Maternal High-Fat Diet during Pregnancy and Lactation Influences Obestatin and Ghrelin Concentrations in Milk and Plasma of Wistar Rat Dams and Their Offspring

Maternal programming by high-energy diets primes ghrelin sensitivity in the offspring of rats exposed to chronic immobilization stress

Maternal overnutrition during pregnancy leads to metabolic and immune alterations, including obesity, hyperphagia, and central and peripheral inflammation in offspring. Exposure to high-energy diets during pregnancy primes ghrelin sensitivity to overfeeding in the offspring at early stages of life. Overfeeding has also been partially related to the early stages of chronic stress. We hypothesized that maternal programming sensitizes ghrelin-induced overfeeding following a chronic stress schedule in the offspring. We used a nutritional programming model exposing female Wistar rats to a cafeteria (CAF) or control diet from prepregnancy to weaning. Male offspring were injected with ghrelin and then subjected to a chronic immobilization stress (CIS) schedule, after which food intake was determined. Hypothalamic and plasma accumulation of cytokines and cortisol were evaluated using BioPlex analysis and enzyme-linked immunosorbent assay, respectively. We found that rats exposed to the CAF diet exhibited overfeeding after fasting and peripheral ghrelin administration, which was exacerbated in rats exposed to chronic stress. Offspring exposed to the CAF diet accumulated pro-inflammatory interleukin-6 (IL-6), interferon-γ, and monocyte chemoattractant protein-1 cytokines in plasma, and IL-6 cytokine in the hypothalamus. Ghrelin-sensitive overfeeding in rats exposed to CAF diet + CIS display increased cortisol levels and decreased IL-6 accumulation in plasma. Together, our results suggest that maternal nutritional programming primes susceptibility to ghrelin response for overfeeding after a CIS schedule that mirrors plasma cortisol accumulation in male offspring.

The ghrelin system follows a precise post-natal development in mini-pigs that is not impacted by dietary medium chain fatty-acids

The ghrelin-ghrelin receptor (GHSR1) system is one of the most important mechanisms regulating food intake and energy balance. To be fully active, ghrelin is acylated with medium-chain fatty acids (MCFA) through the ghrelin-O-acetyl transferase (GOAT). Several studies reported an impact of dietary MCFA on ghrelin acylation in adults. Our study aimed at describing early post-natal development of the ghrelin system in mini-pigs as a model of human neonates and evaluating the impact of dietary MCFA. Suckled mini-pigs were sacrificed at post-natal day (PND) 0, 2, 5, and 10 or at adult stage. In parallel, other mini-pigs were fed from birth to PND10 a standard or a dairy lipid-enriched formula with increased MCFA concentration (DL-IF). Plasma ghrelin transiently peaked at PND2, with no variation of the acylated fraction except in adults where it was greater than during the neonatal period. Levels of mRNA coding pre-proghrelin (GHRL) and GOAT in the antrum did not vary during the post-natal period but dropped in adults. Levels of antral pcsk1/3 (cleaving GHRL into ghrelin) mRNA decreased significantly with age and was negatively correlated with plasma acylated, but not total, ghrelin. Hypothalamic ghsr1 mRNA did not vary in neonates but increased in adults. The DL-IF formula enriched antral tissue with MCFA but did not impact the ghrelin system. In conclusion, the ghrelin maturation enzyme PCSK1/3 gene expression exhibited post-natal modifications parallel to transient variations in circulating plasma ghrelin level in suckling piglets but dietary MCFA did not impact this post-natal development.

Effects of poor maternal nutrition during gestation on ewe and offspring plasma concentrations of leptin and ghrelin

