Abstract
The effects of cold acclimation on cellularity, lipoprotein lipase (LPL) activity and lipolysis were studied in white adipose tissue of rats fed a high fat diet. Male Osborne-Mendel rats (7 weeks old) were exposed at either 28 or 5 °C for 10 weeks. The rats were fed a semipurified diet (normal fat (NL): 5% lard, high fat (HL): 54% lard) for the last 9 weeks. Caloric intake with NL and HL diets were comparable and cold exposure led to the same increase with both diets. At 28 °C, HL diet initiated both hypertrophy and hyperplasia; however, at 5 ° C only hyperplasia was observed. Total LPL activity showed high stimulation both in 28 and 5 °C HL rats. In vitro lipolytic stimulation by norepinephrine was lowered at 5 °C and abolished at 28 °C in HL-fed rats. HL diet resulted in enhanced lipid deposition without an increase in caloric intake. Even in cold-adapted Osborne-Mendel rats a relative obesity could be produced by a HL diet.