Ellen Paula Santos da Conceição

Postnatal early overfeeding induces hypothalamic higher SOCS3 expression and lower STAT3 activity in adult rats

Postnatal early overnutrition (EO) is a risk factor for future obesity and metabolic disorders. Rats raised in small litters (SLs) develop overweight, hyperphagia, hyperleptinemia, hyperinsulinemia and hypertension when adults. As obesity is related to hyperleptinemia, leptin resistance and metabolic syndrome, we aimed to investigate body composition, plasma hormone levels, glucose tolerance and the leptin signaling pathway in hypothalamus from early overfed animals at weaning and adulthood. To induce postnatal EO, we reduced litter size to three pups/litter (SL), and the groups with normal litter size (10 pups/litter) were used as control. Rats had free access to standard diet and water postweaning. Body weight and food intake were monitored daily, and offspring were killed at 21 (weaning) and 180 days old (adulthood). Postnatal EO group had higher body weight and total and visceral fat mass at both periods. Lean mass and serum high-density lipoprotein cholesterol (HDL-C) were higher at 21 days and lower at 180 days. Small litter rats presented higher levels of globulins at both periods, while albumin levels were higher at weaning and lower at adulthood. There was higher leptin, insulin and glucose serum concentrations at 21 days old, while no glucose intolerance was observed in adulthood. Leptin signaling pathway was unaffected at weaning. However, postnatal EO induced lower JAK2 and p-STAT3, and higher SOCS3 expression in adult animals, indicating central leptin resistance in adulthood. In conclusion, postnatal EO induces obesity, higher total and visceral fat mass, lower HDL-C and central leptin resistance in adult life.

Oxidative stress programming in a rat model of postnatal early overnutrition — role of insulin resistance ☆ ☆☆

Postnatal early overfeeding (EO) is related to later development of overweight and other metabolic disorders. As oxidative stress is implicated in most human diseases, as obesity and diabetes, we decided to study some parameters related to oxidative stress and insulin signaling in liver from EO animals in adult life. To induce EO, litter size was reduced to three pups per litter (SL: small litter) and groups with normal litter size (NL:10 pups per litter) were used as control. After weaning, rats had free access to standard diet and water. Body weight and food intake were monitored daily and offspring were killed at 180 days-old. Significant differences had P<.05 or less. As expected, SL rats had hyperphagia, higher body weight and higher visceral fat mass at weaning and adulthood. In liver, postnatal EO programmed for lower catalase (-42%), superoxide dismutase (-45%) and glutathione peroxidase (-65%) activities. The evaluation of liver injury in adult SL group showed lower nitrite content (-10%), higher liver and plasma malondialdehyde content (+25% and 1.1-fold increase, respectively). No changes of total protein bound carbonyl or Cu/Zn superoxide dismutase protein expression in liver were detected between the groups. Regarding insulin signaling pathway in liver, SL offspring showed lower IRβ (-66%), IRS1 (-50%), phospho-IRS1 (-73%), PI3-K (-30%) and Akt1 (-58%). Indeed, morphological analysis showed that SL rats presented focal areas of inflammatory cell infiltrate and lipid drops in their cytoplasm characterizing a microsteatosis. Thus, we evidenced that postnatal EO can program the oxidative stress in liver, maybe contributing for impairment of the insulin signaling.

Euterpe oleracea Mart.-Derived Polyphenols Protect Mice from Diet-Induced Obesity and Fatty Liver by Regulating Hepatic Lipogenesis and Cholesterol Excretion

The aim of this study was to investigate the effect of a polyphenol-rich Açaí seed extract (ASE, 300 mg/kg-1d-1) on adiposity and hepatic steatosis in mice that were fed a high-fat (HF) diet and its underlying mechanisms based on hepatic lipid metabolism and oxidative stress. Four groups were studied: C57BL/6 mice that were fed with standard diet (10% fat, Control), 10% fat + ASE (ASE), 60% fat (HF), and 60% fat + ASE (HF + ASE) for 12 weeks. We evaluated the food intake, body weight gain, serum glucose and lipid profile, hepatic cholesterol and triacyglycerol (TG), hepatic expression of pAMPK, lipogenic proteins (SREBP-1c, pACC, ACC, HMG-CoA reductase) and cholesterol excretion transporters, ABCG5 and ABCG8. We also evaluated the steatosis in liver sections and oxidative stress. ASE reduced body weight gain, food intake, glucose levels, accumulation of cholesterol and TG in the liver, which was associated with a reduction of hepatic steatosis. The increased expressions of SREBP-1c and HMG-CoA reductase and reduced expressions of pAMPK and pACC/ACC in HF group were antagonized by ASE. The ABCG5 and ABCG8 transporters expressions were increased by the extract. The antioxidant effect of ASE was demonstrated in liver of HF mice by restoration of SOD, CAT and GPx activities and reduction of the increased levels of malondialdehyde and protein carbonylation. In conclusion, ASE substantially reduced the obesity and hepatic steatosis induced by HF diet by reducing lipogenesis, increasing cholesterol excretion and improving oxidative stress in the liver, providing a nutritional resource for prevention of obesity-related adiposity and hepatic steatosis.

