Chemogenetic activation of histamine neurons promotes retrieval of apparently lost memories.

Memory retrieval can become difficult over time, but it is important to note that memories that appear to be forgotten might still be stored in the brain, as shown by their occasional spontaneous retrieval. Histamine in the central nervous system is a promising target for facilitating the recovery of memory retrieval. Our previous study demonstrated that histamine H3 receptor (H3R) inverse agonists/antagonists, activating histamine synthesis and release, enhance activity in the perirhinal cortex and help in retrieving forgotten long-term object recognition memories. However, it is unclear whether enhancing histaminergic activity alone is enough for the recovery of memory retrieval, considering that H3Rs are also located in other neuron types and affect the release of multiple neurotransmitters. In this study, we employed a chemogenetic method to determine whether specifically activating histamine neurons in the tuberomammillary nucleus facilitates memory retrieval. In the novel object recognition test, control mice did not show a preference for objects based on memory 1 week after training, but chemogenetic activation of histamine neurons before testing improved memory retrieval. This selective activation did not affect the locomotor activity or anxiety-related behavior. Administering an H2R antagonist directly into the perirhinal cortex inhibited the recovery of memory retrieval induced by the activation of histamine neurons. Furthermore, we utilized the Barnes maze test to investigate whether chemogenetic activation of histamine neurons influences the retrieval of forgotten spatial memories. Control mice explored all the holes in the maze equally 1 week after training, whereas mice with chemogenetically activated histamine neurons spent more time around the target hole. These findings indicate that chemogenetic activation of histamine neurons in the tuberomammillary nucleus can promote retrieval of seemingly forgotten object recognition and spatial memories.

Density predictive model for an outbreak in adult female Aedes albopictus (Diptera: Culicidae) in Japan.

We developed a predictive model for activities and outbreaks of female Aedes albopictus Skuse, using meteorological data. The number of Ae. albopictus collected from human bait-sweep net collection (h-BNC) surveillance, conducted by the local government between 2010 and 2019 in Japan, was adopted as a mosquito-activity indicator. The best model was composed of the backward cumulative and backward moving mean of meteorological data (parameters that were measured daily include mean, maximum, and minimum temperature, mean humidity, amount of precipitation, maximum wind speed, and sunshine hours). The root mean squared error (RMSE) and the coefficient of determination (R2) of the best model for the test set, which was not included in the training dataset, were 1.33 and 0.74, respectively. The best model was applied to predict the number of Ae. albopictus obtained from our own h-BNC surveillance in Okazaki City, Japan. RMSE and R2 of the results were 1.17 and 0.92, respectively. The present model, using publicly available meteorological values, can predict the collection number of adult Ae. albopictus using h-BNC surveillance thereby providing information to control mosquito activities and outbreaks. Therefore, it may be possible to mitigate the risk of mosquito-borne infections and secondary adverse effects of mosquito bites, such as infectious impetigo and deterioration of the quality of life.

Evaluation of behavioural selection processes in conflict scenarios using a newly developed mouse behavioural paradigm.

Selecting an appropriate behaviour is critical for survival in conflict scenarios, wherein animals face both appetitive and aversive stimuli. Behavioural selection consists of multiple processes: (1) animals remain quiet in a safe place to avoid aversive stimuli (suspension), (2) once they decide to take risks to approach appetitive stimuli, they assess the risks (risk assessment), and (3) they act to reach the reward. However, most studies have not addressed these distinct behavioural processes separately. Here, we developed a new experimental paradigm called the three-compartment conflict task to quantitatively evaluate conflict processes. Our apparatus consisted of start, flat, and grid compartments. Mice needed to explore the grid compartment, where they might receive foot shocks while trying to obtain sucrose. Applying foot shocks increased sucrose acquisition latency in subsequent trials, reflecting elevated conflict levels throughout trials. The time spent in the start compartment and the number of retreats were determined to measure the conflict levels in suspension and risk assessment, respectively. Foot shocks increased these parameters, whereas diazepam decreased them. Our new paradigm is valuable for quantitatively evaluating distinct behavioural processes and contributes to developing effective treatments for psychiatric disorders associated with maladaptive behaviours in conflict scenarios.

[Survey of Arsenic/Heavy Metals and Pesticide Residues in Edible Insects for Human Consumption or Supplied in Japan].