Poor maternal nutrition during gestation can negatively affect offspring growth, development, and health. Leptin and ghrelin, key hormones in energy homeostasis and appetite control, may mediate these changes. We hypothesized that restricted- and over-feeding during gestation would alter plasma concentrations of leptin and ghrelin in ewes and offspring. Pregnant ewes (n = 37) were fed 1 of 3 diets starting on d 30 ± 0.02 of gestation until necropsy at d 135 of gestation or parturition: restricted- [RES; 60% National Research Council (NRC) requirements for total digestible nutrients, n = 13], control- (CON; 100% NRC, n = 11), or over-fed (OVER; 140% NRC, n = 13). Blood samples were collected from pregnant ewes at days 20, 30, 44, 72, 100, 128, and 142 of gestation. Offspring blood samples were collected within 24 h after birth (n = 21 CON, 25 RES, 23 OVER). Plasma leptin and ghrelin concentrations were determined by RIA. Ewe data were analyzed using the MIXED procedure in SAS with ewe as the repeated subject. Offspring data were analyzed using the MIXED procedure. Correlations between BW and leptin and ghrelin concentrations were identified using PROC CORR. At d 100, RES (5.39 ± 2.58 ng/mL) had decreased leptin concentrations compared with OVER (14.97 ± 2.48 ng/mL; P = 0.008) and at d 128, RES (6.39 ± 2.50 ng/mL) also had decreased leptin concentrations compared with OVER (13.61 ± 2.47 ng/mL; P = 0.04). At d 142, RES (0.26 ± 0.04 ng/mL) had increased ghrelin concentrations compared with CON (0.15 ± 0.04 ng/mL; P = 0.04). Leptin and ghrelin concentrations were also altered between days of gestation within a dietary treatment. In CON ewes, plasma concentrations of leptin were increased at d 30 (19.28 ± 7.43 ng/mL) compared with d 44 (5.20 ± 3.10 ng/mL; P = 0.03), and the plasma concentrations of ghrelin at d 128 (0.20 ± 0.03 ng/mL) were increased compared with d 30 (0.16 ± 0.03 ng/mL; P = 0.01) and d 100 (0.17 ± 0.03 ng/mL; P = 0.04). Maternal diet did not alter plasma ghrelin or leptin concentrations in the offspring (P > 0.50). There were no strong, significant correlations between ewe BW and leptin (r < 0.33; P > 0.06) or ghrelin (r > -0.47; P > 0.001) concentrations or lamb BW and leptin or ghrelin concentrations (r > -0.32, P > 0.06). Maternal alterations in circulating leptin and ghrelin may program changes in energy balance that could result in increased adiposity in adult offspring. Alterations in energy homeostasis may be a mechanism behind the long-lasting changes in growth, body composition, development, and metabolism in the offspring of poorly nourished ewes.

Maternal High-Fat Diet Exposure During Gestation and Lactation Affects Intestinal Development in Suckling Rats

Maternal health and diet influence metabolic status and play a crucial role in the development of metabolic function in offspring and their susceptibility to metabolic diseases in adulthood. The pathogenesis of various metabolic disorders is often associated with impairment in intestinal structure and function. Thus, the aim of the current study was to determine the effects of maternal exposure to a high fat diet (HFD), during gestation and lactation, on small intestinal growth and maturation in rat pups at 21 days old. Female, Wistar Han rats were fed either a breeding diet (BD) or high fat diet (HFD), from mating until the 21st day of lactation. Maternal HFD exposure increased body weight, BMI and adiposity. Compared to the maternal BD, HFD exposure influenced small intestine histomorphometry in a segment-dependent manner, changed the activity of brush border enzymes and had an impact on intestinal contractility via changes in cholinergic signaling. Moreover, offspring from the maternal HFD group had upregulated mRNA expression of cyclooxygenase (COX)-2, which plays a role in the inflammatory process. These results suggest that maternal HFD exposure, during gestation and lactation, programs the intestinal development of the offspring in a direction toward obesity as observed changes are also commonly reported in models of diet-induced obesity. The results also highlight the importance of maternal diet preferences in the process of developmental programming of metabolic diseases.

The effects of intra-stomach obestatin administration on intestinal contractility in neonatal piglets fed milk formula

A 23-amino acid peptide named obestatin is derived from the ghrelin gene. The aim of the experiment was to study the effects of enteral obestatin administration for a 6-day period on intestinal contractility in piglets fed milk formula. Pigs were treated with 0.9% NaCl (group C) or varying doses of obestatin: 2 μg/kg body weight (BW) (group O2), 10 μg/kg BW (O10) or 15 μg/kg BW (O15) every 8 hours via a stomach tube. Blood was sampled for assessment of obestatin concentration. Duodenal and middle jejunum whole-thickness preparations were studied in an organ bath for isometric recording under electric field stimulation (EFS) and increasing doses of acetylcholine (ACh), and in the presence of atropine and tetrodotoxin (TTX). Additionally, the measurement of intestinal muscularis layer and the immunodetection of Muscarinic Acetylcholine Receptors (M1 and M2) were performed. In comparison to C animals, the obestatin concentration in blood plasma was significantly increased in groups O10 and O15. In both studied intestinal segments, significant increases in the frequency and amplitude of spontaneous contractions were observed in O15 and C groups. In the duodenum and middle jejunum significant differences in responsiveness to EFS (0.5, 5 and 50 Hz) were observed between the groups. The addition of 10⁻⁴ M ACh to the duodenum significantly increased the responsiveness in tissues. In contrast, in the middle jejunum a significant increase in the amplitude of contraction was observed after the addition of 10⁻⁹ and 10⁻⁶ M ACh (groups O15 and O10, respectively). Pretreatment with atropine and TTX resulted in a significant decrease in the responsiveness of the intestinal preparations from all groups, in both studied segments. The increased contractility was not dependent on the expression of muscarinic receptors. Results indicate the importance of enteral obestatin administration in the regulation of intestinal contractility in neonatal piglets.

