Biology subjects

Saitoh, A.

Publications and source records attributed to Saitoh, A..

4 recordsLinked to original sources

bioRxiv2025

In vivo deep-brain microscopy at submicrometer resolution with refractive index-matched prism interfaces

The mammalian brain is a thick and densely layered structure comprising a huge number of neurons that work together to process information and regulate brain functions. Although various optical methods have been developed to investigate deep brain dynamics, they are limited by technical constraints, invasiveness, suboptimal spatial resolution, and/or a restricted field of view. To overcome these limitations, we developed an implantable, optically optimized microprism interface with a refractive index matched to that of brain tissue and water, enabling minimally-invasive, wide-field two-photon imaging method with enhanced brightness and sub-micron resolution in deep prefrontal areas.

neuroscience↗

bioRxiv2025

Pain-stimulated ultrasound vocalizations and their impact on pain response in mice

Pain is a complex phenomenon encompassing both the physiological and psychological aspects of sensation and emotion, respectively. In recent years, pain has been clarified to arise even without direct injury, with emotional transmission as a cause. However, the specific mechanisms behind emotional transmission are still not well understood. In this study, sounds in the ultrasonic domain that were recorded during pain stimulation in mice were used as sound stress to examine the effects of psychological stress caused by exposure to ultrasound on tactile thresholds. We also examined the effects of psychological stress caused by the ultrasound on an inflammatory pain model of mice. The tactile threshold decreased the next and three days after sound stress exposure in mice. DNA microarray analysis of the mouse thalamus exposed to sound stress revealed increased expression of inflammation-related genes, Prostaglandin-endoperoxide synthase 2 and C-X-C motif chemokine ligand 1. Their respective inhibitors, loxoprofen and SB225002, significantly improved hyperalgesia induced by sound stress. When sound stress was applied to a mouse model of inflammatory pain in which pain thresholds were restored 14 days after complete Freunds adjuvant administration, prolonged pain and attenuated analgesic effects of loxoprofen were observed. These results suggest that sound stress not only induces inflammation in the brain that causes hyperalgesia but may also be partially responsible for exacerbating inflammatory pain, hence complicating treatment.

pharmacology and toxicology↗

bioRxiv2024

Low-invasive, wide-field, and cellular resolution two-photon imaging of neural population activity in brainstem and nucleus tractus solitarii

Brain-viscera communication plays a crucial role in regulating mental health, with the vagus nerve being a key structure mediating this interaction. Clinically, artificial vagus nerve stimulation (VNS) is used to treat various neuropsychiatric disorders, highlighting the importance of vagal afferent fibers in regulating emotion. The nucleus tractus solitarii (NTS) is a brainstem structure proposed to receive signals from vagal afferents and relay them to brain networks for emotion regulation. However, due to the anatomical complexity and difficulty in accessing the deep-brain NTS region in living animals, the mechanisms remain unclear. Here, we developed a wide-field and deep-brain two-photon imaging method using a double-prism based optical interface. This approach enables the identification of cellular-resolution neural activities in the NTS while preserving the cerebellum, which covers the NTS and is important for emotion regulation, intact. We systematically evaluated how NTS neurons respond to VNS and a gastrointestinal hormone, suggesting the usefulness of this method for investigating the role of the vagus-NTS pathway in vivo.

neuroscience↗

bioRxiv2020

Changes in subcellular structures and states of Pumilio1 regulate the translation of target Mad2 and Cyclin B1 mRNAs

Temporal and spatial control of mRNA translation has emerged as a major mechanism for promoting diverse biological processes. However, the molecular nature of temporal control of translation remains unclear. In oocytes, many mRNAs are deposited as a translationally repressed form and are translated at appropriate timings to promote the progression of meiosis and development. Here, we show that changes in structures and states of the RNA-binding protein Pumilio1 regulate the translation of target mRNAs and progression of oocyte maturation. Pumilio1 was shown to bind to Mad2 and Cyclin B1 mRNAs, assemble highly clustered solid-like aggregates, and surround Mad2 and Cyclin B1 RNA granules in mouse oocytes. These Pumilio1 aggregates were dissolved by phosphorylation prior to the translational activation of target mRNAs. Stabilization of Pumilio1 aggregates prevented the translational activation of target mRNAs and oocyte maturation. Together, our results provide an aggregation-dissolution model for the temporal and spatial control of translation.

cell biology↗