Gender-related long-term effects in adult rats by perinatal dietary ratio of n-6/n-3 fatty acids

Impact of maternal dietary fatty acid composition on glucose and lipid metabolism in male rat offspring aged 105 d

In recent years the intake ofn-6 PUFA andtrans-fatty acids (TFA) has increased, whereasn-3 PUFA intake has decreased. The present study investigated the effects of maternal diet high inn-6 PUFA,n-3 PUFA or TFA on glucose metabolism, insulin sensitivity and fatty acid profile in male offspring. Female weanling Wistar/NIN rats were randomly assigned to receive either a diet high in linoleic acid (LA), or α-linolenic acid (ALA), or long-chainn-3 PUFA (fish oil; FO), or TFA, for 90 d, and mated. Upon weaning, pups were randomly divided into seven groups (mother's diet-pup's diet): LA-LA, LA-ALA, LA-FO, ALA-ALA, FO-FO, TFA-TFA and TFA-LA. At the age of 105 d, an oral glucose tolerance test, adipocyte glucose transport and muscle phospholipid fatty acid composition were measured in the pups. All animals displayed normal insulin sensitivity as evidenced by similar plasma insulin and area under the curve of insulin after an oral glucose load. Maternal intake ofn-3 PUFA (ALA or FO) resulted in highern-3 PUFA in the offspring. Plasma cholesterol and NEFA were significantly higher in the TFA-TFA group compared with the other groups. Adipocyte insulin-stimulated glucose transport and adiponectin mRNA expression were lower in TFA-TFA and TFA-LA offspring compared with the other groups. While most mother-pup fatty acid combinations did not influence the measured variables in the pups, these results indicate that maternal intake of TFA led to an unfavourable profile in the pups through to the age of 105 d, whether the pups consumed TFA, or not.

An emerging risk factor for obesity: does disequilibrium of polyunsaturated fatty acid metabolism contribute to excessive adipose tissue development?

A positive energy balance (energy intake>energy expenditure), in which total fat intake plays an important role, is commonly regarded as a major factor contributing to obesity. Adipose tissue development, i.e. both size (hypertrophy) and number (hyperplasia), is stimulated by high dietary fat intake during early postnatal development, a susceptibility that now appears to continue well into adulthood. Recent human and animal studies suggest that by altering rates of adipocyte differentiation and proliferation, differences in the composition of dietary fat may also contribute to adipose tissue development. At least in rodent models, the relative intake of n-6 to n-3 PUFA is clearly emerging as a new factor in this development. In these models, higher linoleate intake raises tissue arachidonic acid, which increases prostacyclin production and, in turn, stimulates signalling pathways implicated in adipogenesis. Signalling pathways stimulated by arachidonic acid probably include phospholipase and/or cyclo-oxygenase activation and may be linked as much to relatively low intake of n-3 PUFA as to excessive dietary linoleate. One factor potentially contributing to oversight about the apparent role of dietary n-6 PUFA (especially excess dietary linoleate) in adipose tissue development is the historical overestimation of linoleate requirements and the enthusiasm for higher intake of 'essential fatty acids'. More research is needed to address whether disequilibration of dietary PUFA intake contributes to the risk of obesity in humans.

Diet-induced obesity in female mice leads to offspring hyperphagia, adiposity, hypertension, and insulin resistance: a novel murine model of developmental programming

Maternal obesity is increasingly prevalent and may affect the long-term health of the child. We investigated the effects of maternal diet-induced obesity in mice on offspring metabolic and cardiovascular function. Female C57BL/6J mice were fed either a standard chow (3% fat, 7% sugar) or a palatable obesogenic diet (16% fat, 33% sugar) for 6 weeks before mating and throughout pregnancy and lactation. Offspring of control (OC) and obese dams (OO) were weaned onto standard chow and studied at 3 and 6 months of age. OO were hyperphagic from 4 to 6 weeks of age compared with OC and at 3 months locomotor activity was reduced and adiposity increased (abdominal fat pad mass; P<0.01). OO were heavier than OC at 6 months (body weight, P<0.05). OO abdominal obesity was associated with adipocyte hypertrophy and altered mRNA expression of beta-adrenoceptor 2 and 3, 11 beta HSD-1, and PPAR-gamma 2. OO showed resistance artery endothelial dysfunction at 3 months, and were hypertensive, as assessed by radiotelemetry (nighttime systolic blood pressure at 6 months [mm Hg] mean+/-SEM, male OO, 134+/-1 versus OC, 124+/-2, n=8, P<0.05; female OO, 137+/-2 versus OC, 122+/-4, n=8, P<0.01). OO skeletal muscle mass (tibialis anterior) was significantly reduced (P<0.01) OO fasting insulin was raised at 3 months and by 6 months fasting plasma glucose was elevated. Exposure to the influences of maternal obesity in the developing mouse led to adult offspring adiposity and cardiovascular and metabolic dysfunction. Developmentally programmed hyperphagia, physical inactivity, and altered adipocyte metabolism may play a mechanistic role.