Programming of rat adrenal medulla by neonatal hyperleptinemia: adrenal morphology, catecholamine secretion, and leptin signaling pathway

Leptin serum concentration in early life is an important factor for adequate future development of the offspring. Previously, we demonstrated that hyperleptinemia on lactation programmed for hyperleptinemia, central leptin resistance with lower expression of the long form of leptin receptor at hypothalamus, and higher medullary catecholamine levels with cardiovascular consequences at adulthood. The central objective of this study was to determine the direct effect of leptin on adrenal medullary function of adult rats that were leptin treated during lactation. Adrenal morphology was also accessed. Recombinant murine leptin was injected in the pups during the first 10 days of life (group L, leptin-programmed) or at adulthood during 6 days (group LC). The controls of both experiments received saline (groups C and CC). Both treatments resulted in hyperleptinemia at 150 days old (+78% and 2-fold increase, respectively; P < 0.05). Programmed animals showed hypertrophy of adrenal and higher adrenal catecholamine content at 150 days old (3-fold increase, P < 0.05), and no changes were observed in the LC group. However, LC rats had lower adrenal content of tyrosine hydroxylase (-17%, P < 0.05). Leptin-programmed rats had a lower response to leptin in vitro stimulation (-22%, P < 0.05) and lower expression of key proteins of the leptin signaling pathway, leptin receptor and janus tyrosine kinase 2 in the medullas (-61% and -29%, respectively, P < 0.05). However, they presented higher expression of phosphorylated signal transducer and activator of transcription 3 (+2-fold, P < 0.05). Leptin treatment at adulthood did not affect these parameters. The higher catecholamine synthesis and secretion in the leptin-programmed rats observed in our previous study does not seem to be a consequence of the direct effect of leptin on the medullas. We suggest that the hyperleptinemia of the programmed animals increases adrenal medullary function through sympathetic nervous system activation. In conclusion, high leptin levels on lactation program the activity of the sympathoadrenal system at adulthood that may contribute to the development of adult chronic diseases such as hypertension.

Cis-9, trans-11 and trans-10, cis-12 CLA Mixture does not Change Body Composition, Induces Insulin Resistance and Increases Serum HDL Cholesterol Level in Rats

Synthetic supplements of conjugated linoleic acid (CLA) containing 50:50 mixture of cis-9, trans-11 and trans-10, cis-12 CLA isomers have been commercialized in some places for reducing body fat. However the safety of this CLA mixture is controversial and in some countries the CLA usage as food supplement is not authorized. Changes in insulinemic control and serum lipids profile are potential negative effects related to consumption of CLA mixture. The present study aimed to evaluate the effects of a diet containing mixture of cis-9, trans-11 and trans-10, cis-12 CLA on prevention of obesity risk as well as on potential side effects such as insulin resistance and dyslipidemia in Wistar rats. Thirty male Wistar rats were randomly assigned to the following dietary treatments (n=10/group), for 60 days: Normolipidic Control (NC), diet containing 4.0% soybean oil (SO); High Fat-Control (HF-C), diet containing 24.0% SO; High Fat-synthetic CLA (HF-CLA), diet containing 1.5% of an isomeric CLA mixture (Luta-CLA 60) and 22.5% SO. Luta-CLA 60 (BASF) contained nearly 60% of CLA (cis-9, trans-11 and trans-10, cis-12 CLA at 50:50 ratio). The HF-CLA diet contained 0.3% of each CLA isomer. HF-CLA diet had no effect on dietary intake and body composition. HF-CLA-fed rats had lower levels of PPARγ protein in retroperitoneal adipose tissue, hyperinsulinemia compared to HF-C-fed rats, hyperglycemia compared to NC-fed rats while no differences in glycemia were observed between NC and HF-C groups, increased HOMA index and higher levels of serum HDL cholesterol. Thus, feeding rats with a high fat diet containing equal parts of cis-9, trans-11 and trans-10, cis-12 CLA isomers had no effect on body composition and induced insulin resistance. Despite HF-CLA-fed rats had increased serum HDL cholesterol levels, caution should be taken before synthetic supplements containing cis-9, trans-11 and trans-10, cis-12 CLA are recommended as a nutritional strategy for weight management.

