Maternal High-Fat Diet During Pre-Conception and Gestation Predisposes Adult Female Offspring to Metabolic Dysfunction in Mice

Circadian Disruption across Lifespan Impairs Glucose Homeostasis and Insulin Sensitivity in Adult Mice

Circadian rhythm disruption is associated with impaired glucose homeostasis and type 2 diabetes. For example, night shift work is associated with an increased risk of gestational diabetes. However, the effects of chronic circadian disruption since early life on adult metabolic health trajectory remain unknown. Here, using the "Short Day" (SD) mouse model, in which an 8 h/8 h light/dark (LD) cycle was used to disrupt mouse circadian rhythms across the lifespan, we investigated glucose homeostasis in adult mice. Adult SD mice were fully entrained into the 8 h/8 h LD cycle, and control mice were entrained into the 12 h/12 h LD cycle. Under a normal chow diet, female and male SD mice displayed a normal body weight trajectory. However, female but not male SD mice under a normal chow diet displayed glucose intolerance and insulin resistance, which are associated with impaired insulin signaling/AKT in the skeletal muscle and liver. Under high-fat diet (HFD) challenges, male but not female SD mice demonstrated increased body weight gain compared to controls. Both male and female SD mice developed glucose intolerance under HFD. Taken together, these results demonstrate that environmental disruption of circadian rhythms contributes to obesity in a sexually dimorphic manner but increases the risk of glucose intolerance and insulin resistance in both males and females.

Parental obesity-induced changes in developmental programming

Many studies support the link between parental obesity and the predisposition to develop adult-onset metabolic syndromes that include obesity, high blood pressure, dyslipidemia, insulin resistance, and diabetes in the offspring. As the prevalence of obesity increases in persons of childbearing age, so does metabolic syndrome in their descendants. Understanding how parental obesity alters metabolic programs in the progeny, predisposing them to adult-onset metabolic syndrome, is key to breaking this cycle. This review explores the basis for altered metabolism of offspring exposed to overnutrition by focusing on critical developmental processes influenced by parental obesity. We draw from human and animal model studies, highlighting the adaptations in metabolism that occur during normal pregnancy that become maladaptive with obesity. We describe essential phases of development impacted by parental obesity that contribute to long-term alterations in metabolism in the offspring. These encompass gamete formation, placentation, adipogenesis, pancreas development, and development of brain appetite control circuits. Parental obesity alters the developmental programming of these organs in part by inducing epigenetic changes with long-term consequences on metabolism. While exposure to parental obesity during any of these phases is sufficient to alter long-term metabolism, offspring often experience multiple exposures throughout their development. These insults accumulate to increase further the susceptibility of the offspring to the obesogenic environments of modern society.

The dynamic effects of maternal high-calorie diet on glycolipid metabolism and gut microbiota from weaning to adulthood in offspring mice

Dysbiosis of gut microbiota can contribute to the progression of diabetes and obesity. Previous studies have shown that maternal high-fat (HF) diet during the perinatal period can alter the microbiota and induce metabolic disorders at weaning. However, whether dysbiosis of gut microbiota and metabolism could be recovered by a normal diet after weaning and the dynamic changes of gut microbiota have not been fully studied. In this study, C57BL/6J female mice were fed with a normal chow (NC) or HF diet for 4 weeks preconception, during gestation, and until pup weaning. After weaning, male offspring were fed with an NC diet until 9 weeks of age. The microbiota of offspring at weaning and 9 weeks of age was collected for 16S rRNA gene amplicon sequencing. We found that dams fed with an HF diet showed glucose intolerance after lactation. Compared with the offspring from NC dams, the offspring from HF dams exhibited a higher body weight, hyperglycemia, glucose intolerance, hyperinsulinemia, hypercholesterolemia, and leptin resistance and lower adiponectin at weaning. Fecal analysis indicated altered microbiota composition between the offspring of the two groups. The decrease in favorable bacteria (such as norank f Bacteroidales S24-7 group) and increase in unfavorable bacteria (such as Lachnoclostridium and Desulfovibrio) were strongly associated with a disturbance of glucose and lipid metabolism. After 6 weeks of normal diet, no difference in body weight, glucose, and lipid profiles was observed between the offspring of the two groups. However, the microbiota composition of offspring in the HF group was still different from that in the NC group, and microbiota diversity was lower in offspring of the HF group. The abundance of Lactobacillus was lower in the offspring of the HF group. In conclusion, a maternal HF diet can induce metabolic homeostasis and gut microbiota disturbance in offspring at weaning. Gut microbiota dysbiosis can persist into adulthood in the offspring, which might have a role in the promotion of susceptibility to obesity and diabetes in the later life of the offspring.

Programming by maternal obesity: a pathway to poor cardiometabolic health in the offspring

There is an ever increasing prevalence of maternal obesity worldwide such that in many populations over half of women enter pregnancy either overweight or obese. This review aims to summarise the impact of maternal obesity on offspring cardiometabolic outcomes. Maternal obesity is associated with increased risk of adverse maternal and pregnancy outcomes. However, beyond this exposure to maternal obesity during development also increases the risk of her offspring developing long-term adverse cardiometabolic outcomes throughout their adult life. Both human studies and those in experimental animal models have shown that maternal obesity can programme increased risk of offspring developing obesity and adipose tissue dysfunction; type 2 diabetes with peripheral insulin resistance and β-cell dysfunction; CVD with impaired cardiac structure and function and hypertension via impaired vascular and kidney function. As female offspring themselves are therefore likely to enter pregnancy with poor cardiometabolic health this can lead to an inter-generational cycle perpetuating the transmission of poor cardiometabolic health across generations. Maternal exercise interventions have the potential to mitigate some of the adverse effects of maternal obesity on offspring health, although further studies into long-term outcomes and how these translate to a clinical context are still required.

Diet Modification before or during Pregnancy on Maternal and Foetal Outcomes in Rodent Models of Maternal Obesity

The obesity epidemic has serious implications for women of reproductive age; its rising incidence is associated not just with health implications for the mother but also has transgenerational ramifications for the offspring. Increased incidence of diabetes, cardiovascular disease, obesity, and kidney disease are seen in both the mothers and the offspring. Animal models, such as rodent studies, are fundamental to studying maternal obesity and its impact on maternal and offspring health, as human studies lack rigorous controlled experimental design. Furthermore, the short and prolific reproductive potential of rodents enables examination across multiple generations and facilitates the exploration of interventional strategies to mitigate the impact of maternal obesity, both before and during pregnancy. Given that obesity is a major public health concern, it is important to obtain a greater understanding of its pathophysiology and interaction with reproductive health, placental physiology, and foetal development. This narrative review focuses on the known effects of maternal obesity on the mother and the offspring, and the benefits of interventional strategies, including dietary intervention, before or during pregnancy on maternal and foetal outcomes. It further examines the contribution of rodent models of maternal obesity to elucidating pathophysiological pathways of disease development, as well as methods to reduce the impact of obesity on the mothers and the developing foetus. The translation of these findings into the human experience will also be discussed.