In utero exposure to maternal obesity and diabetes: animal models that identify and characterize implications for future health

The developed and developing worlds are experiencing an epidemic of obesity and associated predisposition to diabetes. This epidemic places a major drain on health care resources. It is now clear that maternal obesity and gestational diabetes have major adverse effects on the developing fetus that lead to increased neonatal morbidity and mortality, as discussed elsewhere in this issue. Obesity in pregnancy and gestational diabetes represent a special problem, not only as a result of their immediate adverse effects on maternal health and pregnancy outcome, but also because of growing evidence for their persistent and deleterious effects on the developing child.

Fatty acid composition in breast milk and serum phospholipids of healthy term Chinese infants during first 6 weeks of life

AIM

To compare the fatty acid (FA) pattern in early and mature breast milk with that in plasma phospholipids of cord blood and breast-fed infants.

METHODS

Forty-five mother-infant pairs from western Shanghai were studied. All infants, born at term with normal weight and length, were examined at birth and days 5 and 42. FA was analyzed by capillary gas-liquid chromatography.

RESULTS

Cord blood showed higher concentration of long-chain polyunsaturated FA (LCPUFA) but lower saturated (SFA) and monounsaturated (MUFA) FA than postnatal infants' plasma. SFA decreased with age in the infants, but MUFA and linoleic acid (LA, 18:2omega6) increased. LCPUFA were lower in the plasma of 5-day-old infants than in cord blood, but LA was 80%, alpha-linolenic acid (ALA, 18:3omega3) 33% and the ratio omega-6/omega-3 42% higher. At day 42, LA increased further, LCPUFA remained similar, and was in breast milk lower than at day 5, while ALA and gamma-linolenic acid (18:3omega6) were higher. The activity index of desaturases indicated high Delta9 activity in breast milk and high activity of Delta5 desaturase in the infants.

CONCLUSION

Breast milk FA composition changed markedly from day 5 to 42 with increasing correlation to infants' plasma. Calculation of desaturase activities suggested high capacity of LCPUFA synthesis.

Effects of diets enriched in omega-3 and omega-6 polyunsaturated fatty acids on offspring sex-ratio and maternal behavior in mice

There have been many trials describing the effects of polyunsaturated fatty acids (PUFA) on fecundity, neonatal development, and maternal behavior in humans, but few controlled studies in rodents. We examined the effects of a maternal diet high in omega 3 (N-3) or omega 6 (N-6) PUFA on NIH Swiss mice. Female mice were ad libitum fed one of three complete and balanced diets (N-3, enriched in menhaden oil; N-6, enriched in corn oil; C, control diet, Purina 5015) from age 4 wk until the end of the study. Mice were bred at approximately 19 wk and 27 wk of age, providing a total of 838 pups from 129 litters in two experiments. After weaning their pups from parity 1, behavior of dams was assessed on elevated-plus and open-field mazes. Although the fraction of male pups from the N-3 and C groups was not different from 0.5, dams on the N-6 diet birthed more daughters than sons (213 vs. 133; P < 0.001). Although maternal stress has been reported to favor birth of daughters, the behavior of N-6 dams was not different from controls. By contrast, the N-3 dams displayed greater anxiety, spending less time in the open arms and more time in the closed arms of the elevated maze and traveling less distance and exhibiting less exploratory behavior in the open field (P < 0.05). N-3 dams tended to produce smaller litters than C dams, and N-3-suckled pups gained less weight (P < 0.05). In conclusion, the N-3 diet had negative effects on murine fecundity and maternal behavior, whereas the N-6 diet favored birth of daughters.

