Abstract:
Activities of lipoprotein lipase (LPL) and hormone-sensitive
lipase (HSL) in adipose tissue, accumulation of carcass fat, and
serum triglyceride have been determined in meal-fed (MF) and
ad libitum-fed (AD) rats. At each feeding frequency, the animals
received diets providing total fat as 15% or 30% of calories and
polyunsaturated fatty acids (PUFA) as 2.5% or 11% of calories.
The food intake of the MF rats was 75% of that consumed by
the AD rats but MF rats utilized their food more efficiently, as
evidenced by weight gain per 100 Kcal consumed. Meal feeding, as
contrasted to ad libitum feeding, resulted in greater activities
of both LPL and HSL. This suggested a higher turnover of fat in
the adipose tissue of MF rats. In AD rats, body fat was significantly
correlated with LPL and the ratio of LPL:HSL. Meal feeding
significantly increased the ratio of LPL:HSL, indicating a greater
capacity for energy storage and fat deposition in the MF rat. However, at the limited caloric intake, MF rats failed to realize
this potential; there was no significant difference in percentage
of body fat at the two feeding frequencies.
Body fat deposition was greater in rats fed the 30% fat diet,
as compared with the 15% diet, regardless of the rate of food
ingestion. This was coupled with a higher ratio of LPL:HSL. The
significant correlation of serum triglycerides with body fat and
with the ratio of LPL:HSL in AD rats suggests that LPL activity and
fat deposition may be controlled by the concentration of circulating
triglycerides. Both serum triglycerides and adipose LPL activity
were significantly reduced when the diet contained high levels of
PUFA. The percentage of body fat was also lower in animals whose
intake of PUFA was high.
