Details of a Researcher - Tanaka, Kenji

Papers - Tanaka, Kenji

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A rapidly progressive multiple system atrophy-cerebellar variant model presenting marked glial reactions with inflammation and spreading of α-synuclein oligomers and phosphorylated α-synuclein aggregates.

Yamaguchi H, Nishimura Y, Matsuse D, Sekiya H, Masaki K, Tanaka T, Saiga T, Harada M, Kira YI, Dickson DW, Fujishima K, Matsuo E, Tanaka KF, Yamasaki R, Isobe N, Kira JI

Brain, behavior, and immunity 121 122 - 141 2024.07

ISSN 0889-1591

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Neurogenesis-independent mechanisms of MRI-detectable hippocampal volume increase following electroconvulsive stimulation.

Abe Y, Yokoyama K, Kato T, Yagishita S, Tanaka KF, Takamiya A

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 49 ( 8 ) 1236 - 1245 2024.07

ISSN 0893-133X

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Glutamatergic signaling from melanin-concentrating hormone-producing neurons: A requirement for memory regulation, but not for metabolism control.

Pham XT, Abe Y, Mukai Y, Ono D, Tanaka KF, Ohmura Y, Wake H, Yamanaka A

PNAS nexus 3 ( 7 ) pgae275 2024.07

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Optogenetic activation of dorsal raphe serotonin neurons induces brain-wide activation.

Hamada HT, Abe Y, Takata N, Taira M, Tanaka KF, Doya K

Nature communications 15 ( 1 ) 4152 2024.05

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Brain-derived neurotrophic factor from microglia regulates neuronal development in the medial prefrontal cortex and its associated social behavior.

Komori T, Okamura K, Ikehara M, Yamamuro K, Endo N, Okumura K, Yamauchi T, Ikawa D, Ouji-Sageshima N, Toritsuka M, Takada R, Kayashima Y, Ishida R, Mori Y, Kamikawa K, Noriyama Y, Nishi Y, Ito T, Saito Y, Nishi M, Kishimoto T, Tanaka KF, Hiroi N, Makinodan M

Molecular psychiatry 29 ( 5 ) 1338 - 1349 2024.05

ISSN 1359-4184

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Neurobiological mechanisms of electroconvulsive therapy for depression: Insights into hippocampal volumetric increases from clinical and preclinical studies.

Abe Y, Erchinger VJ, Ousdal OT, Oltedal L, Tanaka KF, Takamiya A

Journal of neurochemistry 2024.01

ISSN 0022-3042

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Metabolites for monitoring symptoms and predicting remission in patients with depression who received electroconvulsive therapy: a pilot study

Uchida T., Sugiura Y., Sugiyama E., Maeda R., Tanaka K.F., Suematsu M., Mimura M., Uchida H.

Scientific Reports (Scientific Reports) 13 ( 1 ) 13218 2023.12

The lack of biomarkers to monitor and predict the efficacy of electroconvulsive therapy (ECT) has hindered its optimal use. To establish metabolomic markers for monitoring and predicting the treatment efficacy of ECT, we comprehensively evaluated metabolite levels in patients with major depressive disorder (MDD) by performing targeted and non-targeted metabolomic analyses using plasma samples before and after the first, third, and final ECT sessions, and 3–7 days after the final session. We compared the plasma metabolomes of age- and sex-matched healthy controls (HCs). Thirteen hospitalized patients with MDD and their corresponding HCs were included in this study. We observed that patients with MDD exhibited lower levels of amino acids, including gamma-aminobutyric acid (GABA), and metabolites involved in tryptophan metabolism and the kynurenine pathway, and higher levels of cortisol at baseline. Furthermore, we investigated the relationship between metabolite levels and depression severity across seven measurement timepoints along with one correlation analysis and found that amino acids, including GABA and tryptophan catabolites, were significantly correlated with the severity of depression. Despite the exploratory nature of this study due to the limited sample size necessitating further validation, our findings suggest that the blood metabolic profile has potential as a biomarker for ECT.