Neonatal growth rate and development of mice raised on milk transgenically enriched with omega-3 fatty acids

The n-3 polyunsaturated fatty acid (PUFA) status of the neonatal brain has been associated with cognitive capability in mice. Previously, transgenic mice expressing the Caenorhabditis elegans (C. elegans) n-3 fatty acid (FA) desaturase gene under the control of a lactation-induced mammary gland promoter were found to produce milk containing significantly elevated levels of alpha-linolenic (ALA) and eicosapentaenoic (EPA) acid. In this study, the preweaning growth rate and development of mouse pups consuming elevated n-3 PUFA milk produced by transgenic dams were evaluated using the Wahlsten observational test battery and the object novelty preference test. Brains were collected at weaning and analyzed for FA composition. Pups nursed on transgenic dams had earlier eye opening, higher visual placement scores, and 1.6-fold more docosahexaenoic acid (DHA) in their brains compared with pups raised on wildtype dams. There was no significant effect of milk treatment (transgenic versus control) on other developmental parameters or novelty preference behavior. The pups consuming the elevated n-3 PUFA transgenic milk had slower preweaning growth rates such that pups reared on wildtype dams producing control milk were heavier than pups reared on transgenic dams producing high n-3 PUFA milk by postnatal day 18. This transgenic model enables the provision of a high n-3 PUFA lactational environment independent of maternal diet or gestational FA status.

In utero exposure to maternal obesity and diabetes: animal models that identify and characterize implications for future health

The developed and developing worlds are experiencing an epidemic of obesity and associated predisposition to diabetes. This epidemic places a major drain on health care resources. It is now clear that maternal obesity and gestational diabetes have major adverse effects on the developing fetus that lead to increased neonatal morbidity and mortality, as discussed elsewhere in this issue. Obesity in pregnancy and gestational diabetes represent a special problem, not only as a result of their immediate adverse effects on maternal health and pregnancy outcome, but also because of growing evidence for their persistent and deleterious effects on the developing child.

Interactions between protein and vegetable oils in the maternal diet determine the programming of the insulin axis in the rat

The available evidence suggests that metabolic control mechanisms are programmed early in life. Previous studies of pregnant rats fed low-protein diets have suggested that the vegetable oils used in the experimental diets influence the outcome. The present study investigated the offspring of female rats fed semi-synthetic diets containing either 180 or 90 g casein/kg with 70 g/kg (w/w) of either corn oil or soya oil during gestation. During lactation, the dams received stock diet, and the offspring were subsequently weaned onto the stock diet. The offspring of dams fed the low-protein diets were smaller at birth. At 25 weeks of age, the offspring were subjected to an oral glucose tolerance test. In the offspring of dams fed the diet containing soya oil, the area under the insulin curve was affected by the protein content of the maternal diet. There was no effect of protein on the area under the insulin curve in the offspring of dams fed the diet prepared with corn oil. There were no differences in plasma glucose concentrations. The levels of mRNA for acetyl-CoA carboxylase-1 in the livers of female offspring were affected by the protein and oil content of the maternal diet. The level of carnitine palmitoyl transferase mRNA was affected by the protein content of the maternal diet. The present study suggests that PUFA in the maternal diet can interact with protein metabolism to influence the development of the offspring. This may involve the higher content of α-linolenic acid in soya oil compared with corn oil.

Developmental programming of obesity in mammals

Converging lines of evidence from epidemiological studies and animal models now indicate that the origins of obesity and related metabolic disorders lie not only in the interaction between genes and traditional adult risk factors, such as unbalanced diet and physical inactivity, but also in the interplay between genes and the embryonic, fetal and early postnatal environment. Whilst studies in man initially focused on the relationship between low birth weight and risk of adult obesity and metabolic syndrome, evidence is also growing to suggest that increased birth weight and/or adiposity at birth can also lead to increased risk for childhood and adult obesity. Hence, there appears to be increased risk of obesity at both ends of the birth weight spectrum. Animal models, including both under- and overnutrition in pregnancy and lactation lend increasing support to the developmental origins of obesity. This review focuses upon the influence of the maternal nutritional and hormonal environment in pregnancy in permanently programming appetite and energy expenditure and the hormonal, neuronal and autocrine mechanisms that contribute to the maintenance of energy balance in the offspring. We discuss the potential maternal programming 'vectors' and the molecular mechanisms that may lead to persistent pathophysiological changes resulting in subsequent disease. The perinatal environment, which appears to programme subsequent obesity, provides a potential therapeutic target, and work in this field will readily translate into improved interventional strategies to stem the growing epidemic of obesity, a disease which, once manifest, has proven particularly resistant to treatment.

