Insulin Resistance In Adult Offspring Research Articles

Low Protein Programming Causes Increased Mitochondrial Fusion and Decreased Oxygen Consumption in the Hepatocytes of Female Rats.

The liver is one of the major organs involved in the regulation of glucose and lipid homeostasis. The effectiveness of metabolic activity in hepatocytes is determined by the quality and quantity of its mitochondria. Mitochondrial function is complex, and they act via various dynamic networks, which rapidly adapt to changes in the cellular milieu. Our present study aims to investigate the effects of low protein programming on the structure and function of mitochondria in the hepatocytes of adult females. Pregnant rats were fed with a control or isocaloric low-protein diet from gestational day 4 until delivery. A normal laboratory chow was given to all dams after delivery and to pups after weaning. The rats were euthanized at 4 months of age and the livers were collected from female offspring for investigating the mitochondrial structure, mtDNA copy number, mRNA, and proteins expression of genes associated with mitochondrial function. Primary hepatocytes were isolated and used for the analysis of the mitochondrial bioenergetics profiles. The mitochondrial ultrastructure showed that the in utero low-protein diet exposure led to increased mitochondrial fusion. Accordingly, there was an increase in the mRNA and protein levels of the mitochondrial fusion gene Opa1 and mitochondrial biogenesis genes Pgc1a and Essra, but Fis1, a fission gene, was downregulated. Low protein programming also impaired the mitochondrial function of the hepatocytes with a decrease in basal respiration ATP-linked respiration and proton leak. In summary, the present study suggests that the hepatic mitochondrial dysfunction induced by an in utero low protein diet might be a potential mechanism linking glucose intolerance and insulin resistance in adult offspring.

Long-chain n-3 PUFA given before and throughout gestation and lactation in rats prevent high-fat diet-induced insulin resistance in male offspring in a tissue-specific manner.

This study investigated whether long-chain n-3 PUFA (LC n-3 PUFA) given to pregnant rats fed a high-fat (HF) diet may prevent fetal programming in male offspring at adulthood. Six weeks before mating, and throughout gestation and lactation, female nulliparous Sprague-Dawley rats were given a chow (C) diet, HF (60·6 % fat from maize, rapeseed oils and lard) or HF in which one-third of fat was replaced by fish oil (HF n-3). At weaning, the three offspring groups were randomly separated in two groups fed C diet, or HF without LC n-3 PUFA, for 7 weeks until adulthood. Glucose tolerance and insulin sensitivity were assessed by an oral glucose tolerance test both at weaning and at adulthood. Insulin signalling was determined in liver, muscle and adipose tissue by quantification of the phosphorylation of Akt on Ser 473 at adulthood. At weaning, as at adulthood, offspring from HF-fed dams were obese and displayed glucose intolerance (GI) and insulin resistance (IR), but not those from HFn-3 fed dams. Following the post-weaning C diet, phosphorylation of Akt was strongly reduced in all tissues of offspring from HF dams, but to a lesser extent in liver and muscle of offspring from HFn-3 dams. However, it was abolished in all tissues of all offspring groups fed the HF post-weaning diet. Thus, LC n-3 PUFA introduced in a HF in dams partially prevented the transmission of GI and IR in adult offspring even though they were fed without LC n-3 PUFA from weaning.

Fish oil supplementation of rats fed a high fat diet during pregnancy improves offspring insulin sensitivity.

IntroductionIn rats, a maternal high-fat diet (HFD) leads to adverse metabolic changes in the adult offspring, similar to the children of mothers with obesity during pregnancy. Supplementation with a high dose of fish oil (FO) to pregnant rats fed a HFD has been shown to prevent the development of insulin resistance in adult offspring. However, the effects of supplementation at a translationally relevant dose remain unknown.AimTo determine whether supplementation with a human-relevant dose of FO to pregnant rats can prevent the long-term adverse metabolic and cardiovascular effects of a maternal HFD on adult offspring.MethodsFemale rats (N = 100, 90 days of age) were assigned to HFD (45% kcal from fat) or control diet (CD) for 14 days prior to mating and throughout pregnancy and lactation. Following mating, dams received a gel containing 0.05 ml of FO (human equivalent 2–3 ml) or a control gel on each day of pregnancy. This produced 4 groups, CD with control gel, CD with FO gel, HFD with control gel and HFD with FO gel. Plasma and tissue samples were collected at day 20 of pregnancy and postnatal day 2, 21, and 100. Adult offspring were assessed for insulin sensitivity, blood pressure, DXA scan, and 2D echocardiography.ResultsThere was an interaction between maternal diet and FO supplementation on insulin sensitivity (p = 0.005) and cardiac function (p < 0.01). A maternal HFD resulted in impaired insulin sensitivity in the adult offspring (p = 0.005 males, p = 0.001 females). FO supplementation in the context of a maternal HFD prevented the reduction in insulin sensitivity in offspring (p = 0.05 males, p = 0.0001 females). However, in dams consuming CD, FO supplementation led to impaired insulin sensitivity (p = 0.02 males, p = 0.001 females), greater body weight and reduced cardiac ejection fraction.ConclusionThe effects of a human-relevant dose of maternal FO on offspring outcomes were dependent on the maternal diet, so that FO was beneficial to the offspring if the mother consumed a HFD, but deleterious if the mother consumed a control diet. This study suggests that supplementation with FO should be targeted to women expected to have abnormalities of metabolism such as those with overweight and obesity.

