Maternal obesity-impaired insulin signaling in sheep and induced lipid accumulation and fibrosis in skeletal muscle of offspring

The prevalence of maternal obesity is increasing rapidly in recent decades. We previously showed that maternal obesity affected skeletal muscle development during the fetal stage. The objective of this study was to evaluate the effects of maternal obesity on the skeletal muscle properties of offspring. Ewes were fed a control diet (100% energy requirement, Con) or an obesogenic diet (150% energy requirement, OB) from 2 mo before pregnancy to weaning. After weaning, the offspring lambs were fed a maintenance diet until 19 mo of age and then ad libitum for 12 wk to measure feed intake. At 22 mo old, the longissimus dorsi (LD) muscle was biopsied. The downstream insulin signaling was lower in OB than Con lambs as shown by reduction in the phosphorylation of protein kinase B, mammalian target of rapamycin, and 4-E binding protein 1. On the other hand, the phosphorylation of protein kinase C and insulin receptor substrate 1 was higher in OB compared to Con lambs. More intramuscular adipocytes were observed in OB compared to Con offspring muscle, and the expression of peroxisome proliferator-activated receptor gamma, an adipocyte marker, was also higher, which was consistent with the higher intramuscular triglyceride content. Both fatty acid transport protein 1 and cluster of differentiation 36 (also known as fatty acid translocase) were increased in the OB group. In addition, higher collagen content was also detected in OB compared to Con offspring. In conclusion, our data show that offspring from obese mothers had impaired insulin signaling in muscle compared with control lambs, which correlates with increased intramuscular triglycerides and higher expression of fatty acid transporters. These data clearly show that maternal obesity impairs the function of the skeletal muscle of offspring, supporting the fetal programming of adult metabolic diseases.     

Wagyu–Angus cross improves meat tenderness compared to Angus cattle but unaffected by mild protein restriction during late gestation

For the spring-calving beef herds, late gestation coincides with winter and early spring, when cows are dependent on feed supplements with low quality hay, which is hard to meet their nutrient requirements. However, the effects of deficiencies of metabolizable protein intake during late gestation on offspring beef quality are unclear. Wagyu cattle have excellent marbling, and insemination with Wagyu vs Angus semen is a practical option for beef producers to improve beef quality. To test, Angus cows (621 ± 73 kg) were selected and randomly separated into two groups. Each group was inseminated with either Angus or Wagyu semen. During the last 90 days of gestation, cows in each group were further separated and received either a low protein diet (85% of the NRC metabolizable protein requirement), which was a low quality hay-based diet common in northwestern region of the U.S., or an adequate protein diet (108% NRC requirement). All progeny was managed together and harvested at a final BW of 576.5 ± 16.6 kg. Wagyu-sired offspring had higher marbling scores and quality grades than Angus (P < 0.01). Protein supplementation did not affect Slice Shear Force (SSF) in either breeds (P = 0.60). However, Wagyu-sired cattle had lower SSF than Angus-sired (P < 0.01). In addition, Wagyu-sired cattle had higher intramuscular fat (P < 0.05) and total collagen content (P < 0.05), but Angus-sired had greater mature collagen cross-links, as shown by higher contents of Pyridinoline (P < 0.01) and Ehrlich Chromogen (P < 0.01). Consistently, the mRNA expression of enzymes catalyzing collagen cross-linking was higher in Angus-sired offspring, including Plod 1 (P < 0.05), Plod 2 (P = 0.08), and P4Hα 2 (P < 0.01). In conclusion, Wagyu-sired cattle had greater tenderness and marbling score compared to Angus-sired, which was associated with lower collagen cross-links. Feeding mature grass hay-based diet with relatively low protein content during late gestation had no major effect on beef quality of subsequent cattle.     

Different levels of overnutrition and weight gain during pregnancy have differential effects on fetal growth and organ development

Background

Nearly 50% of U.S. women of child-bearing age are overweight or obese, conditions linked to offspring obesity and diabetes.

Methods

Utilizing the sheep, females were fed a highly palatable diet at two levels of overfeeding designed to induce different levels of maternal body weight increase and adiposity at conception, and from conception to midgestation. Fetal growth and organ development were then evaluated at midgestation in response to these two different levels of overfeeding. Ewes were fed to achieve: 1) normal weight gain (control, C), 2) overweight (125% of National Research Council [NRC] recommendations, OW125) or 3) obesity (150% of NRC recommendations, OB150) beginning 10 wks prior to breeding and through midgestation. Body fat % and insulin sensitivity were assessed at three points during the study: 1) diet initiation, 2) conception and 3) mid-gestation. Ewes were necropsied and fetuses recovered at mid-gestation (day 78).

