshi, Volume 158, Issue 3, Page 229-232). Here, we present our study alongside the latest clinical and preclinical research on the antidepressant effects of psilocybin and provide an overview of the potential and issues related to psilocybin therapy.

Growing evidence has indicated that delta opioid receptor (DOP) agonists are potential psychotropic drugs such as for depression, anxiety, and PTSD. In rodent studies, we have also demonstrated that DOP agonists exhibit potent anxiolytic-like effects via the inhibition of the excitatory neuronal activity which projects to the amygdala from the prelimbic prefrontal cortex and facilitate extinction learning of contextual fear memory through PI3K-Akt signaling pathway in the infralimbic prefrontal cortex and MEK-ERK signaling pathway in the amygdala. In this article, we introduce the functional mechanisms underlying antidepressant-like effects and anti-stress effects of DOP agonists. Then, we employed a valid animal model of depression, chronic vicarious social defeat stress (cVSDS) mice, and investigated that the influence of DOP activation on pathopsychological factors in depression such as the adult hippocampal neurogenesis, hypothalamic-pituitary-adrenal (HPA) axis, and neuroinflammation. First, repeated administrations after the stress period to cVSDS mice with a selective DOP agonist, KNT-127, improved social interaction behaviors and reduced hyperactivation of the HPA axis without affecting hippocampal neurogenesis. Meanwhile, repeated KNT-127 administrations during the cVSDS period prevented the exacerbation of social interaction behaviors, dysregulation of the HPA axis, and excessive new-born neuronal cell death in the hippocampal dentate gyrus. Moreover, in both administration paradigms, KNT-127 suppressed microglial overactivation in the dentate gyrus of cVSDS mice. These results indicate that the underlying mechanism of DOP-induced antidepressant-like effects differ from those of conventional monoaminergic antidepressants. Furthermore, we propose that DOP agonists might have prophylactic effects as well as therapeutic effects on pathophysiological changes in depression.

Major depressive disorder (MDD) is a psychiatric disorder that affects more than 300 million people worldwide and has a serious impact on society. Conventional antidepressants targeting monoamines in the brain based on the monoamine hypothesis are known to take a prolonged time to be effective or less effective in 30% of MDD patients. Hence, there is a need to develop antidepressants that are effective against treatment-resistant depression and have a new mechanism different from the monoamine hypothesis. An increasing number of research groups including us have been establishing that pituitary adenylate cyclase-activating polypeptide (PACAP) and one of its receptors, PAC1 receptor, are closely related to the etiology of stress-related diseases such as MDD. Therefore, it is strongly suggested that the PAC1 receptor is a promising target in the treatment of psychiatric disorders. We developed a novel, non-peptidic, small-molecule, high-affinity PAC1 receptor antagonists and conducted behavioral pharmacology experiments in mice to characterize a novel PAC1 receptor antagonist as a new option for MDD therapy. The results show that our novel PAC1 receptor antagonist has the potential to be a new antidepressant with a high safety profile. In this review, we would like to present the background of developing our novel PAC1 receptor antagonist and its effects on mouse models of acute stress.

Allergic diseases (e.g., food allergies) are a growing problem, with increasing numbers of individuals experiencing them worldwide. Congruently, the adverse reactions (e.g., anaphylaxis) associated with the administration of vaccines against emerging infectious diseases such as coronavirus disease 2019 (COVID-19) have become a familiar problem. Allergic diseases, which have a wide variety of symptoms, are difficult to prevent or cure; treatment is currently limited to therapeutic drugs or allergen immunotherapy. Therefore, elucidating new allergic regulatory factors that control the allergic (i.e., mast cell) responses is important. While investigating the regulatory mechanisms of the wide range of allergic responses of mast cells, we found that the affinity of allergens to immunoglobin E (IgE) regulates allergic inflammation through the differences in the secretory responses of mast cells and the types and interactions of the cells infiltrating the tissues. Here, we present our recent findings regarding the affinity of allergens to IgE in regulating allergic inflammation, heterogeneous secretory granules inducing diverse secretory responses, and mast cells interacting with neutrophils, thereby regulating the various allergic responses.

The epigenome can adequately regulate the on/off states of genes in response to external environmental factors and stress. In recent years, it has been observed that the epigenome, which is modulated through DNA methylation, histone modifications, and chromatin remodeling, changes with age. Alterations in the epigenome lead to the loss of cell-specific epigenome/identity, which in turn triggers a decline in tissue function. In mammals, postnatal epigenomic variations are not only caused by metabolic diseases, such as diabetes or DNA damage, but also by social stress and infectious diseases. Unlike Genome-Wide Association Studies (GWAS), dynamically changing epigenomes, along with their cellular roles, need to be established as objective biomarkers in conjunction with various biological signals, such as walking speed, brain waves, and clinical data. The biological age/aging clock, determined by methylated DNA, has attracted attention, and calorie restriction not only slows the progression of aging, but also seems to suppress it. However, as indicated by gene expression analysis in aging mice, aging is not a linear model, but is represented by nonlinear dynamic changes. Consequently, the development of experimental models and analytical methods that enhance temporal resolution through time-series analysis, tailored to spatial resolution, such as cell distribution and organ specificity, is progressing. Moreover, in recent years, in addition to anti-aging efforts targeting epigenomic variations, global attention has increasingly focused on research and development aimed at rejuvenating treatments, thus leading to the birth of many biotech companies. Aging Hallmarks such as inflammation, stem cells, metabolism, genomic instability, and autophagy, interact closely with the epigenome. Various postnatal and reversible epigenomic controls of aging, including Yamanaka factors (OKSM and OSK), are now entering a new phase. In the future, the development of aging control using diverse modalities, such as mRNA, artificial peptides, and genome editing, is expected, along with an improved molecular understanding of aging and identification of useful biomarkers.