Prenatal Low-Protein Diet Affects Mitochondrial Structure and Function in the Skeletal Muscle of Adult Female Offspring.

Gestational low-protein (LP) diet leads to glucose intolerance and insulin resistance in adult offspring. We had earlier demonstrated that LP programming affects glucose disposal in females. Mitochondrial health is crucial for normal glucose metabolism in skeletal muscle. In this study, we sought to analyze mitochondrial structure, function, and associated genes in skeletal muscles to explore the molecular mechanism of insulin resistance LP-programmed female offspring. On day four of pregnancy, rats were assigned to a control diet containing 20% protein or an isocaloric 6% protein-containing diet. Standard laboratory diet was given to the dams after delivery until the end of weaning and to pups after weaning. Gestational LP diet led to changes in mitochondrial ultrastructure in the gastrocnemius muscles, including a nine-fold increase in the presence of giant mitochondria along with unevenly formed cristae. Further, functional analysis showed that LP programming caused impaired mitochondrial functions. Although the mitochondrial copy number did not show significant changes, key genes involved in mitochondrial structure and function such as Fis1, Opa1, Mfn2, Nrf1, Nrf2, Pgc1b, Cox4b, Esrra, and Vdac were dysregulated. Our study shows that prenatal LP programming induced disruption in mitochondrial ultrastructure and function in the skeletal muscle of female offspring.

Maternal high-fat diet exaggerates diet-induced insulin resistance in adult offspring by enhancing inflammasome activation through noncanonical pathway of caspase-11

ObjectiveMaternal high-fat diet (HFD) has been shown to promote the development of insulin resistance (IR) in adult offspring; however, the underlying mechanisms remain unclear. MethodsEight-week-old female wild-type mice (C57BL/6) were fed either an HFD or a normal diet (ND), one week prior to mating, and the diet was continued throughout gestation and lactation. Eight-week-old male offspring of both groups were fed an HFD for 8 weeks. ResultsOffspring of HFD-fed dams (O-HFD) exhibited significantly impaired insulin sensitivity compared with the offspring of ND-fed dams (O-ND). The adipocyte size of the eWAT increased significantly in O-HFD and was accompanied by abundant crown-like structures (CLSs), as well as a higher concentration of interleukin 1β (IL-1β) in the eWAT. Treatment with an inflammasome inhibitor, MCC950, completely abrogated the enhanced IR in O-HFD. However, ex vivo caspase-1 activity in eWAT revealed no difference between the two groups. In contrast, noncanonical inflammasome activation of caspase-11 was significantly augmented in O-HFD compared with O-ND, suggesting that membrane pore formation, but not cleavage of pro-IL-1β by caspase-1, is augmented in O-HFD. To examine the membrane pore formation, we performed metabolic activation of bone marrow-derived macrophages (BMDMs). The percentage of pore formation assessed by ethidium bromide staining was significantly higher in BMDMs of O-HFD, accompanied by an enhanced active caspase-11 expression. Consistently, the concentration of IL-1β in culture supernatants was significantly higher in the BMDMs from O-HFD than those from O-ND. ConclusionsThese findings demonstrate that maternal HFD exaggerates diet-induced IR in adult offspring by enhancing noncanonical caspase-11-mediated inflammasome activation.

