caa a22 4500 477082831 CHVBK 20180405111454.0 cr unu---uuuuu 170330e19960701xx s 000 0 eng 10.1007/BF01925576 doi (NATIONALLICENCE)springer-10.1007/BF01925576 Vitamin B12 amplifies circadian phase shifts induced by a light pulse in rats [Elektronische Daten] [M. Ikeda, K. Honda, S. Inoue] Vitamin B12 (VB12) is a putative modulator of the human circadian clock, improving entrainability to the 24 h light-dark cycle. The present study was intended to elucidate the mechanism of VB12 action in an animal model. In male rats free-running under constant dim illumination, a single light pulse of 50-1000 lux for 20 min given at circadian time (CT) 20 induced a 0.28 to 1.08 h phase advance and at CT 14 induced a 0.54 to 2.10 h phase delay. A 3 h intracerebroventricular (icv) infusion of 30 nmol VB12 starting 2 h prior to a 20 min 200 lux light pulse significantly amplified phase shifts in comparison with saline-treated or untreated controls. The mean phase advance (1.13 h) was 1.8-fold greater than that of saline-infused controls, whereas the mean phase delay (2.28 h) was 2.9-fold greater. These values were comparable to the maximal phase shifts caused by 1000 lux light pulses in untreated rats. Since the same VB12 treatment alone had failed to induce a phase shift in a previous experiment, these results indicate that VB12 strongly enhanced light pulse-induced phase shifts and thus augmented the entrainability of the circadian clock to light. Birkhäuser Verlag, 1996 Circadian rhythm nationallicence intracerebroventricular infusion nationallicence light pulse nationallicence phase shift nationallicence rats nationallicence vitamin B12 nationallicence Ikeda M. Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, 101, Tokyo, (Japan) aut Honda K. Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, 101, Tokyo, (Japan) aut Inoue S. Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, 101, Tokyo, (Japan) aut Experientia Birkhäuser-Verlag 52/7(1996-07-01), 691-694 0014-4754 52:7<691 1996 52 18 https://doi.org/10.1007/BF01925576 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01925576 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ikeda M. Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, 101, Tokyo, (Japan) aut NATIONALLICENCE 700 1- Honda K. Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, 101, Tokyo, (Japan) aut NATIONALLICENCE 700 1- Inoue S. Institute for Medical and Dental Engineering, Tokyo Medical and Dental University, Kanda-Surugadai 2-3-10, Chiyoda-ku, 101, Tokyo, (Japan) aut NATIONALLICENCE 773 0- Experientia Birkhäuser-Verlag 52/7(1996-07-01), 691-694 0014-4754 52:7<691 1996 52 18 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer