Tolstun D. A. CIRCADIAN RHYTHMS OF THE ENERGY HOMEOSTASIS IN MICE OF DIFFERENT AGES

State institution " D. F. Chebotarev Institute of Gerontology NAMS Ukraine", 04114 Kyiv

Circadian rhythms of the main variables of energy homeostasis, namely, energy balance (EB), rates of O2 consumption (Vo2) and CO2 production (Vco2), as well as food and water consumption and spontaneous motor activity (SMA) have been studied in around-clock experiments performed on adult female FVBcg mice. Significant circadian alterations have been found, primarily expressed in elevated midnight rates of both energy expenditure (Vo2, Vco2 and SMA) and especially intake (3-4 fold increase of the food consumption rate). Statistically significant positive EB was found immediately after onset of the dark (21-24 h), whereas negative EB was observed with onset of the daylight (6-9 h). EB demonstrated highly significant positive correlations with food (P < 1016) and water consumption (P < 108). Surprisingly, positive pair-wise correlations were found between EB and energy expenditure variables (Vo2 and Vco2) and SMA, as well.

However, the latter relations became negative when analyses with more relevant partial correlations were applied.

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