5220Maternal high-fat diet exaggerates the development of diet-induced insulin resistance in adult offspring by enhancing pyroptosis through augmented gasdermin D-mediated pore formation

Abstract Background Maternal high-fat diet (HFD) has been shown to promote the development of insulin resistance (IR) in adult offspring; however, the underlying mechanisms remain unclear. Approach and results Eight-week-old female wild-type mice (C57BL/6) were fed a HFD or normal diet (ND) one week prior to mating, and received during pregnancy and lactation. Eight-week-old male offspring of both groups were fed a HFD for 8 weeks. Offspring of HFD-fed dams (O-HFD) showed significantly enhanced IR compared with offspring of ND-fed dams (O-ND). There was no difference in body weight, epidydimal white adipose tissue (eWAT) weight, and cumulative caloric intake between the 2 groups. However, eWAT adipocyte size was significantly increased in O-HFD, accompanied by the abundant crown-like structures. Flow cytometric analysis revealed an increased percentage of M1, but not M2, macrophages. Serum and eWAT concentrations of IL-1β, but not TNF-α, were significantly higher in O-HFD than O-ND (3.7-fold and 2.0-fold, respectively, P&lt;0.05). Treatment with NLRP3 inflammasome inhibitor MCC950 completely abrogated the enhanced IR in O-HFD to a similar extent of that in O-ND, although IR was modestly, but not significantly, ameliorated in O-ND even after MCC950 treatment. Consistent with in vivo findings, in vitro polarization of bone marrow-derived macrophages (BMDMs) did not show any difference in TNF-α mRNA expression after conventional stimulation. In contrast, palmitate acid (PA)-mediated metabolic activation of BMDMs following LPS priming showed a significantly higher concentration of IL-1β in culture supernatants from O-HFD (45%, P&lt;0.05). However, protein expression levels of NLRP-3, ASC, and procaspase-1 after LPS priming were equivalent between the 2 groups. Consistently, intracellular flow cytometric analysis of caspase-1 activity after PA activation did not show any difference, which was compatible with the finding that ex vivo caspase-1 activity of eWAT assessed by fluorescent image of IVIS revealed no difference between the 2 groups. To further examine the mechanism of augmented IL-1β release in BMDM of O-HFD, we examined the cleavage of caspase substrate gasdermin D (GSDMD) and subsequent pore formation. Protein and gene expression levels of GSDM-D after LPS priming were significantly higher in O-HFD (50% and 381%, respectively, P&lt;0.05). At 2 hrs after PA stimulation following LPS priming, cleaved GSDM-D was significantly increased in O-HFD (80%, P&lt;0.01). Consistently, percentage of pore formation assessed by ethidium bromide staining was significantly higher in O-HFD (60%, P&lt;0.05), while LDH release could not be observed. Conclusions Our findings demonstrate that maternal HFD exaggerates diet-induced insulin resistance in adult offspring by enhancing pyroptosis through augmented GSDM-D-mediated pore formation.

1774-P: Maternal Apical Periodontitis Promotes Insulin Resistance in Adult Offspring

Background: Adverse stimuli applied during early fetal development can increase the risk of diseases in adulthood. Aim: This study investigated the plasma concentrations of glucose, insulin, and tumor necrosis factor-α (TNF-α) of rats with maternal apical periodontitis (AP). We also explored the effect of maternal inflammation on the initial steps of insulin signaling and the inflammatory pathway in the gastrocnemius muscle (GM) of adult offspring. Methodology: Fifteen female Wistar rats were distributed into control group (CN), group with 1 AP (1AP) and group with 4 AP (4AP). Thirty days following induction of AP, female rats from all groups were mated with healthy male rats. When male offspring reached 75 days of age, plasma concentrations of glucose, insulin, and TNF-α were quantified. Insulin resistance was evaluated by the homeostasis model assessment of insulin resistance (HOMA-IR) index. Phosphorylation status of pp185 tyrosine, insulin receptor substrate 1 (IRS-1) serine, IκB kinase α/β (IKKα/β), and c-Jun N-terminal kinase (JNK) in the GM were measured by western blot. Results: Maternal AP promotes insulin resistance, impairs the initial steps of insulin signaling, increases plasma concentrations of insulin and TNF-α, and enhances IKKα/β phosphorylation in the GM of adult offspring. However, maternal AP does not seem to affect fasting glycemia and JNK phosphorylation in the GM of adult offspring. Conclusions: Maternal AP promotes important alterations in insulin signaling and inflammation pathways, and leads to insulin resistance in adult offspring. Disclosure T.V. Tsosura: None. F.Y. Chiba: None. M.S. Mattera: None. R.F. Pereira: None. C.A. Garbin: None. L.T. Cintra: None. D.H. Sumida: None. Funding São Paulo Research Foundation (2017-01128-1)

Maternal apical periodontitis is associated with insulin resistance in adult offspring.