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Prostaglandin E<inf>2</inf> Induces Long-Lasting Inhibition of Noradrenergic Neurons in the Locus Coeruleus and Moderates the Behavioral Response to Stressors

Mukai Y., Okubo T.S., Lazarus M., Ono D., Tanaka K.F., Yamanaka A.

Journal of Neuroscience (Journal of Neuroscience) 43 ( 47 ) 7982 - 7999 2023.11

ISSN 02706474

Neuronal activity is modulated not only by inputs from other neurons but also by various factors, such as bioactive substances. Noradrenergic (NA) neurons in the locus coeruleus (LC-NA neurons) are involved in diverse physiological functions, including sleep/wakefulness and stress responses. Previous studies have identified various substances and receptors that modulate LC-NA neuronal activity through techniques including electrophysiology, calcium imaging, and single-cell RNA sequencing. However, many substances with unknown physiological significance have been overlooked. Here, we established an efficient screening method for identifying substances that modulate LC-NA neuronal activity through intracellular calcium ([Ca21]i) imaging using brain slices. Using both sexes of mice, we screened 53 bioactive substances, and identified five novel substances: gastrin-releasing peptide, neuromedin U, and angiotensin II, which increase [Ca21]i, and pancreatic polypeptide and prostaglandin D2, which decrease [Ca21]i. Among them, neuromedin U induced the greatest response in female mice. In terms of the duration of [Ca21]i change, we focused on prostaglandin E2 (PGE2), since it induces a long-lasting decrease in [Ca21]i via the EP3 receptor. Conditional knock-out of the receptor in LC-NA neurons resulted in increased depression-like behavior, prolonged wakefulness in the dark period, and increased [Ca21]i after stress exposure. Our results demonstrate the effectiveness of our screening method for identifying substances that modulate a specific neuronal population in an unbiased manner and suggest that stress-induced prostaglandin E2 can suppress LC-NA neuronal activity to moderate the behavioral response to stressors. Our screening method will contribute to uncovering previously unknown physiological functions of uncharacterized bioactive substances in specific neuronal populations.

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Shared GABA transmission pathology in dopamine agonist- and antagonist-induced dyskinesia

Abe Y., Yagishita S., Sano H., Sugiura Y., Dantsuji M., Suzuki T., Mochizuki A., Yoshimaru D., Hata J., Matsumoto M., Taira S., Takeuchi H., Okano H., Ohno N., Suematsu M., Inoue T., Nambu A., Watanabe M., Tanaka K.F.

Cell Reports Medicine (Cell Reports Medicine) 4 ( 10 ) 101208 2023.10

Dyskinesia is involuntary movement caused by long-term medication with dopamine-related agents: the dopamine agonist 3,4-dihydroxy-L-phenylalanine (L-DOPA) to treat Parkinson's disease (L-DOPA-induced dyskinesia [LID]) or dopamine antagonists to treat schizophrenia (tardive dyskinesia [TD]). However, it remains unknown why distinct types of medications for distinct neuropsychiatric disorders induce similar involuntary movements. Here, we search for a shared structural footprint using magnetic resonance imaging-based macroscopic screening and super-resolution microscopy-based microscopic identification. We identify the enlarged axon terminals of striatal medium spiny neurons in LID and TD model mice. Striatal overexpression of the vesicular gamma-aminobutyric acid transporter (VGAT) is necessary and sufficient for modeling these structural changes; VGAT levels gate the functional and behavioral alterations in dyskinesia models. Our findings indicate that lowered type 2 dopamine receptor signaling with repetitive dopamine fluctuations is a common cause of VGAT overexpression and late-onset dyskinesia formation and that reducing dopamine fluctuation rescues dyskinesia pathology via VGAT downregulation.

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Starburst amacrine cells amplify optogenetic visual restoration through gap junctions.

