Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Altered food-cue processing in chronically ill and recovered women with anorexia nervosa
Sanders, N. ; Smeets, P.A.M. ; Elburg, A.A. van; Danner, U.N. ; Meer, F. van; Hoek, H.W. ; Adan, R.A.H. - \ 2015
Frontiers in Behavioral Neuroscience 9 (2015). - ISSN 1662-5153 - 12 p.
default mode network - high-calorie foods - eating-disorders - functional-anatomy - reward - fmri - stimuli - leptin - energy - cortex
Anorexia nervosa (AN) is a severe mental disorder characterized by food restriction and weight loss. This study aimed to test the model posed by Brooks et al. (2012a,b) that women suffering from chronic AN show decreased food-cue processing activity in brain regions associated with energy balance and food reward (bottom-up; BU) and increased activity in brain regions associated with cognitive control (top-down; TD) when compared with long-term recovered AN (REC) and healthy controls (HC). Three groups of women, 15 AN (mean illness duration 7.8 ± 4.1 years), 14 REC (mean duration of recovery 4.7 ± 2.7 years) and 15 HC viewed alternating blocks of food and non-food images preceded by a short instruction during functional magnetic resonance imaging (fMRI), after fasting overnight. Functional region of interests (fROIs) were defined in BU (e.g., striatum, hippocampus, amygdala, hypothalamus, and cerebellum), TD (e.g., medial and lateral prefrontal cortex, and anterior cingulate), the insula, and visual processing areas (VPA). Food-cue processing activation was extracted from all fROIs and compared between the groups. In addition, functional connectivity between the fROIs was examined by modular partitioning of the correlation matrix of all fROIs. We could not confirm the hypothesis that BU areas are activated to a lesser extent in AN upon visual processing of food images. Among the BU areas the caudate showed higher activation in both patient groups compared to HC. In accordance with Brooks et al.’s model, we did find evidence for increased TD control in AN and REC. The functional connectivity analysis yielded two clusters in HC and REC, but three clusters in AN. In HC, fROIs across BU, TD, and VPA areas clustered; in AN, one cluster span across BU, TD, and insula; one across BU, TD, and VPA areas; and one was confined to the VPA network. In REC, BU, TD, and VPA or VPA and insula clustered. In conclusion, despite weight recovery, neural processing of food cues is also altered in recovered AN patients.
Direct comparison of health effects by dietary polyphenols at equimolar doses in wildtype moderate high-fat fed C57BL/6JOlaHsd mice
Schothorst, E.M. van; Bunschoten, A. ; Hoevenaars, F.P.M. ; Stelt, I. van der; Janovska, P. ; Venema, D.P. ; Kopecky, J. ; Hollman, P.C.H. ; Keijer, J. - \ 2014
Food Research International 65 (2014)Part A. - ISSN 0963-9969 - p. 95 - 102.
adipose-tissue - body-weight - induced obesity - disease risk - quercetin - bioavailability - expression - flavonoids - leptin - (-)-epigallocatechin-3-gallate
Polyphenols generally show beneficial health effects upon supplementation in diet-induced obese rodent models, including reduced body weight gain and reduced levels of markers for cardiovascular diseases (CVD). However, there appear to be large differences between studies, which might be due to differences in models, strains, dietary background, or even concentration of polyphenol that is used. Therefore, we performed a systematic phenotypic evaluation of the effects of selected polyphenols in wildtype C57BL/6JOlaHsd mice. Epigallocatechin-gallate, quercetin, and resveratrol, representing three different phenolic classes, were each added in equimolar amounts (0.50% (w/w), 0.33%, and 0.25%, respectively) to a purified moderate high fat (30energy%) diet for 12 weeks. We studied the polyphenol-induced physiological and molecular effects between them and relative to the nonsupplemented control group during and at the end of the nutritional intervention. Results showed that these polyphenols were present in circulation, but did not induce beneficial health effects as analysed by oral glucose tolerance testing or serum adipokines and CVD-markers such as vascular adhesion molecules. Remarkably, transcriptomics of white adipose tissue showed overlapping sets of significantly differential transcript levels between these polyphenols; AMPK and Notch signalling were affected by these polyphenols. However, mitochondrial processes and mitochondrial density in this tissue did not differ between the polyphenols, which suggested that there was no direct effect on adipose tissue.
