Effects of diet composition and length of feeding restriction on the locomotor rhythms of Mus musculus
Robertson, Mark Graham
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Changes in locomotor rhythms of Mus musculus as a response to combinations of lighting and feeding cues were quantitatively assessed in this study. Time allowed for feeding was varied (3, 5, and 7 hours) to examine effect of different zeitgeber strengths on locomotor pattens. The effect of temporal light/dark cue removal on locomotor rhythms was examined in conjunction with restricted feeding regimes. The potential to use blood glucose levels as a temporal feeding cue was examined by comparing the locomotor rhythms of mice consuming either a high glucose or high starch diet. Blood glucose curves for animals under restricted feeding regimes of 1 and 5 hour lengths were determined for the two diets. Most of the locomotor activity records from animals in total darkness and a restricted feeding regime contained rhythm splitting. Only the anticipatory component of locomotor activity was synchronized by the 7 hour and 5 hour restricted feeding regimes in total darkness. Mice on a 3 hour restriction regime also exhibited a free run component in locomotor activity. The two experimental diets did not produce statistical differences in plasma glucose concentrations when animals were placed on a 5 hour restricted feeding regime in total darkness, but did when they were placed in a light/dark l2:l2 lighting cycle with a 1 hour feeding regime. The locomotor records indicated that free-running locomotor components were synchronized only by light/dark transitions, while the anticipatory component was synchronized by food presentation. The results of this study are consistent with a Two-Oscillator Model for control of activity rhythms.
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