Katada Y, Kunimi H, Serizawa N, Lee D, Kobayashi K, Negishi K, Okano H, Tanaka KF, Tsubota K, Kurihara T

Molecular therapy. Methods & clinical development (Molecular Therapy Methods and Clinical Development) 30 1 - 13 2023.09

ISSN 2329-0501

Ectopic induction of optogenetic actuators, such as channelrhodopsin, is a promising approach to restoring vision in the degenerating retina. However, the cell type-specific response of ectopic photoreception has not been well understood. There are limits to obtaining efficient gene expression in a specifically targeted cell population by a transgenic approach. In the present study, we established a murine model with high efficiency of gene induction to retinal ganglion cells (RGCs) and amacrine cells using an improved tetracycline transactivator-operator bipartite system (KENGE-tet system). To investigate the cell type-specific visual restorative effect, we expressed the channelrhodopsin gene into RGCs and amacrine cells using the KENGE-tet system. As a result, enhancement in the visual restorative effect was observed to RGCs and starburst amacrine cells. In conclusion, a photoresponse from amacrine cells may enhance the maintained response of RGCs and further increase or improve the visual restorative effect.

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Brain Response to Interferential Current Compared with Alternating Current Stimulation

Xin Z., Abe Y., Kuwahata A., Tanaka K.F., Sekino M.

Brain Sciences (Brain Sciences) 13 ( 9 ) 2023.09

ISSN 2076-3425

Temporal interference (TI) stimulation, which utilizes multiple external electric fields with amplitude modulation for neural modulation, has emerged as a potential noninvasive brain stimulation methodology. However, the clinical application of TI stimulation is inhibited by its uncertain fundamental mechanisms, and research has previously been restricted to numerical simulations and immunohistology without considering the acute in vivo response of the neural circuit. To address the characterization and understanding of the mechanisms underlying the approach, we investigated instantaneous brainwide activation patterns in response to invasive interferential current (IFC) stimulation compared with low-frequency alternative current stimulation (ACS). Results demonstrated that IFC stimulation is capable of inducing regional neural responses and modulating brain networks; however, the activation threshold for significantly recruiting a neural response using IFC was higher (at least twofold) than stimulation via alternating current, and the spatial distribution of the activation signal was restricted. A distinct blood oxygenation level-dependent (BOLD) response pattern was observed, which could be accounted for by the activation of distinct types of cells, such as inhibitory cells, by IFC. These results suggest that IFC stimulation might not be as efficient as conventional brain modulation methods, especially when considering TI stimulation as a potential alternative for stimulating subcortical brain areas. Therefore, we argue that a future transcranial application of TI on human subjects should take these implications into account and consider other stimulation effects using this technique.

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The gut microbiota-induced kynurenic acid recruits GPR35-positive macrophages to promote experimental encephalitis

Miyamoto K., Sujino T., Harada Y., Ashida H., Yoshimatsu Y., Yonemoto Y., Nemoto Y., Tomura M., Melhem H., Niess J.H., Suzuki T., Suzuki T., Suzuki S., Koda Y., Okamoto R., Mikami Y., Teratani T., Tanaka K., Yoshimura A., Sato T., Kanai T.

Cell Reports (Cell Reports) 42 ( 8 ) 113005 2023.08

The intricate interplay between gut microbes and the onset of experimental autoimmune encephalomyelitis (EAE) remains poorly understood. Here, we uncover remarkable similarities between CD4+ T cells in the spinal cord and their counterparts in the small intestine. Furthermore, we unveil a synergistic relationship between the microbiota, particularly enriched with the tryptophan metabolism gene EC:1.13.11.11, and intestinal cells. This symbiotic collaboration results in the biosynthesis of kynurenic acid (KYNA), which modulates the recruitment and aggregation of GPR35-positive macrophages. Subsequently, a robust T helper 17 (Th17) immune response is activated, ultimately triggering the onset of EAE. Conversely, modulating the KYNA-mediated GPR35 signaling in Cx3cr1+ macrophages leads to a remarkable amelioration of EAE. These findings shed light on the crucial role of microbial-derived tryptophan metabolites in regulating immune responses within extraintestinal tissues.

