A Sustainable Translational Sheep Model for Planned Cesarean Delivery of Contraction-Free Ewes.

We evaluated whether the sheep constitutes a useful translational model to evaluate anatomical and surgical aspects of cesarean delivery (CD) from a human medical perspective with the aim of both maternal and neonatal well-being. Our hypothesis was that CD in contraction-free ewes is not associated with major complications. Primary endpoint was the transferability of anatomical conditions and surgical techniques of CD from the ewe to the human. Secondary endpoints were maternal and fetal survival, occurrence of retained fetal membranes, metritis, mastitis, or wound infections. Forty-eight Merino ewes were delivered by CD after 95% gestation (142-144 days). Both ewes and newborn lambs were cared for intensively after the delivery. Ovine uterine anatomy during CD appeared slightly different but comparable to the human uterus. Uterine incisions were mostly performed in the uterine horns, not in the uterine corpus. The ovine uterine wall is thinner than in humans. All ewes survived without any major complications. Seventy-seven (88.5%) out of 87 live-born lambs survived without any complications. The contraction-free ewe constitutes an appropriate and safe model to evaluate anatomical and surgical aspects of CD from a human medical perspective. We present a step-by-step manual for successfully planned cesarean delivery for sheep including the perioperative management illustrated with photographs and a five-minute video. With adequate planning and a reasonable number of staff, it is possible to safeguard both maternal and neonatal survival. This sustainable translational medicine model offers additional potential for the offspring to be used for further research studies (e.g., transgenerational inheritance research).

Uterine scars after caesarean delivery: From histology to the molecular and ultrastructural level.

Uterine rupture during a trial of labor after caesarean delivery (CD) is a serious complication for mother and fetus. The lack of knowledge on histological features and molecular pathways of uterine wound healing has hindered research in this area from evolving over time. We analysed collagen content and turnover in uterine scars on a histological, molecular and ultrastructural level. Therefore, tissue samples from the lower uterine segment were obtained during CD from 16 pregnant women with at least one previous CD, from 16 pregnant women without previous CD, and from 16 non-pregnant premenopausal women after hysterectomy for a benign disease. Histomorphometrical collagen quantification showed, that the collagen content of the scar area in uterine wall specimens after previous CD was significantly higher than in the unscarred myometrium of the same women and the control groups. Quantitative real-time PCR of uterine scar tissue from FFPE samples delineated by laser microdissection yielded a significantly higher COL3A1 expression and a significantly lower COL1A2/COL3A1 ratio in scarred uteri than in samples from unscarred uteri. Histological collagen content and the expression of COL1A2 and COL3A1 were positively correlated, while COL1A2/COL3A1 ratio was negatively correlated with the histological collagen content. Transmission electron microscopy revealed a destroyed myometrial ultrastructure in uterine scars with increased collagen density. We conclude that the high collagen content in uterine scars results from an ongoing overexpression of collagen I and III. This is a proof of concept to enable further analyses of specific factors that mediate uterine wound healing.

Altered SOCS3 DNA methylation within exon 2 is associated with increased mRNA expression in visceral adipose tissue in gestational diabetes.

Overweight/obesity is the main risk factor for gestational diabetes mellitus (GDM). In our cohort of pregnant women with GDM, n = 19, and without, n = 22, we previously reported a significant increase in SOCS3 mRNA expression (+62%) in visceral adipose tissue (VAT) according to GDM, without altered promoter DNA-methylation. Here, we examined methylation status of additional SOCS3 exon 2 regions in VAT and maternal blood. We found significantly altered methylation at specific CpG sites corresponding to aberrant mRNA expression levels of SOCS3 in VAT. We propose a potential regulatory element/region within exon 2; however, this region does not appear to be a good blood-marker representing VAT.

Maternal but Not Paternal High-Fat Diet (HFD) Exposure at Conception Predisposes for 'Diabesity' in Offspring Generations.