Arsenic (As) and heavy metals (Cd, Hg, Pb, and Cu) and pesticide residues in 14 edible insects were investigated. The maximum levels of elements were 6.15 for As, 0.82 for Cd, 0.50 for Hg, 0.67 for Pb, and 297.7 ppm for Cu. Fenobucarb (or BPMC) has been quantified through GC- and LC-MS/MS analysis at a concentration of approximately 3 ppm. Further studies of the contaminants may help ensure the safety of edible insect consumption.

The impact of pitolisant, an H3 receptor antagonist/inverse agonist, on perirhinal cortex activity in individual neuron and neuronal population levels.

Histamine is a neurotransmitter that modulates neuronal activity and regulates various brain functions. Histamine H3 receptor (H3R) antagonists/inverse agonists enhance its release in most brain regions, including the cerebral cortex, which improves learning and memory and exerts an antiepileptic effect. However, the mechanism underlying the effect of H3R antagonists/inverse agonists on cortical neuronal activity in vivo remains unclear. Here, we show the mechanism by which pitolisant, an H3R antagonist/inverse agonist, influenced perirhinal cortex (PRh) activity in individual neuron and neuronal population levels. We monitored neuronal activity in the PRh of freely moving mice using in vivo Ca2+ imaging through a miniaturized one-photon microscope. Pitolisant increased the activity of some PRh neurons while decreasing the activity of others without affecting the mean neuronal activity across neurons. Moreover, it increases neuron pairs with synchronous activity in excitatory-responsive neuronal populations. Furthermore, machine learning analysis revealed that pitolisant altered the neuronal population activity. The changes in the population activity were dependent on the neurons that were excited and inhibited by pitolisant treatment. These findings indicate that pitolisant influences the activity of a subset of PRh neurons by increasing the synchronous activity and modifying the population activity.

Chronic pain-induced neuronal plasticity in the bed nucleus of the stria terminalis causes maladaptive anxiety.

The comorbidity of chronic pain and mental dysfunctions such as depression and anxiety disorders has long been recognized, but the underlying mechanisms remain poorly understood. Here, using a mouse model of neuropathic pain, we demonstrated neuronal plasticity in the bed nucleus of the stria terminalis (BNST), which plays a critical role in chronic pain-induced maladaptive anxiety. Electrophysiology demonstrated that chronic pain increased inhibitory inputs to lateral hypothalamus (LH)-projecting BNST neurons. Chemogenetic manipulation revealed that sustained suppression of LH-projecting BNST neurons played a crucial role in chronic pain-induced anxiety. Furthermore, using a molecular genetic approach, we demonstrated that chronic pain elevated the excitability of a specific subpopulation of BNST neurons, which express cocaine- and amphetamine-regulated transcript (CART). The elevated excitability of CART-positive neurons caused the increased inhibitory inputs to LH-projecting BNST neurons, thereby inducing anxiety-like behavior. These findings shed light on how chronic pain induces psychiatric disorders, characterized by maladaptive anxiety.

Temporal trend and cross-sectional characterization of urinary concentrations of glyphosate in Japanese children from 2006 to 2015.

BACKGROUND: Over the past two decades, domestic shipments of glyphosate (Gly), in the form of an ionic salt, have been increasing steadily in Japan. This increase has raising concerns about the effects of chemical exposure on children. The International Agency for Research on Cancer classified Gly as a "probably carcinogenic to humans (Group 2A)" in 2015. The purpose of the current study was to analyze Gly in urine samples of Japanese children to determine temporal changes, seasonal changes, and gender differences. METHOD: First-morning urine samples were obtained from 50 Japanese children (4-6-year-old) in October of 2006, 2011, and 2015 (total = 150) to investigate the temporal trends in urinary Gly concentrations. Additionally, first-morning urine samples were collected from 3-year-old children in August-September of 2012 (summer; n = 42) and in February of 2013 (winter; n = 42) to investigate the seasonal and gender differences, and the correlations between urinary Gly concentrations and insecticide exposure biomarkers. Urine samples were analyzed to measure for Gly using a liquid chromatography with tandem mass spectrometry (LC-MS/MS). RESULTS: Detectable Gly concentrations were found in 41% of the 234 children. The 75th percentile and maximum concentrations of urinary Gly were 0.20 and 1.33 µg/L, respectively. The urinary Gly concentration in 2015 was significantly higher than in 2006, suggesting that the Gly exposure levels have been increasing. No seasonal or gender-specific differences in urinary Gly concentrations were observed, and no correlation with insecticide exposure biomarkers was found. CONCLUSION: This study revealed that Gly exposure trends show an increase between 2006 and 2015, and that season and gender were not the exposure-determining factors. Overall, urinary concentrations of Gly were comparable with studies from other countries.

