Metabolic heat production and cold tolerance during cold stress of different intensity of adult and aged male C57BL/6J mice.
Adult and aged male C57BL/6J mice were subjected to a 3-h cold stress test at either 24 degrees C, 18 degrees C, 12 degrees C, or 6 degrees C. Body mass was measured before the test, and colonic temperature, O2 consumption, and CO2 production were measured during the test. The slopes of colonic temperature over time of test and the mean metabolic heat production were calculated for each animal. While adult mice had a relatively small reduction in colonic temperature during the test at all four ambient temperatures, in the aged mice ambient temperatures resulted in steeper reductions of colonic temperature. In adult mice, an increase in metabolic heat production was proportional to ambient cold. The thermogenic response of aged mice at 24 degrees C and at 18 degrees C was similar to adult mice, suggesting that the ability of aged mice to respond to cold by increasing heat production does not diminish with age. However, in aged mice metabolic heat production at 12 degrees C and 6 degrees C was significantly below that of adult mice, which indicated a reduced capacity for thermogenesis.
Tatelman
H M
HM
Laboratory of Behavioral Sciences, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224.
Talan
M I
MI
D000375:Aging / Q000502:physiology*; D000818:Animals; D001833:Body Temperature Regulation; D003080:Cold Temperature; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL