Intrauterine Food Restriction Research Articles

Intrauterine food restriction impairs the lipogenesis process in the mesenteric adipocytes from low-birth-weight rats into adulthood.

Intrauterine food restriction (IFR) during pregnancy is associated with low birth weight (LBW) and obesity in adulthood. It is known that white adipose tissue (WAT) plays critical metabolic and endocrine functions; however, this tissue's behavior before weight gain and obesity into adulthood is poorly studied. Thus, we evaluated the repercussions of IFR on the lipogenesis and lipolysis processes in the offspring and described the effects on WAT inflammatory cytokine production and secretion. We induced IFR by providing gestating rats with 50% of the necessary chow daily amount during all gestational periods. After birth, we monitored the offspring for 12 weeks. The capacity of isolated fat cells from mesenteric white adipose tissue (meWAT) to perform lipogenesis (14C-labeled glucose incorporation into lipids) and lipolysis (with or without isoproterenol) was assessed. The expression levels of genes linked to these processes were measured by real-time PCR. In parallel, Multiplex assays were conducted to analyze pro-inflammatory markers, such as IL-1, IL-6, and TNF-α, in the meWAT. Twelve-week-old LBW rats presented elevated serum triacylglycerol (TAG) content and attenuated lipogenesis and lipolysis compared to control animals. Inflammatory cytokine levels were increased in the meWAT of LBW rats, evidenced by augmented secretion by adipocytes and upregulated gene and protein expression by the tissue. However, there were no significant alterations in the serum cytokines content from the LBW group. Additionally, liver weight, TAG content in the hepatocytes and serum glucocorticoid levels were increased in the LBW group. The results demonstrate that IFR throughout pregnancy yields LBW offspring characterized by inhibited lipogenesis and lipolysis and reduced meWAT lipid storage at 12 weeks. The increased serum TAG content may contribute to the augmented synthesis and secretion of pro-inflammatory markers detected in the LBW group.

Intrauterine Food Restriction is Associated with Obesity in Young Rats

The purpose of this study was to examine the effects of malnutrition during the first 2 wk of intrauterine life on the regulation of energy metabolism and the activity of brown adipose tissue in rats at 53 d of age. Intrauterine malnutrition led to an imbalance in the control of energy metabolism that was influenced by gender. In males, the intrauterine malnutrition resulted in impairment of normal weight gain and fat deposition during 1 to 53 d of age, in association with low plasma total triiodothyronine concentration, in spite of normal food intake. In contrast, the intrauterine malnutrition in females led to a marked fat accumulation by 53 d of age with normal food intake, and decreased brown adipose tissue weight, protein content and cytochrome c oxidase activity, indicating a lower sympathetic activity. These data indicate that nutrient availability during the first 2 wk of intrauterine life determines the control of energy utilization during early post-weaning period.

Glomerular filtration barrier in rat offspring exposed to maternal undernutrition

Poor diet during pregnancy can increase blood pressure in offspring of human and laboratory animals. The present study examined the effects of moderate intrauterine undernutrition on the ultrastructure of the glomerular filtration barrier in 20-day-old rat fetuses and six-month-old rat offspring. Pregnant rats were provided with either ad libitum food during pregnancy (control group, C) or restricted to 50% of ad libitum food until delivery (food-restricted group, FR). Both groups were given free access to food after birth. The kidneys of embryonic day 20 and six-month-old rats were harvested. Transmission electron micrographs in glomeruli from both groups were obtained to study the ultrastructure of the glomerular filtration barrier. Blood pressure and glomerular filtration rate were measured in six-month-old rats. In comparison to the control group, the FR group had smaller body and kidney weights in both ages. Systemic blood pressure was significantly elevated in the FR group. The glomerular filtration rate was similar in both groups. A study of the glomerular ultrastructure showed a remarkable retardation in the development of the podocyte foot process in the FR group at embryonic day 20. Micrographs also showed remarkable changes in the glomerular filtration barrier of six-month-old rats including an increase in the thickness of the glomerular basement membrane and an increase in the width of filtration slits. These results suggest that maternal food restriction disturbs the development of the glomerular filtration barrier, which may contribute to hypertension in adult rat offspring. The long-term exposure to hypertension and glomerular hyperfiltration may have contributed to the damages observed in the glomerular filtration barrier of six-month-old rats exposed to intrauterine food restriction.

