Animals and diets. Wistar male rats(175-185 g body wt, Shizuoka Agricultural
Cooperative Assoc. for Laboratory Animals,Hamamatsu, Japan) were individually housed
in stainless steel wire-bottom cages in a room maintained at 22-24 °Cwith about50 % relative humidity. The room was lighted from 0600 to 1800. Rats were fed each diet
for 10 d. In all experiments, rats were fed a commercial nonpurified diet (MF, Oriental
Yeast Co., Tokyo, Japan) (12) for 3 d to allow them to adjust to the new environment and
then were starved for 1 d before starting experiments. Water was provided ad libitum.