ROLE OF ACTIVITY-INDUCED THERMOGENESIS IN TWENTY-FOUR HOUR ENERGY EXPENDITURE OF LEAN AND GENETICALLY OBESE (OB/OB) MICE

¹ AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge CB2 4AT
² AFRC Statistics Group, Department of Applied Biology, University of Cambridge, Pembroke Street, Cambridge CB2 3DX

The contribution made by spontaneous physical activity to 24 h energy expenditure has been assessed in lean and ob/ob mice living at 28°C. Measurements were made in young animals when the ob/ob mice were the same body weight as their lean littermates, and again when they were adult and the ob/ob mice were twice as heavy as their littermates.

In the young ob/ob mice, not only was 24 h heat production lower than in their lean littermates (P 0·005) but so also was motor activity (P 0·01). In adults, total 24 h heat production was similar in lean and obese animals, and thus on the basis of metabolic body size it was considerably lower in the obese adults (P 0·005). The obese adults were also significantly less active than their lean littermates (P 0·05). Differences between genotypes were particularly marked during the night. Partition of 24 h energy expenditure into the two components of rest and activity showed that in the young ob/ob mice the lower heat production occurred because they expended 31% less energy on rest and 47% less on activity than did their lean littermates. In the obese adults, the lower heat production per unit metabolic body size was accounted for by 16% less energy being expended on rest and 74% less on activity than in the lean mice. It is concluded that differences in motor activity between lean and ob/ob mice could account, at least in part, for the development and maintenance of obesity in these animals.

This article has been cited by other articles:

				A. G. Roseberry, T. Painter, G. P. Mark, and J. T. Williams Decreased Vesicular Somatodendritic Dopamine Stores in Leptin-Deficient Mice J. Neurosci., June 27, 2007; 27(26): 7021 - 7027. [Abstract] [Full Text] [PDF]

				H. S. Jurgens, A. Schurmann, R. Kluge, S. Ortmann, S. Klaus, H.-G. Joost, and M. H. Tschop Hyperphagia, lower body temperature, and reduced running wheel activity precede development of morbid obesity in New Zealand obese mice. Physiol Genomics, April 13, 2006; 25(2): 234 - 241. [Abstract] [Full Text] [PDF]

				K. Holtkamp, B. Herpertz-Dahlmann, C. Mika, M. Heer, N. Heussen, M. Fichter, S. Herpertz, W. Senf, W. F. Blum, U. Schweiger, et al. Elevated Physical Activity and Low Leptin Levels Co-occur in Patients with Anorexia Nervosa J. Clin. Endocrinol. Metab., November 1, 2003; 88(11): 5169 - 5174. [Abstract] [Full Text] [PDF]

				J. C.L. Tou and C. E. Wade Determinants Affecting Physical Activity Levels In Animal Models Experimental Biology and Medicine, September 1, 2002; 227(8): 587 - 600. [Abstract] [Full Text] [PDF]

				J. A. Levine, N. L. Eberhardt, and M. D. Jensen Leptin Responses to Overfeeding: Relationship with Body Fat and Nonexercise Activity Thermogenesis J. Clin. Endocrinol. Metab., August 1, 1999; 84(8): 2751 - 2754. [Abstract] [Full Text]