Does bromocriptine play a role in decreasing oxidative stress for early weaned programmed obesity

AIMS Studies have demonstrated that early weaning can promote metabolic syndrome during adulthood and that obesity increases oxidative stress. Thus, we aimed to evaluate redox status in a pharmacological early weaning rodent model programmed for metabolic syndrome at adulthood. MAIN METHODS Lactating dams were randomly assigned into 2 groups: the early weaning group (BRO), which was treated intraperitoneally with bromocriptine (1 mg/day) to inhibit prolactin secretion for the last 3 days of lactation, and the control group (C), which received the BRO diluent for the same time period. The offspring were killed at 90 (PN90) and 180 (PN180) days after birth. KEY FINDINGS Early weaning induced greater visceral adiposity and dyslipidemia. At PN90, the BRO offspring showed glucose intolerance with normoinsulinemia and increased plasma and liver superoxide dismutase, and liver glutathione peroxidase activities, which reduced the liver malondialdehyde but not the increased plasma malondialdehyde levels. However, the BRO offspring showed insulin resistance at PN180 and increased plasma glutathione peroxidase, liver superoxide dismutase, and catalase activities. These changes reduced the plasma and liver malondialdehyde levels, which aided in hepatocyte architecture preservation. Additionally, we observed that sirtuin 1 was overexpressed in the BRO group at PN90, but the increased expression was not maintained through PN180, which suggests unfavorable metabolic conditions in the older offspring. SIGNIFICANCE Despite the observed obesity and glucose homeostasis dysfunction, our data suggest that the early weaning programming induced by bromocriptine can improve the offsprings redox status and may prevent liver damage during adulthood.

Dietary calcium supplementation in adult rats reverts brown adipose tissue dysfunction programmed by postnatal early overfeeding

Brown adipose tissue (BAT) dysfunction is associated with obesity and its comorbidities, such as hypertension, and the improvement of BAT function seems important for obesity management. Here we investigated the effects of dietary calcium supplementation on BAT autonomic nerve activity, sympathoadrenal function and cardiovascular parameters in adult obese rats that were raised in small litters (SL group). Three days after birth, SL litters were adjusted to three pups to induce early overfeeding. The control group remained with 10 pups/litter until weaning (NL group). At PN120, the SL group was randomly divided into the following: rats fed with standard chow (SL) and rats fed with dietary calcium carbonate supplementation (SL-Ca, 10g/kg chow). Animals were killed either at PN120 or PN180. At both ages, SL rats had higher BAT autonomic nervous system activity, mass and adipocyte area, as well as increased heart rate and blood pressure (systolic and diastolic); 2 months of calcium supplementation normalized these parameters. At PN180 only, UCP1 and TRβ1 in BAT were decreased in SL rats. These changes were also prevented by calcium treatment. Also at PN180, the SL group presented higher tyrosine hydroxylase and adrenal catecholamine contents, as well as lower hypothalamic POMC and MC4R contents. Calcium supplementation did not revert these alterations. Thus, we demonstrated that dietary calcium supplementation was able to improve cardiovascular parameters and BAT thermogenesis capacity in adult animals that were early overfed during lactation.

Locomotor response to acute nicotine in adolescent mice is altered by maternal undernutrition during lactation.

