Effect of Maternal Food Restriction on the Uterus of Female Rats from the First and Second Generation

Postnatal life is affected by changes in fetal development due to adverse events. The present study examined the effect of maternal food restriction on uterine structure and capacity in female rats from the first and second generations (FR1 and FR2) before and after puberty. Pregnant rats were fed ad libitum (Control, C) or maintained under food-restriction conditions (50%FR) during pregnancy. After delivery, all groups were given free access to food. Females from the first generation (FR1) were divided into two subgroups for either uterine dissection or to produce the next generation (FR2). Similar to FR1, FR2 females were exposed to maternal food restriction following the same procedure. FR2 females were also assigned into two subgroups for either uterine dissection or for mating to examine pregnancy outcomes. Uteri from the C, FR1 and FR2 groups were dissected at 4 weeks of age (before puberty) or at 8 weeks of age (after puberty) to evaluate uterine weight and uterine horn length. Tissues were stained with eosin and haematoxylin for examination vialight microscopy. The results showed that food restriction did not affect uterine weight or uterine horn length in FR1 and FR2 females before puberty. However, there were effects of maternal food restriction on uterine weight and length at 8 weeks of age. Uterine weight and uterine horn length were significantly reduced in the FR1 and FR2 groups compared with the values of the controls. This was associated with changes in pregnancy outcomes. Litter size was not affected in the FR1 group;however, litter weight was significantly reduced, leading to an 18% reduction in pup weight at birth. Unlike with FR1 litters, the size of FR2 litters was significantly reduced, leading to a lower degree of pup body weight reduction at birth (only 7%). The gestational length was normal in FR1 females but was significantly decreased in FR2 females. No histopathological changes were observed. These results showed that the uterus was affected by maternal food restriction. It seemed that FR2 females had a different reproductive strategy: they tended to reduce litter size to maintain pup weight at birth. In conclusion, maternal food restriction affects the uteri of the first and second generation. Females from the FR1 and FR2 groups followed different reproductive strategies according to their previous experience with exposure to intrauterine food restriction.