Men with benign prostatic hyperplasia (BPH) often experience symptoms of overactive bladder (OAB), and bladder outlet obstruction (BOO) is one of cause of BPH. It has been suggested that bladder myogenic microcontractions or micromotions may partly contribute to the development of urgency (bladder sensory (afferent) hypersensitivity) in OAB related to BOO. We have investigated the direct effects of drugs (β3-adrenoceptor agonists, α1-adrenoceptor antagonists, PDE type5 inhibitors) on the bladder afferent function in BOO rats. In our results, almost all drugs may act on the bladder afferent function, and mirabegron inhibits the afferent activities through the suppression of the bladder myogenic microcontractions in BOO condition. Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) causes long-standing pain and/or storage symptoms including storage symptoms, such as urgency and frequency. We evaluated the likelihood of deterioration of bladder sensation in a carrageenan-induced CP/CPPS model. In results, the carrageenan-induced CP/CPPS rat model showed edema, ischemia, and inflammatory pain in the prostate, whereas a little change was detected in bladder sensation. These findings demonstrated that the bladder sensation is unlikely deteriorated in this model, suggesting CP/CPPS is possibly overlapping with symptoms in BPH.

Infertility is one of the late side effects of cancer treatment. Expansion of anti-cancer treatment allow patients to have more life time, however infertility is becoming a matter damaging QOL during the young cancer survivors. The passive strategy such as avoiding the gonad-toxic drug or decreasing the total volume of them and shielding the gonads against cancer therapy has been conducted. To preserve the fertility of young female, ovary tissue cryopreservation is becoming a standard over the world after the success of offspring from cryopreserved ovary tissue autograft was reported. Sperm preservation method is established for the male fertility preservation method, however this is only applicable for sexually matured male patients. For the sake of preserving fertility of sexually immature male patients, many trials using cryopreserved testis tissues or testicular cells have been undergone. Recently, in vitro gametogenesis from stem cell of the human and the mouse to primordial germ cell like cell has been achieved. Here the previous challenges and the latest reports for obtaining functional sperm from immature testis and the reconstruction of spermatogonial niche as a potential approach for preserving fertility procedure are described.

It has long been known that nitric oxide (NO) is involved in the initiation and maintenance of erection. For this reason, NO supplementation has been considered a useful target for the treatment of erectile dysfunction (ED), and many studies have been conducted. However, to date, no compounds have been launched for a variety of reasons. One of the reasons is the systemic adverse reactions. In order to solve this problem, we focused on light-controlled NO donors and investigate their potential application in ED treatment. Light-controlled NO donors have three main characteristics: first, they release NO only at the site of light irradiation, second, they release NO only during the time of light irradiation, and third, the amount of NO released can be controlled according to the light intensity. These features suggest that light-responsive NO donors may be useful for ED therapy. Our group has been working on the development of light-controlled NO donors, and has so far developed the blue light-controlled NO donor “NOBL-1”, the yellowish-green light-controlled NO donor “NO-Rosa”, and the red light-controlled NO donor “NORD-1”. Our recent studies have shown that NORD-1 and red light can enhance the erectile response in rats at the in vivo level. Next, we examined the effects of NORD-1 and red light using a neurogenic ED model, which is believed to be less effective than existing ED drugs. The results showed that red light irradiation after NORD-1 administration enhanced the erectile response and improved ED in the neurogenic ED model. These results suggest that NORD-1, a light-controlled NO donor, and red light can enhance the erectile response in rats and may have potential as an ED drug. Although optimization of the compound is essential, it is expected that a new therapeutic approach called photobiotherapy for ED will be developed in the future.

Mammalian sperm have to undergo several physiological and biochemical changes to be fertilization-competent. These changes are collectively called “capacitation”. Capacitated sperm show frantic whiplash-like flagellar movement called “hyperactivation”. Recently, it has been reported that treatments of sperm to enhance hyperactivation improve in vitro fertilization (IVF) and development of the fertilized embryos. This fact indicates that hyperactivation is an attractive target to improve assisted reproductive technologies. However, the detailed mechanisms which regulate hyperactivation have not been fully elucidated. Recently, it was found out that Na⁺ and K⁺ concentration of the oviductal fluid considerably differs from those in the medium used for IVF. Thus, the effect of the Na⁺ and K⁺ concentration on sperm hyperactivation was investigated using hamsters as a model. The results revealed that hamster sperm hyperactivation was suppressed by extracellular Na⁺ via an action of Na⁺/Ca²⁺ exchanger. Moreover, it was shown that the activity of testis specific isoform of Na⁺/K⁺ ATPase (NKA) α subunit, α4, is necessary for the hyperactivation-associated change of the flagellar movement. By contrast, there was no significant effect of raising the K⁺ concentration up to 20 mM on sperm hyperactivation although it significantly depolarized the membrane potential. These results suggests that transporters involved in primary and secondary active transport which regulates cellular Na⁺ homeostasis has a crucial role in the regulation of hyperactivation, and these transporters can be an attractive target for the improvement of assisted reproductive technologies.

