Plasma cholesterol levels in eviscerated rats

Eviscerated rat models with a functional liver in which the kidneys or pancreas could be left in situ or removed were used. We found that removal of the gastrointestinal tract leaving the liver and kidneys intact resulted in a significant elevation above normal of the plasma cholesterol. In the absence of the liver, esterified cholesterol is decreased. The presence or absence of the kidneys plays no role here; esterification of cholesterol is primarily a liver function. The elevation in total cholesterol levels after removal of the gastrointestinal tract and pancreas is probably due to a lack of insulin action on peripheral tissues. This elevation in cholesterol is similar to that seen in genetic, surgical and chemical diabetes. Complete restoration of plasma cholesterol patterns to intact animal levels was seen only when the pancreas, liver and kidneys were left functional in the eviscerated rat. These data indicate that in this experimental model the absence of the intestinal tract per se does not significantly modify plasma cholesterol levels and that the critical regulators of cholesterol metabolism appear to be the liver and the endocrine pancreas.