While environmental epigenetics mainly focuses on xenobiotic endocrine disruptors, dietary composition might be one of the most important environmental exposures for epigenetic modifications, perhaps even for offspring generations. We performed a large-scale rat study on key phenotypic consequences from parental (F0) high-caloric, high-fat diet (HFD) food intake, precisely and specifically at mating/conception, focusing on 'diabesity' risk in first- (F1) and second- (F2) generation offspring of both sexes. F0 rats (maternal or paternal, respectively) received HFD overfeeding, starting six weeks prior to mating with normally fed control rats. The maternal side F1 offspring of both sexes developed a 'diabesity' predisposition throughout life (obesity, hyperleptinemia, hyperglycemia, insulin resistance), while no respective alterations occurred in the paternal side F1 offspring, neither in males nor in females. Mating the maternal side F1 females with control males under standard feeding conditions led, again, to a 'diabesity' predisposition in the F2 generation, which, however, was less pronounced than in the F1 generation. Our observations speak in favor of the critical impact of maternal but not paternal metabolism around the time frame of reproduction for offspring metabolic health over generations. Such fundamental phenotypic observations should be carefully considered in front of detailed molecular epigenetic approaches on eventual mechanisms.

Visceral Adipose Tissue Inflammatory Factors (TNF-Alpha, SOCS3) in Gestational Diabetes (GDM): Epigenetics as a Clue in GDM Pathophysiology.

Gestational diabetes (GDM) is among the most challenging diseases in westernized countries, affecting mother and child, immediately and in later life. Obesity is a major risk factor for GDM. However, the impact visceral obesity and related epigenetics play for GDM etiopathogenesis have hardly been considered so far. Our recent findings within the prospective 'EaCH' cohort study of women with GDM or normal glucose tolerance (NGT), showed the role, critical factors of insulin resistance (i.e., adiponectin, insulin receptor) may have for GDM pathophysiology with epigenetically modified expression in subcutaneous (SAT) and visceral (VAT) adipose tissues. Here we investigated the expression and promoter methylation of key inflammatory candidates, tumor necrosis factor-alpha (TNF-α) and suppressor of cytokine signaling 3 (SOCS3) in maternal adipose tissues collected during caesarian section (GDM, n = 19; NGT, n = 22). The mRNA expression of TNF-α and SOCS3 was significantly increased in VAT, but not in SAT, of GDM patients vs. NGT, accompanied by specific alterations of respective promoter methylation patterns. In conclusion, we propose a critical role of VAT and visceral obesity for the pathogenesis of GDM, with epigenetic alterations of the expression of inflammatory factors as a potential factor.

Sex-specific epigenetic alterations of the hypothalamic Agrp-Pomc system do not explain 'diabesity' in the offspring of high-fat diet (HFD) overfed maternal rats.

Maternal high-fat diet (HFD) overfeeding pre- and during pregnancy and lactation may 'program' a 'diabesity' predisposition in the offspring, for inconclusive reasons. Acquired alterations of the hypothalamic promoter methylation and mRNA expression of the satiety neurohormone Pomc are possibly of critical importance here. We investigated within one developmental approach, including male and female rats, the sex-specific DNA methylation pattern and corresponding mRNA expression of both Pomc and its endogenous functional antagonist Agrp in the hypothalamus of adult HFD offspring. Obesity and diabetic disturbances occurred in both male and female HFD offspring, accompanied by altered Pomc promoter methylation pattern. However, this was not related to significant Pomc mRNA expression alterations. In contrast, male-specific alterations of Agrp promoter methylation were found, even associated with reduced mRNA expression of this orexigenic/anabolic Pomc antagonist. In conclusion, acquired epigenetic alterations of the hypothalamic Agrp-Pomc system hardly explain the 'diabesity' phenotype in HFD offspring, while distinct vulnerability and functionality of Agrp promoter and related genomic regions methylation should be further investigated.

Visceral adipose tissue alteration of PI3KR1 expression is associated with gestational diabetes but not promoter DNA methylation.

Obesity and diabetes are at an epidemic rate, as well as growing incidences of gestational diabetes mellitus (GDM) which causes pregnancy risks, and harm in both maternal and child health. It remains unclear which molecular mechanisms are driving the functional differences between visceral and subcutaneous fat and how these types directly affect an individual's health outcome. Paired abdominal subcutaneous and omental visceral adipose tissue were collected from women with GDM (n = 20) and with normal glucose tolerance (NGT, n = 22) during planned caesarian section. Both groups had similar maternal age (average 32.5 years) and BMI at delivery (average 33.3 kg/m2). Adipose tissue mRNA expression analyses of insulin signalling genes: PI3KCA, PI3KR1, IRS1 and IRS2 showed significantly decreased PI3KR1 expression (-23%) in visceral fat in GDM with no association to promoter DNA methylation. Reduced visceral fat PI3KR1 expression appears to be a pathogenic factor in GDM but not through altered promoter methylation.