Histamine: A Key Neuromodulator of Memory Consolidation and Retrieval.

In pharmacological studies conducted on animals over the last four decades, histamine was determined to be a strong modulator of learning and memory. Activation of histamine signaling enhances memory consolidation and retrieval. Even long after learning and forgetting, it can still restore the retrieval of forgotten memories. These findings based on animal studies led to human clinical trials with histamine H3 receptor antagonists/inverse agonists, which revealed their positive effects on learning and memory. Therefore, histamine signaling is a promising therapeutic target for improving cognitive impairments in patients with various neuropsychiatric disorders, including Alzheimer's disease. While the memory-modulatory effects of histamine receptor agonists and antagonists have been confirmed by several research groups, the underlying mechanisms remain to be elucidated. This review summarizes how the activation and inhibition of histamine signaling influence memory processes, introduces the cellular and circuit mechanisms, and discusses the relationship between the human histaminergic system and learning and memory.

[Practices and challenges of online laboratory work in pharmacology].

Laboratory work is an essential part of natural science education because it provides students with a valuable opportunity to experience practical scientific research firsthand. In laboratory work in pharmacology, students generally learn about biological mechanisms and drug action mechanisms by analyzing drug actions using laboratory animals. Actual experience with hands and eyes is an important factor in the laboratory work. Under the COVID-19 epidemic, however, we were forced to conduct the laboratory work online. For the laboratory work using isolated organs, we used simulation software, in which students can examine effects of a range of drugs on the smooth muscle within the guinea pig ileum. For the behavioral observation practice, we showed the video of the experiments conducted by the instructors beforehand to the students, and asked them to observe and analyze the behavior. In this review, we will share our challenges to online laboratory work.

[Histamine signaling restores retrieval of forgotten memories].

Histamine is a biological amine that functions as a neurotransmitter in the brain to regulate arousal, appetite, and cognitive functions. Many pharmacological studies using histamine receptor agonists and antagonists have found that histamine promotes memory consolidation and retrieval. More recently, we have revealed that the activation of the brain histaminergic system by H3R antagonists/inverse agonists restores retrieval of forgotten long-term memory in mice and humans. The recovery of memory retrieval may involve histamine-induced excitatory effects. Histamine may increase neuronal excitability throughout the neural circuit, including both neurons that are and are not recruited into the memory trace, similar to noise added to the neural circuits for memory retrieval. Stochastic resonance can explain how adding noise to the circuit enhances memory retrieval. Memory is processed not only by consolidation and retrieval, but also by various processes such as maintenance, reconsolidation, extinction, and reinstatement. Further studies that separately analyze the memory processes are needed to elucidate the whole picture of the effects of histamine on learning and memory. Regarding the human histaminergic system, alterations in histamine signaling have been reported in several neuropsychiatric disorders, and these changes have been suggested to be involved in cognitive dysfunction in patients with the neuropsychiatric disorders. Therefore, the drugs that modulate histamine signaling, including H3R antagonists/inverse agonists, may be effective in the treatment of cognitive dysfunction, including Alzheimer's disease.

Simultaneous herpes zoster rash in the upper extremity and interscapular region that resembles innervation zone of the dorsal ramus of the cervical nerve root: a case report.

