Effects of maternal diet-induced obesity on metabolic disorders and age-associated miRNA expression in the liver of male mouse offspring

Objective: This study investigated the effect of maternal obesity on aged-male offspring liver phenotype and hepatic expression of a programmed miRNA. Methods: A mouse model (C57BL/6 J) of maternal diet-induced obesity was used to investigate fasting-serum metabolites, hepatic lipid content, steatosis, and relative mRNA levels (RT-PCR) and protein expression (Western blotting) of key components involved in hepatic and mitochondrial metabolism in 12-month-old offspring. We also measured hepatic lipid peroxidation, mitochondrial content, fibrosis stage, and apoptosis in the offspring. To investigate potential mechanisms leading to the observed phenotype, we also measured the expression of miR-582 (a miRNA previously implicated in liver cirrhosis) in 8-week-old and 12-month-old offspring. Results: Body weight and composition was similar between 8-week-old offspring, however, 12-month-old offspring from obese mothers had increased body weight and fat mass (19.5 ± 0.8 g versus 10.4 ± 0.9 g, p < 0.001), as well as elevated serum levels of LDL and leptin and hepatic lipid content (21.4 ± 2.1 g versus 12.9 ± 1.8 g, p < 0.01). This was accompanied by steatosis, increased Bax/Bcl-2 ratio, and overexpression of p-SAPK/JNK, Tgfβ1, Map3k14, and Col1a1 in the liver. Decreased levels of Bcl-2, p-AMPKα, total AMPKα and mitochondrial complexes were also observed. Maternal obesity was associated with increased hepatic miR-582-3p (p < 0.001) and miR-582-5p (p < 0.05). Age was also associated with an increase in both miR-582-3p and miR-582-5p, however, this was more pronounced in the offspring of obese dams, such that differences were greater in 12-month-old animals (−3p: 7.34 ± 1.35 versus 1.39 ± 0.50, p < 0.0001 and −5p: 4.66 ± 1.16 versus 1.63 ± 0.65, p < 0.05). Conclusion: Our findings demonstrate that maternal diet-induced obesity has detrimental effects on offspring body composition as well as hepatic phenotype that may be indicative of accelerated-ageing phenotype. These whole-body and cellular phenotypes were associated with age-dependent changes in expression of miRNA-582 that might contribute mechanistically to the development of metabolic disorders in the older progeny

Weight Loss after Roux-en-Y Gastric Bypass in Obese Patients Heterozygous for MC4R Mutations

BackgroundHeterozygous mutations in melanocortin-4 receptor (MC4R) are the most frequent genetic cause of obesity. Bariatric surgery is a successful treatment for severe obesity. The mechanisms of weight loss after bariatric surgery are not well understood.MethodsNinety-two patients who had Roux-en-Y gastric bypass (RYGB) surgery were screened for MC4R mutations. We compared percent excess weight loss (%EWL) in the four MC4R mutation carriers with that of two control groups: 8 matched controls and with the remaining 80 patients who underwent RYGB.ResultsFour patients were heterozygous for functionally significant MC4R mutations. In patients with MC4R mutations, the %EWL after RYGB (66% EWL) was not significantly different compared to matched controls (70% EWL) and non-matched controls (60% EWL) after 1 year of follow-up.ConclusionsThis study suggests that patients with heterozygous MC4R mutations also benefit from RYGB and that weight loss may be independent of the presence of such mutations

Esophageal Cancer Related Gene-4 Is a Choroid Plexus-Derived Injury Response Gene: Evidence for a Biphasic Response in Early and Late Brain Injury