Hypothalamic insulin receptor expression and DNA promoter methylation are sex-specifically altered in adult offspring of high-fat diet (HFD)-overfed mother rats.

Maternal overnutrition around reproduction has been shown to increase the offspring's risk for "diabesity," mediated by altered hypothalamic neuropeptide expression. In this report, a possible contribution of altered hypothalamic sensing capacity for the peripheral satiety signals glucose, insulin and leptin will be addressed, taking into account potential sex differences. Specifically, we evaluated the effects a maternal high-fat diet (HFD) overfeeding has in rats pre- and during pregnancy and lactation on the hypothalamic gene expression patterns of insulin and leptin receptors (InsR, ObRb) and glucose transporter 3 (Glut3) as well as DNA methylation in the offspring at adult age (day 200 of life). Maternal HFD consumption resulted in a metabolic syndrome phenotype, i.e., obesity, hyperleptinemia, hyperinsulinemia, impaired glucose tolerance and increased homeostatic model assessment of insulin resistance. Interestingly, in turn, insulin resistance was more pronounced in male offspring, accompanied by decreased hypothalamic InsR-mRNA. This was linked with hypermethylation of an activating transcription factor binding site within the hypothalamic InsR promoter. The degree of methylation correlated inversely with respective InsR expression, while InsR expression itself was inversely related to phenotypic "diabesity." Expression of ObRb and Glut3 mRNA was not significantly changed. In conclusion, sex-specific alterations of hypothalamic InsR expression and DNA promoter methylation in adult offspring of HFD-overfed dams may lead to hypothalamic insulin resistance and "diabesity," with males predisposed to this epigenetic malprogramming.

Reduced Insulin Receptor Expression and Altered DNA Methylation in Fat Tissues and Blood of Women With GDM and Offspring.

Context: Altered expression of the insulin receptor (IR) in adipose tissue (AT) could contribute to gestational diabetes mellitus (GDM) etiopathogenesis. Transcriptional regulation via epigenetic mechanisms (e.g., DNA methylation) may play a critical role. However, the human IR promoter DNA methylation patterns and involvement in gene expression are unknown. Objective: We evaluated IR mRNA and protein expression accompanied by targeted DNA methylation analyses in AT and blood cells of women with GDM and their offspring. Design: Prospective observational study. Setting: Academic clinic and research unit. Participants: GDM-affected (n = 25) and matched control (n = 30) mother-child dyads. Main Outcome Measures: Maternal IR gene and protein expression in paired subcutaneous (SAT) and visceral adipose tissue samples (VAT). DNA methylation levels in IR promoter and intronic regions in maternal AT and blood cells of mother-offspring pairs. Results: In SAT and VAT, IR mRNA/protein expressions were significantly reduced in women with GDMs (P < 0.05). The decrease in VAT was more pronounced and independent of maternal body mass index. VAT IR protein levels were inversely associated with key maternal and neonatal anthropometric and metabolic parameters (P < 0.05). DNA methylation patterns were similar across tissues, with significant yet small size alterations between groups in mothers and offspring (P < 0.05). Conclusion: Decreased IR levels in AT may be a relevant pathogenic factor in GDM, affecting materno-fetal metabolism. Further investigation of causal factors for IR dysregulation is necessary, especially in VAT. Potential functional and/or clinical roles of altered DNA methylation also should be evaluated.

Alterations of adiponectin gene expression and DNA methylation in adipose tissues and blood cells are associated with gestational diabetes and neonatal outcome.

BACKGROUND: Adiponectin critically contributes to metabolic homeostasis, especially by insulin-sensitizing action. Gestational diabetes mellitus (GDM) is characterized by insulin resistance leading to materno-fetal hyperglycemia and detrimental birth outcomes. By investigating paired subcutaneous (SAT) and visceral adipose tissue (VAT) as well as blood (cell) samples of GDM-affected (n = 25) vs. matched control (n = 30) mother-child dyads of the prospective "EaCH" cohort study, we addressed whether alterations of adiponectin plasma, mRNA, and DNA methylation levels are associated with GDM and offspring characteristics. RESULTS: Hypoadiponectinemia was present in women with GDM, even after adjustment for body mass index (BMI). This was accompanied by significantly decreased mRNA levels in both SAT and VAT (P < 0.05), independent of BMI. Maternal plasma adiponectin showed inverse relations with glucose and homeostatic model assessment of insulin resistance (both P < 0.01). In parallel to reduced mRNA expression in GDM, significant (P < 0.05) yet small alterations in locus-specific DNA methylation were observed in maternal fat (~ 2%) and blood cells (~ 1%). While newborn adiponectin levels were similar between groups, DNA methylation in GDM offspring was variously altered (~ 1-4%; P < 0.05). CONCLUSIONS: Reduced adiponectin seems to be a pathogenic co-factor in GDM, even independent of BMI, affecting materno-fetal metabolism. While altered maternal DNA methylation patterns appear rather marginally involved, functional, diagnostic, and/or predictive implications of cord blood DNA methylation should be further evaluated.

