Maternal and postweaning folic acid supplementation interact to influence body weight, insulin resistance, and food intake regulatory gene expression in rat offspring in a sex-specific manner.

Maternal intake of multivitamins or folic acid above the basal dietary requirement alters the growth and metabolic trajectory of rat offspring. We hypothesized that a modest increase in the folic acid content of maternal diets would alter the offspring's metabolic phenotype, and that these effects could be corrected by matching the folic acid content of the offspring's diet with that of the maternal diet. Female Sprague-Dawley rats were placed on a control or a 2.5× folic acid-supplemented diet prior to mating and during pregnancy and lactation. At weaning, pups from each maternal diet group were randomized to the control or to the 2.5× folic acid-supplemented diet for 25 weeks. Male pups from dams fed the folic acid-supplemented diet were 3.7% heavier than those from control-fed dams and had lower mRNA expression for leptin receptor Obrb isoform (Lepr) (11%) and Agouti-related protein (Agrp) (14%). In contrast, female pups from folic acid-supplemented dams were 5% lighter than those from control-fed dams and had lower proopiomelanocortin (Pomc) (42%), Lepr (32%), and Agrp (13%), but higher neuropeptide Y (Npy) (18%) mRNA expression. Folic acid supplementation ameliorated the alterations induced by maternal folic acid supplementation in male pups and led to the lowest insulin resistance, but the effects were smaller in female pups and led to the highest insulin resistance. In conclusion, maternal folic acid supplementation at 2.5× the control level was associated with alterations in body weight and hypothalamic gene expression in rat offspring in a sex-specific manner, and some of these effects were attenuated by postweaning folic acid supplementation.

Increasing vitamin A in post-weaning diets reduces food intake and body weight and modifies gene expression in brains of male rats born to dams fed a high multivitamin diet.

High multivitamin gestational diets (HV, 10-fold AIN-93G levels) increase body weight (BW) and food intake (FI) in rat offspring weaned to a recommended multivitamin (RV), but not to a HV diet. We hypothesized that high vitamin A (HA) alone, similar to HV, in post-weaning diets would prevent these effects of the HV maternal diet consistent with gene expression in FI and reward pathways. Male offspring from dams fed HV diets were weaned to a high vitamin A (HA, 10-fold AIN-93G levels), HV or RV diet for 29 weeks. BW, FI, expression of genes involved in regulation of FI and reward and global and gene-specific DNA methylation of pro-opiomelanocortin (POMC) in the hypothalamus were measured. Both HV and HA diets slowed post-weaning weight gain and modified gene expression in offspring compared to offspring fed an RV post-weaning diet. Hypothalamic POMC expression in HA offspring was not different from either HV or RV, and dopamine receptor 1 was 30% (P<.05) higher in HA vs. HV, but not different from RV group. Hippocampal expression of serotonin receptor 1A (40%, P<.01), dopamine receptor 2 (40%, P<.05) and dopamine receptor 5 (70%, P<.0001) was greater in HA vs. RV fed pups and is 40% (P<.01), 50% (P<.05) and 40% (P<.0001) in HA vs. HV pups, respectively. POMC DNA methylation was lower in HA vs. RV offspring (P<.05). We conclude that high vitamin A in post-weaning diets reduces post-weaning weight gain and FI and modifies gene expression in FI and reward pathways.

High folate gestational and post-weaning diets alter hypothalamic feeding pathways by DNA methylation in Wistar rat offspring.

Excess vitamins, especially folate, are consumed during pregnancy but later-life effects on the offspring are unknown. High multivitamin (10-fold AIN-93G, HV) gestational diets increase characteristics of metabolic syndrome in Wistar rat offspring. We hypothesized that folate, the vitamin active in DNA methylation, accounts for these effects through epigenetic modification of food intake regulatory genes. Male offspring of dams fed 10-fold folate (HFol) diet during pregnancy and weaned to recommended vitamin (RV) or HFol diets were compared with those born to RV dams and weaned to RV diet for 29 weeks. Food intake and body weight were highest in offspring of HFol dams fed the RV diet. In contrast, the HFol pup diet in offspring of HFol dams reduced food intake (7%, p = 0.02), body weight (9%, p = 0.03) and glucose response to a glucose load (21%, p = 0.02), and improved glucose response to an insulin load (20%, p = 0.009). HFol alone in either gestational or pup diet modified gene expression of feeding-related neuropeptides. Hypomethylation of the pro-opiomelanocortin (POMC) promoter occurred with the HFol pup diet. POMC-specific methylation was positively associated with glucose response to a glucose load (r = 0.7, p = 0.03). In conclusion, the obesogenic phenotype of offspring from dams fed the HFol gestational diet can be corrected by feeding them a HFol diet. Our work is novel in showing post-weaning epigenetic plasticity of the hypothalamus and that in utero programming by vitamin gestational diets can be modified by vitamin content of the pup diet.

A decreased n-6/n-3 ratio in the fat-1 mouse is associated with improved glucose tolerance.