In daily medical practice, scapular pain associated with cervical radiculopathy is commonly seen prior to the onset of pain of the upper extremity; however, the cause of the scapular pain is uncertain. We report a case of herpes zoster with simultaneous skin rash in both the upper extremity and interscapular region, which corresponds to the painful scapular region in case of C8 cervical radiculopathy. A 71-year-old healthy woman complained of shoulder and scapular pain followed by a blistering skin rash on both the ulnar side of her upper extremity and intrascapular region on the right side. She was diagnosed with herpes zoster and was prescribed amenamevir as oral treatment with vidarabine ointment. After 1 year, she still had mild causalgia on her III-V fingers and needed oral treatment with pregabalin. To our knowledge, this is the first case report of a herpes zoster rash in the upper extremity and intrascapular region simultaneously. We speculate that the rash in the two regions is caused by the varicella zoster virus (VZV) traveling from the same ganglion, probably the C8 ganglion, considering the dermatome of the rash area in the upper extremity and the intrascapular region correspond to the innervation zone of the medial branches of the dorsal ramus of the cervical nerve root, which resembles the scapular region in case of cervical radiculopathy. This phenomenon implies the mechanism of scapular pain is related to cervical radiculopathy. Further case reports are needed to confirm this.

Development and validation of an analysis method for pesticide residues by gas chromatography-tandem mass spectrometry in Daikenchuto.

Daikenchuto (DKT) is one of the most widely used "Kampo" in Japan as a representative of herbal medicine. Because DKT is made from a natural product like food, it requires the management of pesticides; therefore, an analysis of residual pesticides in Kampo is required. The World Health Organization (WHO) indicates that pesticide residue analysis by the U.S. Pharmacopeia (USP) is required. USP defines 107 compounds containing organochlorine pesticides and organophosphorus pesticides and their metabolites, which have a high residual risk. Accordingly, to guarantee the safety of herbal medicines according to global standards is a very important issue. In this study, we developed an analytical method for 91 compounds, which are listed in USP, using DKT as the subject. The method could extract pesticides from DKT with acetone, elute pesticides with acetonitrile using a SepPak C18 column (5 g) and with ethyl acetate using a DSC-NH2 column (2 g), and perform simultaneous analyses by gas chromatography-tandem mass spectrometry (GC-MS/MS). This method, which could quantify 88 compounds, was validated according to USP. A pesticide residue analysis method that meets USP requirements enables the analysis of pesticide residues with a high residue risk and contributes to improving the safety of "Kampo" and other herbal medicines.

Optimization and validation of a highly sensitive method for determining glyphosate in human urine by solid-phase extraction and liquid chromatography with tandem mass spectrometry: a methodological study.

BACKGROUND: Glyphosate and its salt formulations are nonselective herbicides that have been extensively used worldwide, both for residential and agricultural purposes. The possible carcinogenicity and teratogenicity of glyphosate remain to be elucidated. We developed a sensitive and high-throughput analytical method for urinary glyphosate using liquid chromatography-tandem mass spectrometry with the aim of contributing to glyphosate exposure assessment in epidemiological studies. METHODS: After urine dilution (creatinine matching dilution to 0.05 g creatinine/L), glyphosate was extracted using two types of solid phase extraction columns (SCX and NH2) with automated sample preparation instruments. The eluate was dried and dissolved in the mobile phase, followed by liquid chromatography-tandem mass spectrometry analysis. The optimized method was applied to urine samples obtained from 54 Japanese adults and children. RESULTS: The results from the validation study demonstrated good recoveries (91.0-99.6%), within- and between-run precisions (< 15%), low detection limits (0.1 µg/L), and lower limit of quantification (0.3 µg/L). The detection frequency and median concentration of the urinary glyphosate in Japanese subjects were 59% and 0.25 µg/L (0.34 µg/g creatinine). CONCLUSIONS: Our reliable determination method was successful in measuring urinary glyphosate concentration. Moreover, this is the first biomonitoring report of urinary glyphosate levels in the Japanese general population.

Sacral fatigue fracture in a young girl with no history of trauma or reported athletic activity: a case report.

Sacral fatigue fractures in the young population usually occur due to repetitious physical strain from vigorous athletic activity; they are extremely rare in those younger than 13 years without intense physical activity. We report a case of sacral fatigue fracture in a healthy elementary school girl without any history of trauma or excessive athletic activity. A healthy 11-year-old girl experienced sudden low back pain upon standing after a short break in a normal running exercise for physical education at school. At her first orthopaedic visit, she was unable to walk independently and was limping on her left leg. Neurological examination revealed that the left straight leg raising test was positive at 80 degrees with associated left buttock pain but without motor and sensory deterioration. Radiological examination showed no obvious fractures in the lumbar vertebrae or pelvis. Magnetic resonance imaging demonstrated high intensity signal changes on the short tau inversion recovery image of the left ala, and sacral fatigue fracture in the left ala was diagnosed. She was instructed to rest at home and allowed minimal walking with a crutch under endurable pain for 4 weeks. Within 3 weeks, her low back pain gradually reduced, and after 4 weeks, she could walk independently without gait pain. Sacral fatigue fractures should be considered in the diagnosis of young patients who present with unexplained low back pain.