Food restriction during pregnancy alters brain’s antioxidant network in dams and their offspring

Dietary restriction increases life span and protects distinct organisms against a series of diseases, among which, those related to oxidative stress, like neurodegenerative diseases. Interferences in the maternal environment are known to reprogram the offspring metabolism response, impacting in the risk of chronic diseases development in adulthood. We aimed to assess the effects of 40% food restriction on reactive species levels, enzymatic and non-enzymatic antioxidant defenses, and oxidative damage parameters in the cerebellum and total cerebral cortex of pregnant rats and their offspring. Dams and pups showed oxidative modulation caused by food restriction in both structures. Dichlorofluorescein oxidation, reflecting reactive species levels, was reduced in the cerebellum of dams and offspring, while the cerebral cortex was not affected. Decreased mitochondrial superoxide levels were found in the cerebellum and cerebral cortex of pups, while nitric oxide was increased in the cortex. We also measured the activities of important antioxidant enzymes responsible by reactive oxygen species elimination. Superoxide dismutase activity was increased in the cerebellum of dams and in both structures of pups, while it was decreased in dams’ cerebral cortex. Both brain structures were affected concerning to catalase, glutathione peroxidase, and glutaredoxin activities, which were reduced in pups and dams. Non-enzymatic defenses were decreased in pups, while dams showed an adaptive pattern in the cerebellum and no alteration in the cerebral cortex. Even though the results suggest increased oxidative status, lipids and proteins were not oxidatively affected. Our data suggest that intrauterine food restriction may disrupt oxidative status, impairing the antioxidant network.

Effect of Maternal Food Restriction on the Uterus of Female Rats from the First and Second Generation

Postnatal life is affected by changes in fetal development due to adverse events. The present study examined the effect of maternal food restriction on uterine structure and capacity in female rats from the first and second generations (FR1 and FR2) before and after puberty. Pregnant rats were fed ad libitum (Control, C) or maintained under food-restriction conditions (50%FR) during pregnancy. After delivery, all groups were given free access to food. Females from the first generation (FR1) were divided into two subgroups for either uterine dissection or to produce the next generation (FR2). Similar to FR1, FR2 females were exposed to maternal food restriction following the same procedure. FR2 females were also assigned into two subgroups for either uterine dissection or for mating to examine pregnancy outcomes. Uteri from the C, FR1 and FR2 groups were dissected at 4 weeks of age (before puberty) or at 8 weeks of age (after puberty) to evaluate uterine weight and uterine horn length. Tissues were stained with eosin and haematoxylin for examination vialight microscopy. The results showed that food restriction did not affect uterine weight or uterine horn length in FR1 and FR2 females before puberty. However, there were effects of maternal food restriction on uterine weight and length at 8 weeks of age. Uterine weight and uterine horn length were significantly reduced in the FR1 and FR2 groups compared with the values of the controls. This was associated with changes in pregnancy outcomes. Litter size was not affected in the FR1 group; however, litter weight was significantly reduced, leading to an 18% reduction in pup weight at birth. Unlike with FR1 litters, the size of FR2 litters was significantly reduced, leading to a lower degree of pup body weight reduction at birth (only 7%). The gestational length was normal in FR1 females but was significantly decreased in FR2 females. No histopathological changes were observed. These results showed that the uterus was affected by maternal food restriction. It seemed that FR2 females had a different reproductive strategy: they tended to reduce litter size to maintain pup weight at birth. In conclusion, maternal food restriction affects the uteri of the first and second generation. Females from the FR1 and FR2 groups followed different reproductive strategies according to their previous experience with exposure to intrauterine food restriction.

