講師資料
Talks：
Sleep-wake rhythms and peripheral clock movements in the diurnal grass rat, Arvicanthis niloticus
Name：
Masayuki Ikeda
Position：
Professor
Affiliation：
School of Science, University of Toyama
Email：
Photo：
Research Interests：
Calcium signaling, Clock genes, Diurnal grass rats, Sleep, Suprachiasmatic nucleus
Selected Publications：
1. Morioka E, Matsumoto A & Ikeda M (2012) Neuronal influence on peripheral circadian oscillators in pupal Drosophila prothoracic glands. Nature Communications 3: 909.
2. Morioka E, Kasuga Y, Kanda Y, Moritama S, Koizumi H, Yoshikawa T, Miura N, Ikeda M, Higashida H, Holmes TC, & Ikeda M (2022) Mitochondrial LETM1 drives ionic and molecular clock rhythms in circadian pacemaker neurons. Cell Reports 39: 110787.
3. Tamogami S, Okeya M, Suzuki R, Amano H, Yamamoto R, Mochizuki T, Cherasse Y, Sakurai T, Yoshikawa T, Morioka E, Ikeda M (2025) Sex differences in serotonergic control of daytime activities in diurnal Nile grass rats. Brain Res 1865: 149862.
Abstract：
Analyzing sleep in laboratory mice or rats allows for pharmacological and genetic approaches and has significantly advanced our knowledge of sleep. However, their circadian behavioral phenotypes are out of phase with our sleep-wake cycles, which limits their use as human models. In this regard, alternative use of diurnal laboratory rodents may be an ideal approach, whereas knowledge regarding their sleep profiles is yet limited. Therefore, we examined EEG and EMG recordings in Nile grass rats and characterized their sleep under 12:12-h light-dark cycles of various lighting intensity. Consequently, we observed bimodal activity patterns coinciding with crepuscular elevation of wakefulness at lower light intensities (10 or 100 lux). Meanwhile, enhancement of wakefulness and a reversal reduction in NREM sleep were observed during the daytime at higher light intensities (300 or 1,000 lux), creating apparent diurnal sleep-wake patterns. The results are consistent with clinical aspects to treat patients with seasonal affective disorders and thus suggest possible use of Nile grass rats as a model of bright light therapy. To further study the peripheral clock movements in Nile grass rats, we established a fibroblast cell line (GrLBmal1-luc) from the lungs of diurnal Nile grass rats stably expressing the Bmal1-luciferase reporter gene. The adrenergic stimulation phase-delayed or phase-advanced Bmal1 transcriptional rhythms, depending on the timing of stimulation as in the human type-0 phase-response-curve. Thus, this cell line may have potential application in modeling human clocks. 
2025年會：