Biological & pharmaceutical bulletin最新文献

QO58 (5-(2,6-dichloro-5-fluoropyridin-3-yl)-3-phenyl-2-(trifluoromethyl)-1H-[1,5-a] pyrimidin-7-one) is currently used as a specific activator of the Kv7 (KCNQ) family of K⁺ channels. Here, we report an unexpected potentiating effect of this drug on nicotinic acetylcholine receptors. We recorded the whole-cell responses to the rapid application of nicotine with the Cs⁺-based pipette solution in intracardiac ganglion neurons freshly dissociated from the rat heart. Nicotine-induced inward currents were concentration-dependently blocked by mecamylamine, but not by 1 μM atropine at a holding potential of -60 mV. While the application of QO58 per se evoked a persistent inward current at this holding potential, 10 μM QO58 potentiated the peak amplitude of the nicotine-induced current. The QO58-induced inward currents were inhibited by the Kv7 channel blockers XE991 and Ba²⁺, but not by mecamylamine. On the other hand, the nicotine-induced current potentiated by QO58 was fully inhibited by mecamylamine. The facilitatory action of QO58 on the nicotinic response was unaffected by Ba²⁺. QO58 did not affect the reversal potential of the nicotine-induced current. QO58 apparently shifted the concentration-response curve of nicotine to the left. The half-maximal effective concentrations for nicotine in the absence and presence of 10 μM QO58 were 10.2 and 4.3 μM, respectively. These results suggest that QO58 acts as a positive allosteric modulator of nicotinic acetylcholine receptors. Given the prevalence of nicotinic receptor signaling, the present observations should be considered in future studies on the roles of Kv7 channels in the function of neural circuits and diseases.

The central histamine system is involved in several physiological behaviors and neurological disorders, including the sleep-wake cycle, anxiety-related behaviors (both high and low anxiety), and attention deficit hyperactivity disorder (ADHD). Histamine is synthesized from l-histidine by histidine decarboxylase (HDC) and primarily metabolized by histamine-N-methyltransferase (HNMT) in the central nervous system. We previously reported that mice with intermittent sleep deprivation may exhibit impulsive-like symptoms resembling ADHD and low-anxiety behavior. However, the specific role of histaminergic systems in these behaviors remains unclear. In this study, we evaluated HDC expression levels in the hypothalamus as well as the expression of histamine H1 to H4 receptors and HNMT in the hypothalamus and frontal cortex of sleep-deprived mice. Moreover, the effects of administering histidine, a histamine precursor, and inhibitors of each histamine receptor on sleep deprivation-induced low-anxiety and impulsive-like behaviors were examined using an elevated plus maze test. The expressions of HDC and histamine H1 and H3 receptors in the hypothalamus increased, while that of histamine H1 receptors in the frontal cortex of sleep-deprived mice decreased. The low-anxiety and impulsive-like behaviors in intermittent sleep-deprived mice significantly decreased and increased, respectively, following the administration of histamine H1 and H3 receptor blockers and histidine. Collectively, these findings suggest that the low-anxiety behavior and impulsive-like ADHD symptoms induced by intermittent sleep deprivation may result from the overstimulation of histamine H1 and H3 receptors by elevated histamine, together with increased hypothalamic HDC expression. Furthermore, they suggest that sufficient sleep may contribute to ameliorating ADHD symptoms.

Selenium (Se) is an essential micronutrient for animals. Various chemical forms of Se exist in nature, each with distinct physiological, nutritional, and toxicological properties. In this study, we aimed to determine whether dimethyldiselenide (DMDSe, a monomethylated Se (MMSe) compound) and dimethylselenide (DMSe, a dimethylated Se compound), known gut bacterial metabolites, could serve as Se sources in rats. DMDSe could be utilized for selenoprotein biosynthesis and was metabolized into urinary selenometabolites. By contrast, DMSe was not utilized for selenoprotein biosynthesis but was further methylated to trimethylselenonium ion (TMSe), one of the urinary Se metabolites. Our findings indicate that dimethylated Se is not readily available as an Se source in rats, unlike MMSe. Selenoprotein biosynthesis requires selenide, an unmethylated form of Se, in the metabolic pathway. Our observations support the hypothesis that demethylation occurs on MMSe as a reversible methylation step but not on dimethylated Se. This suggests that the second methylation step is crucial for inactivating Se and plays a significant role in metabolism to maintain Se homeostasis in animals. Gut microbiota, which can synthesize both DMDSe and DMSe, may contribute to host Se metabolism through methylation processes.

