Takenori Omori

Publications (4)6.46 Total impact

• Article: Enhancing effect of cerebral blood volume by mild exercise in healthy young men: a near-infrared spectroscopy study.

  Akkaranee Timinkul, Morimasa Kato, Takenori Omori, Custer C Deocaris, Akira Ito, Tomohiro Kizuka, Yosuke Sakairi, Takeshi Nishijima, Takashi Asada, Hideaki Soya
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  ABSTRACT: A mechanism by which exercise improves brain function may be attributed to increase in cerebral blood volume (CBV) with physical activity. However, the exact exercise intensity that influences CBV is still uncertain. To clarify this issue, 10 healthy young male participants were asked to perform a graded cycling exercise to the point of exhaustion while their prefrontal cortex CBVs are being monitored using near-infrared spectroscopy. Overall responsive cerebral oxygenation showed a non-linear pattern with three distinct phases. The CBV-threshold (CBVT), an event where rapid oxygenation takes place, occurred at approximately 42% of the V O2max. The CBVT preceded the lactate threshold (LT), which was at approximately 55% of the V O2max. The V O2max was not predictive of the CBVT in among the subjects. Our results indicate that oxygenation of the prefrontal cortex increases during graded cycling even at exercise intensities below the LT, suggesting the potential role of mild exercise in enhancing CBV.
  Neuroscience Research 08/2008; 61(3):242-8. · 2.25 Impact Factor
• Article: Activation of A1 and A2 noradrenergic neurons in response to running in the rat.

  Nao Ohiwa, Tsuyoshi Saito, Hyukki Chang, Takenori Omori, Takahiko Fujikawa, Takashi Asada, Hideaki Soya
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  ABSTRACT: Since running accompanied with blood lactate accumulation stimulates the release of adrenocorticotropic hormone (ACTH), running above the lactate threshold (LT) acts as stress (running stress). To examine whether A1/A2 noradrenergic neurons that project to the hypothalamus activate under running stress, c-Fos immunohistochemistry was used to compare the effects of running with or without stress response on A1/A2 noradrenergic neurons. Blood lactate and plasma ACTH concentrations significantly increased in the running stress group, but not in the running without stress response and control groups, confirming different physiological impacts between different intensity of running with or without stress. Running stress markedly increased c-Fos accumulation in the A1/A2 noradrenergic neurons. Running without stress response also induced a significant increase in c-Fos expression in the A1/A2 noradrenergic neurons, and the percentage of the increase was smaller than that of running stress. The extent of c-Fos expression in the A1/A2 noradrenergic neurons correlates with exercise intensity, signifying that this neuronal activation is running speed-dependent. We thus suggest that A1/A2 noradrenergic neurons are activated in response to not only running stress, but also to other physiological running, enhanced by non-stressful running. These findings will be helpful in studies of specific neurocircuits and in identifying their functions in response to running at different intensities.
  Neuroscience Letters 03/2006; 395(1):46-50. · 2.11 Impact Factor
• Article: Increased c-fos gene expression in alpha motoneurons in rat loaded hindlimb muscles with inclined locomotion.

  Takenori Omori, Hitoshi Kawashima, Tomohiro Kizuka, Nao Ohiwa, Masaru Tateoka, Hideaki Soya
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  ABSTRACT: The potential usefulness of c-fos gene expression as an indicator of the activity level of spinal alpha motoneurons was examined in loaded locomotive rats. The motor pools of the plantaris (PL) and soleus muscles (SOL), mainly composed respectively of fast- and slow-twitch muscle fibers, were investigated in rats under locomotion at 25 m/min on a 20% incline. We first labeled motoneurons with a retrograde tracer, Nuclear Yellow (NY), and then quantified the c-fos mRNA expression level in the NY-labeled alpha motoneurons by means of in situ hybridization. Electromyographic (EMG) activities were also recorded. The c-fos expression level per alpha motoneuron showed a greater increase in the PL (75%) than in the SOL motor pool (38%). EMG activities also showed a greater increase in the PL (159%) than in the SOL (43%). Taken together, these results suggest that c-fos expression levels in alpha motoneurons are associated with the activity levels of their corresponding muscle. This cytochemical method for identifying the c-fos expression level has potential for use as a tool for estimating the activity level of large populations of alpha motoneurons in unrestricted animals.
  Neuroscience Letters 12/2005; 389(1):25-9. · 2.11 Impact Factor
• Article: Higher c-fos Gene Expression in Alpha Motoneurons of Slow-twitch Muscle than those of Fast-twitch Muscle in Freely Moving Rats

  Takenori Omori, Hitoshi Kawashima, Tomohiro Kizuka
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  ABSTRACT: http://www.tulips.tsukuba.ac.jp/mylimedio/dl/page.do?issueid=871889&tocid=100066484&page=9-13