Priming of Hypothalamic Ghrelin Signaling and Microglia Activation Exacerbate Feeding in Rats' Offspring Following Maternal Overnutrition

Maternal overnutrition during pregnancy leads to metabolic alterations, including obesity, hyperphagia, and inflammation in the offspring. Nutritional priming of central inflammation and its role in ghrelin sensitivity during fed and fasted states have not been analyzed. The current study aims to identify the effect of maternal programming on microglia activation and ghrelin-induced activation of hypothalamic neurons leading to food intake response. We employed a nutritional programming model exposing female Wistar rats to a cafeteria diet (CAF) from pre-pregnancy to weaning. Food intake in male offspring was determined daily after fasting and subcutaneous injection of ghrelin. Hypothalamic ghrelin sensitivity and microglia activation was evaluated using immunodetection for Iba-1 and c-Fos markers, and Western blot for TBK1 signaling. Release of TNF-alpha, IL-6, and IL-1β after stimulation with palmitic, oleic, linoleic acid, or C6 ceramide in primary microglia culture were quantified using ELISA. We found that programmed offspring by CAF diet exhibits overfeeding after fasting and peripheral ghrelin administration, which correlates with an increase in the hypothalamic Iba-1 microglia marker and c-Fos cell activation. Additionally, in contrast to oleic, linoleic, or C6 ceramide stimulation in primary microglia culture, stimulation with palmitic acid for 24 h promotes TNF-alpha, IL-6, and IL-1β release and TBK1 activation. Notably, intracerebroventricular (i.c.v.) palmitic acid or LPS inoculation for five days promotes daily increase in food intake and food consumption after ghrelin administration. Finally, we found that i.c.v. palmitic acid substantially activates hypothalamic Iba-1 microglia marker and c-Fos. Together, our results suggest that maternal nutritional programing primes ghrelin sensitivity and microglia activation, which potentially might mirror hypothalamic administration of the saturated palmitic acid.

Small intestinal development in suckling rats after enteral obestatin administration

This study investigated the effect of enteral administration of obestatin on the development of small intestine, as well as oxidative stress markers and trancriptomic profile of gastrointestinal genes. Suckling rats were assigned to 3 groups treated with: C-saline solution; OL-obestatin (125 nmol/kg BW); OH-obestatin (250 nmol/kg BW) administered twice daily, from the 14th to the 21st day of life. Enteral administration of obestatin in both studied doses had no effect neither on the body weight of animals nor the BMI calculated in the day of euthanasia. Compared to the control group (C), treatment with obestatin resulted in significant changes in the histometry of the small intestinal wall as well as intestinal epithelial cell remodeling. The observed changes and their possible implications for intestinal development were dependent on the dosage of peptide. The enteral administration of high dose (OH) of obestatin significantly decreased its expression in the stomach and increased markers of oxidative stress. The gene profile revealed MAPK3 (mitogen-activated protein kinase-3) as the key regulator gene for obestatin action in the gastrointestinal track. In conclusion, we have showed that enteral administration of obestatin influences the gut mucosa remodeling. It is also suggested that the administration of high dose (OH) has inhibitory effect on the intestinal maturation of suckling rats.

Plasma Ghrelin Concentrations Were Altered with Oestrous Cycle Stage and Increasing Age in Reproductively Competent Wistar Females

Changes in appetite occur during the ovarian cycle in female mammals. Research on appetite-regulatory gastrointestinal peptides in females is limited, because reproductive changes in steroid hormones present additional experimental factors to control for. This study aimed to explore possible changes in the orexigenic (appetite-stimulating) gastrointestinal peptide hormone ghrelin during the rodent oestrous cycle. Fed and fasted plasma and stomach tissue samples were taken from female Wistar rats (32-44 weeks of age) at each stage of the oestrous cycle for total ghrelin quantification using radioimmunoassay. Sampling occurred during the dark phase when most eating takes place in rats. Statistical analysis was by paired-samples t-test, one-way ANOVA on normally distributed data, with Tukey post-hoc tests, or Kruskal-Wallis if not. GLM univariate analysis was used to assess main effects and interactions in ghrelin concentrations in the fed or fasted state and during different stages of the ovarian cycle, with age as a covariate. No consistent fed to fasted ghrelin increases were measured in matched plasma samples from the same animals, contrary to expectations. Total ghrelin concentrations did not significantly change between cycle stages with ANOVA, in either fed or fasted plasma or in stomach tissue. This was despite significantly decreased fasted stomach contents at oestrus (P = 0.028), suggesting decreased food intake. There was however a significant interaction in ghrelin plasma concentrations between fed and fasted proestrus rats and a direct effect of age with rats over 37 weeks old having lower circulating concentrations of ghrelin in both fed and fasted states. The biological implications of altered ghrelin plasma concentrations from 37 weeks of age are as yet unknown, but warrant further investigation. Exploring peripheral ghrelin regulatory factor changes with increasing age in reproductively competent females may bring to light potential effects on offspring development and nutritional metabolic programming.