Identification of early transcriptome-based biomarkers related to lipid metabolism in peripheral blood mononuclear cells of rats nutritionally programmed for improved metabolic health
Konieczna, J. ; Sánchez, J. ; Schothorst, E.M. van; Torrens, J.M. ; Bunschoten, A. ; Palou, M. ; Pico, C. ; Keijer, J. ; Palou, A. - \ 2014
Genes & Nutrition 9 (2014). - ISSN 1555-8932 - 15 p.
acute regulatory protein - moderate caloric restriction - hormone-sensitive lipase - energy homeostasis - insulin-resistance - gene-expression - microarray data - leptin - model - overexpression
Moderate maternal calorie restriction during lactation protects rat offspring against obesity development in adulthood, due to an improved ability to handle and store excess dietary fuel. We used this model to identify early transcriptome-based biomarkers of metabolic health using peripheral blood mononuclear cells (PBMCs), an easily accessible surrogate tissue, by focusing on molecular markers of lipid handling. Male and female offspring of control and 20 % calorie-restricted lactating dams (CR) were studied. At weaning, a set of pups was killed, and PBMCs were isolated for whole-genome microarray analysis. The remaining pups were killed at 6 months of age. CR gave lower body weight, food intake and fat accumulation, and improved levels of insulin and leptin throughout life, particularly in females. Microarray analysis of weaned rat PBMCs identified 278 genes significantly differentially expressed between control and CR. Among lipid metabolism-related genes, expression of Cpt1a, Lipe and Star was increased and Fasn, Lrp1 and Rxrb decreased in CR versus control, with changes fully confirmed by qPCR. Among them, Cpt1a, Fasn and Star emerged as particularly interesting. Transcript levels of Cpt1a in PBMCs correlated with their levels in WAT and liver at both ages examined; Fasn expression levels in PBMCs at an early age correlated with their expression levels in WAT; and early changes in Star expression levels in PBMCs correlated with their expression levels in liver and were sustained in adulthood. These findings reveal the possibility of using transcript levels of lipid metabolism-related genes in PBMCs as early biomarkers of metabolic health status.
Adiposity, mediating biomarkers and risk of colon cancer in the european prospective investigation into cancer and nutrition study
Aleksandrova, K. ; Drogan, D. ; Boeing, H. ; Jenab, M. ; Bueno de Mesquita, H.B. ; Duijnhoven, F.J.B. van - \ 2014
International Journal of Cancer 134 (2014)3. - ISSN 0020-7136 - p. 612 - 621.
density-lipoprotein cholesterol - colorectal-cancer - rectal-cancer - missing data - c-peptide - hdl - adiponectin - obesity - models - leptin
Adiposity is a risk factor for colon cancer, but underlying mechanisms are not well understood. We evaluated the extent to which 11 biomarkers with inflammatory and metabolic actions mediate the association of adiposity measures, waist circumference (WC) and body mass index (BMI), with colon cancer in men and women. We analyzed data from a prospective nested case–control study among 662 incident colon cancer cases matched within risk sets to 662 controls. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression. The percent effect change and corresponding CIs were estimated after adjusting for biomarkers shown to be associated with colon cancer risk. After multivariable adjustment, WC was associated with colon cancer risk in men (top vs. bottom tertile RR 1.68, 95% CI 1.06–2.65; ptrend¿=¿0.02) and in women (RR 1.67, 95% CI 1.09–2.56; ptrend¿=¿0.03). BMI was associated with risk only in men. The association of WC with colon cancer was accounted mostly for by three biomarkers, high-density lipoprotein cholesterol, non-high-molecular-weight adiponectin and soluble leptin receptor, which in combination explained 46% (95% CI 37–57%) of the association in men and 50% (95% CI 40–65%) of the association in women. Similar results were observed for the associations with BMI in men. These data suggest that alterations in levels of these metabolic biomarkers may represent a primary mechanism of action in the relation of adiposity with colon cancer. Further studies are warranted to determine whether altering their concentrations may reduce colon cancer risk
Plasma Proteome Profiles Associated with Diet-Induced Metabolic Syndrome and the Early Onset of Metabolic Syndrome in a Pig Model
Pas, M.F.W. te; Koopmans, S.J. ; Kruijt, L. ; Calus, M.P.L. ; Smits, M.A. - \ 2013
PLoS One 8 (2013)9. - ISSN 1932-6203 - 8 p.