Molecular oxygen suffices the ATP production required for the survival of us aerobic organisms. But it is also true that oxygen acts as a source of reactive oxygen species that elicit a spectrum of damages in living organisms. To cope with such intrinsic ambiguity of biological activity oxygen exerts, aerobic mechanisms are equipped with an exquisite adaptive system, which sensitively detects partial pressure of oxygen within the body and controls appropriate oxygen supply to the tissues. Physiological responses to hypoxia are comprised of the acute and chronic phases, in the former of which the oxygen-sensing remains controversial particularly from mechanistic points of view. Recently, we have revealed that the prominently redox-sensitive cation channel TRPA1 plays key roles in oxygen-sensing mechanisms identified in the peripheral tissues and the central nervous system. In this review, we summarize recent development of researches on oxygen-sensing mechanisms including that in the carotid body, which has been recognized as the oxygen receptor organ central to acute oxygen-sensing. We also discuss how ubiquitously the TRPA1 contributes to the mechanisms underlying the acute phase of adaptation to hypoxia.

The tumor necrosis factor receptor (TNFR)-associated factor (TRAF) family of molecules are intracellular adaptors that regulate cellular signaling through members of the TNFR and Toll-like receptor superfamily. Mammals have seven TRAF molecules numbered sequentially from TRAF1 to TRAF7. Although TRAF5 was identified as a potential regulator of TNFR superfamily members, the in vivo function of TRAF5 has not yet been fully elucidated. We identified an unconventional role of TRAF5 in interleukin-6 (IL-6) receptor signaling involving CD4 + T cells. Moreover, TRAF5 binds to the signal-transducing glycoprotein 130 (gp130) receptor for IL-6 and inhibits the activity of the janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway. In addition, Traf5-deficient CD4 + T cells exhibit significantly enhanced IL-6-driven differentiation of T helper 17 (Th17) cells, which exacerbates neuroinflammation in experimental autoimmune encephalomyelitis. Furthermore, TRAF5 demonstrates a similar activity to gp130 for IL-27, another cytokine of the IL-6 family. Additionally, Traf5-deficient CD4 + T cells display significantly increased IL-27-mediated differentiation of Th1 cells, which increases footpad swelling in delayed-type hypersensitivity response. Thus, TRAF5 functions as a negative regulator of gp130 in CD4 + T cells. This review aimed to explain how TRAF5 controls the differentiation of CD4 + T cells and discuss how the expression of TRAF5 in T cells and other cell types can influence the development and progression of autoimmune and inflammatory diseases.

Since the approval of HIF-PH inhibitors, HIF-PH inhibitors have been used clinically, and many studies and clinical case reports have been reported in Japan. A lot of information has been accumulated on clinical usage. However, HIF-PH inhibitors require careful administration for cancer patients due to their action mechanism through upregulating hypoxia-inducible factors (HIFs) level. In cancer cells, HIFs affect tumor progression and contribute to chemo- and radio-resistance. On the other hand, upregulation of HIFs in immune cells is associated with inflammation and suppress tumor progression. However, these controversial effects are not clear in in vivo model. It is needed to reveal whether upregulating HIFs level is beneficial for cancer therapy or not. We have previously reported that HIF-PH inhibitor treatment in tumor bearing mice model led to reconstitute tumor blood vessel and inhibit tumor growth. In addition, these phenomena were caused by tumor infiltrated macrophages and they altered these phenotypes. In this review, we will describe our findings on the mechanism of tumor growth suppression by HIF-PH inhibitors. We also want to mention the risks and benefits of future HIF-PH inhibitors.

Recently, feeding damage by the olive weevil Pimelocerus (Dyscerus) perforatus Roelofs, which utilizes olive trees (Olea europaea Linne) as a host plant, has become the biggest obstacle to olive cultivation in Japan. We previously identified several volatile plant-derived natural products that exhibit repellent activity against olive weevils. In this study, we conducted a pilot test of repellents in an olive orchard along with the use of insecticide. During three consecutive years from 2021 to 2023, the first year was the observation period, and the second and third years were set aside for a trial period for o-vanillin and geraniol as repellents, respectively. Using o-vanillin, the number of adult olive weevil outbreaks decreased to almost half a year in the experimental area, the use of geraniol then resulted in a drastic reduction of the number of individual olive weevils in the experimental area. In contrast, adults and larvae outbreaks increased in the control area without a repellent, despite the use of insecticide. These results indicate that the volatile repellents drove the olive weevils away and kept them at bay in the field. Based on the observations, we will be able to provide a new approach for the control of olive cultivation, including fruit and leaves used for commercial purposes, following integrated pest management (IPM) practices, such as reducing environmental poisoning from intense insecticides, and returning olive weevils to their original habitat outside of olive orchards.

