Maternal essential fatty acid deficiency depresses serum leptin levels in suckling rat pups

Dietary lipid quantity and quality have recently been shown to affect serum leptin levels in adult rats. Moreover, suckling pups from dams fed a high fat diet had increased serum leptin levels. The aim of the present study was to analyze the influence of essential fatty acid (EFA) deficiency on serum leptin levels in dams and their pups during the suckling period. For the last 10 days of gestation and throughout lactation, pregnant rats were fed a control or an EFA-deficient (EFAD) diet. The levels of leptin and EFA in the serum of the dams and pups were analyzed 1, 2, and 3 weeks after delivery. In parallel, serum levels of glucose and corticosterone were analyzed in the pups. Low serum leptin levels were found in the control lactating dams during the entire lactation period compared with the age-matched nonlactating animals. The leptin concentrations in the lactating dams fed the EFAD diet were lower compared with those fed the control diet. The serum leptin levels of suckling pups from dams on the EFAD diet were markedly decreased compared with controls (P < 0.05). The reduced serum leptin levels could not be explained by nutritional restriction as evaluated by serum levels of glucose and corticosterone. These results indicate the importance of the EFA composition of the maternal diet for serum leptin levels in both dams and pups. EFA deficiency in lactating dams may cause long-term effects on the pups through dysregulation of leptin and leptin-dependent functions. -- Korotkova, M., B. Gabrielsson, L. A. Hanson, and B. Strandvik. Maternal essential fatty acid deficiency depresses serum leptin levels in suckling rat pups. J. Lipid Res. 2001. 42: 359--365.     

Effect of dietary protein and calorie deficiency on tryptophan levels in the developing rat brain

The pattern of development of brain tryptophan in the rat was studied in the progeny of mothers fed a 7.5% protein diet ad lib., a 20% protein diet ad lib. and those fed a 20% protein diet pair-fed with mothers who received the 7.5% protein. The pattern of development was similar in all three groups. Starting with a high brain tryptophan content at birth, all animals showed a progressive reduction during the next 3 weeks. However, tryptophan levels at birth were several fold higher in the brains of pups born to mothers receiving either the low protein diet fed ad lib. or those born to mothers who received the 20% protein diet in restricted amounts. From the 14th day after birth, tryptophan concentration of brain in undernourished pups was significantly lower until the 35th day. The implications of this finding are discussed.     

Neonatal injury rapidly alters markers of pain and stress in rat pups

Less than 60% of infants undergoing invasive procedures in the neonatal intensive care unit receive analgesic therapy. These infants show long‐term decreases in pain sensitivity and cortisol reactivity. In rats, we have previously shown that inflammatory pain experienced on the day of birth significantly decreases adult somatosensory thresholds and responses to anxiety‐ and stress‐provoking stimuli. These long‐term changes in pain and stress responsiveness are accompanied by two‐fold increases in central met‐enkephalin and β‐endorphin expression. However, the time course over which these changes in central opioid peptide expression occur, relative to the time of injury, are not known. The present studies were conducted to determine whether the observed changes in adult opioid peptide expression were present within the first postnatal week following injury. The impact of neonatal inflammation on plasma corticosterone, a marker for stress reactivity, was also determined. Brain, spinal cord, and trunk blood were harvested at 24 h, 48 h, and 7 d following intraplantar administration of the inflammatory agent carrageenan on the day of birth. Radioimmunoassay was used to determine plasma corticosterone and met‐enkephalin and β‐endorphin levels within the forebrain, cortex, midbrain, and spinal cord. Within 24 h of injury, met‐enkephalin levels were significantly increased in the midbrain, but decreased in the spinal cord and cortex; forebrain β‐endorphin levels were significantly increased as a result of early life pain. Corticosterone levels were also significantly increased. At 7 d post‐injury, opioid peptides remained elevated relative to controls, suggesting a time point by which injury‐induced changes become programmed and permanent. © 2013 Wiley Periodicals, Inc. Develop Neurobiol 74: 42–51, 2014     

Maternal meal quality alters fetal rat brain serotonin concentrations

The quality of food eaten by pregnant animals may influence fetal neurotransmitter biosynthesis by altering the relative availability of precursor amino acids. Fetal brain concentrations of tryptophan and the neurotransmitter serotonin increase following the consumption of a carbohydrate-fat meal or after the injection of insulin in fasting animals; in contrast, the fetal concentrations of these compounds are reduced in animals whose mothers eat a meal containing casein protein or amino acids which compete with tryptophan for uptake from maternal blood into the placenta and fetus.     