A reduction in skeletal muscle fatty acid oxidation (FAO), manifested as a reduction in mitochondrial content and (or) FAO within mitochondria, may contribute to the development of insulin resistance. n-3 polyunsaturated fatty acids (PUFA) have been observed to increase the capacity for FAO and improve insulin sensitivity. We used the fat-1 mouse model, a transgenic animal capable of synthesizing n-3 PUFA from n-6 PUFA, to examine this relationship. Fat-1 mice exhibited a approximately 20-fold decrease in the n-6/n-3 ratio in skeletal muscle, and plasma glucose and the area under the glucose curve were significantly (p < 0.05) lower in fat-1 mice during a glucose challenge test. The improvement in whole-body glucose tolerance in the fat-1 mouse was associated with a approximately 21% (p < 0.05) decrease in whole-muscle citrate synthase (CS) activity (in red muscle only), without alterations in CS activity of isolated mitochondria (either red or white muscle; p > 0.05). These data suggest that the fat-1 mouse has decreased skeletal muscle mitochondrial content. However, the intrinsic ability of mitochondria to oxidize fatty acids was not altered in the fat-1 mouse, as rates of palmitate oxidation in isolated mitochondria from both red and white muscle were unchanged. Overall, this study demonstrates that a decrease in the n-6/n-3 ratio can enhance glucose tolerance in healthy animals, independent of changes in mitochondrial content.

Flaxseed combined with low-dose estrogen therapy preserves bone tissue in ovariectomized rats.

OBJECTIVE: Flaxseed is rich in lignans and alpha-linolenic acid, compounds that may promote healthy skeletons. Many postmenopausal women consume complementary health products such as flaxseed or its components in addition to pharmacological agents such as low-dose estrogen therapy for additional support for menopausal symptoms and related conditions. However, their combined effect on bone health is unknown. The aim of this study was to determine the effects of 10% dietary flaxseed, low-dose estrogen therapy, or their combination on bone mineral density, biomechanical strength, and skeletal fatty acid composition in an ovariectomized rat model of postmenopausal osteoporosis. METHODS: Ovariectomized rats received (1) basal diet (negative control), (2) 10% flaxseed, (3) low-dose estrogen implant (13 microg, 90 day release), or (4) flaxseed + low-dose estrogen implant for 12 weeks. A sham-operated group was included as a positive control. Bone mineral density, biomechanical strength, and fatty acid composition were measured at multiple skeletal sites. RESULTS: Flaxseed + low-dose estrogen therapy resulted in the highest bone mineral density and peak load at the lumbar vertebrae, with no effect on bone mineral density or strength in the tibia and femur. Flaxseed and flaxseed + low-dose estrogen therapy resulted in significantly higher relative levels of alpha-linolenic acid and eicosapentaenoic acid and lower levels of linoleic acid, arachidonic acid, and n-6/n-3 ratio in the lumbar vertebrae and tibia compared with all other groups. CONCLUSION: Flaxseed + low-dose estrogen therapy provides the greatest protection against ovariectomy-induced bone loss at the lumbar vertebrae. Moreover, this study is the first to demonstrate that flaxseed, rich in alpha-linolenic acid, alters fatty acid composition in the ovariectomized rat skeleton.

High multivitamin intake by Wistar rats during pregnancy results in increased food intake and components of the metabolic syndrome in male offspring.

The effect of high multivitamin intake during pregnancy on the metabolic phenotype of rat offspring was investigated. Pregnant Wistar rats (n=10 per group) were fed the AIN-93G diet with the recommended vitamin (RV) content or a 10-fold increase [high vitamin (HV) content]. In experiment 1, male and female offspring were followed for 12 wk after weaning; in experiment 2, only males were followed for 28 wk. Body weight (BW) was measured weekly. Every 4 wk, after an overnight fast, food intake over 1 h was measured 30 min after a gavage of glucose or water. An oral glucose tolerance test was performed every 3-5 wk. Postweaning fasting glucose, insulin, ghrelin, glucagon-like peptide-1, and systolic blood pressure were measured. No difference in BW at birth or litter size was observed. Food intake was greater in males born to HV dams (P<0.05), and at 28 wk after weaning, BW was 8% higher (P<0.05) and fat pad mass was 27% higher (P<0.05). Food intake reduction after the glucose preload was nearly twofold less in males born to HV dams at 12 wk after weaning (P<0.05). Fasting glucose, insulin, and ghrelin were 11%, 62%, and 41% higher in males from HV dams at 14 wk after weaning (P<0.05). Blood glucose response was 46% higher at 23 wk after weaning (P<0.01), and systolic blood pressure was 16% higher at 28 wk after weaning (P<0.05). In conclusion, high multivitamin intake during pregnancy programmed the male offspring for the development of the components of metabolic syndrome in adulthood, possibly by its effects on central mechanisms of food intake control.

Seizure resistance in fat-1 transgenic mice endogenously synthesizing high levels of omega-3 polyunsaturated fatty acids.

N-3 polyunsaturated fatty acids (PUFA), derived from marine oils, have been shown to protect against various neurological diseases. However, very little is known about their potential anticonvulsant properties. The objective of the present study was to determine whether enrichment of brain lipids with n-3 PUFA inhibits seizures induced by pentylenetetrazol. We demonstrate that increased brain levels of n-3 PUFA in transgenic fat-1 male mice, which are capable of de novo synthesis of n-3 PUFA from n-6 PUFA, increases latency to seizure onset by 45%, relative to wildtype controls (p = 0.08). Compared with wildtype littermates, transgenic fat-1 mice have significantly (p < 0.05) higher levels of docosahexaenoic acid and total n-3 PUFA in brain total lipid extracts and phospholipids. Levels of brain docosahexaenoic acid were positively correlated to seizure latency (p < 0.05). These findings demonstrate that n-3 PUFA have anticonvulsant properties and suggest the possibility of a novel, non-drug dietary approach for the treatment of epilepsy.