Maternal Programming of Body Weight in Syrian Hamsters

Maternal programming of offspring energy balance has been viewed as an adaptation in which the gestational environment prepares the offspring to thrive and reproduce in that same postnatal environment. Programming might have the opposite effect, however, when gestational and postnatal environments are mismatched. Gestational programming would represent a trade-off if the mother can maximize fitness in one possible energetic future but cannot maximize fitness in another. The vast majority of research concerns rats, mice, or sheep, and dams are typically food restricted by 30-70% of ad libitum intake resulting in low birth weight and adult obesity in offspring. Few previous studies have used a lower level of food restriction, and no experiments, to the best of our knowledge, were designed to determine whether the effects of gestational restriction have postgestational effects independent of the effects that occurred during gestation. In the present experiment, Syrian hamsters were either restricted to 90% of their ad libitum food intake or fed ad libitum during pregnancy. All litters were cross-fostered at birth and all were fed ad libitum during lactation. Half of the litters from ad libitum-fed pregnant dams were fostered to dams that had been food restricted during pregnancy and half of the litters from food-restricted pregnant dams were fostered to ad libitum-fed dams. The latter group allowed us to test the hypothesis that the effects of having a gestationally food-restricted mother affects offspring characteristics independent of the prenatal programming. First, we found significant increases in the postnatal body weight of the offspring of ad libitum-fed mothers fostered to food-restricted dams, supporting the hypothesis that the effects of gestational restriction carry over to postnatal maternal ability (e.g., milk yield, milk content, or parental behavior). Second, the carry-over effects of gestational food restriction on offspring postnatal body weight were significant in male but not female offspring. This occurred even though this group had significantly lower food intake than offspring of ad libitum-fed mothers with ad libitum-fed foster mothers. In addition, and contrary to expectation, gestational food restriction had no significant effect on adult baseline food hoarding or food hoarding in response to food restriction. These results suggest that even mild energetic challenges during gestation can have postgestational effects on maternal ability, and the effects on offspring are sex-specific.