To investigate the plasma concentrations of glucose, insulin and tumour necrosis factor-α (TNF-α) of rats with maternal apical periodontitis (AP) and to explore the effect of maternal inflammation on the initial steps of insulin signalling and the inflammatory pathway in the gastrocnemius muscle (GM) and periepididymal white adipose tissue (pWAT) of adult offspring. Fifteen female Wistar rats were distributed into a control group (CN), a group with 1 tooth with AP (1AP) and a group with 4 teeth with AP (4AP). Thirty days following induction of AP, female rats from all groups were mated with healthy male rats. When male offspring reached 75days of age, plasma concentrations of glucose, insulin and TNF-α were quantified. Insulin resistance was evaluated by the homoeostasis model assessment of insulin resistance (HOMA-IR) index. Phosphorylation status of pp185 tyrosine, insulin receptor substrate 1 (IRS-1) serine, IκB kinase α/β (IKKα/β) and c-Jun N-terminal kinase (JNK) in the GM and pWAT were measured by Western blot. Analysis of variance was performed, followed by the Tukey's post hoc test. P values <0.05 were considered to be statistically significant. Maternal AP promoted insulin resistance, impaired the initial steps of insulin signalling, significantly increased plasma concentrations of insulin (P<0.001) and TNF-α (P<0.05), and enhanced IKKα/β phosphorylation in the GM and pWAT (P<0.05) of adult offspring. However, maternal AP did not affect fasting glycaemia and JNK phosphorylation in the GM and pWAT of adult offspring. Maternal AP was associated with insulin resistance in adult offspring through alterations in insulin signalling and inflammation pathways. The study provides information on the impact of maternal AP on the development of metabolic alterations such as insulin resistance in adult offspring and reinforces the importance of preventing maternal AP in order to maintain the general health of offspring.

Gestational Protein Restriction Impairs Glucose Disposal in the Gastrocnemius Muscles of Female Rats.

Gestational low-protein (LP) diet causes hyperglycemia and insulin resistance in adult offspring, but the mechanism is not clearly understood. In this study, we explored the role of insulin signaling in gastrocnemius muscles of gestational LP-exposed female offspring. Pregnant rats were fed a control (20% protein) or an isocaloric LP (6%) diet from gestational day 4 until delivery. Normal diet was given to mothers after delivery and to pups after weaning until necropsy. Offspring were euthanized at 4 months, and gastrocnemius muscles were treated with insulin ex vivo for 30 minutes. Messenger RNA and protein levels of molecules involved in insulin signaling were assessed at 4 months. LP females were smaller at birth but showed rapid catchup growth by 4 weeks. Glucose tolerance test in LP offspring at 3 months showed elevated serum glucose levels (P < 0.01; glycemia Δ area under the curve 342 ± 28 in LP vs 155 ± 23 in controls, mmol/L * 120 minutes) without any change in insulin levels. In gastrocnemius muscles, LP rats showed reduced tyrosine phosphorylation of insulin receptor substrate 1 upon insulin stimulation due to the overexpression of tyrosine phosphatase SHP-2, but serine phosphorylation was unaffected. Furthermore, insulin-induced phosphorylation of Akt, glycogen synthase kinase (GSK)-3α, and GSK-3β was diminished in LP rats, and they displayed an increased basal phosphorylation (inactive form) of glycogen synthase. Our study shows that gestational protein restriction causes peripheral insulin resistance by a series of phosphorylation defects in skeletal muscle in a mechanism involving insulin receptor substrate 1, SHP-2, Akt, GSK-3, and glycogen synthase causing dysfunctional GSK-3 signaling and increased stored glycogen, leading to distorted glucose homeostasis.

Maternal High Fat Diet Alters Skeletal Muscle Mitochondrial Catalytic Activity in Adult Male Rat Offspring.

A maternal high-fat (HF) diet during pregnancy can lead to metabolic compromise, such as insulin resistance in adult offspring. Skeletal muscle mitochondrial dysfunction is one mechanism contributing to metabolic impairments in insulin resistant states. Therefore, the present study aimed to investigate whether mitochondrial dysfunction is evident in metabolically compromised offspring born to HF-fed dams. Sprague-Dawley dams were randomly assigned to receive a purified control diet (CD; 10% kcal from fat) or a high fat diet (HFD; 45% kcal from fat) for 10 days prior to mating, throughout pregnancy and during lactation. From weaning, all male offspring received a standard chow diet and soleus muscle was collected at day 150. Expression of the mitochondrial transcription factors nuclear respiratory factor-1 (NRF1) and mitochondrial transcription factor A (mtTFA) were downregulated in HF offspring. Furthermore, genes encoding the mitochondrial electron transport system (ETS) respiratory complex subunits were suppressed in HF offspring. Moreover, protein expression of the complex I subunit, NDUFB8, was downregulated in HF offspring (36%), which was paralleled by decreased maximal catalytic linked activity of complex I and III (40%). Together, these results indicate that exposure to a maternal HF diet during development may elicit lifelong mitochondrial alterations in offspring skeletal muscle.