Nickel deficiency alters nickel flux in rat everted intestinal sacs

This study was conducted to determine nickel absorption in nickel-deficient rats. Jejunal segments obtained from dietary nickeldepleted (13 μg nickel/kg diet) and nickel-control (1 mg nickel/kg diet) adult rats from the first generation, and suckling pups from the second offspring were used. The nickel transfer across the intestinal epithelium and nickel uptake into the intestine were measured by use of everted jejunal sacs using a wide range of nickel concentrations administered on the luminal side (1.1 x 10^-8 M til 1.0 x 10^-4 M). Both the intestinal nickel transfer and nickel uptake were influenced by the dietary nickel supply in rat offspring, but not in the adult rats from the first generation. However, in nickel-deficient offspring, the nickel transfer across the small intestine was higher than in nickelcontrol offspring. This difference was greater using low intraluminal nickel concentrations than high nickel concentrations, and was significant at 1.1 x 10^-8 M, 6.1 x 10^-8 M, 5.1 x 10^-7 M, 1.0 x 10^-6 M, and 5.0 x 10^-6 M. Also, nickel uptake into the intestine was somewhat greater in nickel-deficient rat pups than in nickel-control pups, and significant using 1.1 x 10^-7 M and 1.0 x 10^-6 M nickel. A definite saturation type kinetic for the intestinal nickel absorption in relation to the intraluminal nickel concentration could not be observed.     

Maternal dietary fat alters amniotic fluid and fetal intestinal membrane essential n-6 and n-3 fatty acids in the rat

We investigated whether maternal fat intake alters amniotic fluid and fetal intestine phospholipid n-6 and n-3 fatty acids. Female rats were fed a 20% by weight diet from fat with 20% linoleic acid (LA; 18:2n-6) and 8% alpha-linolenic acid (ALA; 18:3n-3) (control diet, n = 8) or 72% LA and 0.2% ALA (n-3 deficient diet, n = 7) from 2 wk before and then throughout gestation. Amniotic fluid and fetal intestine phospholipid fatty acids were analyzed at day 19 gestation using HPLC and gas-liquid chromotography. Amniotic fluid had significantly lower docosahexaenoic acid (DHA; 22:6n-3) and higher docosapentaenoic acid (DPA; 22:5n-6) levels in the n-3-deficient group than in the control group (DHA: 1.29 +/- 0.10 and 6.29 +/- 0.33 g/100 g fatty acid; DPA: 4.01 +/- 0.35 and 0.73 +/- 0.15 g/100 g fatty acid, respectively); these differences in DHA and DPA were present in amniotic fluid cholesterol esters and phosphatidylcholine (PC). Fetal intestines in the n-3-deficient group had significantly higher LA, arachidonic acid (20:4n-6), and DPA levels; lower eicosapentaenoic acid (EPA; 20:5n-3) and DHA levels in PC; and significantly higher DPA and lower EPA and DHA levels in phosphatidylethanolamine (PE) than in the control group; the n-6-to-n-3 fatty acid ratio was 4.9 +/- 0.2 and 32.2 +/- 2.1 in PC and 2.4 +/- 0.03 and 17.1 +/- 0.21 in PE in n-3-deficient and control group intestines, respectively. We demonstrate that maternal dietary fat influences amniotic fluid and fetal intestinal membrane structural lipid essential fatty acids. Maternal dietary fat can influence tissue composition by manipulation of amniotic fluid that is swallowed by the fetus or by transport across the placenta.     

Maternal n-3 PUFA deficiency alters uterine artery remodeling and placental epigenome in the mice

The maternal n-3 polyunsaturated fatty acid (PUFA) deficiency on decidual vascular structure and angiogenesis in mice placenta was investigated. Namely, we studied uterine artery remodeling, fatty acid metabolism, and placental epigenetic methylation in this animal model. Weanling female Swiss albino mice were fed either alpha-linolenic acid (18:3 n-3, ALA) deficient diets (0.13% energy from ALA) or a sufficient diet (2.26% energy from ALA) throughout the study. The dietary n-3 PUFA deficiency altered uteroplacental morphology and vasculature by reversing luminal to vessel area and increased luminal wall thickness at 8.5-12.5gD. Further, placentas (F0 and F1) showed a significant decrease in the expression of VCAM1, HLAG proteins and an increase in MMP9, KDR expression. The conversion of ALA to long-chain (LC) n-3 PUFAs was significantly decreased in plasma and placenta during the n-3 deficiency state. Reduced n-3 LCPUFAs increased the placental expression of intracellular proteins FABP3, FABP4, and ADRP to compensate decreased availability of these fatty acids in the n-3 deficient mice. The N-3 PUFA deficiency significantly increased the 5-methylcytosine levels in the placenta but not in the liver. The alteration in DNA methylation continued to the next generation in the placental epigenome with augmented expression of DNMT3A and DNMT3B. Our study showed that maternal n-3 PUFA deficiency alters placental vascular architecture and induces epigenetic changes suggesting the importance of n-3 PUFA intake during the development of the fetus. Moreover, the study shows that the placenta is the susceptible target for epigenetic alteration in maternal deficiency n-3 fatty acids.     