early atherosclerosis - insulin-resistance - gene-expression - diabetic pigs - streptozotocin - fat - dysfunction - alloxan - obesity - leptin
Obesity and related diabetes are important health threatening multifactorial metabolic diseases and it has been suggested that 25% of all diabetic patients are unaware of their patho-physiological condition. Biomarkers for monitoring and control are available, but early stage predictive biomarkers enabling prevention of these diseases are still lacking. We used the pig as a model to study metabolic disease because humans and pigs share a multitude of metabolic similarities. Diabetes was chemically induced and control and diabetic pigs were either fed a high unsaturated fat (Mediterranean) diet or a high saturated fat/cholesterol/sugar (cafeteria) diet. Physiological parameters related to fat metabolism and diabetes were measured. Diabetic pigs' plasma proteome profiles differed more between the two diets than control pigs plasma proteome profiles. The expression levels of several proteins correlated well with (patho)physiological parameters related to the fat metabolism (cholesterol, VLDL, LDL, NEFA) and diabetes (Glucose) and to the diet fed to the animals. Studying only the control pigs as a model for metabolic syndrome when fed the two diets showed correlations to the same parameters but now more focused on insulin, glucose and abdominal fat depot parameters. We conclude that proteomic profiles can be used as a biomarker to identify pigs with developing metabolic syndrome (prediabetes) and diabetes when fed a cafeteria diet. It could be developed into a potential biomarkers for the early recognition of metabolic diseases.
Contributions to an animal trait ontology
Hulsegge, B. ; Smits, M.A. ; Pas, M.F.W. te; Woelders, H. - \ 2012
Journal of Animal Science 90 (2012)6. - ISSN 0021-8812 - p. 2061 - 2066.
database - gene - leptin - tool
Improved understanding of the biology of traits of livestock species necessitates the use and combination of information that is stored in a variety of different sources such as databases and literature. The ability to effectively combine information from different sources, however, depends on a high level of standardization within and between various resources, at least with respect to the used terminology. Ontologies represent a set of concepts that facilitate standardization of terminology within specific domains of interest. The biological mechanisms underlying quantitative traits of farm animal species related to reproduction and host pathogen interactions are complex and not well understood. This knowledge could be improved through the availability of domain specific ontologies that provide enhanced possibilities for data annotation, data retrieval, data integration, data exchange, data analysis, and ontology-based searches. Here we describe a framework for domain specific ontologies and the development of two first-generation ontologies: the Reproductive Trait and Phenotype Ontology (REPO) and the Host Pathogen Interactions Ontology (HPIO). In these first-generation ontologies, we focused on 'female fertility in cattle' and 'interactions between pigs and Salmonella'. Through this, we contribute to the global initiative towards the development of an Animal Trait Ontology (ATO) for livestock species. To demonstrate its usefulness, we show how REPO can be used to select candidate genes for fertility. Availability: The Reproductive Trait and Phenotype Ontology (REPO) is at NCBO BioPortal: The Host Pathogen Interaction Ontology (HPIO) is at NCBO BioPortal:
During Rapid Weight Loss in Obese Children, Reductions in TSH Predict Improvements in Insulin Sensitivity Independent of Changes in Body Weight or Fat
Aeberli, I. ; Jung, A. ; Murer, S.B. ; Wildhaber, J. ; Wildhaber-Brooks, J. ; Knopfli, B.H. ; Zimmermann, M.B. - \ 2010
Journal of Clinical Endocrinology and Metabolism 95 (2010)12. - ISSN 0021-972X - p. 5412 - 5418.