Abstract 12540: Epigenetic Modulation of Macrophage Polarization Toward a Proinflammatory Phenotype Increases the Susceptibility to Insulin Resistance in Adult Offspring of High-fat Diet Fed-dams

Background: Maternal high-fat diet (HFD) has been shown to promote the development of metabolic disorders such as obesity and insulin resistance in adult offspring; however, its underlying mechanisms remains undefined. Method and Result: Eight-week-old female wild-type mice were fed a HFD or normal diet (ND) one week prior to mating, and received either HFD or ND during gestation and lactation. Offspring of both groups were fed a ND after weaning and then fed a HFD from 8 to 20 weeks of age. After 4 weeks of HFD feeding, insulin tolerance test in male offspring of HFD-fed dams (O-HFD) showed a significantly impaired insulin sensitivity compared with those of ND-fed dams (O-ND), which was more prominent after 8 weeks of HFD feeding. In contrast, glucose tolerance did not differ between the 2 groups after 4 and 8 weeks of HFD feeding. The weight of epididymal white pads and adipocyte size were comparable between the 2 groups. Although the fraction of macrophages (F4/80 + CD11b + ) in epididymal white pads assessed by flow cytometry did not differ between the 2 groups, the ratio of M1/M2 macrophages (M1:CD11c + CD206 - , M2:CD11c - CD206 + ) was markedly increased in O-HFD compared with O-ND (18.3 vs. 1.6, O-HFD vs. O-ND; P &lt; 0.05). We examined the effect of maternal HFD on the bone marrow (BM) monocytosis and macrophage polarization in adult offspring before HFD feeding. The fraction of BM pro-monocyte (CD11b high Ly-6G low ) did not differ between the 2 groups; however, BM-derived macrophages (BMDMs) in O-HFD showed a higher expression levels of M1 marker genes after stimulation of IFN-γ, concomitant with the lower expression levels of M2 marker genes after stimulation of IL-4. Further, BMDMs in O-HFD showed a 2.9-fold increase in the mRNA expression levels of histone deacetylase 3 ( HDAC3 ) after stimulation of IL-4 ( P &lt; 0.05), whereas its expression was decreased by 64 % in O-ND ( P &lt; 0.05). Conclusion: Our findings demonstrated for the first time that BMDMs in adult offspring of HFD-fed dams are likely to be polarized toward a proinflammatory phenotype, thereby contributing to the increased susceptibility to insulin resistance. Modulation of epigenetic-mediated macrophage polarization could be a potential therapeutic target for preventing metabolic disorders.

Glucose metabolism and hepatic Igf1 DNA methylation are altered in the offspring of dams fed a low-salt diet during pregnancy

A low-salt (LS) diet during pregnancy has been linked to insulin resistance in adult offspring, at least in the experimental setting. However, it remains unclear if this effect is due to salt restriction during early or late pregnancy. To better understand this phenomenon, 12-week-old female Wistar rats were fed a LS or normal-salt (NS) diet during gestation or a LS diet during either the first (LS10) or second (LS20) half of gestation. Glucose tolerance test, HOMA-IR, gene expression analysis and DNA methylation measurements were conducted for the Insr, Igf1, Igf1r, Ins1 and Ins2 genes in the livers of neonates and in the liver, white adipose tissue and muscle of 20-week-old male offspring. Birth weight was lower in the LS20 and LS animals compared with the NS and LS10 rats. In the liver, the Igf1 levels in the LS10, LS20 and LS neonates were lower than those in the NS neonates. Methylation of the Insr, Igf1r, Ins1 and Ins2 genes was influenced in a variable manner by low salt intake during pregnancy. Increased liver Igf1 methylation was observed in the LS and LS20 neonates compared with their NS and LS10 counterparts. Glucose intolerance was observed in adult offspring as an effect of low salt intake over the duration of pregnancy. Compared to the NS animals, the HOMA-IR was higher in the 12-week-old LS and 20-week-old LS-10 rats. Based on these results, it appears that the reason a LS diet during pregnancy induces a low birth weight is its negative correlation with Igf1 DNA methylation in neonates.