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Inhibition of the dorsomedial striatal direct pathway is essential for the execution of action sequences.

Kono A, Shikano Y, Tanaka KF, Yamaura K, Tsutsui-Kimura I

Neuropsychopharmacology reports (Neuropsychopharmacology Reports) 43 ( 3 ) 414 - 424 2023.08

Contrary to the previous notion that the dorsomedial striatum (DMS) is crucial for acquiring new learning, accumulated evidence has suggested that the DMS also plays a role in the execution of already learned action sequences. Here, we examined how the direct and indirect pathways in the DMS regulate action sequences using a task that requires animals to press a lever consecutively. Cell-type-specific bulk Ca2+ recording revealed that the direct pathway was inhibited at the time of sequence execution. The sequence-related response was blunted in trials where the sequential behaviors were disrupted. Optogenetic activation at the sequence start caused distraction of action sequences without affecting motor function or memory of the task structure. By contrast with the direct pathway, the indirect pathway was slightly activated at the start of the sequence, but the optogenetic suppression of such sequence-related signaling did not impact the behaviors. These results suggest that the inhibition of the DMS direct pathway promotes sequence execution potentially by suppressing the formation of a new association.

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Acceleration of the Development of Microcirculation Embolism in the Brain due to Capillary Narrowing.

Murata J, Unekawa M, Kudo Y, Kotani M, Kanno I, Izawa Y, Tomita Y, Tanaka KF, Nakahara J, Masamoto K

Stroke (Stroke) 54 ( 8 ) 2135 - 2144 2023.08

ISSN 0039-2499

BACKGROUND: Cerebral microvascular obstruction is critically involved in recurrent stroke and decreased cerebral blood flow with age. The obstruction must occur in the capillary with a greater resistance to perfusion pressure through the microvascular networks. However, little is known about the relationship between capillary size and embolism formation. This study aimed to determine whether the capillary lumen space contributes to the development of microcirculation embolism. METHODS: To spatiotemporally manipulate capillary diameters in vivo, transgenic mice expressing the light-gated cation channel protein ChR2 (channelrhodopsin-2) in mural cells were used. The spatiotemporal changes in the regional cerebral blood flow in response to the photoactivation of ChR2 mural cells were first characterized using laser speckle flowgraphy. Capillary responses to optimized photostimulation were then examined in vivo using 2-photon microscopy. Finally, microcirculation embolism due to intravenously injected fluorescent microbeads was compared under conditions with or without photoactivation of ChR2 mural cells. RESULTS: Following transcranial photostimulation, the stimulation intensity-dependent decrease in cerebral blood flow centered at the irradiation was observed (14%-49% decreases relative to the baseline). The cerebrovascular response to photostimulation showed significant constriction of the cerebral arteries and capillaries but not of the veins. As a result of vasoconstriction, a temporal stall of red blood cell flow occurred in the capillaries of the venous sides. The 2-photon excitation of a single ChR2 pericyte demonstrated the partial shrinkage of capillaries (7% relative to the baseline) around the stimulated cell. With the intravenous injection of microbeads, the occurrence of microcirculation embolism was significantly enhanced (11% increases compared to the control) with photostimulation. CONCLUSIONS: Capillary narrowing increases the risk of developing microcirculation embolism in the venous sides of the cerebral capillaries.

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Pupil Dynamics-derived Sleep Stage Classification of a Head-fixed Mouse Using a Recurrent Neural Network.

