Core temperature, O2 consumption, and early detection of ob-ob genotype in mice.

KAPLAN, MURRAY L., AND GILBERT A. LEVEILLE. Core temperature, 02 consumption, and early detection of ob/ob genotype in mice. Am. J. Physiol. 227(4) : 912-915. 1974.-Oxygen consumption and core temperature of ob/ob mice and their thin littermates were measured at various ambient temperatures from 10 to 30°C. At every ambient temperature studied, adult obese mice exhibited lower 02 consumptions and lower core temperatures than those of thin animals. Among the obese mice, changes in 02 consumption with decreasing ambient temperature were minimal; among the thins, significant increases in 02 consumption .occurred with each 5OC decrease in ambient temperature. By raising the ambient temperature from 20 to 25”C, 02 consumptions of preweaned ob/ob mice were markedly lower than ?/+ mice, so that ob/ob individuals could be identified on day 18 with approximately 91 u/0 reliability prior to the phenotypic expression of obesity. This is a much earlier preobese identification than previously reported (Kaplan, M. L., and G. A. Leveille. Proc. Sot. Exptl. Biol. Afed. 143 : 925-928, 1973). Grouped data of the 02 consumption of these animals suggest the existence of a gradient; with ob/ob individuals at the low end of the gradient, ob/+ individuals in the middle, and +/ + individuals at the high end of the gradient. The earlier identification of ob/ob individuals during the preobese phase of development hopefully will enable investigators to more precisely identify the sequence of distinctive metabolic patterns in tissues preceding the phenotypic expression of obesity.