Results

OB150 ewes had a higher % body fat than OW125 ewes prior to breeding (P = 0.03), but not at mid-gestation (P = 0.37). Insulin sensitivity decreased from diet initiation to mid-gestation (P = 0.04), and acute insulin response to glucose tended to be greater in OB150 ewes than C ewes (P = 0.09) and was greater than in OW125 ewes (P = 0.02). Fetal crown-rump length, thoracic and abdominal girths, and fetal perirenal fat were increased in the OW125 and OB150 versus C ewes at mid-gestation. However, only fetal heart, pancreas, and liver weights, as well as lipid content of fetal liver, were increased (P < 0.05) in OB150 ewes versus both C and OW125 ewes at midgestation.

Conclusions

These data demonstrate that different levels of overfeeding, resulting in differing levels of maternal weight gain and adiposity prior to and during pregnancy, lead to differential effects on fetal overgrowth and organ development.     

Early maternal undernutrition programs increased feed intake, altered glucose metabolism and insulin secretion, and liver function in aged female offspring

Insulin resistance and obesity are components of the metabolic syndrome that includes development of cardiovascular disease and diabetes with advancing age. The thrifty phenotype hypothesis suggests that offspring of poorly nourished mothers are predisposed to the various components of the metabolic syndrome due to adaptations made during fetal development. We assessed the effects of maternal nutrient restriction in early gestation on feeding behavior, insulin and glucose dynamics, body composition, and liver function in aged female offspring of ewes fed either a nutrient-restricted [NR 50% National Research Council (NRC) recommendations] or control (C: 100% NRC) diet from 28 to 78 days of gestation, after which both groups were fed at 100% of NRC from day 79 to lambing and through lactation. Female lambs born to NR and C dams were reared as a single group from weaning, and thereafter, they were fed 100% NRC recommendations until assigned to this study at 6 yr of age. These female offspring were evaluated by a frequently sampled intravenous glucose tolerance test, followed by dual-energy X-ray absorptiometry for body composition analysis prior to and after ad libitum feeding of a highly palatable pelleted diet for 11 wk with automated monitoring of feed intake (GrowSafe Systems). Aged female offspring born to NR ewes demonstrated greater and more rapid feed intake, greater body weight gain, and efficiency of gain, lower insulin sensitivity, higher insulin secretion, and greater hepatic lipid and glycogen content than offspring from C ewes. These data confirm an increased metabolic "thriftiness" of offspring born to NR mothers, which continues into advanced age, possibly predisposing these offspring to metabolic disease.     

Collagen and elastin cross-linking: a mechanism of constrictive remodeling after arterial injury

Constrictive remodeling after arterial injury is related to collagen accumulation. Cross-linking has been shown to induce a scar process in cutaneous wound healing and is increased after arterial injury. We therefore evaluated the effect of cross-linking inhibition on qualitative and quantitative changes in collagen, elastin, and arterial remodeling after balloon injury in the atherosclerotic rabbit model. Atherosclerotic-like lesions were induced in femoral arteries of 28 New Zealand White rabbits by a combination of air desiccation and a high-cholesterol diet. After 1 mo, balloon angioplasty was performed in both femoral arteries. Fourteen rabbits were fed beta-aminopropionitrile (beta-APN, 100 mg/kg) and compared with 14 untreated animals. The remodeling index, i.e., the ratio of external elastic lamina at the lesion site to external elastic lamina at the reference site, was determined 4 wk after angioplasty for both groups. Pyridinoline was significantly decreased in arteries from beta-APN-treated animals compared with controls, confirming inhibition of collagen cross-linking: 0.30 (SD 0.03) and 0.52 (SD 0.02) mmol/mol hydroxyproline, respectively (P = 0.002). Scanning and transmission electron microscopy showed a profound disorganization of collagen fibers in arteries from beta-APN-treated animals. The remodeling index was significantly higher in beta-APN-treated than in control animals [1.1 (SD 0.3) vs. 0.8 (SD 0.3), P = 0.03], indicating favorable remodeling. Restenosis decreased by 33% in beta-APN-treated animals: 32% (SD 16) vs. 48% (SD 24) (P = 0.02). Neointimal collagen density was significantly lower in beta-APN-treated animals than in controls: 23.0% (SD 3.8) vs. 29.4% (SD 4.0) (P = 0.004). These findings suggest that collagen and elastin cross-linking plays a role in the healing process via constrictive remodeling and restenosis after balloon injury in the atherosclerotic rabbit model.     