Maternal overweight is not an independent risk factor for increased birth weight, leptin and insulin in newborns of gestational diabetic women: observations from the prospective 'EaCH' cohort study.

BACKGROUND: Both gestational diabetes mellitus (GDM) as well as overweight/obesity during pregnancy are risk factors for detrimental anthropometric and hormonal neonatal outcomes, identified to 'program' adverse health predispositions later on. While overweight/obesity are major determinants of GDM, independent effects on critical birth outcomes remain unclear. Thus, the aim of the present study was to evaluate, in women with GDM, the relative/independent impact of overweight/obesity vs. altered glucose metabolism on newborn parameters. METHODS: The prospective observational 'Early CHARITÉ (EaCH)' cohort study primarily focuses on early developmental origins of unfavorable health outcomes through pre- and/or early postnatal exposure to a 'diabetogenic/adipogenic' environment. It includes 205 mother-child dyads, recruited between 2007 and 2010, from women with treated GDM and delivery at the Clinic of Obstetrics, Charité - Universitätsmedizin Berlin, Germany. Recruitment, therapy, metabolite/hormone analyses, and data evaluation were performed according to standardized guidelines and protocols. This report specifically aimed to identify maternal anthropometric and metabolic determinants of anthropometric and critical hormonal birth outcomes in 'EaCH'. RESULTS: Group comparisons, Spearman's correlations and unadjusted linear regression analyses initially confirmed that increased maternal prepregnancy body-mass-index (BMI) is a significant factor for elevated birth weight, cord-blood insulin and leptin (all P < 0.05). However, consideration of and adjustment for maternal glucose during late pregnancy showed that no maternal anthropometric parameter (weight, BMI, gestational weight gain) remained significant (all n.s.). In contrast, even after adjustment for maternal anthropometrics, third trimester glucose values (fasting and postprandial glucose at 32nd and 36th weeks' gestation, HbA1c in 3rd trimester and at delivery), were clearly positively associated with critical birth outcomes (all P < 0.05). CONCLUSIONS: Neither overweight/obesity nor gestational weight gain appear to be independent determinants of increased birth weight, insulin and leptin. Rather, 3rd trimester glycemia seems to be crucial for respective neonatal outcomes. Thus, gestational care and future research studies should greatly consider late pregnancy glucose in overweight/obese women with or without GDM, for evaluation of critical causes and interventional strategies against 'perinatal programming of diabesity' in the offspring.

Short-term regulation of the hypothalamic melanocortinergic system under fasting and defined glucose-refeeding conditions in rats: a laser capture microdissection (LMD)-based study.

It is well established that under fasting conditions the expression of the orexigenic neuropeptide agouti-related peptide (AGRP) is up-regulated in the hypothalamic arcuate nucleus (ARC), while inconsistent data exist regarding fasting regulation of the anorexigenic neurohormone proopiomelanocortin (POMC). Inconsistencies might have methodological reasons, especially concerning neuromorphological and/or experimental (nutritional) specificity. We analyzed the expression of both neuropeptides in ARC neurons, using lasercapture microdissection (LMD) and real-time PCR in 12h fasted vs. fed Wistar rats as well as after a standardized glucose load, i.e., under clinically relevant conditions in terms of diagnosing glucose intolerance in the human. Under fasting conditions, clear up-regulation of AGRP was observed, with increasing magnitude in ARC single neurons (SNP) as compared to ARC cell layers (+125% vs. +23%, resp.), closely correlated to hypoinsulinemia and hypoleptinemia. Surprisingly, in the fasting state POMC was not found to be down-regulated, neither in ARC cell layers nor in ARC single neurons (+9% vs. +6%). However, glucose-refeeding under diagnostically relevant conditions led to strong neuronal up-regulation of POMC expression in ARC SNP (+128%), and AGRP down-regulation (-50%). In conclusion, experimentally, topographically, and analytically specific and standardized conditions confirmed AGRP in ARC neurons as being neuronally up- and down-regulated, resp., depending on the general nutritional state, while POMC was found to be (up-) regulated only after peripheral glucose load. Findings suggest that POMC in ARC neurons acts glucose-mediated as an "anti-orexigenic" neurohormone, specifically responding to hyperglycemia.

