Methylcobalamin amplifies melatonin-induced circadian phase shifts by facilitation of melatonin synthesis in the rat pineal gland

Masayuki Ikeda, Makoto Asai, Takahiro Moriya, Masami Sagara, Shojiro Inoué, Shigenobu Shibata

研究成果: Article査読

7 被引用数 (Scopus)

抄録

Effects of methylcobalamin (methyl-B12), a putative drug for treating human circadian rhythm disorders, on the melatonin-induced circadian phase shifts were examined in the rat. An intraperitoneal injection of 1-100 μg/kg melatonin 2-h before the activity onset time (CT 10) induced phase advances of free-running activity rhythms in a dose-dependent manner (ED50 = 1.3 μg/kg). Injection of methyl-B12 (500 μg/kg) prior to melatonin (1 μg/kg) injection induced larger phase advances than saline preinjected controls, while the injection of methyl-B12 in combination with saline did not induce a phase advance. These results indicate amplification of melatonin-induced phase advances by methyl-B12. Pinealectomy abolished the phase alternating effect of methyl-B12, suggesting a site of action within the pineal gland. In fact, methyl-B12 significantly increased the content of melatonin in the pineal collected 2-h after activity onset (CT 14). In contrast, no difference in melatonin content was found at CT 10, indicating that the effect of methyl-B12 may be gated after the activity onset time when endogenous melatonin synthesis is known to increase. These results suggest that methyl- B12 amplifies melatonin-induced phase advances via an increase in melatonin synthesis during the early subjective night at a point downstream from the clock regulation.

本文言語English
ページ(範囲)98-104
ページ数7
ジャーナルBrain research
795
1-2
DOI
出版ステータスPublished - 1998 6月 8
外部発表はい

ASJC Scopus subject areas

  • 神経科学(全般)
  • 分子生物学
  • 臨床神経学
  • 発生生物学

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