Surveillance of antimicrobial consumption (AMC) is important for controlling antimicrobial resistance (AMR). In recent years, the landscape of infectious diseases has changed due to factors such as the introduction of the National Action Plan (NAP) on AMR and the coronavirus disease 2019 (COVID-19) pandemic. However, their impact on the consumption of broad-spectrum antimicrobial and anti-methicillin-resistant Staphylococcus aureus (MRSA) agents remains unexplored. This study aimed to clarify trends in the consumption of these agents up to 2021, considering the spread of NAP and the COVID-19 pandemic. We used sales data from IQVIA Japan, which were analyzed using an interrupted time-series analysis, with April 2016 (introduction of NAP) and April 2020 (first declaration of a state of emergency) as key change points. The oral broad-spectrum antimicrobial agents consumption decreased, and the spread of the NAP (p-value: 8.15 * 10^-3, 95% confidence intervals (95% CI): -7.70 * 10^-3 to -2.06 * 10^-3) and behavioral restrictions for the COVID-19 pandemic (p value: 1.60 * 10^-8, 95% CI: -0.35 to -0.17) were significantly related to this change. Conversely, there was no notable change in the consumption of anti-MRSA agents from 2013 to 2021. Thus, the introduction of NAP and the COVID-19 pandemic may have been more effective in decreasing the consumption of oral broad-spectrum antimicrobial agents. Since antibiotics are used to treat infections across multiple anatomical therapeutic chemical classifications, continuous evaluation based on treatment purposes is important.

Nephropathy II Decoction (NED) is a widely used Chinese medicinal formulation for managing chronic kidney disease (CKD). Despite its extensive application, the precise mechanisms underlying its therapeutic effects remain poorly understood. This study aims to elucidate the role of NED in attenuating renal fibrosis and to explore its impact on the gut-kidney axis. The principal constituents of NED were analyzed using ultra-performance LC-tandem mass spectrometry (UPLC-MS/MS). A bilateral renal ischemia-reperfusion injury (bIRI) model was employed to induce fibrosis. RT-qPCR was utilized to assess the expression of mRNA related to the toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) and nuclear factor-κB (NF-κB) signaling pathway. Western blotting analysis was performed to identify changes in renal fibrosis markers, TLR4/MyD88/NF-κB pathway proteins, and the colon proteins ZO-1 and Occludin-1. Serum levels of uremic toxins were quantified using enzyme-linked immunosorbent assay (ELISA), and 16S ribosomal RNA (rRNA) gene sequencing was conducted to explore changes in the gut microbiome of the mice. Our study demonstrated that mice in the NED group exhibited reduced serum creatinine, blood urea nitrogen, and urinary protein levels, alongside improvements in kidney damage and a decrease in renal fibrosis markers. In the bIRI group, TLR4/MyD88/NF-κB protein and mRNA levels, as well as intestinal tight junction proteins and enterogenic uremic toxins, were significantly reduced. NED treatment reversed these changes and modified the gut microbiota. Furthermore, fecal microbial transplantation (FMT) alleviated kidney damage and fibrosis in bIRI mice. In summary, NED ameliorates kidney injury and fibrosis by modulating the gut microbiota and may further attenuate fibrosis through the inhibition of TLR4 expression, thereby influencing the gut-kidney axis.

In rats, platelet-activating factor (PAF) has been reported to increase mechanical activity in various gastrointestinal smooth muscles (SMs) except for esophagus SM. The aim of this study was to examine whether PAF increases mechanical activity in rat esophagus longitudinal SM (LSM) and to compare PAF actions in esophagus LSM with those in other gastrointestinal LSMs. PAF (10^-9-10^-6 M) increased esophagus LSM mechanical activities in a concentration-dependent manner; PAF mainly elicited basal tension increases that were almost eliminated by a PAF receptor antagonist CV-6209 (10^-5 M; against 10^-6 M PAF). In the LSM of the gastric fundus, which is similar to esophagus LSM in that it is derived from the foregut during development, PAF (10^-6 M) increased basal tension to a comparable, albeit significantly different, magnitude as in esophagus LSM. In contrast, in LSMs of the duodenum-jejunum, ileum, and ascending colon, which are derived from the midgut, and the descending colon, which is derived from the hindgut, the ability of PAF (10^-6 M) to increase basal tension was less than that in esophagus and gastric fundus LSMs. Interestingly, in ascending colon LSMs, PAF (10^-6 M) induced oscillatory contractions with a small increase in basal tension. PAF-induced contractions were positively correlated with the mRNA expression levels of the PAF-degrading enzymes Pafah2 (R = 0.82) and Pafah1b3 (R = 0.51). These results suggest that PAF strongly stimulates mechanical activities that are mainly accompanied by basal tension increases in rat LSMs of the gastrointestinal tracts that are derived from the foregut during embryogenesis.