Maternal methyl-containing dietary supplementation alters the ability to learn in adult rats in swimming Morris test

Maternal choline diet influences the spatial learning processes. In this work, the learning ability of adult progeny of mothers who had received methyl diet enriched with choline and betain during pregnancy and lactation was studied in Morris test. The introduction of the diet to pregnant rats resulted in an increase in the time of search for invisible platform and time of swimming near the pool walls in offsprings, which meant a worsening of their learning ability. It was also found that change in platform searching strategy was not associated with an increase in anxiety of male rats. Possible involvement of maternal methyl diet in the change of expression of genes which control development of the nervous system is discussed.     

Maternal nicotine exposure: reponse of type II pneumocytes of neonatal rat pups.

The influence of maternal nicotine exposure during pregnancy and lactation on the Type II cells of lung tissue of one day old neonatal rat pups was investigated. The results clearly show that maternal nicotine exposure resulted in an increase in the type II cell count in the lungs of the offspring. In addition the lamellar body content of the type II cells of the nicotine exposed rat pups were significantly (P< 0.01) higher than that of the control animals. The type II cell mitochondria of lung tissue of nicotine exposed rat pups were swollen and no microvilli occurred on the alveolar surface. This clearly illustrates that nicotine interfered with type II cell integrity of tlte neonatal lung and may subsequently interfere with the normal development of the alveolar region of the lung.     

Vitamin B6 deficiency alters tissue iron concentrations in the Wistar rat

PurposeWe investigated the effect of a vitamin B6 deficiency and pair-feeding on tissue trace element status.MethodTissue zinc, copper and iron concentrations were measured in 3 groups of young, male Wistar rats receiving a diet of 3.5 mg/kg (control group), 0 mg/kg (deficient group) and a pair-fed group over 8 weeks. The pair-fed group received the same diet consumed by the control. Tissue trace element analysis was performed using atomic absorption spectrophotometry and plasma vitamin B6 status was determined using HPLC.ResultsDeficiency resulted in elevation in liver iron concentration and reduction in muscle iron concentration. Muscle copper concentrations were reduced in the pair-fed and deficient groups vs. the control group. Tissue zinc concentrations remained unaffected by the deficiency. Kidney iron and heart copper levels were elevated in the pair-fed group.ConclusionsThe liver and muscle iron changes were due to the deficiency and not to reduced calorie intake and the latter may be due to impaired heme synthesis. The differences in copper between the groups were due to reduced food intake. Zinc seems to form a fixed pool in these animals. A dietary deficiency of vitamin B6 impacts on the trace element status of certain tissues in key metabolic tissues and hence needs to be factored into the amelioration of the condition.     

Maternal attenuation of hypothalamic paraventricular nucleus norepinephrine switches avoidance learning to preference learning in preweanling rat pups

Infant rats learn to prefer stimuli paired with pain, presumably due to the importance of learning to prefer the caregiver to receive protection and food. With maturity, a more 'adult-like' learning system emerges that includes the amygdala and avoidance/fear learning. The attachment and 'adult-like' systems appear to co-exist in older pups with maternal presence engaging the attachment system by lowering corticosterone (CORT). Specifically, odor-shock conditioning (11 odor-0.5 mA shock trials) in 12-day-old pups results in an odor aversion, although an odor preference is learned if the mother is present during conditioning. Here, we propose a mechanism to explain pups ability to 'switch' between the dual learning systems by exploring the effect of maternal presence on hypothalamic paraventricular nucleus (PVN) neural activity, norepinephrine (NE) levels and learning. Maternal presence attenuates both PVN neural activity and PVN NE levels during odor-shock conditioning. Intra-PVN NE receptor antagonist infusion blocked the odor aversion learning with maternal absence, while intra-PVN NE receptor agonist infusion permitted odor aversion learning with maternal presence. These data suggest maternal control over pup learning acts through attenuation of PVN NE to reduce the CORT required for pup odor aversion learning. Moreover, these data also represent pups' continued maternal dependence for nursing, while enabling aversion learning outside the nest to prepare for pups future independent living.     