Resistance training improves skeletal muscle insulin sensitivity in elderly offspring of overweight and obese mothers.

Maternal obesity predisposes offspring to adulthood morbidities, including type 2 diabetes. Type 2 diabetes and insulin resistance have been associated with shortened telomere length. First, we aimed to investigate whether or not maternal obesity influences insulin sensitivity and its relationship with leucocyte telomere length (LTL) in elderly women. Second, we tested whether or not resistance exercise training improves insulin sensitivity in elderly frail women. Forty-six elderly women, of whom 20 were frail offspring of lean/normal weight mothers (OLM, BMI ≤26.3 kg/m2) and 17 were frail offspring of overweight/obese mothers (OOM,BMI ≥28.1 kg/m2), were studied before and after a 4 month resistance training (RT) intervention. Muscle insulin sensitivity of glucose uptake was measured using 18F-fluoro-2-deoxyglucose and positron emission tomography with computed tomography during a hyperinsulinaemic–euglycaemic clamp. Muscle mass and lipid content were measured using magnetic resonance and LTL was measured using real-time PCR. The OOM group had lower thigh muscle insulin sensitivity compared with the OLM group (p=0.048) but similar whole body insulin sensitivity. RT improved whole body and skeletal muscle insulin sensitivity in the OOM group only (p=0.004 and p=0.013, respectively), and increased muscle mass in both groups (p <0 .01). In addition, in the OOM group, LTL correlated with different thigh muscle groups insulin sensitivity (ρ ≥ 0.53; p ≤ 0.05). Individuals with shorter LTL showed a higher increase in skeletal muscle insulin sensitivity after training (ρ ≥ −0.61; p ≤ 0.05). Maternal obesity and having telomere shortening were associated with insulin resistance in adult offspring. A resistance exercise training programme may reverse this disadvantage among offspring of obese mothers. Trial registration: ClinicalTrials.gov NCT01931540.

Dietary enrichment with alpha-linolenic acid during pregnancy attenuates insulin resistance in adult offspring in mice

Objective: Our objective was to test the contribution of dietary enrichment in essential or saturated fatty acids, in normocaloric diets, on the lipid accumulation and insulin resistance in the adult offspring in a C57Bl6/J mice model. Methods: Pregnant mothers were fed normocaloric diets containing 6% fat enriched in essential fatty acids (EFA): alpha-linolenic (ALA-18:3, n-3), linoleic (LA-18:2, n-6), or saturated fatty acids (SFA). After a washing-out period with regular diet, the offspring received a high-fat diet before euthanization. Results: Adult mice fed maternal ALA showed lower body weight gain and lower liver fat accumulation, lower HOMA index and lower stearoyl-CoA desaturase (SCD1) activity than those fed maternal SFA. Conclusion: The results observed using this novel model suggest that ALA in maternal diet may have the potential to inhibit insulin resistance in adult offspring.

Gestational protein restriction impairs insulin-regulated glucose transport mechanisms in gastrocnemius muscles of adult male offspring.

Type II diabetes originates from various genetic and environmental factors. Recent studies showed that an adverse uterine environment such as that caused by a gestational low-protein (LP) diet can cause insulin resistance in adult offspring. The mechanism of insulin resistance induced by gestational protein restriction is not clearly understood. Our aim was to investigate the role of insulin signaling molecules in gastrocnemius muscles of gestational LP diet-exposed male offspring to understand their role in LP-induced insulin resistance. Pregnant Wistar rats were fed a control (20% protein) or isocaloric LP (6%) diet from gestational day 4 until delivery and a normal diet after weaning. Only male offspring were used in this study. Glucose and insulin responses were assessed after a glucose tolerance test. mRNA and protein levels of molecules involved in insulin signaling were assessed at 4 months in gastrocnemius muscles. Muscles were incubated ex vivo with insulin to evaluate insulin-induced phosphorylation of insulin receptor (IR), Insulin receptor substrate-1, Akt, and AS160. LP diet-fed rats gained less weight than controls during pregnancy. Male pups from LP diet-fed mothers were smaller but exhibited catch-up growth. Plasma glucose and insulin levels were elevated in LP offspring when subjected to a glucose tolerance test; however, fasting levels were comparable. LP offspring showed increased expression of IR and AS160 in gastrocnemius muscles. Ex vivo treatment of muscles with insulin showed increased phosphorylation of IR (Tyr972) in controls, but LP rats showed higher basal phosphorylation. Phosphorylation of Insulin receptor substrate-1 (Tyr608, Tyr895, Ser307, and Ser318) and AS160 (Thr642) were defective in LP offspring. Further, glucose transporter type 4 translocation in LP offspring was also impaired. A gestational LP diet leads to insulin resistance in adult offspring by a mechanism involving inefficient insulin-induced IR, Insulin receptor substrate-1, and AS160 phosphorylation and impaired glucose transporter type 4 translocation.