Intrauterine food restriction alters the expression of uncoupling proteins in brown adipose tissue of rat newborns

A previous study from our laboratory showed that maternal food restriction (MFR) delays thermoregulation in newborn rats. In neonates brown adipose tissue (BAT) is essential for thermogenesis due to the presence of uncoupling proteins (UCPs). The aim of this study was to evaluate the influence of MFR on the UCPs mRNA and protein expression in BAT and skeletal muscle (SM) of the newborn rat. Female Wistar EPM-1 control rats (CON) received chow ad libitum during pregnancy, whereas food-restricted dams (RES) received 50% of the amount ingested by CON. Fifteen hours after birth, the litters were weighed and sacrificed. Blood was collected for hormonal analysis. BAT and SM were used for determination of UCPs mRNA and protein expression, and Ca2+-ATPase sarcoplasmic reticulum (SERCA1). RES pups showed a significant reduction in body weight and fat content at birth. MFR caused a significant increase in the expression of UCP1 and UCP2 in BAT, without changes in UCP3 and SERCA1 expression in BAT and SM. No differences between groups were found for leptin, T4 and glucose levels. RES pups showed increased insulin and decreased T3 levels. The delay in development of thermoregulation previously described in RES animals appears not to result from impairment in thermogenesis, but from an increase in heat loss, since MFR caused low birth weight in pups, leading to greater surface/volume ratio. The higher expression of UCP1 and UCP2 in BAT suggests a compensatory mechanism to increased thermogenesis.

Established maternal obesity in the rat reprograms hypothalamic appetite regulators and leptin signaling at birth

Key appetite regulators and their receptors are already present in the fetal hypothalamus, and may respond to hormones such as leptin. Intrauterine food restriction or hyperglycemia can reprogram these circuits, possibly predisposing individuals to adverse health outcomes in adulthood. Given the global obesity epidemic, maternal overweight and obesity is becoming more prevalent. Earlier, we observed rapid growth of pups from obese dams during the suckling period. However, it is unclear whether this is because of alterations in leptin and hypothalamic appetite regulators at birth. Female Sprague-Dawley rats were fed palatable high-fat diet (HFD) or chow for 5 weeks to induce obesity before mating. The same diet continued during gestation. At day 1, after birth, plasma and hypothalamus were collected from male and female pups. Body weight and organ mass were recorded. Leptin and insulin levels were measured in the plasma by radioimmunoassay. Hypothalamic mRNA expression of neuropeptide-Y (NPY), pro-opiomelanocortin, leptin receptor and its downstream signal, STAT3 (signal transducer and activator of transcription 3), were measured using real-time PCR. Body and organ weights of pups from obese dams were similar to those from lean dams, across both genders. However, plasma leptin levels were significantly lower in offspring from obese dams (male: 0.53+/-0.13 vs 1.05+/-0.21 ng ml(-1); female: 0.33+/-0.09 vs 2.12+/-0.57 ng ml(-1), respectively; both P<0.05). Hypothalamic mRNA expression of NPY, pro-opiomelanocortin, leptin receptor and STAT3 were also significantly lower in pups from obese dams. Long-term maternal obesity, together with lower leptin levels in pups from obese dams may contribute to the lower expression of key appetite regulators on day 1 of life, suggesting altered intrauterine neuron development in response to intrauterine overnutrition, which may contribute to eating disorders later in life.

Effects of Intrauterine Food Restriction and Long-Term Dietary Supplementation with l-Arginine on Age-Related Changes in Renal Function and Structure of Rats