Dietary flax oil during pregnancy and lactation retards disease progression in rat offspring with inherited kidney disease

Dietary flax oil (FO) retards disease progression in growing or adult animal models of kidney disease. To determine whether dietary flax oil during the perinatal period would alter renal disease progression in offspring, Han-SPRD-cy rats with inherited cystic kidney disease were given diets with either 7% FO or corn oil (CO), throughout pregnancy and lactation. At 3 wk of age, offspring were then given either the same or the alternate diet for 7 wk. Rats given FO during the maternal period had 15% less renal cyst growth compared with rats given FO only in the postweaning period. Dietary FO, compared with CO, in the maternal period also resulted in 12% lower cell proliferation and 15% less oxidant injury in diseased kidneys of offspring. Including FO in both the maternal and postweaning period resulted in 29-34% less renal interstitial fibrosis and 22-23% lower glomerular hypertrophy. Along with improved histology, these rats exhibited 13% less proteinuria and 30% lower creatinine clearance when dietary FO was given in the maternal period. The potential for dietary FO during pregnancy and lactation to positively modulate adult renal disease has significant implications for the 1 in 1000 individuals with congenital cystic kidney disease.

Mice raised on milk transgenically enriched with n-3 PUFA have increased brain docosahexaenoic acid

The brain contains high levels of the long-chain n-3 FA DHA (22:6n-3), mainly in the gray matter and synaptosomes. Adequate intake of DHA is crucial for optimal nervous system function, particularly in infants. Supplementation of infant formulas with DHA at levels similar to human breast milk is recommended for biochemical and functional benefits to neonates. We generated transgenic mice that produce elevated levels of n-3 PUFA in their milk by expressing the Caenorhabditis elegans n-3 FA desaturase under the control of a lactation-induced goat beta-casein promoter. To examine the postnatal effects of consuming the n-3-enriched milk, we compared the growth and brain and plasma FA composition of mouse pups raised on milk from transgenic dams with those observed for pups raised on milk from nontransgenic dams. A significant decrease in arachidonic acid (ARA, 20:4n-6) and concomitant increases in n-3 PUFA were observed in the phospholipid fraction of transgenic mouse milk. The n-6:n-3 FA ratios were 4.7 and 34.5 for the transgenic and control milk phospholipid fractions, respectively. DHA and DPA (22:5n-6) comprised 15.1% and 2.8% of brain FA from weanling mice nursed on transgenic dams, as compared with 6.9% and 9.2% for weanling mice nursed on control dams, respectively. This transgenic mouse model offers a unique approach to disassociate the effects and fetal programming resulting from a high n-6:n-3 FA ratio gestational environment from the postnatal nutritional effects of providing milk with differing n-6:n-3 FA ratios.

Metabolic markers in relation to nutrition and growth in healthy 4-y-old children in Sweden

BACKGROUND

The worldwide increase in overweight and obesity probably involves dietary factors, and early indicators of risk must be identified.

OBJECTIVE

We aimed to analyze metabolic markers in relation to dietary intake and anthropometry in healthy 4-y-old children.

DESIGN

A cross-sectional study of nutritional intake was performed in 95 children by use of 7-d food records. Fasting blood samples were analyzed for glucose, insulin, and lipids.

RESULTS

The study population was representative of Swedish children except that more parents than the average had a university education. The boys' mean energy intake was higher (6.6 +/- 0.75 MJ) than the girls' (5.7 +/- 0.79 MJ). Significant associations were found between the percentage of energy from carbohydrates and that from fat (r = -0.91) and sucrose (r = 0.59). High body mass index was associated with a low percentage of energy from fat (r = -0.32). Serum triacylglycerol, insulin, and the HOMA (homeostatic model assessment) index were higher in girls than in boys. In girls, HOMA beta-cell function was significantly negatively associated with fat intake and serum fasting insulin, and HOMA insulin resistance indexes were significantly associated with the increment in z scores for height and weight from birth to age 4 y. Compared with children with fasting insulin concentrations below the group mean + SD, the children with concentrations above that value were smaller as newborns and had larger increments in growth z scores from birth to age 4 y.

CONCLUSION

In healthy Swedish 4-y-olds from well-educated families, low fat intake was related to high body mass index. Upward weight and height percentile crossings were related to insulin resistance, especially in girls.

Serum phospholipid fatty acids, adipose tissue, and metabolic markers in obese adolescents

OBJECTIVE

Fatty acid (FA) composition has a role in adipogenesis. The objective was to study serum phospholipid (PL) FAs in adolescents and their relation to abdominal adipose tissue (AT) compartments and metabolic markers.

RESEARCH METHODS AND PROCEDURES

Abdominal AT was measured by magnetic resonance imaging and FA pattern was determined in serum PL of 10 obese adolescents (5 females), median age 12.0 years (range, 10.4 to 16.4) and BMI 30.7 (26.8 to 40.4), and 15 lean control subjects (9 females), median age 12.6 years (range, 11.3 to 15.4), and BMI 19.5 (17.1 to 23.4).

