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Leptin selectively increases energy expenditure of food-restricted lean mice
H Döring1, K Schwarzer, B Nuesslein-Hildesheim
1Max-Planck-Institut für physiologische und klinische Forschung, WG Kerckhoff-Institut, Bad Nauheim, FRG.
Objective:
To find out whether leptin can attenuate hypometabolic torpor-like states of metabolic rate (MR) in adult lean animals, as it attenuates the morning suppression of thermoregulatory thermogenesis in suckling-age rat pups.
Design:
Leptin effects on MR and food intake were studied in mice aged 4-7 months, in which a high incidence of exaggerated circadian reductions of MR had been induced by chronic food-restriction and, for comparison, in free-feeding mice.
Protocol:
Continuous recordings of MR, for a group of seven mice maintained at an ambient temperature of 24 degrees C, while they were repeatedly-with pauses of at least six days-treated for three consecutive days with either recombinant murine leptin (20, 200 or 600 pmol x g(-1) x d[-1]) or saline.
Results:
Leptin treatment caused dose-dependent 5-15% increases in energy expenditure by moderating the decreases in MR during the circadian minima, without affecting either the MR during the circadian maxima or food intake. Similar treatment of free-feeding mice caused dose-dependent decreases of food intake without changing MR.
Conclusion:
Leptin controls thermoregulatory energy expenditure when food supplies are scarce and changes food intake, rather than energy expenditure, when food is abundant.