Pyrroloquinoline quinone improves growth and reproductive performance in mice fed chemically defined diets

Growth, reproductive performance, and indices of collagen maturation and expression were investigated in Balb/c mice fed chemically defined, amino acid-based diets with or without the addition 6 micro Mpyrroloquinoline quinone (PQQ)/kg diet. The diets were fed to virgin mice for 8 weeks before breeding. At weaning, the pups from successful pregnancies were fed the same diet as their respective dams. Reproductive performance was compromised in mice fed diets devoid of PQQ, and their offspring grew at slower rates than offspring from mice fed diets supplemented with PQQ. Successful mating (confirmed vaginal plugs) was not affected by the presence or absence of PQQ; however, pup viability (number of pups at parturition/number of pups at Day 4 of lactation) was decreased in PQQ-deprived mice. Conception (percentage of females giving live births) and fertility (percentage of births) were also decreased in PQQ-deprived mice. The slower rates of growth in offspring from PQQ-deprived mice were associated with decreased steady-state mRNA levels for Type I procollagen alpha(1)-chains in skin and lungs from neonatal mice. Values for lysyl oxidase accumulation as protein in PQQ-deficient mice also tended to be lower than corresponding values from PQQ-supplemented or -replete mice. Skin collagen solubility was increased in PQQ-deprived mice. These results indicate that PQQ supplementation can improve reproductive performance, growth, and may modulate indices of neonatal extracellular matrix production and maturation in mice fed chemically defined, but otherwise nutritionally complete diets.     

Neonatal low-protein diet changes deiodinase activities and pituitary TSH response to TRH in adult rats

Protein malnutrition during neonatal programs for a lower body weight and hyperthyroidism in the adult offspring were analyzed. Liver deiodinase is increased in such animals, contributing to the high serum triiodothyronine (T3) levels. The level of deiodinase activities in other tissues is unknown. We analyzed the effect of maternal protein restriction during lactation on thyroid, skeletal muscle, and pituitary deiodinase activities in the adult offspring. For pituitary evaluation, we studied the in vitro, thyrotropin-releasing hormone (TRH)-stimulated thyroid-stimulating hormone (TSH) secretion. Lactating Wistar rats and their pups were divided into a control (C) group, fed a normal diet (23% protein), and a protein-restricted (PR) group, fed a diet containing 8% protein. At weaning, pups in both groups were fed a normal diet until 180 days old. The pituitary gland was incubated before and after TRH stimulation, and released TSH was measured by radioimmunoassay. Deiodinase activities (D1 and D2) were determined by release of (125)I from [(125)I]reverse triiodothyronine (rT3). Maternal protein malnutrition during lactation programs the adult offspring for lower muscle D2 (-43%, P<0.05) and higher muscle D1 (+83%, P<0.05) activities without changes in thyroidal deiodinase activities, higher pituitary D2 activity (1.5 times, P<0.05), and lower TSH response to in vitro TRH (-56%, P<0.05). The evaluations showed that the lower in vivo TSH detected in adult PR hyperthyroid offspring, programmed by neonatal undernutrition, may be caused by an increment of pituitary deiodination. As described for liver, higher skeletal muscle D1 activity suggests a hyperthyroid status. Our data broaden the knowledge about the adaptive changes to malnutrition during lactation and reinforce the concept of neonatal programming of the thyroid function.     