We have previously demonstrated that restricting intrauterine food by 50% in 3-mo-old rats produced lower nephron numbers and early-onset hypertension, the latter being normalized by L-arginine administration. In 18-mo-old rats, such restriction increased glomerulosclerosis. In this study, we expanded our investigation, evaluating functional, morphologic, and immunohistochemical parameters in intrauterine-food-restricted 18-mo-old rats, either receiving L-arginine (RA18) or not (R18). Age-matched, non-food-restricted controls were assigned to similar groups with L-arginine (CA18) and without (C18). After weaning, L-arginine was given daily for 17 mo. No functional or morphologic changes were observed in C18 rats. The R18 rats developed early-onset hypertension, which persisted throughout the observation period, as well as significant proteinuria from 12 mo on. In RA18 rats, L-arginine decreased both blood pressure levels and proteinuria, and glomerular diameter was significantly smaller than in R18 rats (115.63 +/- 2.2 versus 134.8 +/- 1.0 mum, p < 0.05). However, in RA18 rats, glomerular filtration rate remained depressed. Although L-arginine prevented glomerulosclerosis (R18 = 14%, RA18 = 4%; p < 0.05), glomerular expression of fibronectin and desmin was still greater in RA18 rats than in controls. Our data show that, although L-arginine prevented hypertension and proteinuria, glomerular injury still occurred, suggesting that intrauterine food restriction may be one of the leading causes of impaired renal function in adult life.

Food restriction in pregnant rat-like hamsters ( Cricetulus triton) affects endocrine, immune function and odor attractiveness of male offspring

We studied the effect of intrauterine food restriction (FR) on the immune function, endocrine status and attractiveness of scents of male rat-like hamsters, Cricetulus triton. Work was conducted on field-caught parents from the North China plain and their laboratory-born progeny. Restricted pregnant dams were fed 70% of the mean daily intake of hamsters with free access to food. FR caused a marked and protracted weight reduction of the body, adrenal, testes and epididymides in males. During the refeeding period, the spleen and thymus, but not the adrenal weight of the malnourished offspring caught up with that of the control after about 60 days. The present results demonstrated that estrous females preferred the odors of control males to that of FR males. Males whose mothers were food restricted during gestation had lower testosterone concentrations, immune responses and reproductive organ mass but had higher circulating cortisol than did the males in the control group. Thus, the effect of maternal FR may be an important cause in population regulation in the rat-like hamster. The testosterone level was positively correlated with immune function in rat-like hamsters, but the lower immunity was not suppressed by higher level of testosterone, as previously suggested. We also found a negative relationship between cortisol and immune function in the rat-like hamster.

Postnatal oxytocin alleviates adverse effects in adult rat offspring caused by maternal malnutrition.

Repeated oxytocin administration to adult rats causes a long-term decrease of plasma levels of corticosterone and blood pressure and stimulates growth and fat retention. Maternal undernutrition increases blood pressure and plasma corticosterone in adult offspring. We hypothesized that oxytocin treatment early in life would alleviate adverse effects of intrauterine food restriction. Male pups from ad libitum-fed and food-restricted (fed 60% of ad libitum intake) dams were injected with oxytocin or saline in days 1-14 after birth. At 4 mo, blood pressure, plasma levels of corticosterone, and adiposity were assessed. Oxytocin treatment decreased blood pressure independently of nutrition, whereas the increased plasma levels of corticosterone were lowered to normal levels in food-restricted offspring. Blood pressure and adiposity were not affected by in utero food restriction, whereas birth and adult weight were. In conclusion, postnatal events may alleviate adverse effects caused by in utero food restriction. In contrast to more severe food restriction, a moderate general food restriction during gestation had no effect on blood pressure in the offspring.

L-Arginine effects on blood pressure and renal function of intrauterine restricted rats.