coronary-heart-disease - subclinical hypothyroidism - thyroid-function - reference range - morbid-obesity - in-vivo - leptin - risk - adolescents - population
Background: Although serum TSH is often elevated in obesity and may be linked to disorders of lipid and glucose metabolism, the clinical relevance of these relationships remains unclear. Subjects: Subjects were obese children and adolescents (n = 206; mean age 14 yr) undergoing rapid weight and fat loss in a standardized, multidisciplinary, 2-month, in-patient weight loss program. Design: This was a prospective study that determined thyroid function, glucose and lipid parameters, leptin, anthropometric measures, and body composition measured by dual-energy x-ray absorption at baseline and at the end of the intervention. Results: At baseline, 52% of children had TSH concentrations in the high normal range (> 2.5 mU/liter), but TSH was not correlated with body weight, body mass index SD scores, lean body mass, or body fat percentage. At baseline, independent of adiposity, TSH significantly correlated with total cholesterol (P = 0.008), low-density lipoprotein cholesterol (P = 0.013), fasting insulin (P = 0.010), homeostatic model assessment (HOMA) (P = 0.004), and leptin (P = 0.006). During the intervention, mean body fat, TSH, HOMA, and fasting insulin decreased by 21, 11, 53, and 54%, respectively. Change (Delta) in TSH did not correlate with Delta body weight or Delta body composition, but Delta TSH significantly correlated with, Delta fasting insulin and Delta HOMA, independent of Delta body weight or Delta body composition (P <0.05). Conclusion: TSH concentrations are elevated in obese children but are not correlated with the amount of excess body weight or fat. During weight loss, independent of changes in body weight or composition, decreases in elevated serum TSH predict decreases in fasting insulin and HOMA. These findings suggest interventions that target high TSH concentrations during weight loss in obese subjects may improve insulin sensitivity. (J Clin Endocrinol Metab 95: 5412-5418, 2010)
Peripheral blood mononuclear cells as a model to study the response of energy homeostasis-related genes to acute changes in feeding conditions
Caimari, A. ; Oliver, P. ; Keijer, J. ; Palou, A. - \ 2010
OMICS - A Journal of Integrative Biology 14 (2010)2. - ISSN 1536-2310 - p. 129 - 141.
expression signatures - autoimmune-disease - metabolic syndrome - beta-oxidation - adipose-tissue - messenger-rna - insulin - obese - rats - leptin
Peripheral blood mononuclear cells (PBMCs) are readily accessible biological material and a potential tissue source to discover novel biomarkers of response to environmental exposures including nutrition. We analyzed whether PBMCs could reflect molecular changes that take place in response to different feeding conditions in key organs/tissues involved in energy homeostasis. We studied energy balance-related genes whose expression was altered in normoweight (control) rats and in diet-induced (cafeteria) obese rats in response to ad libitum feeding, 14-h fasting, and 6-h refeeding after fasting, using whole-genome microarray analysis. In PBMCs, the expression of the genes central to energy metabolism was altered by the feeding conditions. The number of affected genes was 75 in the control rats, but only 23 in the cafeteria obese rats. Most of these genes play a role in metabolic pathways regulated by nutritional changes, such as lipid metabolism (the metabolic pathway mainly reflected in blood cells), carbohydrate metabolism, central energy metabolism, respiratory chain/mitochondrial ATPase system, and food intake regulation. Importantly, our results showed a similar behavior to that of the mesenteric white adipose tissue. In conclusion, metabolic adaptations to acute changes in feeding conditions are reflected in the expression of genes central to energy homeostasis in PBMCs of normoweight rats, while response is impaired in cafeteria obese animals. The lower number of genes affected in obese animals indicates impaired nutritional regulation. PBMCs appear as a suitable potential model to characterize metabolic adaptations to food intake and body weight maintenance in experimental animals. These findings may also inform the development of future peripheral tissue models in the emerging field of clinical nutrigenomics.
Adipose tissue dysfunction signals progression of hepatic steatosis towards nonalcoholic steatohepatitis in C57BL/6 mice
Duval, C.N.C. ; Thissen, U. ; Keshtkar, S. ; Accart, B. ; Stienstra, R. ; Boekschoten, M.V. ; Roskams, T. ; Kersten, A.H. ; Müller, M.R. - \ 2010
Diabetes 59 (2010)12. - ISSN 0012-1797 - p. 3181 - 3191.