G-quadruplex (G4) is a unique nucleic acid structure that formed when a four-stranded structure is produced within a single-stranded guanine-rich sequence. Four guanine molecules form a square planar arrangement, termed G-quartet, which are stacked on top of each other to form the G4 structure in DNA (G4DNA) and in RNA (G4RNA). Recent studies have revealed that G4DNA and G4RNA are folded in cells, which suggested their biological and pharmacological significance in DNA replication, transcription, epigenetic modification, and RNA metabolism. So far, we have reported the following; 1) G4 is a target of cognitive function therapy for ATR-X intellectual disability syndrome, in which mutations are found in a G4 binding protein ATRX. 2) G4 is formed in heterochromatin depending on neuronal development. 3) G4 promotes prionoids in a CGG triplet repeat disease, Fragile X-associated tremor/ataxia syndrome (FXTAS). 4) 5-aminolevulinic acid is a potential candidate drug for treating some neurological diseases through the G4 binding ability. In this review, we summarized the significant roles of G4 in neurological diseases.

Autism spectrum disorder (ASD) is a developmental disorder characterized by communication disorders and behavioral limitations, and its high prevalence has attracted increasing social attention in recent years. However, the pathogenesis of ASD is still not fully understood because of its diversity and the suspected involvement of many causative genes and environmental factors. Therefore, analyses using animal models that can isolate and simplify the causes of ASD are thought to be helpful in understanding the disease. In this article, we will introduce the pathogenic mechanism of ASD revealed by the analysis using a mouse model reproducing the mutation of CHD8, which is a reliable candidate gene for the cause of ASD, and discuss the possibility of therapeutic targets predicted from this analysis.

Glutamate receptors mediate excitatory neurotransmission in the central nervous system, which have essential roles in our learning and memory. Recent studies have revealed that the trafficking of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA)-type glutamate receptors (AMPA receptors) are dynamically regulated during synaptic plasticity, the cellular basis of learning and memory. Conventionally, biochemical methods such as surface-biotin labeling or genetic incorporation of fluorescent proteins have been utilized to analyze the AMPA receptors dynamics. However, conflicting findings have been reported because of serious issues in these conventional methods. As the alternative, we have developed a new method for labeling AMPA receptors endogenously expressed in neurons by chemical approaches. This is based on a covalent chemical labeling strategy driven by selective ligand-protein recognition to tether small fluorophores to the target receptors, termed ligand-directed acyl imidazole chemistry. This method has successfully visualized AMPA receptors endogenously expressed in neurons. However, the original method required several hours for fluorophore labeling, which hampered analyzing the dynamics of AMPA receptors in detail. As the alternative, we have recently developed an improved strategy for rapid and selective labeling of chemical probes to cell-surface AMPA receptors by combining ligand-directed chemistry and bio-orthogonal click chemistry. This method allowed to quantify their trafficking, which revealed unique features of AMPA receptors such as long lifetime and rapid recycling in neurons. Notably, this method can be expanded to other receptors. Thus, the two-step labeling method would be a useful tool for understanding the physiological or pathophysiological roles of glutamate receptors in neurons.

The excitatory glutamate AMPA receptor is the most important molecule for processing information in the brain. We have succeeded in developing the first-in-class PET drug ([¹¹C] K-2) that visualizes AMPA receptors in the living human brain (Nature Medicine 2020). AMPA-PET imaging of patients with psychiatric disorders can disclose the molecular pathology underlying the diseases, contributing to the creation of novel disease animal models based on the phenotype of patients. Our research approach, basic and clinical fusion research, is expected to elucidate the biological basis for multiple neuropsychiatric disorders. AMPA-PET is attributed to the development of therapeutic methods targeting AMPA receptors, which have been delayed worldwide due to the inability of the technology to visualize AMPA receptors in human, leading to the foundation for the development of innovative diagnostic and therapeutic methods based on the molecular evidence of “seeing and treating AMPA receptors.”

We are constructing the “Percellome Database” containing many transcriptomes of mice exposed to a series of chemicals to elucidate the molecular mechanism of toxicity and to develop toxicity prediction technology. Acute toxicity of a chemical can be predicted to a certain extent by searching the similarity of the transcriptomes obtained by the single-dose exposure experiments. In addition, we are analyzing the relation between the transcriptome and the epigenome i.e. histone modification and genomic DNA methylation to understand the molecular mechanism of the repeated dose toxicity. We are attempting to expand the scale and improve the efficiency of the analysis by introducing artificial intelligence technologies. This approach should maximize the use of toxicogenomics technology for optimizing the experimental protocols for repeated dose toxicity studies towards 3Rs principle, and optimizing the process of in silico toxicity prediction by combining the available big data.