Leptin determination in colostrum and early human milk from mothers of preterm and term infants.

BACKGROUND: Leptin is involved in the regulation of food intake and energy expenditure and is therefore important for growth and brain development. Analytical methods used for leptin measurement in human milk differ widely in the literature and yield varying results. AIMS: To compare different preparation methods for the analysis of leptin in human milk and to investigate the leptin levels in colostrum and mature human milk from mothers of preterm or term infants. METHODS: Mothers delivering a preterm (n=37) or a term infant (n=40) were recruited for a prospective study and were ask to collect breast milk on the 3rd and 28th day of lactation. Leptin, protein and fat concentrations were analysed. Clinical data of mother and child were recorded prospectively. RESULTS: Skim milk was most appropriate for leptin analysis. Human milk leptin concentrations did not differ between preterm and term human milk. In term milk, leptin concentration on day 28 was lower than on day 3 (p<0.05). Milk leptin levels on the 3rd and 28th day were positively correlated with mothers' body mass index, but not with fat content in milk. CONCLUSION: Skim milk was the most stabile preparation for leptin analysis. Preterm and term human milk contain leptin in equal concentrations. Human milk leptin depends on mothers' body mass index.

Epigenetic malprogramming of the insulin receptor promoter due to developmental overfeeding.

AIM: Prenatal and neonatal overfeeding programs a permanent obesity and diabetes disposition, e.g., due to induction of hypothalamic insulin resistance. We investigated acquired alterations of the DNA methylation pattern of the hypothalamic insulin receptor promoter (IRP) which might be an underlying molecular mechanism. METHODS: Neonatal overfeeding was induced by rearing Wistar rats in small litters (SL). Methylation of CpG-dinucleotides of the hypothalamic IRP was mapped using bisulfite sequencing. RESULTS: Neonatal overfeeding led to rapid early weight gain, resulting in a metabolic syndrome phenotype, i.e., obesity, hyperleptinemia, hyperglycemia, hyperinsulinemia, and increased insulin/glucose-ratio. The proportion of animals carrying any methylated CpG residue in the 322 bp CpG island of the IRP was increased in neonatally overfed SL rats (n=8), as compared to controls (n=8; P=0.04). Moreover, the mean percentage of methylated CpG positions was also higher in SL rats (P=0.01). Over both groups, neonatal blood glucose levels were positively correlated to the extent of promoter methylation (r=0.52; P=0.04). CONCLUSIONS: This study characterizes for the first time the IRP epigenomically in any species and tissue. Our data reveal that the IRP is vulnerable to hypermethylation due to overnutrition, probably especially glucose-dependent in a dose-response manner. This paradigmatically indicates the impact of nutrient-dependent epigenetic malprogramming, leading to a "diabesity" disposition which may become pathogenic throughout life.

Hypothalamic proopiomelanocortin promoter methylation becomes altered by early overfeeding: an epigenetic model of obesity and the metabolic syndrome.

Pre- and neonatal overfeeding programmes a permanent obesity disposition and accompanying diabetic and cardiovascular disorders, by unknown mechanisms. We proposed that early overfeeding may alter DNA methylation patterns of hypothalamic promoter regions of genes critically involved in the lifelong regulation of food intake and body weight. We induced neonatal overfeeding by rearing Wistar rats in small litters (SL) and thereafter mapped the DNA methylation status of CpG dinucleotides of gene promoters from hypothalamic tissue, using bisulfite sequencing. Neonatal overfeeding led to rapid early weight gain, resulting in a metabolic syndrome phenotype, i.e. obesity, hyperleptinaemia, hyperglycaemia, hyperinsulinaemia, and an increased insulin/glucose ratio. Accompanying, without group difference to controls, the promoter of the main orexigenic neurohormone, neuropeptide Y, was methylated at low levels (i.e. < 5%). In contrast, in SL rats the hypothalamic gene promoter of the main anorexigenic neurohormone, proopiomelanocortin (POMC), showed hypermethylation (P < 0.05) of CpG dinucleotides within the two Sp1-related binding sequences (Sp1, NF-kappaB) which are essential for the mediation of leptin and insulin effects on POMC expression. Consequently, POMC expression lacked upregulation, despite hyperleptinaemia and hyperinsulinaemia. Accordingly, the extent of DNA methylation within Sp1-related binding sequences was inversely correlated to the quotients of POMC expression/leptin (P = 0.02) and POMC expression/insulin (P < 0.001), indicating functionality of acquired epigenomic alterations. These data for the first time demonstrate a nutritionally acquired alteration of the methylation pattern and, consequently, the regulatory 'set point' of a gene promoter that is critical for body weight regulation. Our findings reveal overfeeding as an epigenetic risk factor of obesity programming and consecutive diabetic and cardiovascular disorders and diseases, in terms of the metabolic syndrome.