Cysts are abnormal fluid-filled sacs found in various human organs, including the liver. Liver cysts can be associated with known causes such as parasite infections and gene mutations, or simply aging. Among these causes, simple liver cysts are often found in elderly people. While they are generally benign, they may occasionally grow but rarely shrink with age, indicating their clear association with aging. However, the mechanism behind the formation of simple liver cysts has not been thoroughly investigated. Recently, we have generated transgenic mice that specifically overexpress fibroblast growth factor (FGF)18 in hepatocytes. These mice exhibit severe liver fibrosis without inflammation and spontaneously develop liver cysts that grow with age. Our findings suggest that simple liver cysts can be induced by fibrosis accompanied by sterile inflammation or injury, whereas fibrosis accompanied by severe inflammation or injury may lead to cirrhosis. We also discuss the detrimental effects of disease- and aging-associated fibrosis in various organs, such as the heart, lungs, and kidneys. Additionally, we provide a brief summary of the two currently approved anti-fibrotic drugs for idiopathic pulmonary fibrosis, nintedanib and pirfenidone, as well as their possibility of future expansion of application toward other fibrotic diseases.

Sleep is fundamental for living animals. Although they are not conscious during sleep, their brains are continuously working. This neural activity during sleep can be reflected by neural oscillations closely related to cognitive function. While the relationship between neural activity in sleep and cognition has been extensively investigated, it is not fully understood how neural activity in sleep and relevant memory are modulated by specific receptors. In particular, I focused on melatonin receptors and their agonist, ramelteon. While the effects of ramelteon on sleep have been widely documented, it is still poorly understood how ramelteon affects learning and memory as well as neural activity in sleep. To address this question, I first recorded neural oscillations in the neocortex of rats treated with ramelteon and found that ramelteon promoted non-rapid eye movement (NREM) sleep and increased fast gamma power in the primary motor cortex during NREM sleep. I then evaluated the behavioral performance of ramelteon-treated mice using the novel object recognition task and the spontaneous alternation task, demonstrating that ramelteon enhanced object recognition memory and spatial working memory. These results shed light on new aspects of the functions of melatonin receptors.

Recently, radiotheranostics, which systematically combines diagnosis by nuclear medicine imaging and treatment by internal radiotherapy, constitutes a new modality in cancer treatment, with some clinical reports showing marked effects on cancer. We have been developing multifunctional chelates containing a target recognition unit, a radiation release unit, and a radioactivity pharmacokinetics control unit in the same molecule to develop efficient agents for cancer radiotheranostics based on chemical control of radioactivity pharmacokinetics. Using these compounds, we have achieved improved cancer accumulation and reduced renal accumulation in tumor-bearing mice, and have developed novel hybrid radiotheranostic agents that can be applied to simultaneously perform target-specific molecular imaging using γ-ray emitting radionuclides and internal radiotherapy using α-particle-emitting radionuclides. For example, 111 In/ 225 Ac-labeled PSMA-DA1, which targets prostate-specific membrane antigen (PSMA) for radiotheranostics, achieved clear in vivo imaging of PSMA in tumor-bearing mice and showed marked tumor growth inhibition. In addition to PSMA, this platform for radiotheranostics has also shown efficacy against various cancer target molecules, including carbonic anhydrase IX (CA-IX), which is highly expressed in hypoxic regions of cancer, and glucagon-like peptide-1 receptor (GLP-1R), which is highly expressed in insulinomas. This review presents these recent results of our studies on radiotheranostics for cancer.

The present study verified that it is possible to analyze melengesterol acetate using the existing multi-residue method. Melengestrol acetate was extracted from livestock products using acidic acetonitrile acidified with acetic acid in the presence of n-hexane and anhydrous sodium sulfate. The crude extracts were cleaned up using an octadecylsilanized silica gel cartridge column. Separation by HPLC was performed using an octadecylsilanized silica gel column with linear gradient elution of 0.1 vol% formic acid and acetonitrile containing 0.1 vol% formic acid. For the determination of the analyte, tandem mass spectrometry with positive ion electrospray ionization was used. In recovery tests using four livestock products fortified with maximum residue limits levels of melengestrol acetate (0.001-0.02 mg/kg), the truenesses ranged from 82% to 100%, and the repeatabilities for the entire procedure ranged from 0.5 RSD% to 5.6 RSD%. In recovery tests using 11 livestock products fortified with 0.0005 mg/kg of melengestrol acetate, the truenesses ranged from 88% to 99%, and the repeatabilities ranged from 1.3 RSD% to 5.4 RSD%. The limit of quantification for melengestrol acetate in livestock products was 0.0005 mg/kg.