Prepronociceptin-Expressing Neurons in the Extended Amygdala Encode and Promote Rapid Arousal Responses to Motivationally Salient Stimuli.

Motivational states consist of cognitive, emotional, and physiological components controlled by multiple brain regions. An integral component of this neural circuitry is the bed nucleus of the stria terminalis (BNST). Here, we identify that neurons within BNST that express the gene prepronociceptin (PnocBNST) modulate rapid changes in physiological arousal that occur upon exposure to motivationally salient stimuli. Using in vivo two-photon calcium imaging, we find that PnocBNST neuronal responses directly correspond with rapid increases in pupillary size when mice are exposed to aversive and rewarding odors. Furthermore, optogenetic activation of these neurons increases pupillary size and anxiety-like behaviors but does not induce approach, avoidance, or locomotion. These findings suggest that excitatory responses in PnocBNST neurons encode rapid arousal responses that modulate anxiety states. Further histological, electrophysiological, and single-cell RNA sequencing data reveal that PnocBNST neurons are composed of genetically and anatomically identifiable subpopulations that may differentially tune rapid arousal responses to motivational stimuli.

The Efficacy of Imatinib Mesylate in the Treatment of a Rare Lytic Bone Lesion Caused by Hypereosinophilic Syndrome/Chronic Eosinophilic Leukemia: A Case Report.

CASE: We report a patient with hypereosinophilia-associated massive osteolytic lesion of the sacrum who was admitted to our hospital. Genetic analysis revealed that atypical eosinophilic cells were positive for FIP1-like-1-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFRA) fusion gene. Treatment was initiated with oral administration of imatinib mesylate. The patient responded rapidly to this medication with a marked reduction in eosinophilia both from the peripheral blood and FIP1L1-PDGFRA fusion gene in the bone marrow within 2 weeks, followed by gradual osteosclerotic repair of the sacrum. CONCLUSIONS: This case study found that the drug imatinib proved very effective in the treatment of this rare condition.

Disappearance of the inhibitory effect of neuropeptide Y within the dorsolateral bed nucleus of the stria terminalis in rats with chronic pain.

We recently showed that the mesolimbic dopaminergic system was tonically suppressed during chronic pain by enhanced corticotropin releasing factor (CRF) signaling within the dorsolateral bed nucleus of the stria terminalis (dlBNST), and that inhibition of intra-dlBNST CRF signaling restored the mesolimbic dopaminergic system function. Specifically, bilateral intra-dlBNST injections of the CRF type 1 receptor antagonist NBI27914 increased intra-nucleus accumbens dopamine release and induced reward-related behaviors in rats with chronic pain. Here, we used a conditioned place preference (CPP) test to explore whether intra-dlBNST injections of neuropeptide Y (NPY) restored the mesolimbic reward system function in chronic pain rats, because we previously showed that NPY had an effect opposite to that of CRF in dlBNST neurons. Specifically, CRF depolarized type II dlBNST neurons whereas NPY hyperpolarized them. However, unexpectedly, intra-dlBNST NPY injections had no effect on CPP test outcomes. Then, we compared the effects of NPY on the membrane potentials of type II dlBNST neurons of sham-operated control rats and those of chronic pain animals. Whole-cell patch-clamp electrophysiology revealed that NPY hyperpolarized type II dlBNST neurons in the sham-operated group. By contrast, in the chronic pain group, NPY did not hyperpolarize, but rather depolarized, type II dlBNST neurons. These results indicate that NPY no longer hyperpolarizes type II dlBNST neurons in rats with chronic pain, therefore it does not reverse the excitatory effects of CRF. This may be why intra-dlBNST injections of NPY into chronic pain rats did not exhibit a rewarding effect in the CPP test, whereas intra-dlBNST injections of NBI27914 did. This is the first study to demonstrate a chronic pain-induced neuroplastic change in NPY signaling in the dlBNST. Such a change may be involved in the dysfunction of the mesolimbic reward system under the chronic pain condition.