fatty liver-disease - insulin-resistance - copy number - obesity - leptin - inflammation - fibrosis - nash - adiponectin - markers
Objective: Nonalcoholic fatty liver disease (NAFLD) is linked to obesity and diabetes, suggesting an important role of adipose tissue in the pathogenesis of NAFLD. Here we aim to investigate the interaction between adipose tissue and liver in NAFLD, and identify potential early plasma markers that predict NASH. Research Design and Methods: C57Bl/6 mice were chronically fed a high fat diet to induce NAFLD and compared with mice fed low fat diet. Extensive histological and phenotypical analyses coupled with a time-course study of plasma proteins using multiplex assay was performed. Results: Mice exhibited pronounced heterogeneity in liver histological scoring, leading to classification into 4 subgroups: LF-low (LFL) responders displaying normal liver morphology, LF-high (LFH) responders showing benign hepatic steatosis, HF-low (HFL) responders displaying pre-NASH with macrovesicular lipid droplets, and HF-high (HFH) responders exhibiting overt NASH characterized by ballooning of hepatocytes, presence of Mallory bodies, and activated inflammatory cells. Compared to HFL responders, HFH mice gained weight more rapidly and exhibited adipose tissue dysfunction characterized by decreased final fat mass, enhanced macrophage infiltration and inflammation, and adipose tissue remodelling. Plasma haptoglobin, IL-1ß, TIMP-1, adiponectin and leptin were significantly changed in HFH mice. Multivariate analysis indicated that in addition to leptin, plasma CRP, haptoglobin, eotaxin and MIP-1a early in the intervention were positively associated with liver triglycerides. Intermediate prognostic markers of liver triglycerides included IL-18, IL-1ß, MIP-1¿ and MIP-2, whereas insulin, TIMP-1, GCP-2 and MPO emerged as late markers. Conclusions: Our data support the existence of a tight relationship between adipose tissue dysfunction and NASH pathogenesis and point to several novel potential predictive biomarkers for NASH
Improved appetite after multi-micronutrient supplementation for six months in HIV-infected South African children
Mda, S. ; Raaij, J.M.A. van; MacIntyre, U.E. ; Villiers, F.P.R. de; Kok, F.J. - \ 2010
Appetite 54 (2010)1. - ISSN 0195-6663 - p. 150 - 155.
immunodeficiency-virus-infection - iron status - zinc supplementation - beninese children - young-children - cape-town - growth - leptin - humans - anemia
The aim of the study was to assess the effect of multi-micronutrient supplementation on the appetite of HIV-infected children. HIV-infected children (6-24 months) who had previously been hospitalized were enrolled into a double-blind randomized trial, and given daily multi-micronutrient supplements or placebos for six months. Appetite tests were performed at enrollment and after three and six months. Appetite was measured as ad libitum intake of a commercial cereal test food served after an overnight fast according to standardized procedures. Body weights and total amount of test food eaten were measured. In total, 99 children completed the study (50 on supplements and 49 on placebos). Amounts eaten per kilogram body weight in the supplement group at enrollment and after six months were 36.7+/-17.7 g/kg (mean+/-SD) and 41.3+/-15.0 g/kg respectively, while the amounts in the placebo group were 47.1+/-14.9 g/kg and 45.7+/-13.1g/kg respectively. The change in amount eaten per kilogram body weight over six months was significantly higher in the supplement group (4.7+/-14.7 g/kg) than in the placebo group (-1.4+/-15.1g/kg). Multi-micronutrient supplementation for six months seems to significantly improve the appetite of HIV-infected children
Diet Determines Features of the Metabolic Syndrome in 6-to 14-Year-Old Children
Aeberli, I. ; Spinas, G.A. ; Lehmann, R. ; I'Allemand, D. ; Molinari, L. ; Zimmermann, M.B. - \ 2009
International Journal for Vitamin and Nutrition Research 79 (2009)1. - ISSN 0300-9831 - p. 14 - 23.
