A low-fat diet but not food restriction improves lactational performance in obese rats

Importance of the lactation period in developmental programming in rodents

Lactation is a critical period during which maternal nutritional and environmental challenges affect milk composition and, therefore, organ differentiation, structure, and function in offspring during the early postnatal period. Evidence to date shows that lactation is a vulnerable time during which transient insults can have lasting effects, resulting in altered health outcomes in offspring in adult life. Despite the importance of the developmental programming that occurs during this plastic period of neonatal life, there are few comprehensive reviews of the multiple challenges—especially to the dam—during lactation. This review presents milk data from rodent studies involving maternal nutritional challenges and offspring outcome data from studies involving maternal manipulations during lactation. Among the topics addressed are maternal nutritional challenges and the effects of litter size and artificial rearing on offspring metabolism and neural and endocrine outcomes. The lactation period is an opportunity to correct certain functional deficits resulting from prenatal challenges to the fetus, but, if not personalized, can also lead to undesirable outcomes related to catch up-growth and overnutrition.

Preconception Prebiotic and Sitagliptin Treatment in Obese Rats Affects Pregnancy Outcomes and Offspring Microbiota, Adiposity, and Glycemia

Maternal obesity is associated with increased risk of pregnancy complications and greater risk of obesity in offspring, but studies designed to examine preconception weight loss are limited. The objective of this study was to determine if a combined dietary [oligofructose (OFS)] and pharmacological (sitagliptin) preconception intervention could mitigate poor pregnancy outcomes associated with maternal obesity and improve offspring metabolic health and gut microbiota composition. Diet-induced obese female Sprague-Dawley rats were randomized to one of four intervention groups for 8 weeks: (1) Obese-Control (consumed control diet during intervention); (2) Obese-OFS (10% OFS diet); (3) Obese-S (sitagliptin drug); (4) Obese-OFS + S (combination treatment). Two reference groups were also included: (5) Obese-HFS (untreated obese consumed high fat/sucrose diet throughout study); (6) Lean-Control (lean reference group that were never obese and consumed control diet throughout). Offspring consumed control diet until 11 weeks of age followed by HFS diet until 17 weeks of age. The Obese-OFS + S rats lost weight during the intervention phase whereas the OFS and S treatments attenuated weight gain compared with Obese-HFS (p < 0.05). Gestational weight gain was lowest in Obese-OFS + S rats and highest in Obese-HFS rats (p < 0.05). Prepregnancy intervention did not affect reproductive parameters but did affect pregnancy outcomes including litter size. Male Obese-OFS offspring had significantly lower percent body fat than Obese-HFS at 17 weeks. Female Obese-S and Obese-OFS offspring had significantly lower fasting glucose at 17 weeks compared with Obese-Control and Obese-HFS. Clostridium cluster XI was higher in Obese-HFS and Obese-S dams at birth compared with all other groups. Dams with an adverse pregnancy outcome had significantly lower (p = 0.035) Lactobacillus spp. compared with dams with normal or small litters. At weaning, male offspring of Obese-HFS had higher levels of Methanobrevibacter than all other groups except Obese-S and female Obese-HFS offspring had higher Enterobacteriaceae compared with all other groups. At 11 and 17 weeks of age, Bacteroides/Prevotella spp. was significantly lower in male and female offspring of Obese-HFS dams compared with all other groups except Obese-OFS + S. Modest weight loss induced with a diet-drug combination did not affect maternal fecundity but did have sex-specific effects on offspring adiposity and glycemia that may be linked to changes in offspring microbiota.

Larger infant size at birth reduces the negative association between maternal prepregnancy body mass index and breastfeeding duration

Women who are overweight or obese prepregnancy have shorter durations of producing milk (PM) and feeding breast milk exclusively (FBM-ex) than normal-weight women. We proposed that infant size at birth may reduce the negative associations between prepregnancy BMI and the durations of PM and FBM-ex. We used data from 2798 participants in the Infant Feeding Practices Study II and characterized infant size at birth as weight-for-gestational age (WGA). To assess possible mediation of the associations between maternal BMI and the durations of PM and FBM-ex by infant size at birth, Baron and Kenny's methods, the Sobel test, and bootstrapping were used. As expected, prepregnancy BMI was negatively associated (P < 0.0001) with the durations of PM and FBM-ex; it also was positively associated (P < 0.0001) with infant size at birth. However, infant WGA was positively associated (P < 0.0003) with the durations of PM and FBM-ex after adjustment for BMI. Thus, the negative associations between BMI and the durations of PM and FBM-ex were reduced by infant WGA; i.e. the statistical removal of infant size at birth increased the magnitude of the negative associations between BMI and the durations of PM and FBM-ex. Thus, the tendency of heavier mothers to deliver heavier infants reduces the true magnitude of the association between maternal prepregnancy BMI and shortened breastfeeding duration.

Association of maternal obesity before conception with poor lactation performance

The objective of this review is to evaluate the evidence for a link between maternal obesity and poor lactation performance. In nonhuman species, excess maternal fatness is deleterious for lactation and also for maternal health and survival. These effects occur during pregnancy and as milk production is beginning. They may result in poor growth and survival of the young. In women, there is a negative association between maternal obesity and the initiation as well as the continuation of breastfeeding. This appears to be derived from biological as well as sociocultural factors that are still poorly understood. Excessive gestational weight gain, complications of pregnancy and delivery, and the condition of the infant at birth may also contribute to this association. Given the increasingly high rates of obesity among women of reproductive age worldwide and the importance of breastfeeding for infant health, further study of this association is essential.

Diet-induced obesity impairs mammary development and lactogenesis in murine mammary gland

We have developed a mouse model of diet-induced obesity that shows numerous abnormalities relating to mammary gland function. Animals ate approximately 40% more calories when offered a high-fat diet and gained weight at three times the rate of controls. They exhibited reduced conception rates, increased peripartum pup mortality, and impaired lactogenesis. The impairment of lactogenesis involved lipid accumulation in the secretory epithelial cells indicative of an absence of copius milk secretion. Expression of mRNAs for beta-casein, whey acid protein, and alpha-lactalbumin were all decreased immediately postpartum but recovered as lactation was established over 2-3 days. Expression of acetyl-CoA carboxylase (ACC)-alpha mRNA was also decreased at parturition as was the total enzyme activity, although there was a compensatory increase in the proportion in the active state. By day 10 of lactation, the proportion of ACC in the active state was also decreased in obese animals, indicative of suppression of de novo fatty acid synthesis resulting from the supply of preformed fatty acids in the diet. Although obese animals consumed more calories in the nonpregnant and early pregnant states, they showed a marked depression in fat intake around day 9 of pregnancy before food intake recovered in later pregnancy. Food intake increased dramatically in both lean and obese animals during lactation although total calories consumed were identical in both groups. Thus, despite access to high-energy diets, the obese animals mobilized even more adipose tissue during lactation than their lean counterparts. Obese animals also exhibited marked abnormalities in alveolar development of the mammary gland, which may partially explain the delay in differentiation evident during lactogenesis.