Aging but not dietary restriction alters the activation-induced apoptosis in rat T cells

The aim of this study was to determine if aging or dietary restriction (DR) alters activation-induced cell death, which is known to regulate cell proliferation and eliminate the high number of activated cells during an immune response. Splenic T cells were isolated from young (4-6 months) and old (25-26 months) Fischer 344 rats that had free access to food, ad libitum (AL), and from dietary-restricted (DR) old (25-26 months) rats that beginning at 6 weeks of age were fed 60% (40% food-restricted) of the diet consume by the AL rats. T cells were incubated with anti-CD3 antibody, or staphylococcal enterotoxin B (primary stimulus) for 72-96 h, followed by restimulation with anti-CD3 (secondary stimulus) for 72 h. Activation-induced apoptosis was assessed by DNA fragmentation and the expression of Fas/CD95 receptor and Fas ligand (Fas-L) was measured by flow cytometry. We found that the amount of DNA fragmentation was significantly (P<0.05) higher in the stimulated and restimulated T cells from AL old rats and DR old rats compared to young rats. The increase in DNA fragmentation with age was paralleled by an increase in the proportion of the cells expressing Fas and Fas-L. However, DR had no significant effect on the age-related increase in DNA fragmentation or the expression of Fas or Fas-L. We also measured the levels of Bcl-2 and Bax protein and found that the level of Bcl-2 decreased and Bax increased with age and that DR had no effect on the age-related changes in the level of Bcl-2 or Bax protein. These results demonstrate that aging but not DR alters activation-induced apoptosis in rat T cells.     

Fibroblast growth factor 2 alters the oxytocin receptor in a developmental model of anxiety-like behavior in male rat pups

We aimed to determine the short-term effects of early-life stress in the form of maternal separation (MS) on anxiety-like behavior in male rat pups. In order to assess anxiety, we measured 40 kHz separation-induced ultrasonic vocalizations (USV) on postnatal day (PND) 11. We further aimed to evaluate the potential involvement of two neurochemical systems known to regulate social and anxiety-like behaviors throughout life: oxytocin (OT) and fibroblast growth factor 2 (FGF2). For these purposes, we tested the effects of neonatal administration (on PND1) of an acute dose of FGF2 on USV and its potential interaction with MS. In addition, we validated the anxiolytic effects of OT and measured oxytocin receptor (OTR) gene expression, binding and epigenetic regulation via histone acetylation. Our results show that MS potentiated USV while acute administration of OT and FGF2 attenuated them. Further, we found that both FGF2 and MS increased OTR gene expression and the association of acH3K14 with the OTR promoter in the bed nucleus of the stria terminalis (BNST). Comparable changes, though not as pronounced, were also found for the central amygdala (CeA). Our findings suggest that FGF2 may exert its anxiolytic effects in male MS rats by a compensatory increase in the acetylation of the OTR promoter to overcome reduced OT levels in the BNST.     

Selenium deficiency alters the formation of eicosanoids and signal transduction in rat lymphocytes

Previous reports have shown that selenium (Se) nutrition alters the lipoxygenase pathway and mitogenic responses in bovine lymphocytes. In order to further understand how Se may alter lymphocyte function, we examined the effects of Se nutrition on arachidonic acid (AA) metabolism and phospholipase D (PLD) activation. Lymphocytes were isolated from the lymph nodes of rats fed either Se-deficient diet (-Se) or Se-supplemented diet (+Se) for 12 weeks. Our results revealed that calcium ionophore A23187-stimulated lymphocytes derived from -Se rats produced significantly less prostaglandins (PGs) than those obtained from +Se rats. Phospholipase D (PLD) activation by 12-O-tetradecanoylphorbol-13-acetate (TPA) was significantly lower in lymphocytes obtained from -Se rats when compared to cells from +Se rats. Furthermore, the addition of PGE2, PGD2 or PGF2alpha to suspended lymphocytes from -Se rats significantly enhanced PLD activity. The effects of TPA and PGE2 on PLD activation were additive. However, the addition of PGE2 abolished the significant difference in PLD activation between -Se and +Se cells observed in response to TPA alone. Based on these results, we postulate that dietary Se status plays an important role in the regulation of AA metabolism that subsequently affects PLD activation.