Adipocyte morphology and leptin signaling in rat offspring from mothers supplemented with flaxseed during lactation

ObjectiveWe have recently shown that maternal flaxseed supplementation during lactation induces insulin resistance in adult offspring. Here, we studied the effects of maternal dietary flaxseed during lactation on adipocyte morphology and leptin signaling in the hypothalamic-pituitary-thyroid axis as well as on behavioral traits in the adult progeny. MethodsLactating rats were fed a control (C) diet or a diet with 25% flaxseed (F). After weaning, pups received a standard diet until postnatal day (PN) 180. Male offspring were killed at PN21 and 180. Data were considered significant at P < 0.05. ResultsWeaned F rats presented a lower total and subcutaneous fat mass and higher subcutaneous adipocyte area (+48%), but at adulthood they presented higher subcutaneous and visceral adipocyte areas (+40% and 1.9-fold increase, respectively), with no change in body fat mass. At PN21, F pups had hyperleptinemia (+69%), lower T3 (−33%), higher TSH (2.1-fold increase), higher pituitary leptin receptor (Ob-R, +11%), signal transducer and activator of transcription 3 (STAT3, +21%), and phosphorylated-STAT3 (p-STAT3, +77%) protein content. Adult F offspring only showed lower T4 (−28%) and higher thyroid Ob-R (+52%) expression. Maternal flaxseed intake during lactation did not result in behavioral changes in the adult offspring. ConclusionsMaternal flaxseed supplementation decreases offspring adiposity and increases pituitary leptin signaling at weaning, but it induces hypertrophic adipocytes and higher thyroid leptin receptor in adulthood. The present data suggest that extensive use of flaxseed during lactation is undesirable.

Calcium supplementation reverts central adiposity, leptin, and insulin resistance in adult offspring programed by neonatal nicotine exposure

Obesity is a worldwide epidemic. Calcium influences energy metabolism regulation, causing body weight loss. Because maternal nicotine exposure during lactation programs for obesity, hyperleptinemia, insulin resistance (IR), and hypothyroidism, we decided to evaluate the possible effect of dietary calcium supplementation on these endocrine dysfunctions in this experimental model. Osmotic minipumps containing nicotine solution (N: 6 mg/kg per day for 14 days) or saline (C) were s.c. implanted in lactating rats 2 days after giving birth (P2). At P120, N and C offspring were subdivided into four groups: 1) C - standard diet; 2) C with calcium supplementation (CCa, 10 g calcium carbonate/kg rat chow); 3) N - standard diet; and 4) N with calcium supplementation (NCa). Rats were killed at P180. As expected, N offspring showed higher visceral and total body fat, hyperleptinemia, lower hypothalamus leptin receptor (OB-R) content, hyperinsulinemia, and higher IR index. Also, higher tyrosine hydroxylase (TH) expression (+51%), catecholamine content (+37%), and serum 25-hydroxyvitamin D(3) (+76%) were observed in N offspring. Dietary calcium supplementation reversed adiposity, hyperleptinemia, OB-R underexpression, IR, TH overexpression, and vitamin D. However, this supplementation did not reverse hypothyroidism. In NCa offspring, Sirt1 mRNA was lower in visceral fat (-37%) and higher in liver (+42%). In conclusion, dietary calcium supplementation seems to revert most of the metabolic syndrome parameters observed in adult offspring programed by maternal nicotine exposure during lactation. It is conceivable that the reduction in fat mass per se, induced by calcium therapy, is the main mechanism that leads to the increment of insulin action.