By virtue of its ability to regulate the composition of cerebrospinal fluid (CSF), the choroid plexus (CP) is ideally suited to instigate a rapid response to traumatic brain injury (TBI) by producing growth regulatory proteins. For example, Esophageal Cancer Related Gene-4 (Ecrg4) is a tumor suppressor gene that encodes a hormone-like peptide called augurin that is present in large concentrations in CP epithelia (CPe). Because augurin is thought to regulate senescence, neuroprogenitor cell growth and differentiation in the CNS, we evaluated the kinetics of Ecrg4 expression and augurin immunoreactivity in CPe after CNS injury. Adult rats were injured with a penetrating cortical lesion and alterations in augurin immunoreactivity were examined by immunohistochemistry. Ecrg4 gene expression was characterized by in situ hybridization. Cell surface augurin was identified histologically by confocal microscopy and biochemically by sub-cellular fractionation. Both Ecrg4 gene expression and augurin protein levels were decreased 24–72 hrs post-injury but restored to uninjured levels by day 7 post-injury. Protein staining in the supraoptic nucleus of the hypothalamus, used as a control brain region, did not show a decrease of auguin immunoreactivity. Ecrg4 gene expression localized to CPe cells, and augurin protein to the CPe ventricular face. Extracellular cell surface tethering of 14 kDa augurin was confirmed by cell surface fractionation of primary human CPe cells in vitro while a 6–8 kDa fragment of augurin was detected in conditioned media, indicating release from the cell surface by proteolytic processing. In rat CSF however, 14 kDa augurin was detected. We hypothesize the initial release and proteolytic processing of augurin participates in the activation phase of injury while sustained Ecrg4 down-regulation is dysinhibitory during the proliferative phase. Accordingly, augurin would play a constitutive inhibitory function in normal CNS while down regulation of Ecrg4 gene expression in injury, like in cancer, dysinhibits proliferation

Activation of the hypothalamic-pituitary-adrenal axis by exogenous and endogenous GDF15

\ua9 2021 National Academy of Sciences. All rights reserved.An acute increase in the circulating concentration of glucocorticoid hormones is essential for the survival of severe somatic stresses. Circulating concentrations of GDF15, a hormone that acts in the brain to reduce food intake, are frequently elevated in stressful states. We now report that GDF15 potently activates the hypothalamic-pituitary-adrenal (HPA) axis in mice and rats. A blocking antibody to the GDNF-family receptor α-like receptor completely prevented the corticosterone response to GDF15 administration. In wild-type mice exposed to a range of stressful stimuli, circulating levels of both corticosterone and GDF15 rose acutely. In the case of Escherichia coli or lipopolysaccharide injections, the vigorous proinflammatory cytokine response elicited was sufficient to produce a near-maximal HPA response, regardless of the presence or absence of GDF15. In contrast, the activation of the HPA axis seen in wild-type mice in response to the administration of genotoxic or endoplasmic reticulum toxins, which do not provoke a marked rise in cytokines, was absent in Gdf15−/− mice. In conclusion, consistent with its proposed role as a sentinel hormone, endogenous GDF15 is required for the activation of the protective HPA response to toxins that do not induce a substantial cytokine response. In the context of efforts to develop GDF15 as an antiobesity therapeutic, these findings identify a biomarker of target engagement and a previously unrecognized pharmacodynamic effect, which will require monitoring in human studies

