The influence of milk cholesterol ingested by suckling rats on serum cholesterol concentrations of the adult rat

Abstract

This study was conducted to test the hypothesis that cholesterol in the milk of suckling mammals may establish the system for control of serum cholesterol homeostasis in the adult. A relatively simple method has been developed for self-feeding of twelve-day-old rats using a 20 ml glass bottle with a stainless steel tube of 1/8 inch ID. Two groups of twelve-day-old Holtzman rats were fed a milk formula based on bovine skimmed milk and stripped lard. A low cholesterol semi-synthetic milk (LC) group received less than 5 mg cholesterol/100 ml milk while a second semi-synthetic (NC) group received the normal 35 mg cholesterol/100 ml milk. A third (BM) group was fed a 10% butterfat milk formula based on cows' whole milk and cream. This milk also contained 35 mg cholesterol per 100 ml. The animals of the three groups and of a mother nursed (MM) group were weaned at 30 days of age. Bach group contained ten males and ten females. For 30 days after weaning all rats were fed a low cholesterol semi-synthetic ration and challenged with a 0.5% high cholesterol diet at 60 days of age. By the second week on the high cholesterol diet serum levels of the females in all four groups were significantly higher than those of the males, although the cholesterol levels were similar prior to the addition of the 0.5% cholesterol. ...