Kobayashi G, Tanaka KF, Takata N

The Keio journal of medicine (Keio Journal of Medicine) 72 ( 2 ) 44 - 59 2023.06

ISSN 0022-9717

The standard method for sleep state classification is thresholding the amplitudes of electroencepha-lography (EEG) and electromyography (EMG) data, followed by manual correction by an expert. Al-though popular, this method has some shortcomings: (1) the time-consuming manual correction by human experts is sometimes a bottleneck hindering sleep studies, (2) EEG electrodes on the skull interfere with wide-field imaging of the cortical activity of a head-fixed mouse under a microscope, (3) invasive surgery to fix the electrodes on the thin mouse skull risks brain tissue injury, and (4) metal electrodes for EEG and EMG recording are difficult to apply to some experimental apparatus such as that for functional magnetic resonance imaging. To overcome these shortcomings, we propose a pupil dynamics-based vigilance state classification method for a head-fixed mouse using a long short-term memory (LSTM) model, a variant of a recurrent neural network, for multi-class labeling of NREM, REM, and WAKE states. For supervisory hypnography, EEG and EMG recording were performed on head-fixed mice. This setup was combined with left eye pupillometry using a USB camera and a markerless tracking toolbox, DeepLabCut. Our open-source LSTM model with feature inputs of pupil diameter, pupil location, pupil velocity, and eyelid opening for 10 s at a 10 Hz sampling rate achieved vigilance state estimation with a higher classification performance (macro F1 score, 0.77; accuracy, 86%) than a feed-forward neural network. Findings from a diverse range of pupillary dynamics implied possible subdivi-sion of the vigilance states defined by EEG and EMG. Pupil dynamics-based hypnography can expand the scope of alternatives for sleep stage scoring of head-fixed mice.

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Mesolimbic dopamine release precedes actively sought aversive stimuli in mice.

Yawata Y, Shikano Y, Ogasawara J, Makino K, Kashima T, Ihara K, Yoshimoto A, Morikawa S, Yagishita S, Tanaka KF, Ikegaya Y

Nature communications (Nature Communications) 14 ( 1 ) 2433 2023.04

In some models, animals approach aversive stimuli more than those housed in an enriched environment. Here, we found that male mice in an impoverished and unstimulating (i.e., boring) chamber without toys sought aversive air puffs more often than those in an enriched chamber. Using this animal model, we identified the insular cortex as a regulator of aversion-seeking behavior. Activation and inhibition of the insular cortex increased and decreased the frequencies of air-puff self-stimulation, respectively, and the firing patterns of insular neuron ensembles predicted the self-stimulation timing. Dopamine levels in the ventrolateral striatum decreased with passive air puffs but increased with actively sought puffs. Around 20% of mice developed intense self-stimulation despite being offered toys, which was prevented by administering opioid receptor antagonists. This study establishes a basis for comprehending the neural underpinnings of usually avoided stimulus-seeking behaviors.

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Separate optogenetic manipulation of Nerve/glial antigen 2 (NG2) glia and mural cells using the NG2 promoter

Oishi M., Passlick S., Yamazaki Y., Unekawa M., Adachi R., Yamada M., Imayoshi I., Abe Y., Steinhäuser C., Tanaka K.F.

GLIA (GLIA) 71 ( 2 ) 317 - 333 2023.02

ISSN 08941491

Nerve/glial antigen 2 (NG2) is a protein marker of NG2 glia and mural cells, and NG2 promoter activity is utilized to target these cells. However, the NG2 promoter cannot target NG2 glia and mural cells separately. This has been an obstacle for NG2 glia-specific manipulation. Here, we developed transgenic mice in which either cell type can be targeted using the NG2 promoter. We selected a tetracycline-controllable gene induction system for cell type-specific transgene expression, and generated NG2-tetracycline transactivator (tTA) transgenic lines. We crossed tTA lines with the tetO-ChR2 (channelrhodopsin-2)-EYFP line to characterize tTA-dependent transgene induction. We isolated two unique NG2-tTA mouse lines: one that induced ChR2-EYFP only in mural cells, likely due to the chromosomal position effect of NG2-tTA insertion, and the other that induced it in both cell types. We then applied a Cre-mediated set-subtraction strategy to the latter case and eliminated ChR2-EYFP from mural cells, resulting in NG2 glia-specific transgene induction. We further demonstrated that tTA-dependent ChR2 expression could manipulate cell function. Optogenetic mural cell activation decreased cerebral blood flow, as previously reported, indicating that tTA-mediated ChR2 expression was sufficient to impact cellular function. ChR2-mediated depolarization was observed in NG2 glia in acute hippocampal slices. In addition, ChR2-mediated depolarization of NG2 glia inhibited their proliferation but promoted their differentiation in juvenile mice. Since the tTA–tetO combination is expandable, the mural cell–specific NG2-tTA line and the NG2 glia-specific NG2-tTA line will permit us to conduct observational and manipulation studies to examine in vivo function of these cells separately.