Fibromodulin Interacts with Collagen Cross-linking Sites and Activates Lysyl Oxidase

The hallmark of fibrotic disorders is a highly cross-linked and dense collagen matrix, a property driven by the oxidative action of lysyl oxidase. Other fibrosis-associated proteins also contribute to the final collagen matrix properties, one of which is fibromodulin. Its interactions with collagen affect collagen cross-linking, packing, and fibril diameter. We investigated the possibility that a specific relationship exists between fibromodulin and lysyl oxidase, potentially imparting a specific collagen matrix phenotype. We mapped the fibromodulin-collagen interaction sites using the collagen II and III Toolkit peptide libraries. Fibromodulin interacted with the peptides containing the known collagen cross-linking sites and the MMP-1 cleavage site in collagens I and II. Interestingly, the interaction sites are closely aligned within the quarter-staggered collagen fibril, suggesting a multivalent interaction between fibromodulin and several collagen helices. Furthermore, we detected an interaction between fibromodulin and lysyl oxidase (a major collagen cross-linking enzyme) and mapped the interaction site to 12 N-terminal amino acids on fibromodulin. This interaction also increases the activity of lysyl oxidase. Together, the data suggest a fibromodulin-modulated collagen cross-linking mechanism where fibromodulin binds to a specific part of the collagen domain and also forms a complex with lysyl oxidase, targeting the enzyme toward specific cross-linking sites.     

Eicosanoid synthesis and ornithine decarboxylase activity in mammary tumors of rats fed varying levels and types of N-3 and/or N-6 fatty acids

Virgin female Sprague-Dawley rats (50 days of age) were administered a single intragastric 10 mg dose of 7,12-dimethylbenz(a) anthracene (DMBA). Three weeks later they were placed on diets containing either 20% corn oil (CO), 20% primrose oil (PO), 20% black currant seed oil (BCO), 20% borage oil (BO), 15% menhaden oil plus 5% corn oil (15% MO + 5% CO), 10% menhaden oil plus 10% corn oil (10% MO + 10% CO), 5% menhaden oil plus 15% corn oil (5% MO + 15% CO) or 10% menhaden oil plus 10% borage oil (10% MO + 10% BO). Incidences of mammary tumors at 16 weeks post-DMBA were 80% in rats fed the CO diet, 84% in rats fed PO diet, 67% in rats fed BCO diet, 88% in rats fed BO diet, 60% in rats fed 15% MO + 5% CO diet, 67% in rats fed 10% MO + 10% CO diet, 83% in rats fed 5% MO + 15% CO diet, and 92% in rats fed 10% MO + 10% BO diet. Tumor multiplicity was lowest in PO-fed rats and highest in BO-fed rats. The tumor burden per tumor-bearing rat was lowest in rats fed the 15% MO + 5% CO, and 10% MO + 10% CO, diets and highest in those fed 20% BCO diet. Although body weight at 16 weeks post DMBA was not significantly different among the dietary groups, food intake was significantly greater in rats fed a diet containing 20% BO, or 5% MO + 15% CO.(ABSTRACT TRUNCATED AT 250 WORDS)     

Levels of plasma insulin, leptin and adiponectin, and activities of key enzymes in carbohydrate metabolism in skeletal muscle and liver in fasted ICR mice fed dietary n-3 polyunsaturated fatty acids

The aim of this study was to clarify the mechanisms related to plasma glucose concentration in mice fed a diet rich in n-3 polyunsaturated fatty acids (n-3 PUFAs). Male Crlj:CD-1 (ICR) mice were fed experimental diets containing 6% lard (LD), 6% fish oil (FO) or 4.1% lard plus 1.5% docosahexaenoic acid ethyl ester and 0.4% eicosapentaenoic acid ethyl ester (DE) for 12 weeks. There were no marked differences in plasma glucose and insulin concentration changes on glucose tolerance test between the three dietary groups. At the end of the feeding trial, plasma glucose concentration was significantly lower in fasted mice in the FO group than in those in the LD group (P<.005). Plasma adiponectin concentration was significantly higher in the FO group than in the LD group (P<.05). Hexokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase and glycerophosphate dehydrogenase activities in skeletal muscle tended to be lower in the FO group than in the LD group, while there were no differences in glucokinase and phosphofructokinase activities in liver between the three dietary groups. However, hepatic glycerophosphate dehydrogenase activity was 53-fold and 4.2-fold higher in the FO group than in the LD and DE groups, respectively (P<.0005 and P<.05, respectively). These results suggest that the reduction in plasma glucose concentration in mice fed n-3 PUFAs is mainly caused by acceleration of glucose uptake and glycerol synthesis in the liver rather than in the skeletal muscle.     