RESULTS

Obese adolescents had relatively higher levels of saturated FA (SFA) and nervonic acid compared with controls. Serum PL concentration of n-3 polyunsaturated fatty acids (PUFA) was lower in the obese vs. lean females (p = 0.01), including docosahexaenoic acid (DHA) (p = 0.01). The ratios of arachidonic acid to DHA and total n-6/n-3 FA were increased in obese children (p = 0.02 and 0.01, respectively). n-3 PUFAs were inversely correlated to all subcutaneous AT compartments except visceral AT. The homeostasis model assessment index of beta-cell function related inversely to DHA concentration (p = 0.03). All changes were more marked in the females.

DISCUSSION

Serum FA pattern in obese adolescents differed significantly from that in age-matched lean controls, reflecting a decrease in n-3 PUFA, especially DHA, and an increase in SFA. The subcutaneous AT, but not visceral AT, correlated to the changes in PUFA and SFA, suggesting an abnormal essential FA metabolism in obese adolescents.

Maternal fish oil supplementation during lactation does not affect blood pressure, pulse wave velocity, or heart rate variability in 2.5-y-old children

Maternal (n-3) PUFA deficiency is associated with higher blood pressure (BP) later in life in rat offspring, and early intake of (n-3) PUFA in formula-fed infants was shown to modify later BP. BP, heart rate (HR), and heart rate variability (HRV) are affected by dietary (n-3) PUFA in adults. In this study, we investigated whether fish oil (FO) supplementation of lactating mothers could modify BP, pulse wave velocity (PWV), and HRV in their children after 2 y. Mothers with low fish intake were randomly assigned to FO or olive oil (OO) supplementation for the first 4 mo after delivery. A reference group of mothers with a high habitual fish intake (HFI) was also followed. At the follow-up study at 2.5 y of age, BP and PWV were measured, and electrocardiograms were recorded for 0.5 h. FO supplementation significantly increased RBC levels of long-chain (n-3) PUFA of the 4 mo-old children, but at 2.5 y, the FO and OO groups did not differ. BP, PWV, HR, and HRV also did not differ among the groups. However, for all 3 groups, the children's intake of (n-3) PUFA at 2.5 y was negatively correlated with mean arterial pressure after adjustment for outdoor temperature (r = -0.245, P = 0.04). In conclusion, maternal FO supplementation had no overall effect on BP, PWV, or HRV of the children, indicating that (n-3) PUFA intake of Danish mothers may be sufficient in this sense. However, children's dietary intake of (n-3) PUFA might have a beneficial effect on BP in childhood.

Mediterranean-inspired diet lowers the ratio of serum phospholipid n-6 to n-3 fatty acids, the number of leukocytes and platelets, and vascular endothelial growth factor in healthy subjects

BACKGROUND

Reduced cardiovascular mortality and morbidity have been shown in persons adhering to Mediterranean-inspired diets (MIDs). Although the underlying mechanisms of this association are poorly understood, the importance of increasing dietary amounts of polyunsaturated fatty acids of the n-3 series has been emphasized.

OBJECTIVE

We investigated whether a MID provided to healthy subjects would affect 1) the inflammatory process and endothelial indexes such as vasoregulation and vascular endothelial growth factor (VEGF) and 2) serum phospholipid fatty acid composition.

DESIGN

A total of 22 subjects (10 women) received a MID or an ordinary Swedish diet (OSD) for 4 wk in a crossover fashion. Concentrations of lipids and fatty acids, high-sensitivity C-reactive protein, and interleukin 6, both before and after lipopolysaccharide stimulation; the number of leukocytes and platelets; and VEGF and monocyte chemoattractant protein 1 were analyzed.

RESULTS

The plasma ratio of n-6 to n-3 fatty acids was substantially lower after the MID than after the OSD (x +/- SEM: 4.72 +/- 0.19 and 2.60 +/- 0.17, respectively; P < 0.0001). Neither C-reactive protein nor interleukin 6 concentrations changed significantly after the MID compared with the OSD. The total number of leukocytes and platelets was 10% (P < 0.05) and 15% (P < 0.001) lower, respectively, after the MID than after the OSD. Serum VEGF concentrations were lower after the MID than after the OSD (237 +/- 30 and 206 +/- 25 pg/mL, respectively; P = 0.0014).

CONCLUSIONS

A MID reduces the number of platelets and leukocytes and VEGF concentrations in healthy subjects. This may be linked to higher serum concentrations of n-3 fatty acids, which promote a favorable composition of phospholipids.