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| Titel: |
Circadian time-dependent modulation of sleep and brain temperature (Tbr) by methylcobalamine and resultant prolongation of Tbr freerunning period in rats |
| Auteur: |
Ikeda, Masayuki Honda, Kazuki Inoue, Shojiro |
| Verschenen in: |
Biological rhythm research |
| Paginering: | Jaargang 26 (1995) nr. 5 pagina's 521-531 |
| Jaar: |
1995-11 |
| Inhoud: |
Vitamin B12 (VB12) is known as a putative modulator for the mammalian circadian clock. In an attempt to analyze the mechanism by which VB12 modulates the clock system, circadian time (CT) dependency of two VB12 analogs, methylcobalamin (methyl-B12) and cyanocobalamin (cyano-B12), was investigated by means of recording sleep-wake and brain temperature (Tbr) rhythms over 3 weeks in rats freerunning under continuous dim illumination (dim LL). A 3-h intracerebroventricular infusion of methyl-B12 (30 nmol) was-done at three different CT phases such as CT 12-15 (starting at activity onset), CT 18-21 (starting mid at active period) and CT 0-3 (starting at activity offset). A significant enhancement of both non-rapid-eye-movement sleep and rapid-eye-movement sleep in phase with a significant reduction of Tbr was acutely induced during the late subjective night by the administration of methyl-B12 at CT 12-15 and at CT 18-21. In contrast, sleep and Tbr were little affected by the infusion at CT 0-3. Subsequently, the freerunning period of Tbr during 10 days after the methyl-B12 administration was prolonged in all CT groups by 0.2-0.5 h as compared with that during 10 days prior to the treatment, although a significant difference was found only after the CT 12-15 infusion. Cyano-B12 (30 nmol) similarly infused at CT 12-15 resulted in no significant change in sleep and Tbr parameters. These results indicate that methyl-B12 phase-dependently modulated sleep, Tbr and freerunning period of Tbr, and that central transmethylation caused by methyl-B12 may be responsible for its effects on the circadian pacemaking system and the regulatory systems for sleep and Tbr. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 4 van 11 gevonden artikelen
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