Undernutrition during brain development causes long lasting alterations in different neurotransmitter systems that may alter responses to psychoactive drugs. Despite the recognized effects of early undernutrition on the cholinergic system, no evidence that demonstrates the influence of this insult on nicotine susceptibility has been reported. We investigated the effects of protein/calorie restriction during lactation on the susceptibility to nicotine in adolescent mice. Dams were randomly assigned to one of the following groups: Control (C, 20 litters)—free access to standard laboratory diet (23% protein); Protein Restricted (PR, 12 litters)—free access to a isoenergetic, 8% protein diet; Calorie Restricted (CR, 12 litters)—access to standard laboratory diet in restricted quantities (mean ingestion of PR: pair‐fed group). Undernutrition extended from postnatal day 2 (PN2) to weaning (PN21). At PN30, animals either received an i.p. injection of nicotine (0.5 mg/Kg) or saline and were immediately placed in open field (OF). After the OF, adrenal glands and serum were collected for the analyses of stress‐related endocrine parameters and leptin concentration. PR and CR offspring showed less body mass gain and visceral fat mass. PR offspring presented reduced serum leptin concentration. In the OF, nicotine increased locomotor activity of C and PR, but not of CR. CR and PR offspring showed decreased adrenal catecholamine content, which was not dependent on nicotine exposure. Our results indicate that early undernutrition interferes with nicotine‐elicited locomotor effects in adolescent mice and suggest that endocrine parameters alterations in malnourished animals do not influence the behavioral response to nicotine.

Maternal flaxseed diet during lactation changes adrenal function in adult male rat offspring.

Flaxseed (Linum usitatissimum L.) has been a focus of interest in the field of functional foods because of its potential health benefits. However, we hypothesised that maternal flaxseed intake during lactation could induce several metabolic dysfunctions in adult offspring. In the present study, we aimed to characterise the adrenal function of adult offspring whose dams were supplemented with whole flaxseed during lactation. At birth, lactating Wistar rats were divided into two groups: rats from dams fed the flaxseed diet (FLAX) with 25% of flaxseed and controls dams. Pups received standard diet after weaning and male offspring were killed at age 180 days old to collect blood and tissues. We evaluated body weight and food intake during development, corticosteronaemia, adrenal catecholamine content, hepatic cholesterol, TAG and glycogen contents, and the protein expression of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), 11-β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and adrenaline β2 receptor at postnatal day 180 (PN180). After weaning, pups from the FLAX group had a higher body weight (+10 %) and food intake (+10%). At PN180, the FLAX offspring exhibited higher serum corticosterone (+48%) and lower adrenal catecholamine ( - 23%) contents, lower glycogen ( - 30%), higher cholesterol (4-fold increase) and TAG (3-fold-increase) contents in the liver, and higher 11β-HSD1 (+62%) protein expression. Although the protein expression of hypothalamic CRH was unaffected, the FLAX offspring had lower protein expression of pituitary ACTH ( - 34%). Therefore, induction of hypercorticosteronaemia by dietary flaxseed during lactation may be due to an increased hepatic activation of 11β-HSD1 and suppression of ACTH. The changes in the liver fat content of the FLAX group are suggestive of steatosis, in which hypercorticosteronaemia may play an important role. Thus, it is recommended that lactating women restrict the intake of flaxseed during lactation.

Maternal undernutrition during lactation alters nicotine reward and DOPAC/dopamine ratio in cerebral cortex in adolescent mice, but does not affect nicotine-induced nAChRs upregulation

Early undernutrition causes long lasting alterations that affect the response to psychoactive drugs. Particularly, undernutrition during lactation affects the acute locomotor response to nicotine during adolescence, but the reward effect of continued exposure to nicotine remains unknown. The goal of this study was to investigate the effects of undernutrition during lactation on the nicotine susceptibility indexed via conditioned place preference (CPP), on dopamine content and turnover and on nicotine‐induced nicotinic cholinergic receptor (nAChR) upregulation in the cerebral cortex, midbrain and hippocampus of adolescent mice. The impact of undernutrition and nicotine exposure on stress‐related hormones and leptin was also investigated. From postnatal day 2 (PN2) to weaning (PN21), dams were randomly assigned to one of the following groups: Control (C) – free access to standard laboratory diet (23% protein); Protein Restricted (PR) – free access to isoenergenetic diet (8% protein); Calorie Restricted (CR) – access to standard laboratory diet in restricted quantities (mean ingestion of PR). PR and CR groups showed less mass gain and less visceral fat mass. While C and CR were equally susceptible to nicotine‐induced place preference conditioning, PR failed to show a conditioning pattern. In contrast, all groups presented a nicotine‐evoked nAChR upregulation in the cerebral cortex. While dopamine and DOPAC levels did not differ between groups, the DOPAC/dopamine ratio was increased in CR animals. No differences in endocrine parameters were observed. Taken together, our results indicate that undernutrition during lactation programs for brain alterations later in life. Our data also suggest that early undernutrition does not affect the rewarding associative properties of nicotine at adolescence.