GABAA receptor antagonists prevent abnormalities in leptin, insulin and amylin actions on paraventricular hypothalamic neurons of overweight rats.

The hypothalamic regulatory system of body weight which develops in rats during critical periods of early postnatal life seems to express plastic changes depending on nutrition at that time. Adult rats previously exposed to early postnatal overnutrition by raising them in small litters become persistently predisposed to overweight, hyperphagia and hyperleptinaemia. The hypothesis was raised that feeding-related peptides could be involved through altered effects on neuronal activity of the regulatory systems of such rats. This was studied on brain slices of small-litter rats and normal-weight controls between days 60 and 120 of life. Neurons of the medial parvocellular part of the paraventricular nucleus were significantly activated by the adiposity signals leptin, insulin and amylin in controls. This is a kind of negative feedback, because activation of these neurons is known to be followed in vivo by increased energy expenditure. GABAergic mechanisms seem to affect these neuronal responses because the activating effects of insulin and amylin were reduced in the presence of a GABA(A) receptor antagonist. In overweight small-litter rats, however, the neuronal responses to the adiposity signals were significantly changed; activating effects were reduced and inhibitory effects increased. By means of blockade of GABA(A) receptors, significant alterations in the neuronal responses to leptin, insulin and amylin in small-litter rats were prevented. Responses to the peptides were reversed and now resembled those of controls. In conclusion, changes in neuronal wiring with GABAergic interneurons seem to contribute to a persistently reduced negative feedback of adiposity signals in early postnatally overfed rats.

'Programming' of orexigenic and anorexigenic hypothalamic neurons in offspring of treated and untreated diabetic mother rats.

Exposure to maternal diabetes in utero (GD) may 'program' for obesity. Orexigenic neuropeptides, like neuropeptide Y (NPY) and agouti-related peptide (AGRP), and anorexigenic neuropeptides, like proopiomelanocortin (POMC) and alpha-melanocyte-stimulating hormone (MSH), are decisively involved in body weight regulation. We investigated consequences of GD and its treatment by pancreatic islet transplantation in rats for development of neuropeptidergic neurons in the arcuate hypothalamic nucleus (ARC) in weanling offspring. In GD, islet transplantation on d15 of pregnancy led to normalized blood glucose. Sham-transplanted GD mothers (TSGD) remained hyperglycemic. Twenty-one-day-old TSGD offspring developed hypothalamic 'malorganization'. Despite of normal leptin and insulin levels in TSGD offspring, increased immunopositivity of NPY and AGRP appeared. TSGD offspring showed unchanged POMC, but decreased MSH-immunopositivity. In conclusion, untreated diabetes in pregnant rats leads to 'malprogramming' of hypothalamic neuropeptidergic neurons in offspring, probably contributing to later development of overweight. These acquired alterations are preventable by treatment of maternal GD.

Arcuate neurons of overweight rats differ in their responses to amylin from controls.

Amylin and ghrelin are hormones produced, respectively, in pancreas and stomach. They have a central action on food intake and body weight. Possible changes in their effect on hypothalamic neuronal activity were investigated in overweight rats previously subjected to early postnatal overnutrition compared to controls. Single unit activity of brain slices was recorded in the medial arcuate that contains neuropeptide Y producing neurons. The orexigenic ghrelin activated neurons of both groups of rats. The anorexigenic amylin, however, significantly inhibited neurons of controls but not of overweight rats. The difference in the type of response to amylin shown by arcuate neurons of overweight rats can be regarded as expression of neonatally programmed neurochemical plasticity of the regulatory system of body weight.