Thiopurines, such as 6-mercaptopurine (6-MP) and azathioprine, are converted to the inactive metabolites 6-thioxanthin (6-TX) and 6-thiouric acid (6-TUA). Molybdenum-containing oxidoreductases, aldehyde oxidase (AOX) and xanthine oxidase (XO), are involved in the oxidation of 6-MP to 6-TX; XO inhibitors affect the therapeutic efficacy of thiopurines and the incidence of adverse effects, such as liver and blood disorders. However, the role of AOX in the pharmacokinetics of 6-MP remains unclear. To clarify the clinical importance of AOX-mediated drug-drug interactions, we evaluated whether drugs that inhibit AOX affect 6-MP metabolism. The metabolism of 6-MP to 6-TX was strongly inhibited by AOX inhibitors (amitriptyline, chlorpromazine, clomipramine, clozapine, hydralazine, quetiapine, and raloxifene) in a reaction mixture containing human liver cytosol. The inhibition of 6-TX production rate by each AOX inhibitor was 60-70% at high concentrations, although the XO inhibitor febuxostat showed an inhibition rate of 10-30%. Furthermore, the combination of febuxostat and each AOX inhibitor showed greater inhibition than when each compound was added alone. The AOX inhibitor did not alter 6-MP oxidation by recombinant XO. These results suggest that AOX inhibition may affect the pharmacokinetics of thiopurines. However, because of the lower activity of AOX in rats than that in humans, the contribution of AOX could not be assessed using in vivo experiments. Further studies are needed to evaluate the contribution of AOX to the therapeutic and adverse effects of thiopurines, both in clinical studies and in animal models of liver humanization.

Opioid receptors and their endogenous ligands are novel targets for the treatment of depression. The nociception (NOP) receptor is structurally similar to the opioid receptor, but NOP is known to have a low affinity for the opioid receptor subtypes μ, δ, and κ. In previous studies, we synthesized peptides with a high affinity for opioid receptors and investigated their antidepressant-like effects in mice. However, we have not yet examined whether NOP-related analogs have antidepressant-like effects. Herein, we synthesized NOP analogs (peptide-1-peptide-8) by solid-phase peptide synthesis using the 9-fluorenylmethyloxycarbony (Fmoc) method with Acetyl-Arg-Tyr-Tyr-Arg-Ile-Arg-NH₂ (Ac-RYYRIR-NH₂) as the lead compound. We examined the affinities and antagonistic activities of the analogs for the NOP receptor using receptor-binding and mouse vas deferens assays, and their effects on the duration of immobile behavior in a tail suspension test. Peptide-6 showed a high affinity and antagonistic activity for the NOP receptor. The intracerebroventricular administration of peptide-6 in mice shortened the duration of immobile behavior, whereas the co-administration of NOP inhibited this effect. Moreover, intracerebroventricular administration of the selective NOP receptor antagonist J-113397 showed antidepressant-like effects in mice. These data suggest that peptide-6 exerts an antidepressant-like effect via inactivation of the central NOP receptor in mice and may represent a lead compound for the development of antidepressant drugs in the future.

Cerebral ischemia/reperfusion (I/R) injury caused by resumed blood flow to an infarcted area contributes to poor patient prognosis due to a lack of treatment strategies. While the blood-brain barrier (BBB) is the greatest barrier for drug delivery to the brain, temporary disruption to the BBB after brain I/R injury allows for delivery of cerebroprotective drug-encapsulated nanoparticles into the brain parenchyma. However, issues remain with delivering drugs to the I/R region using nanoparticles, such as the limited therapeutic time window due to BBB repair over time. To overcome these challenges, we developed nanoparticles specifically targeting the I/R environment. Human umbilical vein endothelial cells (HUVECs) were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R), an in vitro I/R model. Low-density lipoprotein receptor (LDLR) mRNA was upregulated early during the reoxygenation process. Furthermore, immunostaining of OGD/R-treated cells showed an increase in LDLR expression. Next, we constructed a peptide that mimics the LDLR binding recognition site on LDL, and modified liposomes to display the peptide on their surface. Peptide-modified liposomes showed targeting ability to the LDLR on cells. Accumulation of peptide-modified liposomes was significantly increased in OGD/R treated cells compared with controls, and was reduced by blocking LDLR using its antibody. These results demonstrate upregulation of LDLR and LDLR-mediated liposome uptake in OGD/R stressed cells. In conclusion, LDLR binding recognition site mimicking peptide-modified liposomes are a useful drug carrier that can recognize I/R injured endothelial cells.

A major oxidized base, 8-oxo-7,8-dihydroguanine (G^O, 8-hydroxyguanine), is involved in cancer initiation. G^O induces untargeted base substitution (action-at-a-distance) mutations as well as targeted G→T transversions in human cells. Uracil also induces similar untargeted mutations. An abasic site is the common product of their specific DNA glycosylases (OGG1 and UNG2, respectively) and is an expected intermediate of the untargeted mutation pathway. Subsequently, the DNA strand is nicked by AP endonuclease. In this study, a shuttle plasmid containing a true (natural) abasic site was introduced into human U2OS cells. The frequency of action-at-a-distance mutations was much lower for the abasic site than that for uracil, although the abasic site is considered the mutational intermediate of the latter. Moreover, nicked DNA containing a 5'-phosphate induced untargeted mutations less frequently than that without a 5'-phosphate, and their mutation frequencies were much higher than that of the abasic site. The unexpectedly low mutagenic potential of the true abasic site suggests that the mechanism of action-at-a-distance mutations is complex.