Obesity induces adipose fibrosis and collagen cross-linking through suppressing AMPK and enhancing lysyl oxidase expression

Collagen is the main component of connective tissue surrounding adipocytes. Collagen cross-linking affects adipose remodeling, which is crucial for maintaining function and metabolic homeostasis of adipose tissue. However, the effects of obesity on collagen cross-linking and adipose fibrosis remain to be examined. Therefore, the objective of this study was to investigate obesity-induced collagen cross-linking in adipose tissue and explore the underlying mechanisms. We found that obesity increased mature nonreducible collagen cross-linking in white adipose tissue (WAT) of mice, which was associated with inhibition of AMPK, up-regulation of transforming growth factor-β (TGF-β) signaling and the expression of lysyl oxidase (LOX), a key enzyme catalyzing the synthesis of mature cross-linking products. In SVCs and 3T3-L1 adipocytes, AMPK activation by metformin or AICAR inhibited TGF-β1-induced fibrogenesis and expression of LOX, which was further confirmed by ectopic expression of AMPK WT and K45R mutant. Consistently, in vivo, knocking out AMPK increased fibrosis and collagen cross-linking. Our study showed that AMPK downregulation due to obesity increases TGF-β signaling and LOX expression, which enhances adipose fibrosis and collagen cross-linking. Thus, AMPK is a therapeutic target for ameliorating the obesity-induced fibrosis, improving metabolic health of adipose tissue.     

Birth weight and postnatal dietary protein level affect performance, muscle metabolism and meat quality in pigs

Intrauterine growth restriction (IUGR), resulting in low birth body weight (LBW) occurs naturally in pigs. However, IUGR may also cause persistent changes in physiology and metabolism resulting in poorer performance, organogenesis and meat quality. As IUGR pigs have a lower daily gain from birth to slaughter they may differ in utilization of nutrients and requirements for dietary protein compared with their larger littermates. Thus, the objective in this study was to examine the interaction between birth body weight (BW) and the postnatal dietary protein level, in relation to postnatal performance, organogenesis, muscle metabolism and meat quality. The experiment was carried out with offspring from 16 purebred Danish Landrace gilts mated to Danish Landrace boars. The female and entire male pigs with LBW that survived at weaning were compared with the female and male pigs with the highest/high birth body weight (HBW) within each litter. The offspring were reared individually from weaning and were fed ad libitum a diet containing either a normal level of protein (NP) for optimal growth or an isocaloric diet containing a 30% lower protein content (LP) from 3 weeks to 150 days of age. At slaughter, we found no interactions between birth weight group and dietary protein level for any of the measured traits. The relative crown-rump length (cm/kg) at birth indicates that LBW pigs were thinner than HBW pigs. Daily gain and feed intake were reduced by 14% and 10%, respectively, while the kg feed/kg gain was slightly increased by 3% in LBW pigs compared with HBW pigs. The LP diet reduced daily gain by 27% due to reduced feed intake and increased kg feed/kg gain by 12% and 21%, respectively compared with the NP diet. LBW male pigs produced meat with a higher shear force than male HBW pigs and also LP pigs produced meat with higher shear force than NP pigs. The activity of lactate dehydrogenase in the Longissimus dorsi muscle (LD) was reduced in pigs fed the LP diet. Calpastatin was increased in LD of LBW pigs and decreased in pigs fed the NP diet. In conclusion, these results suggest a rejection of our hypothesis that low birth weight littermates have a lower requirement for dietary protein compared with heavy weight littermates. Furthermore, LBW male pigs and LP fed pigs of both genders produced less tender meat than HBW pigs or NP fed pigs, respectively.     

Cross your heart? Collagen cross-links in cardiac health and disease

Extracellular matrix (ECM) remodeling occurs in response to various cardiac insults including infarction, pressure overload and dilated myopathies. Each type of remodeling necessitates distinct types of ECM turnover and deposition yet an increase in myocardial fibrillar collagen content is appreciated as a contributing feature to cardiac dysfunction in each of these pathologies. In addition, aging, is also associated with increases in cardiac collagen content. The importance of characterizing differences in ECM composition and processes used by cardiac fibroblasts in the assembly of fibrotic collagen accumulation is critical for the design of strategies to reduce and ultimately regress cardiac fibrosis. Collagen cross-linking is one factor that influences collagen deposition and insolubility with direct implications for tissue properties such as stiffness. In this review, three different types of collagen cross-links shown to be important in cardiac fibrosis will be discussed; those catalyzed by lysyl oxidases, those catalyzed by transglutaminases, and those that result from non-enzymatic modification by the addition of advanced glycation end products. Insight into cellular mechanisms that govern collagen cross-linking in the myocardium will provide novel pathways for exploring new treatments to treat diseases associated with cardiac fibrosis.     