We have previously demonstrated that 3-month-old rats submitted to 50% intrauterine food restriction showed a decreased number of nephrons with increased glomerular diameter, a fact that suggests compensatory hypertrophy. In the present study, we extended the investigation and performed serial blood pressure measurements and renal function evaluation in 8- and 12-week-old rats submitted to 50% intrauterine food restriction (groups R8 and R12) and in age-matched control rats (groups C8 and C12). After weaning, six to eight animals from each group received oral supplements of 2% L-arginine ( L-arg) solution for 4 or 8 weeks (groups CA8, CA12, RA8, RA12). Our findings showed that mean blood pressure (MBP), which was significantly increased from 8 weeks on in R rats, markedly decreased after L-arg supplementation. In control animals, no alterations in MBP were observed with L-arg. Proteinuria was within normal limits in all groups studied but L-arg caused a significant decrease in this parameter in both the RA8 and RA12 groups. Glomerular filtration rate (GFR, ml/min per kg) was significantly decreased in the C8 control group (3.75+/-0.12) and in both restricted groups R8 and R12, (2.47+/-0.13 and 3.76+/-0.16, respectively) compared with the C12 group (6.09+/-0.31; P<0.05 for all comparisons). L-Arg caused an increase in GFR only in the younger groups, C8 and R8. In a separate set of experiments, acetylcholine (ACh)-induced relaxation was examined in mesenteric arteries. The R12 group showed a significant impairment of the response to ACh, which returned to normal values after L-arg supplementation. Urinary excretion of NO(x) (NO3- + NO2-) was significantly decreased in 8- and 12-week-old food-restricted rats relative to control rats. Our data indicate that, besides the known decrease in absolute nephron number, disturbances in the production/sensitivity to the L-arg-nitric oxide system may contribute to the early appearance of hypertension in the offspring of mothers submitted to significant food restriction.

Intrauterine food restriction as a determinant of nephrosclerosis

We previously showed that 3-month-old rats subjected to a 50% intrauterine food restriction had a decreased number of nephrons with increased glomerular diameter, which suggests compensatory hypertrophy. Hypertrophy could be the early event of glomerular damage. In this study, we extended our investigation and performed functional, morphological, and immunohistochemical evaluations in 3- and 18-month-old rats that underwent a 50% intrauterine food restriction (RT3 and RT18, respectively) and age-matched control rats (C3 and C18, respectively). Our findings showed that glomerular filtration rate was significant decreased in RT18 rats (2.42 ± 0.15 mL/min/kg; n = 28; P < 0.05) compared with C18 control rats (4.19 ± 0.10 mL/min/kg; P < 0.05) and the percentage of glomeruli with sclerosis was greater in RT18 rats (13.01% ± 2.95%; n = 9; P < 0.01) than in C18 rats (2.71% ± 0.35%; n = 6). RT18 rats also showed more intense tubulointerstitial lesions and immunohistochemical alterations in the renal cortex. Immunohistochemical studies showed increased fibronectin and desmin expression in glomeruli and tubulointerstitium and increased vimentin and α-smooth muscle actin in the tubulointerstitial area from the renal cortex of RT18 rats (P < 0.05). Desmin was also increased at the edge of glomeruli from RT18 rats, suggesting podocyte injury. Our data show that when food restriction is imposed during pregnancy, permanent damage occurs in the kidney of the offspring. Glomerular lesions were more severe than the tubulointerstitial damage in these animals.

Intrauterine food restriction as a determinant of nephrosclerosis

Intrauterine food restriction as a determinant of nephrosclerosis

Food intake and the kidney: The right amounts at the right times

Food intake and the kidney: The right amounts at the right times

Functional and morphometric evaluation of offspring kidney after intrauterine undernutrition.

Pregnant rats were subjected to 50% food restriction during the first or the second half of pregnancy, or throughout pregnancy. The effects of intrauterine food restriction, on kidney function and morphometry were studied in newborn and adult (3 months) offspring. No differences in glomerular diameter were observed in newborn restricted rats compared with controls. The number of glomeruli was significantly lower both in newborn and 3-month-old restricted rats. However, glomerular diameter was increased in 3-month-old rats, which suggests that hypertrophic stimuli were present. The medulla/cortex ratio increased in adult rats submitted to food restriction during pregnancy, a finding that agrees with the preserved sodium and acid excretion, and the normal osmolar and free water clearance observed in these groups. These results show that the reduction in glomerular number is still present 3 months after birth in the progeny of mothers submitted to severe food restriction during pregnancy, suggesting impairment of glomerulogenesis even after birth. Intra utero undernutrition can be regarded as an experimental model of glomerular hypertrophy.