DIFFERENTIAL NUTRIENT PARTITIONING IN PREGNANT RAT DAMS FED RESTRICTED AMOUNTS OF A BALANCED DIET VERSUS RESTRICTED NONPROTEIN CALORIES

Virgin Charles River female rats weighing 240 +/- 10 g were assigned s equentially on d of mating (d 0) to individual cages and fed one of fi ve dietary regimens: C (standard control diet), 24 g/d from d 0 to d 2 0 (n=5); DR (delayed restricted control diet), 24 g/d from d 0 to d 7, then 12 g/d from d 8 to d 20 (n=5); R (restricted control diet), 12 g /d from d 0 to d 20 (n=6); DRCal (delayed restricted nonprotein calori e diet), 24 g/d of standard control diet from d 0 to d 7, then 12 g/d of a diet restricted in nonprotein calories from d 8 to d 20 (n=6); RC al (restricted nonprotein calorie diet), 12 g/d from d 0 to d 20 (n=5) . Litter size was unaffected by diet, but total litter wt and individu al fetus wt at 20 d were greater in C than in all other groups (C > DR > R = DRCal = RCal, P < 0.01). Maternal liver wt was greater in C rat s than in all other groups. Kidney wt was greater in C, DRCal, and RCa l darns than in DR and R dams (C = DRCal = RCal > DR = (P < 0.056). To tal DNA in liver and kidney was not affected by diet. Small intestinal wt was greater in C darns than in all other groups (C > DRCal = RCal > DR = R, P < 0.01), but protein concentration was unaffected by diet. Although large intestinal wt was less in DR and R dams than in C dams , that of DRCal and RCal darns was not different from C (C = DRCal = R Cal > DR = R, P < 0.06). Empty uterus and placentae wt and their prote in and DNA concentrations were unaffected by maternal diet. Weights of combined perirenal and gonadal fat pads were less in DR and D dams th an in C dams and were even less in DRCal and RCal darns (C > DR = R > DRCal = RCal, P < 0.01). Weight of gastrocnemius plus plantaris muscle s was higher in C dams than in all other groups (C > DR = R = DRCal > RCal, P < 0.05). Our data show that when the intake of an adequate die t is severely restricted during all of pregnancy or during the second and third trimesters, the partitioning of nutrients between tile fetus and the maternal body is altered; fetal wt and protein mass are reduc ed. The greater loss of gonadal and perirenal fat in RCal than in R ra ts reflected the greater energy cost of maintaining kidneys and viscer al organs whose mass was differentially repartitioned in response to t he altered diet composition.