Prenatal hypoxia independent of undernutrition promotes molecular markers of insulin resistance in adult offspring

Molecular mechanisms predisposing people to insulin resistance are starting to emerge. Altered insulin signaling for hepatic gluconeogenesis and muscle glucose uptake is thought to play a central role. Development under suboptimal conditions is also known to increase the risk of insulin resistance in adulthood. However, the partial contributions of reduced oxygen vs. nutrient delivery to the fetus, two common adverse conditions in utero, to developmental programming of insulin resistance remain unknown. The aim of this study was to determine the effects of developmental hypoxia or undernutrition on the expression of insulin-signaling proteins in liver and skeletal muscle in adult rat offspring. We show that the expression of hepatic phospho-Akt and muscle Akt2 were significantly reduced in offspring of hypoxic, relative to offspring from normoxic or undernourished, pregnancies. Hepatic Akt-1, Akt-2, and PKCζ protein expression was reduced in offspring from both hypoxic and undernourished pregnancies. Muscle GLUT4 expression was decreased in undernourished, and further decreased in hypoxic, offspring. These findings link prenatal hypoxia to down-regulation of components of hepatic and muscle Akt expression in adult offspring. Akt may represent a pharmaceutical target for clinical intervention against the developmental programming of metabolic disease resulting from prenatal hypoxia.

Maternal prolactin inhibition during lactation programs for metabolic syndrome in adult progeny

Neonatal malnutrition is associated with metabolic syndrome in adulthood. Maternal hypoprolactinaemia at the end of lactation (a precocious weaning model) caused obesity, leptin resistance and hypothyroidism in adult offspring, suggesting an association of prolactin (PRL) and programming of metabolic dysfunctions. Metabolic syndrome pathogenesis is still unclear, but abdominal obesity, higher triglycerides, lower high-density lipoprotein (HDL-c) and insulin resistance have been proposed to be important factors involved. We studied the consequences of maternal hypoprolactinaemia during lactation on parameters associated with metabolic syndrome. Lactating Wistar rats were treated with bromocriptine (BRO, 1 mg twice a day) or saline on days 19, 20 and 21 of lactation and their offspring were followed from weaning until 180 days old. Adult BRO offspring had higher body weight (+10%, P < 0.05), total body fat (+41%, P < 0.05), visceral fat (+20%, P < 0.05), subcutaneous fat (+3 times, P < 0.05) and total body protein (+24%, P < 0.05). BRO group presented hyperglycaemia (+16%, P < 0.05), lower muscle glycogen (51%, P < 0.05), higher cholesterol (+30%, P < 0.05), higher low-density lipoprotein (LDL-c) (+1.5 times, P < 0.05), higher triglycerides (+49%, P < 0.05), lower HDL-c (28%, P < 0.05), hyperleptinaemia (+2.9 times, P < 0.05), hypoadiponectinaemia (16%, P < 0.05) and hypoprolactinaemia (54%, P < 0.05) as well as higher insulin resistance index (+24%, P < 0.05). Regarding adrenal function, BRO rats showed hypercorticosteronaemia (+46%, P < 0.05) and higher total catecholamine (+37%, P < 0.05). In the hypothalamus, no change was observed in protein expression of the leptin signalling pathway. Thus, neonatal malnutrition induced by maternal PRL inhibition during late lactation programs for obesity, dyslipidaemia and insulin resistance in adult offspring increasing the risk for metabolic syndrome development.

Altered skeletal muscle insulin signaling and mitochondrial complex II-III linked activity in adult offspring of obese mice

We recently reported insulin resistance in adult offspring of obese C57BL/6J mice. We have now evaluated whether parameters of skeletal muscle structure and function may play a role in insulin resistance in this model of developmental programming. Obesity was induced in female mice by feeding a highly palatable sugar and fat-rich diet for 6 wk prior to pregnancy, and during pregnancy and lactation. Offspring of obese dams were weaned onto standard laboratory chow. At 3 mo of age, skeletal muscle insulin signaling protein expression, mitochondrial electron transport chain activity (ETC), muscle fiber type, fiber density, and fiber cross-sectional area were compared with that of offspring of control dams weaned onto the chow diet. Female offspring of obese dams demonstrated decreased skeletal muscle expression of p110beta, the catalytic subunit of PI3K (P < 0.01), as well as reduced Akt phosphorylation at Serine residue 473 compared with control offspring. Male offspring of obese dams demonstrated increased skeletal muscle Akt2 and PKCzeta expression (P < 0.01; P < 0.001, respectively). A decrease in mitochondrial-linked complex II-III was observed in male offspring of obese dams (P < 0.01), which was unrelated to CoQ deficiency. This was not observed in females. There were no differences in muscle fiber density between offspring of obese dams and control offspring in either sex. Sex-related alterations in key insulin-signaling proteins and in mitochondrial ETC may contribute to a state of insulin resistance in offspring of obese mice.