Amount and type of dietary fat regulate pancreatic lipase gene expression in rats

Both amount and type of dietary triglycerides regulate pancreatic lipase, but the mechanism is not fully understood. This study investigated the effects of type (safflower oil and lard) and amount [low (50 g/kg diet) or moderate (174 g/kg diet)] of fat on rat pancreatic lipase (rPL) activity and mRNA levels. Polyunsaturated safflower oil resulted in 80% greater lipase activity compared with the saturated lard at moderate levels, whereas safflower oil resulted in 50% lower lipase activity compared with lard at low levels. The rPL-3 mRNA levels were greater in rats fed the moderate safflower oil diet (163%) or the moderate lard diet (212%) than in those fed the respective low fat diets and were 45% greater in those fed safflower oil than in those fed lard. The rPL-1 mRNA levels were greater in rats fed moderate safflower oil (50%) or lard (135%) than in those fed the respective low fat diet, but these levels were not affected by type of fat, in contrast to rPL-3 mRNA levels. The amount of fat independent of its type regulates pancreatic lipase pre-translationally, because increasing dietary saturated or polyunsaturated fat resulted in parallel changes in rPL-3 and rPL-1 mRNA levels. However, type of fat may regulate pancreatic lipase at other levels such as translational or post-translational, because the 212% increase in rPL-3 mRNA in rats fed the moderate lard diet compared with the low lard diet did not result in greater pancreatic lipase activity.