for-disease-control - blood-pressure - insulin-resistance - swiss children - weight-loss - obesity - leptin - humans - adiponectin - adolescents
Background/Objectives: Insulin resistance (IR) and hypertension are common in overweight children, and the adipocyte-derived hormones resistin, adiponectin, and leptin may modulate IR and blood pressure (BP). Few data exist in children on dietary determinants of IR, BP, or leptin, and no data exist on dietary determinants of resistin and adiponectin. Therefore, the objective of this study was to investigate dietary determinants of IR, BP, resistin, adiponectin, and leptin concentrations, as well as the interrelationship among these variables, in normal and overweight children. Subjects/Methods: In 6- to 14-year-old Swiss children (n=79), nutritional intake was assessed using two 24-hour-recalls and a one-day dietary record. Body mass index (BMI), body fat percentage (BF%), waist/hip ratio (W/H ratio), BP, glucose, insulin, resistin, adiponectin, and leptin were determined. IR was calculated using the quantitative insulin sensitivity check index (QUICKI). Results: BMI, BF%, and W/H ratio were significant predictors of leptin and insulin, QUICKI, and systolic BP, but not resistin or adiponectin. Of the overweight and obese children, 40% were diagnosed pre-hypertensive or hypertensive. Total energy, fat, saturated fat, and protein intakes were significant predictors of fasting insulin and QUICKI, and total fat, saturated fat, and monounsaturated fat intakes were significant predictors of systolic BP, independent of BMI standard deviation score (BMI-SDS) and age. There were no associations between these dietary factors and leptin, adiponectin, or resistin. Conclusion: In children, dietary macronutrient composition is a predictor of IR and systolic BP, but not resistin, adiponectin, or leptin concentrations. Resistin and adiponectin concentrations are not correlated with IR or BP in this age range
Effects of a high-fat, low- versus high-glycemic index diet: retardation of insulin resistance involves adipose tissue modulation
Schothorst, E.M. van; Bunschoten, J.E. ; Schrauwen, P. ; Mensink, R.P. ; Keijer, J. - \ 2009
FASEB Journal 23 (2009). - ISSN 0892-6638 - p. 1092 - 1101.
diabetic-rats - glucose-homeostasis - lipid-metabolism - starch promotes - obesity - carbohydrate - protein - leptin - mice - adiponectin
Beneficial effects of low glycemic index (GI) diets in rodents have been studied using healthy low-fat diets, while the effects might be different on high-fat diets inducing progression of insulin resistance. We fed C57BL/6J male mice high-fat low/high-GI (LGI/HGI) diets for 13 wk. Glucose and insulin tolerance and serum substrates, including adipokines, were measured longitudinally. The LGI group showed a significantly higher glucose tolerance from wk 2 onwards, which was supported by lower serum insulin and free fatty acids levels at 8 wk, and a tendency for lower leptin levels, while resistin levels remained similar. At 11 wk, when differences in serum resistin started to increase, differences in serum insulin were diminished. Although food intake was similar throughout the study, body weights and epididymal adipose tissue mass became significantly lower in the LGI group at necropsy. Several serum substrates and adipose tissue leptin mRNA levels, as analyzed by Q-PCR, were, again, significantly lower, whereas adiponectin mRNA levels were higher. Taken together, an LGI high-fat diet maintains higher glucose tolerance and insulin sensitivity via adipose tissue modulation solely because of a difference in the type of carbohydrate, supporting a nutritional approach in the fight against insulin resistance.¿Van Schothorst, E. M., Bunschoten, A., Schrauwen, P., Mensink, R. P., Keijer, J. Effects of a high-fat, low versus high glycemic index diet: retardation of insulin resistance involves adipose tissue modulation
Voordelen geitenmelk in beeld
Eekeren, N.J.M. van - \ 2008
BioKennis bericht Geiten 2 (2008). - 4
dierhouderij - dierlijke productie - geiten - geitenmelk - biologische voedingsmiddelen - cholesterol - leptine - melksamenstelling - voeding en gezondheid - animal husbandry - animal production - goats - goat milk - organic foods - leptin - milk composition - nutrition and health
Geitenmelk heeft een aantal voordelen boven koemelk. Een deel van deze voordelen is wetenschappelijk bewezen en kan gebruikt worden bij de promotie van geitenmelk. Voor een ander deel moet verder onderzoek uitwijzen of de vermoedens kloppen. Dit bioKennisbericht geeft een overzicht van bewezen en vermoede voordelen.