A procollagen C-proteinase inhibitor diminishes collagen and lysyl oxidase processing but not collagen cross-linking in osteoblastic cultures

The deposition of insoluble functional collagen occurs following extracellular proteolytic processing of procollagens by procollagen N- and C-proteinases, fibril formation, and lysyl oxidase dependent cross-linking. Procollagen C-proteinases in addition process and activate lysyl oxidase. The present study evaluates a possible role for procollagen C-proteinases in controlling different aspects of collagen deposition in vitro. Studies determine whether inhibition of procollagen C-proteinase activity with a specific BMP-1 inhibitor results in perturbations in lysyl oxidase activation, and in collagen processing, deposition, and cross-linking in phenotypically normal cultured murine MC3T3-E1 cells. Data show that BMP-1 Inhibitor dose dependently inhibits lysyl oxidase activation by up to 50% in undifferentiated proliferating cells. In differentiating cultures, BMP-1 inhibitor decreased collagen processing but did not inhibit the accumulation of mature collagen cross-links. Finally, electron microscopy studies show that collagen fibril diameter increased. Thus, inhibition of procollagen C-proteinases results in perturbed collagen deposition primarily via decreased collagen processing.     

Minoxidil exerts different inhibitory effects on gene expression of lysyl hydroxylase 1, 2, and 3: implications for collagen cross-linking and treatment of fibrosis.

Collagen deposits in fibrotic lesions often display elevated levels of hydroxyallysine (pyridinoline) cross-links. The relation between the occurrence of pyridinoline cross-links and the irreversibility of fibrosis suggests that these cross-links contribute to the aberrant accumulation of collagen. Based on its inhibitory effect on lysyl hydroxylase activity minoxidil has been postulated to possess anti-fibrotic properties by limiting the hydroxylysine supply for hydroxyallysine cross-linking. However, to interfere with hydroxyallysine cross-linking specifically lysyl hydroxylation of the collagen telopeptide should be inhibited, a reaction predominantly catalysed by lysyl hydroxylase (LH) 2b. In this study, we demonstrate that minoxidil treatment of cultured fibroblasts reduces LH1>LH2b>LH3 mRNA levels dose-and time-dependently, but has essentially no effect on the total number of pyridinoline cross-links in the collagen matrix. Still the collagen produced in the presence of minoxidil displays some remarkable features: hydroxylation of triple helical lysine residues is reduced to 50% and lysylpyridinoline cross-linking is increased at the expense of hydroxylysylpyridinoline cross-linking. These observations can be explained by our finding that LH1 mRNA levels are the most sensitive to minoxidil treatment, corroborating that LH1 has a preference for triple helical lysine residues as substrate. In addition, the non-proportional increase in cross-links (20-fold) with respect to the decrease in lysyl hydroxylation state of the triple helix (2-fold) even suggests that LH1 preferentially hydroxylates triple helical lysine residues at the cross-link positions. We conclude that minoxidil is unlikely to serve as an anti-fibroticum, but confers features to the collagen matrix, which provide insight into the substrate specificity of LH1.     

The maternal energetic environment affects both egg and offspring phenotypes in green anole lizards (Anolis carolinensis)

Animals exist in dynamic environments that may affect both their own fitness and that of their offspring. Maternal effects might allow mothers to prepare their offspring for the environment in which they will be born via several mechanisms, not all of which are well understood. Resource scarcity and forced resource allocation are two scenarios that could affect maternal investment by altering the amount and type of resources available for investment in offspring, albeit in potentially different ways. We tested the hypothesis that maternal dietary restriction and sprint training have different consequences for the offspring phenotype in an oviparous lizard (Anolis carolinensis). To do this, we collected and reared eggs from adult diet-manipulated females (low-diet [LD] or high-diet [HD]) and sprint-trained females (sprint trained [ST] or untrained [UT]) and measured both egg characteristics and hatchling morphology. ST and LD mothers laid both the fewest and heaviest eggs, and ST, UT, and LD eggs also had significantly longer incubation periods than the HD group. Hatchlings from the diet experiment (LD and HD offspring) were the heaviest overall. Furthermore, both body mass of the mother at oviposition and change in maternal body mass over the course of the experiment had significant and sometimes different effects on egg and offspring phenotypes, highlighting the importance of maternal energetic state to the allocation of maternal resources.     

