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| Titel: |
Re-entrainment of the Rabbit's circadian food intake pattern after inversion of 24-hr sawtooth illuminations and standard light-dark alternations |
| Auteur: |
Bobbert, A. C. van Kempen, A. P. Braakman, J. N. |
| Verschenen in: |
Biological rhythm research |
| Paginering: | Jaargang 25 (1994) nr. 1 pagina's 89-105 |
| Jaar: |
1994-02 |
| Inhoud: |
Long-term recordings of the number of food approaches per 30 min were made from 10 rabbits that were fed ad libitum. They were exposed for long periods to various 24-hr LD alternations and to 24-hr sawtooth illuminations that were suddenly inverted or converted, so that at 10.00 h w.t. there was alternately an L-D or a D-L transition. The directions of the transients showed, unexpectedly, that re-entrainment by phase-advance occurred in less than 8 pct of the cases. The durations of the transients were measured for the pattern as a whole and exhibited that entrainment of the food intake rhythm by standard LD alternations takes less time than in the case of its synchronization by sawtooth illuminations, (i.e., incomplete regimes which comprise only one type of transition) and, further, that entrainment by the sawtooth regime containing abrupt D-L transitions was achieved only after very long exposure - if at all. These results are in full agreement with those of previous experiments which suggested, first: that in rabbits the time course of various circadian rhythms is governed by a central circadian system which consists of a typical light (I)ON oscillator and a light (I) OFF oscillator with quite different properties, and secondly: that synchronization of the rabbit's food intake rhythm to photic 24-hr regimes is largely effected by non-parametric entrainment. The duration of the transients could also be determined separately for each of the two oscillators. From this it became evident that the non-parametric synchronization of the intake rhythm is achieved both by direct entrainment of the two oscillators, each to its appropriate photic transition, and by the indirect entraining actions resulting from the (asymmetric) coupling forces between the two oscillators. It further appeared that the directly entraining action of the L-D transitions on the 1 OFF oscillator is stronger than the same exerted by the D-L transitions upon the 1 ON oscillator and, also, that there are great interindividual differences in the efficacy of photic entrainment. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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