Central Application of IGF-1 Postpones Time of Vaginal Opening in Normally Fed, but Not in Food-Restricted Rats
Zeinoaldini, S. ; Swarts, J.J.M. ; Heijning, B.J.M. van de - \ 2006
Hormone Research 66 (2006)4. - ISSN 0301-0163 - p. 169 - 174.
growth-factor-i - gonadotropin-releasing-hormone - female rats - sexual-maturation - metabolic signal - leptin - puberty - neurons - infusion - initiation
Background/Aims: Central but also peripheral IGF-1 is suggested to play a role in the initiation of puberty as it directly affects GnRH synthesis and release. A possible intermediate in the effects of IGF-1 on puberty might be the adiposity-signaling hormone leptin, whose plasma levels are decreased in food-restricted (FR) rats. Methods: IGF-1 was chronically centrally infused in 23-day-old prepubertal female rats which were either normally fed or 30% FR, and the effects on time of vaginal opening (VO) and plasma leptin levels were monitored. Results: FR treatment postponed time of VO and decreased plasma leptin levels. In normally fed rats centrally infused with IGF-1, time of VO was found to be postponed to the same extent as FR treatment did. The IGF-1 infusion did not affect plasma leptin levels in normally fed animals but increased leptin levels in the FR group compared to controls. Daily food intake was equal between all groups but body weight course was lower in FR rats. IGF-1 treatment did not significantly affect food intake or body weight course. Conclusion: FR treatment delays the moment of vaginal opening to the same extent as observed in normally fed rats that were centrally infused with IGF-1.
Associations between Energy Metabolism, LH Pulsatility and First Ovulation in early Lactating Cows
Jorritsma, R. ; Langendijk, P. ; Kruip, T.A.M. ; Wensing, T.H. ; Noordhuizen, J.P.T.M. - \ 2005
Reproduction in Domestic Animals 40 (2005)1. - ISSN 0936-6768 - p. 68 - 72.
dairy-cows - ovarian activity - dry period - postpartum - cattle - balance - secretion - hormone - leptin - number
This study was designed to elucidate associations between energy metabolism and LH pulsatility characteristics in early lactation, and days to first ovulation, in order to explain the relationship between energy balance and fertility observed in epidemiological studies. To this end, 10 multiparous HF cows were monitored during lactation, after the application of two different feeding strategies during the dry period. Days to first ovulation was assessed using blood progesterone measurements and LH pulsatility was measured in 8-h windows in the third week postpartum. The association between depth of negative energy balance and days to ovulation was confirmed. However, this study does not support the idea that LH pulsatility characteristics in early lactation are predictive for the interval between parturition and first ovulation
Eating behaviour, and preprandial and postprandial correlations in male broiler and layer chickens
Bokkers, E.A.M. ; Koene, P. - \ 2003
British Poultry Science 44 (2003)4. - ISSN 0007-1668 - p. 538 - 544.
food-intake - body-weight - feeding-behavior - japanese quail - domestic-fowls - selection - patterns - mammals - growth - leptin
1. It has been suggested that broiler chickens have a disturbed satiety and hunger mechanism. The satiety mechanism for eating can be expressed as the positive correlation between meal length and the length of the preceding ( preprandial) interval; the hunger mechanism for eating as the positive correlation between meal length and the length of the succeeding ( postprandial) interval. An experiment was conducted to investigate eating behaviour of male broiler and layer chickens by measuring meal and interval lengths. 2. Eight male broilers and 8 male layer chickens were housed individually and visually isolated in floor pens ( 1m(2)/ pen) on wood shavings. From 4 to 7 weeks of age, eating behaviour of each bird was recorded for 3 h in two conditions each week. In the first condition, the birds were not deprived from feed. In the second condition, they were 24-h food deprived and feed was provided just before the observation started. Preprandial and postprandial correlations were calculated based on data of the non-deprived condition. Before and after each observation bird and feeder were weighed to measure weight gain and feed consumption during observation. 3. Under the non-deprived condition, the broilers spent initially more, but at a later age less time on eating. The broilers had fewer meals per hour, consumed more feed per hour, and had longer meal and interval lengths than the layer chickens. After 24-h feed deprivation, the broilers had a longer first meal, consumed more feed per hour and spent more time on eating than the layer chickens. Significant preprandial correlations but no postprandial correlations were found in the broilers. In the layer chickens, both significant preprandial and postprandial correlations were found. This indicates that for regulating eating behaviour, the satiety mechanism dominates the hunger mechanism in broilers, and satiety and hunger mechanisms are equally involved in layer chickens. 4. The typical eating behaviour of broilers and the calculated preprandial and postprandial correlations have given new indications that hunger and satiety mechanisms in broilers have changed compared with layer chickens. In broilers, there is no lower set point, but only an upper set point for controlling eating behaviour, which suggests that broilers eat to their maximal physical capacity.
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