Mitochondrial biogenesis is decreased in skeletal muscle of pig fetuses exposed to maternal high-energy diets

Mitochondria plays an important role in the regulation of energy homeostasis. Moreover, mitochondrial biogenesis accompanies skeletal myogenesis, and we previously reported that maternal high-energy diet repressed skeletal myogenesis in pig fetuses. Therefore, the aim of this study was to evaluate the effects of moderately increased maternal energy intake on skeletal muscle mitochondrial biogenesis and function of the pig fetuses. Primiparous purebred Large White sows were allocated to a normal energy intake group (NE) as recommended by the National Research Council (NRC) and a high energy intake group (HE, 110% of NRC recommendations). On day 90 of gestation, fetal umbilical vein blood and longissimus (LM) muscle were collected. Results showed that the weight gain of sows fed HE diet was higher than NE sows on day 90 of gestation (P<0.05). Maternal HE diet increased fetal umbilical vein serum triglyceride and insulin concentrations (P<0.05), and tended to increase the homeostasis model assessment index (P=0.08). Furthermore, HE fetuses exhibited increased malondialdehyde concentration (P<0.05), and decreased activities of antioxidative enzymes (P<0.05) and intracellular NAD⁺ level (P<0.05) in LM muscle. These alterations in metabolic traits of HE fetuses were accompanied by reduced mitochondrial DNA amount (P<0.05) and down-regulated messenger RNA expression levels of genes responsible for mitochondrial biogenesis and function (P<0.05). Our results suggest that moderately increased energy supply during gestation decreases mitochondrial biogenesis, function and antioxidative capacity in skeletal muscle of pig fetuses.     

Paternal exercise protects mouse offspring from high-fat-diet-induced type 2 diabetes risk by increasing skeletal muscle insulin signaling

Paternal obesity increases, while paternal exercise decreases, offspring obesity and type 2 diabetes (T2D) risk; however, no studies have determined whether a paternal high-fat (HF) diet and exercise interact to alter offspring body weight (BW), adiposity and T2D risk. Three-week-old male C57BL/6 mice were fed a normal-fat (NF) diet (16% fat) or an HF diet (45% fat) and assigned to either voluntary wheel running exercise or cage activity for 3 months prior to mating with NF-diet-fed dams. After weaning, male offspring were fed an NF or HF diet for an additional 3 months. F1 male mice whose fathers ate an HF diet had decreased % body fat accompanied by decreased gene expression of beige adipocyte marker FGF21. However, paternal HF-diet-induced reductions in F1 offspring % body fat normalized but did not reduce T2D risk. Exercise was protective against paternal HF-diet-induced insulin resistance by increasing the expression of insulin signaling (GLUT4, IRS1 and PI3K) markers in skeletal muscle resulting in normal T2D risk. When fathers were fed an HF diet and exercised, a postnatal HF diet increased beiging (PPARγ). Thus, these findings show that increases in T2D risk in male offspring when the father consumes an HF diet can be normalized when the father also exercises preconception and that this protection may occur by increases in insulin signaling potential within offspring skeletal muscle. Future studies should further determine the physiological mechanism(s) underlying the beneficial effects of exercise through the paternal lineage.     

Free radical production in aortic rings from rats fed a fish oil-rich diet

To study the effect of the degree of unsaturation of dietary fatty acids on the production of free radicals and on the vascular smooth muscle tone in rings of the aorta, Sprague-Dawley rats were fed a semipurified diet containing 5% lipids from either corn oil (CO) or menhaden oil (MO) for 8 wk. The MO diet did not change the basal or NADPH-dependent superoxide anion (O2-*) release. There were no significant differences in phenylephrine-induced contractions between the two groups in intact rings. However, these contractions increased in endothelium-intact aortic rings from the MO group after addition of the nitric oxide (*NO) synthase inhibitor NG-nitro-L-arginine and in endothelium-denuded rings, both indicating a greater endothelial basal *NO production in rats fed with the MO diet. Endothelium-dependent relaxations in response to acetylcholine were more prominent in rings from the MO group. These differences were not due to an increased smooth muscle response to.NO, because relaxations were the same using an exogenous *NO donor. Our results indicate that dietary MO did not modify O2-* release by the vessel wall or relaxation due to the cyclooxygenase pathway, but it potentiated endothelial production of *NO.