Studies on dietary intake, eating behavior and meal-related symptoms

Background and aims: Roux-en-Y gastric bypass (RYGB) is now a common treatment for obesity with well-documented effects on long-term weight reduction, health-related quality of life, obesity-related morbidity and mortality. There is a need for a better understanding of changes in dietary intake and meal-related symptoms after RYGB. The aim of this thesis was to study these phenomena and to improve current treatment protocols. Methods: Forty-three adults (31 women, 12 men; mean age 42.6 years, mean BMI 44.5 kg/m²) were followed in a longitudinal cohort study and examined preoperatively and at six weeks, one and two years after surgery (Paper I and II). They completed the Three-Factor Eating Questionnaire (TFEQ-R21) on attitudes to food, and questionnaires on dietary intake and meal pattern; in addition, a test meal ad libitum was administered and portion size and eating rate were assessed. A Dumping Symptom Rating Scale (DSRS) was developed and evaluated for its reliability and construct validity over two years on 124 respondents of whom 43 adults from Paper I and II and in addition 81 adolescents (Paper III). Thirty-one non-obese subjects served as reference group (Paper II and III). Another eight RYGB patients with hypoglycemia -like symptoms and eight patients with no hypoglycemia -like symptoms ingested a liquid carbohydrate meal. Insulin, plasma glucose, glucagon-like peptide 1 (GLP-1) and glucagon were measured intermittently up to 180 minutes after the meal. Results: The dietary questionnaire showed decreased energy intake, Food weight fell initially but was not lower two years after surgery resulting in a significantly decreased dietary energy density at two years after surgery. The meal test showed decreased portion size despite meal duration remaining constant, resulting in a reduced eating rate. Number of meals increased, with more meals in the mornings. TFEQ-R21 revealed decreased emotional and uncontrolled eating, whereas there was a transient increase in cognitive restraint six weeks after surgery. Most subjects reported mild or no dumping symptoms, although 6–12% had persistent problems – in particular, postprandial fatigue, need to lie down, nausea, and feeling faint – two years after surgery. The result of the validation process of DSRS was satisfactory overall. The patients with a history of hypoglycemia-like symptoms after RYGB demonstrated neither lower plasma glucose nor greater insulin response compared to asymptomatic patients in response to a liquid carbohydrate meal, but they perceived more symptoms. Conclusion: After RYGB, patients displayed major changes in eating behavior and meal pattern, suggesting that RYGB drives the individual to an eating behavior that promotes weight loss. Despite lack of association between the reduction in dietary energy density and percentage weight loss, changes in food choice were overall nutritionally beneficial. Dumping symptoms were rarely evident, but some patients reported persistent problems up to two years after surgery. DSRS is a reliable clinical screening instrument to identify patients with pronounced dumping symptoms. The mechanisms of action behind the origin of hypoglycemia-like symptoms remain obscure and need further exploration

Regioselective reactions of 3,4-pyridynes enabled by the aryne distortion model

The pyridine heterocycle continues to play a vital role in the development of human medicines. More than 100 currently-marketed drugs contain this privileged unit, which remains highly sought after synthetically. We report an efficient means to access di- and tri-substituted pyridines in an efficient and highly controlled manner using transient 3,4-pyridyne intermediates. Previous efforts to employ 3,4-pyridynes for the construction of substituted pyridines have been hampered by a lack of regiocontrol or the inability to later manipulate an adjacent directing group. The newly developed strategy relies on the use of proximal halide or sulfamate substituents to perturb pyridyne distortion, which in turn governs regioselectivities in nucleophilic addition and cycloaddition reactions. Following trapping of in situ-generated pyridynes, the neighboring directing groups may be removed or exploited using versatile metal-catalyzed cross-coupling reactions. This methodology now renders 3,4-pyridynes useful synthetic building blocks for the creation of highly decorated derivatives of the medicinally privileged pyridine heterocycle

MC3R links nutritional state to childhood growth and the timing of puberty.

The state of somatic energy stores in metazoans is communicated to the brain, which regulates key aspects of behaviour, growth, nutrient partitioning and development1. The central melanocortin system acts through melanocortin 4 receptor (MC4R) to control appetite, food intake and energy expenditure2. Here we present evidence that MC3R regulates the timing of sexual maturation, the rate of linear growth and the accrual of lean mass, which are all energy-sensitive processes. We found that humans who carry loss-of-function mutations in MC3R, including a rare homozygote individual, have a later onset of puberty. Consistent with previous findings in mice, they also had reduced linear growth, lean mass and circulating levels of IGF1. Mice lacking Mc3r had delayed sexual maturation and an insensitivity of reproductive cycle length to nutritional perturbation. The expression of Mc3r is enriched in hypothalamic neurons that control reproduction and growth, and expression increases during postnatal development in a manner that is consistent with a role in the regulation of sexual maturation. These findings suggest a bifurcating model of nutrient sensing by the central melanocortin pathway with signalling through MC4R controlling the acquisition and retention of calories, whereas signalling through MC3R primarily regulates the disposition of calories into growth, lean mass and the timing of sexual maturation