Relationship of atypical melatonin rhythm with two circadian clock outputs in B6D2F1 mice
1 Laboratoire "Rythmes Biologiques and Chronothérapeutique," Institut du Cancer et d'Immunogénétique et Université Paris XI, Hôpital Paul Brousse, 94807 Villejuif Cedex; 2 Institut de Recherches Internationales Servier, 92415 Courbevoie; and 3 Technologie Servier, 45000 Orléans, Fr...
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Published in | American journal of physiology. Regulatory, integrative and comparative physiology Vol. 278; no. 4; p. 924 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
01.04.2000
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Online Access | Get full text |
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Summary: | 1 Laboratoire "Rythmes Biologiques and
Chronothérapeutique," Institut du Cancer
et d'Immunogénétique et Université Paris XI,
Hôpital Paul Brousse, 94807 Villejuif Cedex;
2 Institut de Recherches Internationales
Servier, 92415 Courbevoie; and 3 Technologie
Servier, 45000 Orléans, France
Circadian rhythms in body
temperature, locomotor activity, and the circadian changes of plasma
and pineal melatonin content were investigated in B6D2F 1
mice synchronized by 12 h of light and 12 h of darkness. During 8 wk
continuous recording, activity and temperature displayed a marked
stable and reproducible circadian rhythm, with both peaks occurring
near the middle of darkness. Both 24- and 12-h rhythmic components were
also significantly detected. Mean plasma melatonin concentration rose
steadily during the light span and reached a maximum (30.6 ± 10.0 pg/ml) at 11 h after light onset (HALO), then gradually decreased after
the onset of darkness to a nadir (4.7 ± 0.4 pg/ml) at 20 HALO. Mean pineal content followed a pattern parallel to that of plasma
concentration (peak at 11 HALO: 17.7 ± 1.0 pg/gland; trough at 17 HALO: 4.7 ± 1.0 pg/gland). In addition, a second sharp peak was
observed at 21 HALO (20.2 ± 3.5 pg/gland). Plasma and pineal contents
displayed large and statistically significant circadian changes, with a composite rhythm of period (24 + 12 h). This mouse model has
predominant production and secretion of melatonin during the day. This
possibly contributes to a similar coupling between chronopharmacology
mechanisms and the rest-activity cycle in these mice and in human subjects.
circadian rhythms; body temperature; locomotor activity; pineal
gland |
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ISSN: | 0363-6119 1522-1490 |
DOI: | 10.1152/ajpregu.2000.278.4.r924 |