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Serotonergic neurons control cortical neuronal intracellular energy dynamics by modulating astrocyte-neuron lactate shuttle.

Natsubori A, Hirai S, Kwon S, Ono D, Deng F, Wan J, Miyazawa M, Kojima T, Okado H, Karashima A, Li Y, Tanaka KF, Honda M

iScience (iScience) 26 ( 1 ) 105830 2023.01

The central serotonergic system has multiple roles in animal physiology and behavior, including sleep-wake control. However, its function in controlling brain energy metabolism according to the state of animals remains undetermined. Through in vivo monitoring of energy metabolites and signaling, we demonstrated that optogenetic activation of raphe serotonergic neurons increased cortical neuronal intracellular concentration of ATP, an indispensable cellular energy molecule, which was suppressed by inhibiting neuronal uptake of lactate derived from astrocytes. Raphe serotonergic neuronal activation induced cortical astrocytic Ca2+ and cAMP surges and increased extracellular lactate concentrations, suggesting the facilitation of lactate release from astrocytes. Furthermore, chemogenetic inhibition of raphe serotonergic neurons partly attenuated the increase in cortical neuronal intracellular ATP levels as arousal increased in mice. Serotonergic neuronal activation promoted an increase in cortical neuronal intracellular ATP levels, partly mediated by the facilitation of the astrocyte-neuron lactate shuttle, contributing to state-dependent optimization of neuronal intracellular energy levels.

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Slow-rising and fast-falling dopaminergic dynamics jointly adjust negative prediction error in the ventral striatum

Shikano Y., Yagishita S., Tanaka K.F., Takata N.

European Journal of Neuroscience (European Journal of Neuroscience) 58 ( 12 ) 4502 - 4522 2023

ISSN 0953816X

The greater the reward expectations are, the more different the brain's physiological response will be. Although it is well-documented that better-than-expected outcomes are encoded quantitatively via midbrain dopaminergic (DA) activity, it has been less addressed experimentally whether worse-than-expected outcomes are expressed quantitatively as well. We show that larger reward expectations upon unexpected reward omissions are associated with the preceding slower rise and following larger decrease (DA dip) in the DA concentration at the ventral striatum of mice. We set up a lever press task on a fixed ratio (FR) schedule requiring five lever presses as an effort for a food reward (FR5). The mice occasionally checked the food magazine without a reward before completing the task. The percentage of this premature magazine entry (PME) increased as the number of lever presses approached five, showing rising expectations with increasing proximity to task completion, and hence greater reward expectations. Fibre photometry of extracellular DA dynamics in the ventral striatum using a fluorescent protein (genetically encoded GPCR activation-based DA sensor: GRABDA2m) revealed that the slow increase and fast decrease in DA levels around PMEs were correlated with the PME percentage, demonstrating a monotonic relationship between the DA dip amplitude and degree of expectations. Computational modelling of the lever press task implementing temporal difference errors and state transitions replicated the observed correlation between the PME frequency and DA dip amplitude in the FR5 task. Taken together, these findings indicate that the DA dip amplitude represents the degree of reward expectations monotonically, which may guide behavioural adjustment.

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Optogenetic demonstration of the involvement of SMA-negative mural cells in the regulation of cerebral blood flow.

Iba C, Abe Y, Tanaka KF

Frontiers in physiology 14 1322250 2023

ISSN 1664-042X

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