Metabolomic approach in milk from calorie-restricted rats during lactation: a potential link to the programming of a healthy phenotype in offspring.

PURPOSE: Mild/moderate maternal calorie restriction during lactation in rats has been associated with a lower predisposition to obesity and a healthier metabolic profile in adult offspring. Here, we aimed to assess the impact of maternal calorie restriction during lactation on milk composition to identify potential candidate components that could be involved in the programming effects in offspring. METHODS: An untargeted metabolomic approach in milk samples from 20%-calorie-restricted lactating (CRL) dams and their controls was performed. Levels of leptin, adiponectin, and irisin hormones in milk were also determined at lactating days 5, 10, and 15. RESULTS: Metabolomic analyses revealed a different metabolite pattern in milk between controls and CRL dams. 29 differential metabolites were tentatively identified (p < 0.05, FC > 1.5). Among them, myo-inositol, which showed greater levels in milk from CRL rats than controls, may be highlighted as one of the biologically plausible candidates that could be related to the beneficial effects of CRL in offspring. Results regarding myo-inositol were validated spectrophotometrically at days 10 and 15 of lactation, and levels in milk were correlated with maternal plasma levels. In addition, milk from CRL dams presented increased levels of adiponectin, decreased levels of irisin, and no changes in leptin levels vs controls throughout lactation. CONCLUSION: These data reveal important changes in milk composition due to calorie restriction during lactation that may be involved in the metabolic programming of the healthier phenotype of adult offspring. However, the possible contribution of the specific components is yet to be determined.

Enhancing hepatic fatty acid oxidation as a strategy for reversing metabolic disorders programmed by maternal undernutrition during gestation.

BACKGROUND/AIMS: Moderate maternal calorie-restriction during gestation programmes offspring for a major propensity to develop metabolic alterations in adulthood. We aimed to assess whether increased hepatic fatty-acid oxidation (FAO), at early ages, by gene transfer of Cpt1am (active mutant of carnitine palmitoyltransferase-1a), may be a strategy for reversing metabolic disturbances associated to maternal calorie-restriction during gestation in rats. METHODS: AAV-Gfp (control) and AAV-Cpt1am vectors were administered by tail vein injection in 18-day-old control-pups and the offspring of 20% calorie-restricted rats during gestation (CR). After weaning, animals were fed with normal-fat diet. At the age of 4 months, they were moved to HF-diet and sacrificed at the age of 6 months to collect tissues. Locomotive activity, energy expenditure and blood pressure were measured. RESULTS: Under HF-diet, CR-animals showed higher HOMA-IR, adipocyte diameter and hepatic triglyceride accumulation than controls; these alterations were reverted in Cpt1am-injected animals. In liver, this treatment ameliorated inflammatory state, decreased expression of lipogenesis-related genes and partially restored the decreased expression of leptin-receptor occurring in CR-animals. Treatment also reverted the decreased energy expenditure and the increased blood pressure of CR-animals. CONCLUSION: Increasing hepatic FAO through AAV-Cpt1am injection at juvenile ages prevents some metabolic disorders associated to gestational maternal calorie-restriction.

Impaired insulin and leptin sensitivity in the offspring of moderate caloric-restricted dams during gestation is early programmed.

We aimed to assess the mechanisms responsible for hyperphagia and metabolic alterations caused by maternal moderate caloric restriction during gestation. Male and female offspring of control and 20% caloric-restricted rats (CR) were studied. They were fed a normal-fat diet until 4 months of age and then moved to a high-fat diet until 6 months of age. Blood parameters and expression of selected genes in hypothalamus, retroperitoneal white adipose tissue (rWAT) and liver were analyzed at 25 days and 6 months of age. Plasma leptin was measured during suckling. Levels of proteins involved in insulin and leptin signaling were determined at 6 months of age. CR ate more calories than controls, but only males gained more weight. A peak in plasma leptin was found in 9-day-old controls, but was absent in CR. Twenty-five-day-old CR showed lower insulin receptor mRNA levels in hypothalamus, rWAT and liver, and long-form leptin receptor (ObRb) in hypothalamus. At the age of 6 months, homeostatic model assessment for insulin resistance index was higher in CR than controls, and CR males also displayed hyperleptinemia. Adult CR also showed lower ObRb mRNA levels in the hypothalamus (only females, but both showed altered neuropeptide Y/proopiomelanocortin mRNA ratio), rWAT and liver (males), and a decrease of protein kinase C zeta levels in rWAT (females) and liver (males) and of phosphorylated signal transducer and activator of transcription 3 in liver (females). These results suggest that CR animals are programmed for insulin and central leptin resistance, which may explain the dysregulation of appetite and other metabolic alterations, favoring obesity development, although only manifested in males. These early programming effects could be associated with the absence of leptin surge during lactation.

Moderate caloric restriction in lactating rats programs their offspring for a better response to HF diet feeding in a sex-dependent manner.

We aimed to assess the lasting effects of moderate caloric restriction in lactating rats on the expression of key genes involved in energy balance of their adult offspring (CR) and their adaptations under high-fat (HF) diet. Dams were fed with either ad libitum normal-fat (NF) diet or a 30% caloric restricted diet throughout lactation. After weaning, the offspring were fed with NF diet until the age of 15 weeks and then with an NF or a HF diet until the age of 28 weeks, when they were sacrificed. Body weight and food intake were followed. Blood parameters and the expression of selected genes in hypothalamus and white adipose tissue (WAT) were analysed. CR ate fewer calories and showed lower body weight gain under HF diet than their controls. CR males were also resistant to the increase of insulin and leptin occurring in their controls under HF diet, and HF diet exposed CR females showed lower circulating fasting triglyceride levels than controls. In the hypothalamus, CR males had higher ObRb mRNA levels than controls, and CR females displayed greater InsR mRNA levels than controls and decreased neuropeptide Y mRNA levels when exposed to HF diet. CR males maintained WAT capacity of fat uptake and storage and of fatty-acid oxidation under HF diet, whereas these capacities were impaired in controls; female CR showed higher WAT ObRb mRNA levels than controls. These results suggest that 30% caloric restriction in lactating dams ameliorates diet-induced obesity in their offspring by enhancing their sensitivity to insulin and leptin signaling, but in a gender-dependent manner.